FR2554866A1 - Measuring instrument intended to be used in a borehole and working during the drilling operation - Google Patents

Abstract

The invention relates to a measuring instrument intended to be used in a borehole and working during the drilling operation, in which the working signals are transmitted by pressure pulses in a drilling fluid circulation system. The instrument comprises a sensor 101 for measuring the value of a parameter in the borehole, a pressure-pulse generator 40 intended to produce pressure pulses in the drilling fluid circulation system, a power source, a storing means for storing the power delivered by the source and a means 103, 104 responding to the sensor in order to release power in a sequential manner between the storing means and the pressure-pulse generator in order to produce sequential pressure pulses which represent the value of the parameter.

Description

 The present invention generally relates to measurements made during the drilling of a groundhole in the ground and more particularly to systems, apparatuses and methods for which hydraulic shock waves are used in the drilling mud column for transmitting, on the ground surface, signals representing one or more parameters of the bottom of the hole. The invention also relates to systems and methods for detecting such signals in the presence of spurious noises.

 The present invention relates to systems for transmitting, at the ground surface, data from the bottom of a well's borehole during the drilling of the well.

 It has long been recognized in the oil industry that obtaining bottom hole data while drilling a well could provide information of interest to the drilling operator. Information such as the actual weight on the bit, the inclination and range of the borehole, the tool's fact, the pressure of the fluid and the temperature at the bottom of the hole and the radioactivity of the substances around or met the drill, all of which were expressed in quantities of interest to the drilling operator. A number of proposals have been issued in the past to measure these quantities during drilling, for subsequent transmission to the drilling operator. the soil surface. In the prior art, different transmission systems have been proposed for this purpose. In this regard reference may be made, for example, to U.S. Patent Nos. 2,787,795 granted to JJ Arps, 2,887,298 granted to HD Hampton, 4,078,620 to J. ii. Westlake et al., 4.001.773 granted to the names of AE Lamel et al., 3.964.556 granted to the names of Marvin Gearhart et al., 3.983.948 leaning on behalf of JDJeter and 3.791.043 granted on behalf of MK Russell . All patents listed above are mentioned here for reference.

 From a practical point of view, the most promising of these earlier proposals is probably that of emitting signals by pressure pulses in the drilling fluid.

Various methods have been suggested in the prior art for producing these sludge pulsations either by controlled slugging of the sludge circuit by means of a flow restrictor valve suitably installed in the sludge main stream, or by means of a sludge valve. bypass valve interposed between the inside of the drill string (high pressure side) and the annular space surrounding this drill string (low pressure side).

 In the prior art, it has been suggested to produce these mud pressure pulses by means of valves intended to reduce the flow of sludge within the drill string or to divert a certain portion of this flow to the zorite. low pressure in the annular space surrounding the drill string. These valves necessarily work slowly because, when they are used inside the drill string, they must control very large volumes of mud and, when they are used to control a bypass, because of the very high pressure differences, these valves are also operated slowly by a motor. For example, in response to a measurement below the soil surface, a motor valve of this type interposed between the inside of the drill string and the annular space has the effect of producing reductions and elevations of mud pressure. These reductions and pressure increases are then detected on the soil surface.

In order to better understand the operation of a slow acting motor valve of the type suggested by the prior art, reference is made to FIG. 1A which shows the opening and closing of a valve of this type as a function of time. Referring more specifically to this FIG. 1A, the time, t, is plotted on the abscissa, while the degree of opening of the flap, R, is plotted on the ordinate.

where S0 indicates the total area of the opening and
S (t) indicates the area that is open at time t during the opening or closing process of the flap. Therefore, when R = 0, the valve is closed and when R = 1, the valve is fully open. The moments intervening in the moment function of the valve are the following
@ (v) = 0A1 is the moment at which the check valve com
start to open;
tb (v) = OB1 is the moment at which the flap is
completely open; (V)
tc (@) = OC1 is the moment at which the flap
begins to close;
td (v) = OD1 is the moment at which the flap is
completely firm.

Time lapse

T(v) sella appelé "temps de débit ouvert". Dès lors,
b la période totale dc fonctionnement du clapet est

T vvJ will be called "opening time or iron
on the flap "Time lapse

T (v) sella called "open flow time". Since then,
b the total operating period of the flap is

 In the tests described above, we had Ta (v) = 1 second, Tb (v) = 2 seconds and, therefore, the total operating time of the valve was T (v) = 4 seconds. These relatively slow openings and closures of the valve gave rise to corresponding slowness reductions and elevations in mud pressure at the soil surface (see Fig. 1B).

It can be seen that the sludge pressure decreased from its normal value which was, for example, 70 kg / cm 2 (when the valve was closed) to its minimum value of 52.5 kg / cm 2 (when the valve was open ). The moments occurring in the pressure variations thus observed were as follows
t (5a) = 0E1 is the moment at which the pressure of
the mud begins to decrease from
its normal value of 70 kg / cm2;
t (b) = OF1 is the moment at which the pressure of
the mud reaches its minimum value at
52.5 kg / cm2, which value it is
maintained until the moment tcc = 0G1;
t1c (s) = 0G1 is the moment at which the pressure of
the mud begins to rise;
t1d (s) = OH1 is the moment at which the pressure of
the mud reaches its normal value of
70 kg / cm2.

puis elle restait constante au cours du laps de temps

et ensuite, elle s'élevait de sa valeur réduite à sa valeur normale au cours du laps de temps

As a result, the pressure decreased during the lapse of time

then she stayed constant over the lapse of time

and then it rose from its value reduced to its normal value over the lapse of time

Therefore, the total time in which the bubble was flowing through the bypass valve as a result of a single operation of the main valve. was ::

In FIG. 1A, we have designated

<tb> titis <SEP> by <SEP> example, <SEP> t (v) <SEP> - <SEP> shot, <SEP> (v) <SEP> (v) <SEP> t (vj <SEP > (v)
<tb> a <SEP> and <SEP>"b<SEP> with <SEP> the exponent <SEP>" v "<SEP> for <SEP> specify
<tb><SEP> b <SEP> t
<tb> these quantities concern the operation of the valve located below the surface of the ground.

<Tb>

<SEP> t5
<tb> Other <SEP> part, <SEP> eli <SEP> figure <SEP> 1D, <SEP> the <SEP> quantities <SEP> t (S),
<tb> (s) <SEP> {, sj <SEP> T (S)} <SEP> (s) <SEP>, <SEP> (s) <SEP> and <SEP> (s)
<tb> tlb <SEP> 2 <SEP> Ic <SEP>) <SEP> tld <SEP> ld <SEP> 1 <SEP> T3 <SEP>T25>,<SEP>T5><SEP> and <SEP> T <SEP> t <SEP> are
<tb><SEP> 3
<tb> designated by the exponent "s" to indicate that these quantities relate to measurements made on the soil surface. This distinction between the quantities carrying the exponent "v" and those carrying the exponent "s" is essential in order to fully understand some of the new features of the present invention. In this respect, it is essential to distinguish between the cause and effect or, in other words, between the phenomena occurring at the bottom of the hole near the valve and those occurring at the surface-mounted detector.

An essential feature of the system previously proposed is based on the following relationships

 These relationships demonstrate that the period of reduction or increase in pressure at the soil surface was the same as the corresponding period of valve opening and closing, while the period during which the pressure was nearly constant ( at a reduced value) was the same as the period during which the valve was fully open.

In other words, the reduction and subsequent rise in mud pressure at the soil surface corresponded exactly with the opening and closing of the valve. In the present specification, it will be stipulated that this condition, expressed by the relations (6), (7) and (8), is related to a "regime of slow variations of pressure".

 As is suggested in the prior art, the regime of slow pressure variations is not suitable for tele-measurement during drilling operations, in particular when several parameters must be measured at the bottom of a hole. . At the moment a first parameter has been measured, coded, transmitted to the surface, and then decoded, the borehole of the well may have deepened and the second parameter may no longer be available for measurement. Relatively long periods of time are required to convert the measured data into a form suitable for detection and recording. The entire recording process is tedious and time-consuming. In addition, additional difficulties arise from various spurious effects such as the pulsations due to the sludge pump and the noises associated with the various drilling operations. It is believed that a slowly operating motor valve such as that suggested in the prior art is not able to meet the usual conditions imposed in the industry.

 Some objects of the present invention are realized using hydraulic shock waves for telemetry of logging information while drilling. These shock waves are produced by a vatiozi valve acting very quickly (almost instantaneously for all practical applications), this valve was inserted between the inside of the string of rods and the annular space surrounding it.

When this bypass valve opens suddenly, the pressure in the immediate vicinity of the valve falls and returns almost instantly to its normal value by emitting a sharp negative impulse while, on the other hand, when the bypass valve closes suddenly, a Positive positive impulse is emitted. The elasticity of the mud column is used to facilitate the formation and transmission of these shock waves. This phenomenon is analogous to the well-known water hammer effect that has been encountered previously in hydraulic transmission systems. (See, for example, Jolin Parmakian, "Water Hammer Analysis,"
Prentice Hall, Inc., New York, NY, USA 1955 or
VL Streeter and EBWylie, 1, Hydraulic Transients "McGraw-Hill Boook Co.," New York, NY, USA).

Important features of the present invention, for example, the formation and detection of hydraulic coke waves, are shown schematically in FIGS. 2A and 2B. The graph in FIG. 2A shows the openings and closures of a quick acting valve producing shock waves, while the glaphi (seen in FIG. 2B) represents the pressure variations detected at the surface of the ground and resulting from the valve operation as shown

<tb> in <SEP> figure <SEP> 2A. <SEP><SEP> symbols <SEP> such <SEP> as <SEP> A1, <SEP> B1, <SEP> C1, <SEP> D1,
<tb>) <SEP> (v) <SEP> tOY) <SEP> (v)
<tb> t (v)><SEP> tgV)) <SEP> tCV) <SEP> tdV) <SEP> T (V), <SEP> T (V) <SEP> and <SEP> and <SEP> you <SEP> from <SEP> the
<tb> Figure 2A have a similar meaning to that of the corresponding symbols of Figure 1A. However, the time scales of FIGS. 1A, 1B, 2A and 2B have been considerably distorted in order to facilitate the description and to make the presentation clearer.

In examining FIG. 2A, it should firstly be noted that the opening and closing times of the shutter according to the present invention are several orders of magnitude shorter than the corresponding times obtained by means of the motor valve described. with reference to Figure 1A. In the previously suggested system (Figure 1A), we had T (v) = 1 second, whereas, according to the pre
(v) invention (Figure 2A), we have T a = 5 milliseconds. it is the same with regard to the time period during which a valve remains open.

In the previously suggested system (Figure 1A), we had TbV) = 2 seconds while in Figure 2A we have T (V) b milliseconds. Therefore, for all
b = 100 practical applications, it can be considered that the openings and closures of the valve shown in Figure 2A are instantaneous or almost instantaneous.

 Rapid or near-instantaneous valve openings and closures have a large and long-lasting influence on the performance of a telemetry system used to perform measurements during a drilling operation.

The pressure variations detected at the ground surface according to the present invention (FIG. 2B) have absolutely no similarity to the pressure variations obtained by means of a slow-action valve (FIG. 1B). Previously, it has been pointed out that equations (6), (7) and (8) show the relationships between the cases illustrated in FIG. 1A and those illustrated in FIG. 1B.

Similar relationships do not exist between the cases illustrated in FIGS. 2A and 2B.

 Coaunc shown in Figures 1A and 1B, the opening of the valve caused a corresponding reduction in the pressure of the sludge at the surface of the soil and, in contrast, the closure of this valve doriziait occurred at a corresponding rise in pressure.

 In order to highlight the situation, it will be repeated that, according to the prior art, the opening of the valve produced a single phenomenon, in particular a reduction in pressure, while the subsequent closure of the valve gave rise to another unique phenomenon. That is to say, a rise in pressure. On the other hand, according to the present invention, the rapid opening of the valve (as shown in FIG. 2A) gives rise to two phenomena, namely: rapid reduction and subsequent elevation of the pressure. pressure (negative pulse 'Mn as shown in Figure 2B) and this, unlike the case shown in Figures 1A and 1B dris which a subsequent opening and closing of the valve are necessary to produce a reduction and a subsequent elevation of the pression.De moreover, the rapid closing of the valve (as shown in FIG. 2A) gives rise to a subsequent rise and reduction of the pressure of the pressure e (positive pulse "N" as shown in FIG. 2B3. This rise and subsequent pressure reduction do not occur in the systems suggested by the prior art. According to the present invention, two shock waves are produced by a single operation of the valve. A waveform such as that shown in FIG. 2D, which comprises both a negative pulse and a positive pulse, will hereinafter be referred to as a "valve wave." The pressure pulses associated with a valve wave have a velocity value. starting from several hundred kg per cm2 per second and they are short-lived.

It is interesting to underline the rapidity of the phenomena associated with the observed valve waves. The moments occurring in Figure 2B are as follows
t1 (s) = OK is the moment of appearance of impulse
Negative "M"
t @ (s) = OL is the moment at which the impulse negates
tive "M"weakens;
t3 (s) = OM is the moment of appearance of impulse
positive "N"; @ (S)
t4 = ON is the moment at which the pulse posi
tive "N" weakens.

la période totale d'écoulement est de 210 millisecondes tandis que, en figure 1B (voir équation 5), la période totale d'écoulement était de @(s) = 4 secondes.The time interval @ (s) representing the length of the negative pulse "M" (or the positive pulse "N") is 100 milliseconds, while the time lapse Tm (s) flowing between the occurrence of the negative pulse "M" and the appearance of the positive pulse "N" is 110 milliseconds. Therefore, in Figure 2B, that is to say in which we have

the total flow period is 210 milliseconds while in Figure 1B (see Equation 5), the total flow period was @ (s) = 4 seconds.

 The graphics of FIGS. 1A, 1B, 2A and 2B have been simplified and idealized by eliminating wave series and other extraneous effects. it should also be noted (see Figure 2B) that the bypass valve is at least partially open during the lapse of time between the moments 1 (s) and t4 (s). During this time, a slow pressure drop occurs which is removed at the point of detection by means of a suitable filter. This pressure decrease is not represented in the gzaplic of FIG. 2B.

 it should also be emphasized that the numerical values shown in FIGS. 2A and 2B are given merely by way of example.

It is understood that these values in no way limit the invention to a particular example.

 It will be stipulated that the method explained with reference to Figs. 2A and 2B is in connection with a "hydraulic shockwave regime".

Accordingly, a distinction is made between the hydraulic shock wave regime shown in FIGS. 2A and 2U, and the slow-change pressure regime shown in FIGS. 1A and 113.

 By providing a regime of hydraulic shock waves, a telemetry system has been obtained by means of which a large number of little information is to be transmitted per unit of time. This system is much better known for meeting the usual conditions imposed in industry than that based on the regime of slow pressure variations.

 The valve according to the present invention is actuated by the output of one or more sensors detecting one or more parameters of the bottom of a hole made in the ground, near the bit. A single measurement of each parameter is represented by a succession of valve waves.

Each valve wave corresponds to a single opening and wie only closure of the valve.

 One aspect of the present invention relates to improvements in which the bistable operation of the assembly 40 of the special telemetry instrument 50 is involved. Another aspect of the present invention relates to the installation of a special mechanical system operating hydraulically and periodically ensuring the positive displacement of the valve 40 to its closed position. In addition, it provides an electrical system that prevents the operation of the valve 40 in the case of electrified blades occurring in the installed apparatus you faithid the borehole.

 Other aspects of the present invention relate to improvements in which the feed source 95 95 and the drive source 104 of the special telemetry instrument 50 are used. These improvements serve to considerably increase the number of satisfactory valve operations. that can be achieved without having to recharge or replace the battery installed at the bottom of the borehole.

The new features of the present invention will be described more particularly hereinafter. The making and implementation of the invention, as well as other objects and advantages thereof, will be better understood on reading the following description of certain examples given by way of illustration with reference to the following attached drawings in which
Figs. 1A, 1B, 2A and 2B are graphs related in part to the description of the prior art and the scope of the present invention; these figures, as well as the others, also relate to the summary of the invention, as well as to the description of the preferred embodiments;
Fig. 1A schematically illustrates the operation of a slow acting valve of the type suggested in the prior art; FIG. 1B diagrammatically represents the pressure variations detected at the ground surface and resulting from the operation of the valve shown in FIG. 1A; FIGS. 1A and 1B describe a state hereinafter referred to as the "regime of slow pressure variations";
Figure 2A schematically shows the operation of a quick acting valve according to the present invention;
Figure 2D schematically shows the pressure variat-iolls detected at the ground surface and resulting from the operation of the valve shown in Figure 2A; Figures 2A and 2B describe a state hereinafter referred to as "hydraulic shock wave regime";
FIG. 3 schematically and generally shows a well drilling system equipped for simultaneous drilling and measurements in accordance with certain aspects of the present invention;
FIG. 4A schematically represents a part of the equipment in the basement comprising a special telemetry instrument according to the present invention
Figure 4B schematically shows part of the equipment illustrated in Figure 4A;
Figure 5A schematically and in more detail shows the electronic trait temerit assembly included in the dashed rectangle of Figure 4A;
Figure 5D schematically illustrates a power source having a capacitor charging and discharging system for providing the power and energy required to operate the valve of the special telemetry instrument;
FIG. 5C schematically illustrates the electronic ciruit which could be used to ensure the automatic shutdown of the drive source of the valve (the special telemetry instrument, while FIGS. 5D and 5E show graphs intended to facilitate the explanation. automatic shutdown of the drive source of the check valve;
FIGS. 6A, 6B and 6C show schematically the operation of the hydraulic system of "automatic closing" of the signal valve;
Figure 6D is a technical drawing of the system shown in Figures 6A, 6B and 6C;
FIG. 6E schematically represents an "integrated safety" electronic system applicable to the check valve;
Figure 7A schematically shows the structure of the housing and the "protector" for the special telemetry instrument;
Figure 7B schematically shows the shape of the cross-section of the centering elements that can be used with the structure illustrated in Figure 7A;
Fig. 7C schematically illustrates special connecting elements that can be used to connect the subsections of the housing portion 250b of Fig. 7A;
FIGS. 8A to 8E are graphs representing the pressure variations measured at the ground surface and corresponding to different values of Ta (v) (opening or closing time of a flap) and Tb (v) (time open debit); the graphs in these figures show the results of some tests that were carried out by the
Applicant to obtain optimal conditions for a hydraulic shock wave regime; more specifically, FIGS. 8A to 8E can be de? ned as follows:
Figure 8A corresponds to Ta (v) = 1 second and Tb (v) = 2 seconds;
Figure 8B corresponds to Ta (v) = 200 milliseconds and Tb (v) - 1 second;
Figure 8C corresponds to Ta (v) = 60 milliseconds and Tb (v) = 0.5 seconds;
Figure 8D corresponds to T a (v) - 20 milliseconds and Tb (v) = 0.25 seconds;
Figure 8E corresponds to Ta (v) = 5 milliseconds and Tb (v) = 10-1 seconds;
FIG. 8F is an exact reproduction of the pressure signal indicating a valve wave received at the surface from a depth of 2.980 or during the actual drilling of an oil well in the East Texas region of the United States of America. America 3
It should be noted that in some of the figures above, like reference numerals have been applied to similar elements. In this case, the description and functions of these elements will not be repeated insofar as this is not necessary to explain the operation of these embodiments.

I. GENERAL DESCRIPTION OF THE TRANSMISSION DEVICE
DATA SESSION DURING DRILLING.

 Figure 3 is a general view of a specific system in which the principles of the present invention are adopted. Reference numeral 20 designates a conventional tower for drilling oil wells, this tower having a rotary table 21, a driving rod 22, a pipe 23, a rising column 24, a drill pipe 25 and a collar 26. One or more sludge pumps 27 and a sludge pit 28 are connected in the usual manner to supply the riser column with pressurized drilling mud.

The high-pressure sludge is pumped down into the drill string via the drill pipe 25 and the conventional drill collars 26, and then through the special telemetry instrument 50 to bit 31. This drill bit 31 comprises the usual devices projecting drilling jets and schematically represented by the reference numeral 33. Tcls that they are represented, the diameters of the collars 26 and the telemetering instrument 50 are exaggerated compared to that of the pipe in order to more clearly illustrate the mechanisms. The drilling mud descends through the drill string as shown by the illustrated arrows, and then back up through the annular space formed between the drill pipe and the wall of the hole. of Wells. When it reaches the surface, the sludge is again discharged into the pit (by means of pipes not shown) where rock fragments and other debris from the well can decant, then be filtered before sludge and return to circulation by means of the pump (s).

 Between the bit 33 and the drill collar 26 is provided the special telemetry trainer assembly or the telemetry instrument designated by the reference numeral 50. This special assembly of the telemetry transmitter 50 includes a housing 250 enclosing a telemetry instrument. valve assembly or more simply a valve 40, an electronic processing assembly 96 and sensors 101.

The valve 40 is designed to momentarily divert some of the sludge from the inside of the drill collar into the annular space 60. Normally (when the valve 40 is closed), all of the drilling mud must be removed by the jets 33 and, consequently, the sludge is under a very high pressure (of the order of 140 to 210 kg / cm 2) in riser 24. When the valve 40 is open under the control of a sensor 101 and of the electronic processing assembly 96, some of the sludge is bypassed, the total flow resistance is momentarily reduced and a pressure change can be detected in the riser 24.

The electronic processing assembly 96 emits a series of coded electrical pulses representing the parameter to be measured by a selected sensor 101, while corresponding openings and closures of the valve 40 are exposed under the effect of the corresponding pulses. resulting pressure in the riser 24.

 The cli ff. reference numeral 51 denotes a prossion transducer producing an electrical voltage representing the pressure changes occurring in the riser 24. This signal representing these pressure changes is processed by an electronic assembly 53 emitting appropriate signals to be recorded in a recorder 54 or any other display apparatus. the graph of the recorder 54 is driven by a command representing the depth of the bit by well known means (not shown).

He. GENERAL DESCRIPTION OF THE SPECIAL TRANSMITTER
TELEMETRY.

 Figure 4A shows some details of the special telemetry transmitter 50.

Some of these details, as well as others, have also been described in the aforementioned U.S. Patent Application No. 857,677 filed by S.A. Scherbatskoy to which this application follows. Figure 4A is a schematic view. In a real instrument, the housing 250 which encloses the valve 40, the electronic processing assembly 96 and the sensors 101, is subdivided into two sections 250a and 250b. The upper section 250a (above the dashed line 249) contains the valve assembly 40 and the mechanical elements associated therewith and, as will be pointed out below, this section has a diameter substantially greater than that of section 250b. The lower section 250b (in sub-dashed lines 249) contains the electronic processing assembly 96, the sensors 101 and the mechanical elements associated therewith and, as will be discussed hereinafter, has a diameter substantially lower than that of the upper section 250a. As shown in FIG. 4A, the drilling mud descends into the special telemetry instrument 250a, 250b (as indicated by the arrows 05), then it passes through the nozzle 33 of the bit and it returns (as indicated by 'arrows 66) to the surface passing through the annular space 60, to finally open into the pit 28 via pipes (not shown). The valve assembly 40 includes a rod 68 and a seat 69. This valve stem and seat are constructed such that the cross section of the closure A is slightly larger than the cross section B of the compensating piston 70. Consequently, when the pressure prevailing in the chamber 77 is greater than that prevailing in the chamber 78, the valve stem 68 is driven downwards, the valve 40 tending to close more and more tightly as one apply a different pressure stronger.

 The fluid pressure (sludge) prevailing in the chamber 77 is at all times substantially equal to the fluid pressure (sludge) prevailing in the drill collar designated by the reference numeral 26 in FIG. FIG. 4A, and cc, due to the opening 77a in the wall of the assembly 250. A fluid filter 77b is interposed in the passage 77a to prevent debris. and solid particles to enter the chamber 77.

When the valve 40 is closed, the fluid pressure (sludge) prevailing in the chamber 78 is equal to the fluid pressure (bouc) prevailing in the annular space 60. When the valve 40 is open and the pumps operate, the sludge flows from the chamber 77 to the chamber 78 and, via the orifice 81, it reaches the annular space 60 undergoing corresponding pressure drops.

 A double acting solenoid solenoid 79 is provided to open or close the valve 40 in response to the electric current distributed by the drivers 90.

It will be assumed that Po indicates the goat pressure prevailing in the annular space 60,
P77, the pressure prevailing in the chamber 77 and P78, the pressure in the chamber 78. Therefore, when the valve 40 is closed, P78 = P60.

 When the pumps 27 operate and the valve 40 is "closed" or almost closed and P77> P78, the valve stem 68 is pushed towards the seat 69.

When the valve 40 is in the "open" position (i.e. when moved upward in the drawing), the slurry then flows from the chamber 77 to the annular space 60 and, because of the resistance offered to the flow through the orifice
C (Figure 4B), we have the following relation: P77 =
P78> P60 Chambers 83 and 94 are filled with an oil of very low viscosity (for example, oil "DOW CORNING 200 FLUID", preferably at a viscosity of 5 centistokes or less) and are connected at the other by the passage 86.

Thanks to a floating piston 82, the pressure P83 prevailing in the chamber filled with oil 83 is, at any time, equal to the pressure P78. Therefore, at any time, we have P78 = P83 = P84. Accordingly, when the valve 40 is "open", since P78 = P84 and P77> P84, the valve 40 is pushed to the "open" position under a force F = (zone B) (P77 - P84) . Accordingly, it can be said that the valve 40 is "bistable", that is to say, when it is "open", it tends to remain "open" while, when "closed" , @@ tends to stay "closed". Moreover, when it is almost open, it tends to move to the open position and, when it is almost closed, it tends to move to the fcrmc position. As a result, valve 40 can switch from one state to another with relatively low energy. It can be considered that the operation of the valve is the mechanical equivalent of the electric bistable multivibrator well known in the art of electronics.

 Figure 4B shows the valve 40 in the open position while in Figure 4A, it is in the closed position.

Referring again to FIG. 4A, reference numeral 91 indicates an electrical "pressure switch" which is electrically conductive when P77> P78 (the pumps are operating), while it is non-electrically conductive when
P77 - P78 (pumps are stopped). As a result, the wire 92 from the pressure switch 91 to the power source 93 can turn the power OFF. Similarly, by means of an electronic counter 94 and an electromagnetic sequential switch 95, the either of the four sensors 101 can be effectively connected to the electronic processing assembly 96 by stopping and sequentially operating the plug pumps 27 or stopping these pumps and then operating them according to a code predetermined that can be interpreted by the circuit mounted in the element 94.

Ill. DISCRIPTION OF THE ASSEMB @ AG @ DE TRAI @ LEMENT
@ IEC @ RONIC OF SPEC @ AL SPEC @ AL
TELLMESURE.

 The operation of the flip-flop 40 and the sequential switch 95 ensuring the selective electrical coriliexiori of the different sensors 101 with the electronic processing assembly 96 has been deformed.

 For further details relating to the electronic processing assembly 96, reference is made to FIG. 5A in which the same reference codes denote the same elements as in FIG. 4A.

 Different types of sensors emitting electrical signals representing an existing parameter at the bottom of a borehole are well known. For example, gamma-ray sensors, temperature sensors, pressure sensors, gas sensors, magnetic compasses, control indicator inclinometers, magnetometers, gyro compasses and many other sensors .

 For the example given by way of illustration in FIG. 5A, a gamma ray sensor such as an ionization chamber or a Geiger counter or a scintillation counter (provided with a suitable electronic circuit) has been chosen. All of these elements can be designed to produce a DC voltage proportional to the ganuna ray flux that is intercepted by the sensor.

 It will be understood that the transition from one type of sensor to another under the control of the switching mechanism 95 illustrated in FIG. 4A is well known according to the state of the art (in most cases an electronic commutation is preferred mechanical switch shown).

Therefore, in FIG. 5A, to make the description clear plastic, only one sensor 101 is represented. Similarly, the power source 93 and the sludge-activated switch 91 (which have been shown in FIG. Figure 4A) are not very illustrative in Figure SA.

 In FIG. 5A, the sensor 101 is cascaded to the analog / digital converter 102, the processor 103 and the drive source 104. The driving source 104 is connected to the windings 105 and 106 of the double acting solenoid indicated in FIG. 79 in Figure 4A. This driving source 104 may be similar to that shown in FIG. 3E of the related patent application. The operation is as follows: the sensor 101 emits an analog output electrical signal represented by the curve 101a of the graph taken immediately above the box 101 indicating the sensor. This curve represents the output of the sensor as a function of the depth at which the telemetry transmitter 50 is located in the borehole. The analog-to-digital converter transforms the analog signal of the sensor 101 into a digital form by successively measuring the amplitude of a large number of ordinates of the curve 101a and translating each individual ordinate into a binary number represented by a binary griot. This process is well known in the art and need not be explained here. All you know is that, if the graph 101a can represent, in hours, the variations of the signal emitted by the transducer, the graph 102a represents a single ordinate (for example, AB of the curve 101b). Therefore, the time scale of the x-axis of Fig. 102a would be expressed in seconds, while the whole graph 102a represents a 12-bit binary word; in fact, it represents the decimal number 2049. Therefore, each 12-bit word of the graph 102a represents a single ordinate such as the ordinate AB of the graph 101a.

The usual binary coding involves rest times between each binary word. After this idle time, a start pulse or preliminary pulse is transmitted to indicate the start of the time allotted to the binary word. This preliminary pulse is not part of the binary word, but it is used to indicate which binary word is about to begin. This binary word is then transmitted and it indicates the value of an ordinate of the graph 10a1; then comes a rest period followed by the next binary word representing the amplitude of the next ordinate and so on, in rapid succession. As a result, the continuous curve of the graph 101a is represented by a series of numbers or words binaries each representing a single point of the graph lova. In this respect, it is important to know that between each binary word there is always a rest period. This idle time (during which no signal is transmitted) frequently has a length corresponding to several binary words and is used for a significant purpose which will be explained below. In order to enable surface decoding, the clock n 1 must be rigorously constant (and in synchronism with the corresponding clock 212 or 309 located on the surface) and it emits a series of equidistant pulses in time so that well known in the art of electronics.

 The graph 103a represents a single bit of the binary word 102a and, in this case also, the x-axis is very different from that of the previous graphs. The time in graph 103a is in milliseconds, since this graph represents only one bit.

Each individual bit @ is converted into two electrical pulses each of a duration tx and separated by a time lapse ty. Chart 104a is a replica of Chart 103a which has been greatly amplified by the drive source 104. The electrical pulse 104b is applied to the solenoid winding 105 (which is the winding of the valve in the "open" position. ), while the electric pulse 104 @ is applied to the winding 106 of the solenoid (which is the winding of the valve in the "closed" position). As soon as possible, the valve 40 of FIG. 4A is opened by the pulse 104b and is closed by the pulse 104c, so that it remains in the "open" position approximately during the time ty. The times tx are set so that the windings of the solenoid are controlled properly, while the time ty is calculated to open the valve 40 for the correct amount of time. These two times are determined and controlled by the clock n 2.

 Laws of the telemetry of information between a sensor and the ground surface, appropriate rest times are provided between the transmission of the successive binary racks. Thanks to these idle times, the noise generated solely by the drilling rig (without the valve wave) can be memorized in a suitable electronic memory forming part of the surface equipment. The systems and processes necessary for this purpose will be described below.

Iv. DESCRIPTION OF THE POWER SOURCE FOR THE
SPECIAL TELEMETRY TRANSMITTER.

 As noted above, the valve 40 illustrated in Figure 4A must be very fast action and, for this purpose, it requires considerable power. (Following appropriate tests, it has been determined that a valve of this type requires about 1/2 to 3/4 horsepower to operate at the required speed).

 Although this power is very important, it is only applied during a very short period of time and, consequently, only a small amount of energy per operation is required.

 In actual operation during tests, it has been found that 1/2 horsepower applied for about 40 milliseconds provides the energy required to ensure proper operation of the valve. This energy can be calculated at about 15 Joules. A group of sufficiently small accumulators to be housed in the housing 250b of FIG. 7A can provide about 4 million Joules, requiring recharging or replacement. As a result, the system is able to ensure 130.000 complete operations of the flapper (open-closing). In reality, the energy consumption is less than 15 Joules per operation. Thanks to the inductance, Q, and the kinetic impedance of the solenoid winding, current accumulation is relatively slow and takes place along the of a curved slope as shown by curve 272A of FIG. 5C and curves 300, 301 of FIG. 6E. Therefore, the total energy per pulse is substantially less than 15 Joules and it was measured at 9 Joules, thus ensuring a capacity of 216,000 complete operations of the valve (an even greater capacity is obtained using the circuit described below). with reference to FIG. 5C). From the above description it can be seen that batteries can perfectly provide the energy required at the bottom of a borehole for a practical telemetry instrument.

 However, obtaining ('t' the very high power required (1/2 horsepower) poses difficult problems.

 It is clear that the solution to this problem would involve the accumulation of energy in a mechanism that could be brought to release it suddenly (in a short time), thus providing the necessary short pulses of high power. A mechanism of this type is that operating by "water hammer" which has been used in the instrument described in the related patent application, but which has sometimes been found to be insufficient.

In other previously contemplated mechanisms, compressed air, compressed springs and the like have been used. Capacitor energy storage systems require high capacities: accumulated energy in a capacitor varies with the first capacity power, as well as the square of the accumulated voltage, and since drive windings < Solenoids of low inductance and fast acting are necessary, it is obvious that one must use low voltage devices, the initial calculations having indicated that capacitors much too important would be necessary.

After further evaluation, it appeared that an operational system could be realized. By mathematical analysis, as well as by experiments and tests, it has been determined that one could establish the following series of optimal circuit parameters
1. Inductance of solenoid winding: 0.1 henry in operating position and 0.07 henry in non-operating position (ie a conical armature solenoid).

 2. Resistance of solenoid winding: A, 5 ohms.

 3. Voltage at which energy is accumulated: 50 volts.

 4. Capacity of the accumulation capacitor: 10,000 microfarads.

 5. Run capacitance of the driver circuit: 10 amperes.

 It was noted that in order to ensure fast operation of the solenoid, low inductance windings were desirable. It was also determined that the current capabilities of the electronic attack Cil'CUitS could be increased well beyond 10 amps. However, low voltage requires much higher capacities.

 Recent advances in so-called molten salt accumulators have provided energy sources of very good compactness. The same recent technology has also developed capacitors with extraordinarily high values (10 farads in a space as small as 16.38 cm3).

These capacitors have proved unacceptable because of the necessity of heating at a high temperature (500 ° C.); it was felt that this was not feasible without the prohibitive cost. As a result, efforts must always be made. After extensive and extensive research, it was finally discovered that a tantalum capacitor made in accordance with the latest developments could meet the specifications imposed if the other parameters and factors listed above were to be optimized to match them. with the characteristics of these capacitors.

 From the above discussion, it can be seen that a battery charge can ensure at least 210,000 complete operations of the valve.

Assuming that the telemetry system can provide continuous and adequate data by transmitting @ing pulses per minute, the system is able to operate continuously in a borehole for a period of 440 hours. It should be emphasized, however, that very often, continuous operation is not essential. The instrument can be used intermittently only under the control of the circuit controlled by the switch 91, as well as the elements 94 and 95 of FIG. 4A.

 In addition, as will be explained below, when taking advantage of the improved circuit illastré in Figure 5C, it can achieve a greater number of valve operations. Ori considers that one-shot operation is practical.

 Another parameter that needs to be determined is proper charging of the capacitor after discharge. This capacitor can be charged by a resistor connected to the accumulator (or to another energy source), but this procedure sometimes proves slow because, when the capacitor is partially charged, the current passing through the resistor decreases and, as per the charging cycle, the charging current approaches zero. the ohmic value of the resistor is low, the accumulators have to carry an excessive momentary current, given that the initial power of the current occurring during the charging cycle would exceed the expected value for the maximum lifetime of the accumulators. The best method is to charge the capacitor by a constant current device.

The capacitor then charges at an optimum current corresponding to the optimum discharge current for the particular type of accumulator for maximum energy accumulation. By correctly determining the charging current, a significant increase (sometimes by a factor of 2 or 3) in the amount of energy available in a given type of battery can be achieved. Constant current devices are well known and are readily available integrated electronic circuits for a wide range of current values.

 FIG. 5 schematically represents a power source that can be incorporated in the power source 104 of FIG. 4A, this source comprising a capacitor charging and decapping system for providing the power and energy required for the windings of the power source. solenoid 79. In FIG. 5B, the reference numeral 450 of the invention is a battery, a turbo generator or other source of direct current electrical potential, the reference numeral 451 denotes the constant current device and the reference numeral 452 > the capacitor. This capacitor is charged by the constant current device 451, while it is discharged via the conductor 453. The controller 454 provides the regular constant power required for the balance of the elcotronic system installed at the bottom of the borehole.

V. DESCRIPTION OF THE "CLOSED" SIGNALING VALVE
AUTOMATIC TURE "HYDRAULIC.

 There is also a system operative in case of malfunction that could occur when the valve is glued in the open position for a long time. A system for automatically closing the valve in the event of malfunctioning of this type (indicated by reference numeral 269 in FIG. 4A) is schematically illustrated in FIGS. 6A, 6B and 6C.

 As further pointed out in this specification, the valve is designed for bistable operation or hydraulic release; in other words, when it is opened by a pulse emitted by the winding 105 of the solenoid, it tends to remain in the open position and, subsequently, when it is closed by a pulse emitted by the winding 106 of the solenoid, it tends to remain in the closed position. Due to faulty electrical or mechanical operation, the valve may remain "stuck" in the open position. It should be noted that if this malfunction occurs, the drilling operation may continue to proceed. Some wear may occur at the orifice 81 illustrated in Figure 4A. However, it is not desirable that the hydraulic circulation system of the sludge is disturbed by the opening of the valve for long periods; furthermore, although the drilling operation may continue, it is advantageous if the valve remains most closed and open only to produce the short pulses required to obtain the hydraulic shock wave .

 In the schematic drawings of the fitters 6A, 6B, 6C, the rod 100 is used to push the valve into the closed position by exerting a downward force on the rod 80 shown in FIG. 4B (solenoid armature rod) .

 Referring now to FIGS. 6A, 6B, 6C and 6D, the upper end of the mechanism is exposed to the sludge in the borehole ", i.e., the slurry undergoing hydrostatic pressure. plus the differential bit plummet or, in other words, the pressure difference between the inside of the instrument 50 and the annular space 60. If the pumps do not operate, the pressure prevailing in the zone 111 is only hydrostatic, and when the pumps operate, the pressure is not only hydrostatic, but also differential.

Since the differential pressure is in the range of 70 to 140 kg / cm 2, a large pressure change occurs in zone 111 when the pumps are started (ie a pressure rise). from 70 to 140 kg / cm 2). In FIG. 6A, if the pumps do not work, the zones 112, 113 are subjected to the pressure prevailing in the annular space, since the tube 114 is connected to the chamber 84 which contains oil under the pressure prevailing in the annular space (see Figure 4A) and also that the orifice 115 connects the areas 112 and 113.

 It will now be assumed that the pumps are turned on. The pressure prevailing in the zone 111 then rises substantially (that is to say from 70 to 140 kg / cm 2), the piston 116 is pushed down by compressing the spring 107 (not represented in FIG. 6B), while the high pressure oil in zone 112 pushes piston 108 downwardly compressing spring 110 (not shown). In sequencing, when the pumps are turned on, the elements shown in FIG. 6A assume the configuration illustrated in FIG. 6B, whereas the two pistons 116 and 108 occupy the position at the bottom of the stroke, the rod 100 also extending towards the bottom as shown in the drawing.

 However, because of the orifice 115 and the a @ tion of the spring 110, the piston 68 is pushed upwards at a speed determined by the size of the orifice 115, the spring restoring constant 110 and the viscosity of the oil present in the zones 112 and 113. This speed can be easily adjusted and brought to any desired value; for example, a rate can be set at which the piston 108 returns to its initial position at the top of the stroke in a period of about 1 minute. Accordingly, after one minute, the system takes the configuration illustrated in Figure 6C.

For the same reasons, when the pump is stopped, under the action of the spring 107 and the orifice 115, the piston 116 back to its initial position shown in Figure 6A.

 As a result, it can be seen that each time the mud pump starts, the rod 100 moves downward a distance "d" as shown in FIG. 6B, and then returns to its normal retracted position. Since, during a normal drilling operation, the pump is stopped each time a drill pipe joint is added, at this time (usually 9 m lengths), the rod 100 executes a single downward stroke, to return then to its initial upper position.

 As previously noted, the rod 100 is designed such that, when extended downward, it pushes the rod 80 of the solenoid armature (FIG. 4A) downwards by closing the valve. Therefore, the device illustrated in Figures 6A, 6B, 6C and 6D is ur, device "security", that is to say, if 1 valve. remains "stuck" in the open position due to an electrical or mechanical malfunction, the valve is then necessarily closed after a maximum drilling length <I '9 ni.

 Figure 6 is the technical drawing of the device schematically illustrated in Figures 6A, 6B and 6C. In the actual instrument, the device illustrated in FIG. 6D is placed at the location 269 illustrated in FIG. 4A. In FIG. 6D, the same reference numerals are used to designate the somblables of FIGS. 6A, 6B, 6C and 4A.

VI. DESCRIPTION OF THE ELECTRONIC SYSTEM WITH SAFETY
INTEGRATED "FOR THE SIGNALING VALVE.

 The hydraulic "automatic closing" system described with reference to FIGS. 6A, 6B, 6C and 6D will automatically close the valve each time the sludge pumps are stopped and restarted, thus making it possible to remedy any mechanical sticking of the valve. However, there is one case requiring even more attention: if the "closing" electrical circuit 103, 109 shown in FIG. 5A fails for any reason (for example, a coil denies burned solenoid) , the valve then reopens electrically shortly after the hydraulic device "automatic closure" has closed.

Figure 6E shows an electrical system preventing the valve from operating in the event of an electrical failure of the apparatus installed at the bottom of the drill hole. The reference designates the winding of the solenoid which "closes" the valve, while the reference S2 designates the winding of the solenoid which "opens" it. Resistance
R1 is connected in series with the portion of the driving circuit 104 of the solenoid which actuates the closing winding s1 of the latter. Resistance
R2 is connected in series with the part of the driver circuit 104 of the solenoid which actuates the "opening" winding s2 thereof. These resistances have a very low ohmic value (about 0.05 to 0.2 oluri) . It will be understood that the operation of the system described in detail with reference to FIG. 5A of the present specification is as follows. The "opening" electrical current pulse is initially transmitted and is shown schematically in FIG. Figure bE by pulse 300 the "closing" electric current pulse is produced later (after a time t) and is schematically represented at 301 in Figure 6E. It should be noted that these electrical pulses 300 and 301 represent the current delivered by the windings of the solenoid and not the applied voltage (the resistors R1 and R2 produce the voltage drops R1i1 and R2i2, i1 and i2 indicating the currents passing through the windings. solenoid accordingly, if one of the windings s1 and S2 is burned or is in open circuit, no current flows and no corresponding pulse is produced (in the same way, in case of any other electrical failure , the current will not go through one or both resistances
R1, R2).

 The time period ty of Figure 6E, as well as the time period tx were explained and defined above with reference to Figure 5A.

 The delay of the element 302 is equal to ty. In other words, at the output of the element 302, a pulse identical to the input pulse is emitted, but delayed by the time ty. These delay systems are well known and require no description here.

 Since the delay of the element 302 is equal to ty, the pulse represented by the number <1 <refer @ nce 303 will be in time coincidence with the pulse 301.

Circuit 304 is an anticoincidence circuit (also known as "gate
OR ") and its output 305 transmits an electrical signal only when it receives one of the pulses 301, 303, while it emits no output signal when the two pulses 301 and 303 are present. a relay actuated by the signal conveyed by the conductor 305, this relay being designed to cut off the power supply to the instrument installed at the bottom of the borehole. Therefore, if it has only one pulse of closing "(without the opening pulse) or if there is only one" opening "pulse (without the" closing "pulse), the current supply to the drive source installed at the bottom the borehole is cut and then the hydraulic system "automatic closing" described in sc referring to Figure 6D provides a mechanical closure.

 In a variant of the system illustrated in FIG. 6E, the relay 306 (which may, of course, be an electronic switch comprising transistors) may be designed to cut off the current supplying only the circuit provided for the opening solenoid. This would have certain advantages, since both the shut-off circuit "would continue to operate, while one of the objectives envisaged is to ensure the" closing "of the shutter and an electronic counter 314 can be installed between the shutter. circuit and relay 306 so that the power supply does not.

not cut by a single electrical malfunction. For example, the power supply will be cut off only after 2, 4 or 8 unsuccessful operations su @@ essifs.

V11. DESCRIPTION OF THE AUTOMATIC CUT SYMIEM
DL THE MOTOR SOURCE OF THE SIGNALING VALVE.

 As previously pointed out in this specification, a very fast operation of the valve 40 illustrated in FIG. 4A is important. 1 rt-quise shock wave will not be produced if the flap operates slowly. Since the valve and its control mechanism represent a considerable mass, a high power is required to open or close the valve at the desired time. This power is of the order of 1/2 to 3/4 horsepower and can be supplied by a power source of the type described in Chapter IV of this specification. As in all such systems, a power margin is required to ensure that the check valve is opened or closed at any time.

The various electronic logic circuits, as well as the different "drive source circuits" shown in FIG. 5A are designed to emit rectangular voltage pulses 104B and 104C of a duration of about 40 to 50 milliseconds in order to provide 1 the solenoid windings 105 and 106 are energized for a period of time sufficient to allow the valve to operate, and Figure 5E shows in more detail the voltage pulse 104b of Fig. 5. At time 0, the voltage is applied suddenly by the drive source 104 and it rises almost instantaneously to the value indicated by chif fre 270, then it stays at that value for 50 milliseconds and then it is cut off and drops (again almost instantaneously) to the value 0.

 It is very instructive to study the movement of the valve by measuring the current flow in the solenoid drive winding and building a graph (see Figure 5D). From this graph, one can study quantitatively the behavior of the valve. FIG. 5D represents a graph of this type in the form of an oscillogram of the current as a function of time. (This current is measured, for example, by the voltage applied to the resistor R1 or R2 of Figure 6E).

 It is important to understand that it is the current flowing through the winding of the solenoid which determines the force exerted on valve stem 68 (shown in FIG. 4A), since both amperes determine electromagnetic attraction. Since the windings of the solenoid have an inductance, the current will not accumulate instantaneously when applying a sudden voltage as shown in Figure 5E. If the solenoid consists of a simple inductor, the current will then accumulate according to a simple exponential curve 271 shown in dashed lines in FIG. 5D. In reality, a very different phenomenon occurs: when the valve operates (FIG. opens or closes), there is a sudden movement of the solenoid armature 79 of FIG. 4B and a counter-electromotive force occurs.

This counter-electromotive force is caused by the speed of the armature which rapidly changes (elevates) the inductance of the winding in cause of the solenoid 79. In FIG. 5D, the curve 271 is the approximate curve of the current as a function of time in the winding solenoid 79 when the armature of the latter and the stem 68 of the valve are "locked" in the "open" or "closed" position.

The solid curve 272 of FIG. 5D represents the actual accumulation of current occurring when the valve is not blocked, ie under the operating conditions (open or closed). . Curves 272 for openings or closures are very similar.

It is found that after the application of the voltage, the curve 272 rises progressively (due to the inductance of the respective windings 105 and 106 of the solenoid) until it reaches, in the example illustrated, the value 4 amps at the moment
T which is 20 milliseconds. Then, there is a sudden drop in current reaching the lower value of 2.2 amps at the T1 moment, which is 25 milliseconds. After the moment T1 = 25 milliseconds, the current rises again according to the usual "exponential" curve until it reaches, asymptotically, the value of about 10 amps at the end of the period of time. about 60 milliseconds (this value is determined by the resistance of the solenoid winding which, in the example given, is 4.7 ohms).

 By studying the curve 272 of FIG. 5D, it will be seen that the valve 40 begins to open or close at the moment T0 = 20 milliseconds and that it completes its movement at the moment T1 = 25 milliseconds. As previously pointed out, an almost identical situation occurs during the "opening" or the "closing" of the valve and the curve 272 indicates that at time T0 = 20 milliseconds, the valve starts its movement, which is completed at time T1 = 25 milliseconds.

It is important to note that the moment T1 = 25 milliseconds shown in Figure 5D is given as a specific example and depends on a number of factors. Thus, at high differential pressures, T1 will be greater than 25 milliseconds and reach 30, 35 or 40 milliseconds. Just stipulate that the moment
T1 in Fig. 5D indicates the moment at which the operation of the valve is completed and that the current flowing between T1 and 50 milliseconds is, in fact "lost", since both the operation of the valve is already completed.This additional time is a "safety factor" by which, even under adverse conditions, the valve always operates when the voltage pulse is applied.

 According to the present invention, the signal transmitted at time T1 is used to cut off any current supply to solenoid 79. As a result, all the current passing between the time T1 and the time of 50 milliseconds is saved (thus substantially reducing the total quantity energy required to operate the valve 40). It should be noted that the above-mentioned safety factor is maintained in its entirety and the current continues to be applied until the operation of the valve (opening or closing) is completed.

The electronic circuit used to achieve the above purpose is illustrated in Figure 5C in which the reference numeral 104 designates the power source illustrated in Figure 4A. Between the driving source 104 and the earth is interposed a resistance (R1 or K>) of low value (compared to the resistance of the solenoid), for example, 0.2 ohm. Consequently, the voltage applied to this resistor is proportional to the current supplying the particular winding 105 or 106 of the solenoid. (Two circuits of the type shown in FIG. 5C are necessary: one for the driving source of the opening solenoid and a second for the driving source of the closing solenoid, however, to simplify the illustration, a single circuit is shown in FIG. Fig. 5C). Reference numeral 273 designates a conventional amplifier and at the output of the latter, the voltage curve 272a of Fig. 5C will be a replica of curve 272 of Fig. 5D. Reference numeral 274 denotes a derivator (well known in the art of electronics) producing an output voltage proportional to the first time derivative of its input voltage. Curve 275 represents this derived voltage. By observing the curve 272 or 272a, it can be seen that the derivative (slope) of the curve is always positive, except for the lapse of time between T0 and
T1 in which the slope (derivative) is negative.

On curve 275, only pulse 276 is negative. Reference numeral 277 represents a conventional repeater designed to pass only pulse 276 as shown in FIG. 278. Reference numeral 279 represents a delay electronic circuit (also well known in the art) that emits a pulse. output 276b which is a replica of the input pulse, but which is delayed by the time T1-T0.

Therefore, as shown in graph 280, pulse 276b is transmitted slightly beyond the moment T1. This pulse 276b is applied to an electronic switch 281 which is designed to cut the power to the power source 104, thereby stopping the flow of current almost immediately after the operation of the valve 40 (opening or closing). This electronic switch 281 is designed to put the power source 104 back into service after a suitable period of time. This process is repeated on transmission of the next pulse 104a (or 104b).

 It is important to note that the energy savings that can be achieved by exploiting this aspect of the present invention can be very important. Since very large powers are required to operate the valve 40 at the required high speed, these savings are very sensitive and, in the example illustrated, they could increase up to five times the life of the batteries.

VIII. DESCRIPTION OF STRUCTURE 1: 1 PROTECTOR
AND HOUSING FOR THE SPECIAL INSTRUMENT
TELEMETRY.

 An important feature of the meter being drilled according to the present invention is its convenience, ie the convenience and ease with which it can be adapted to the drill string, as well as the instruments and existing equipment for drilling oil wells. In the prior art tests, large special steel housings 9 m or longer in length and 203 mm in diameter are required to enclose the complicated instruments; Moreover, the transport of these dwellings from one place to another requires special vehicles. In the apparatus of the present invention, since no flap mechanism is interposed in the main stream of sludge, it is possible to eliminate the special housing of significant weight, length and price (about 9 m long) and only a short section of drill collar (so-called "). In the practical embodiment of the present invention, this protector has a length of 914 mm and a diameter of 171 mm (instead of the length of 9 m which was previously necessary).

 Accordingly, an important feature of the present invention is that special housings of high weight and length must not be used. This feature is particularly advantageous when magnetic measurements such as compass indications (for example, drilling in a deflected hole) are required at the bottom of a borehole. Non-magnetic drill collars are not only of significant weight (2 to 3 tons), but also of an extremely high price (each, 20,000 dollars from the US monetary system). America), since they must be made of a strictly non-magnetic material such as "Monel K. In the construction of the apparatus of the present invention," standardized "drill collars of the" API "(=" American Petroleuni Institute ") having outside diameters of 152 to 228 min (the most common dimensions) All standard 1" API "collars have an inside diameter of 7.1.4 + 1.587 - O mm.

The simplicity, the small dimensions and the coaxial construction of the valve system of the present invention and the associated elements make it possible to realize a special characteristic the whole of the driving source in question and the equipment associated therewith can be installed in a a pressure-resistant tube with a sufficiently small diameter to be able to introduce it into the internal bore (71.4 mm) of a standard "API" drill collar without unduly hindering the flow of sludge. Some sensors may be installed as close as possible to the drill bit.

In particular, a gamma-ray sensor installed at the bottom of the borehole must be able to detect the penetration of the bit into a given lithologic foimation as soon as this penetration takes place. In addition, some sensors such as a compass inclinometer installed at the bottom of a borehole, require precise indexing with respect to the "face of the tool" that is used in directional drilling. In addition, a compass inclinometer must be installed at a significant distance from any magnetic or paramagnetic material. Moreover, when using a compass inclinometer, the housings 250a and 250b of FIG. 7A must be carefully indexed angularly with respect to the protector 253 which, in turn, is indexed with respect to the "curved protector" used in drilling.

directional.

 The "curved protector" has an indexing mark 253a and the angle of this mark must be in a constant angular relation and measured with respect to the indexing mark 254a provided on the telemetry protector 254. This known angle (representing the angle between the indexing marks 253a and 254a) is then introduced into the calculation involved for the determination of the range and the angle vis-à-vis a vertical plane of the "protector curve".

 Fig. 7A is a diagram showing the telemetering special instrument 50 and illustrating the system in which the "special long tool" is removed and in which also only a short section of drill collar is required, as well as mentioned it previously. In Fig. 7A, a housing designated by the reference numeral 250 consists of an upper portion 250a and a lower portion 250b as described above with reference to Fig. 4A. The upper portion 250a is enclosed within a short protector 254 (length: about 914 mm only).

This short protector is specially bored at a distance, i.e. (i.e., 114 nm), sufficient to accommodate the valve assembly 40 and also to allow free flow of the drilling mud in this upper portion 250a via the passages 61 which are also shown in FIG. 44. The housing 250a has a small diameter (preferably an outside diameter of 68.2 mm or less). A user-supplied drill collar 255 (oil company or drilling contractor) is usually 9 meters long, while its weight and price are important.

As will be pointed out above, the inside diameter of a standard API drill collar is 71.4 - 0 + 1.587 mm. Centering members 256 are provided for the lower housing 250b. These members have a diameter slightly smaller than the internal diameter of the standardized drill collar "API", for example, an outer diameter of 69.8 mm.

Low play is very important to prevent "chatter" when the instrument is subjected to vibrations during drilling. The evacuation passage 85 is identical to that shown in FIG. 4A. The housing 250b is suspended inside the protector 254 by fasteners (not shown). The cross section of the centering members 256 (as shown in FIG. 7B) is designed to provide slots or passages 258 for free flow of the drilling mud.

 In fact, the lower section 250b of the housing consists of several sub-sections which are joined to each other by a special element shown in FIG. 7C. As shown in FIG. 7C, each sub-section includes a groove 260 at its upper end, and at its lower end a protrusion or a tooth 261. The projection 261 of the urn under -section comes engage exactly in the groove 260 of the adjacent subsection.Les adjacent subsections are maintained by an assembly sleeve 262 being housed exactly in the ends of the subsections. Circular openings 263 made in the subsections are aligned with respective threaded openings 264 in the assembly sleeve 262 and the members are secured by screws 265. The special assembly member illustrated in FIG. precise angular indexing when the protector 253 is a "curved protector". As previously pointed out, the angle formed between the indexing marks 253a and 254a must be known in order to calculate the angle formed with respect to the vertical of the "curved protector". It is also necessary to know the displacement angle between the axes of a magnetometer / inclinometer and the mark 254a, this angular displacement, not to vary during the drilling operation (it is preferable, but not essential that the angle formed between one of the horizontal axes of the magnetometer / inclinometer and the indexing mark 254a is equal to zero).

For this purpose, the instrument 250b is attentable to the angular indexing teeth 261 as shown in FIGS. 7C and 7A.

 To achieve an effective telemetry system, two conditions must be taken into consideration. One of them relates to the optimal conditions for obtaining the regime of hydraulic shock waves. The other condition relates to obtaining shock waves of sufficient intensity to suppress the effects of foreign noises.

IX. ADDITIONAL REMARKS
(1) In order to obtain the shock waves described in the above specification, certain limits are imposed on the value K2 (average speed @ no change of the opening of the valve), as well as on the value Tb ( v) (open flow time). Experiments have shown that the K2 value should be at least 5 cm2 / second and that it should preferably be in the range of 20 cm2 / scconde to 150 cm2 / second. The value Tb (v) must be at most 500 milliseconds and preferably it should be in the range of 50 milliseconds to 150 milliseconds.

 (2) Although the synchronization impulses (clock 155) of the described examples are emitted by the generator connected to the pump shaft or by the rigid phase loop described in the related patent, it should be noted that may provide other elements ensuring the clock frequency in synchronism with the operation of the pump. For example, it is possible to use the well-known "pump stroke counter" which is usually adapted to the pump in order to produce an electric pulse per stroke of the pump. The period elapsing between each of these successive pulses A suitable number (eg, 512 or 1.024) of equal time by a microprocessor or a rigid phase loop or other means well known in the art of electro - computers and computers. In a system of this type, it is not necessary to know how to access the transmissi.oll shaft of the pump and the clock frequency equal to that of the generator 155 can be produced by the microprocessor and the counter switch. Pump runs.

 (3) In the first part of this specification, the conditions of formation of hydraulic shock waves and associated "valve waves" have been described in detail. At certain depths, for example, at shallow depths, conditions may arise where the valve wave described above is not suitably formed. For a valve wave of this type, it is necessary that a sufficient volume of sludge flows into the borehole and that there is sufficient hydrostatic pressure at the end of the transmitter. It is clearly understood that the present invention is in no way limited to the particular valve wave shown and can be applied to other forms of pressure pulses that can be detected at the surface of the ground as a result of the operation of the flapper 40.

Claims (18)

 1 -Testing apparatus for use in a borehole, operating during drilling and in which operating signals are transmitted by pressure pulses in a drilling fluid circulation system, characterized in that it comprises a sensor (101) for measuring the value of a parameter in the borehole, a pressure pulse generator for producing pressure pulses in the drilling fluid circulation system, a source energy store (450), storage means (452) for storing the energy supplied by the source and means (103, 104) responsive to the sensor for sequentially releasing energy between the storage means and the pulse generator to produce sequential pressure pulses which represent the value of the parameter.  2 - Apparatus according to claim 1, characterized in that the energy is supplied by the source to the storage means (452) during relatively long time intervals, and in that the energy is released by the storage means during the relatively short periods of time to produce relatively intense power pulses for the purpose of operating the pressure pulse generator (40).  3 - Apparatus according to claim 1 or claim 2, characterized in that the means (451) is provided for caan- der the energy supplied by the source to the storage means.  4 - Apparatus according to claim 3, characterized in that the control means (451) limits the rate of energy transferred from the source to the storage means.  5 - Apparatus according to claim 1, characterized in that the energy storage means (452) is a capacitor.  6 - Apparatus according to claim 1, characterized in that the energy source (450) is a battery.  7 - Apparatus according to claim 1, characterized in that the energy source (45 (?) Is a turbo-generator.  8 - Apparatus according to claim 1, characterized in that the pressure pulse generator (4C) comprises a valve and wherein the means responsive to the sensor (101) is for releasing energy sequentially to open the valve.  9 - Apparatus according to claim 1, characterized in that the generator (40) of pressure pulses is in a housing (250a) and the sensor (101) is located in a subsection (250b) of the diameter housing which is attached to the housing of the generator extending along a common axis therefrom, and that means (260,261) is provided for establishing and maintaining a predetermined angular relationship about this common axis between the housing (250a) of the generator and the subsection (250b) of the sensor housing.  10 - Apparatus according to claim 8, characterized in that the valve (40) is in the loaement (= 5Ca) and the sensor in a subsection (250b) of a reduced diameter housing fixed to the housing of the valve and claiming along a common axis therefrom, and that means (265, 261) are provided for establishing and maintaining a predetermined angular relationship about said common axis between the valve housing and the sub-section sensor housing.  11 - Measuring apparatus during drilling, for use in a borehole, in which signals are transmitted by pressure pulses in a drilling fluid circulation system, characterized in that it comprises a sensor ( 1C1) for measuring the value of a pa parameter in the borehole, an electrically actuated pressure pulse generator (40) responsive to the sensor for producing pressure pulses in the drilling fluid circulation system, a source power supply (450) for supplying electric power to the pulse generator, and a constant current device (451) interposed between the power source and the pulse generator.  12 - Apparatus for performing measurements in a borehole during drilling operations, characterized in that it comprises a valve (40) which can be energized to produce variations in the pressure of the sludge. a mud column as a result of recurrent movement of the valve, a sensor (101) for detecting a value of a parameter in the borehole, a first means (104) for providing electrical power by generating a an electric current and for recurrently displacing the valve in response to the sensor, resulting in the production of the pressure variations in the sludge column to indicate the magnitude of the parameter and a second means (274-281 ) responding to the movement of the valve to control the supply of power.  13 - Apparatus according to claim 12, characterized in that the recurrent movement of the valve results in valve openings and closures, in that the first means comprises solenoid winding (105, 106). and in that the opening and closing of the valve results in a momentary reversal of the intensity of the current flowing through the winding of the solenoid while the valve is respectively open or closed.  14 - Apparatus according to claim 12, characterized in that the valve (40) is in a valve housing (250a) and the sensor is placed in a housing sub-section (250b) of reduced diameter which is attached to the housing of the valve extending along a common axis therefrom, and that means (260, 261) are provided for establishing and maintaining a predetermined angular relationship about the common axis between the housing of valve and housing sub-section of the sensor.  15 - Measuring apparatus during drilling operations, intended to be used in a borehole, characterized in that it comprises a drill string (25) by means of which drilling fluid can flow in a circulation system, a flow restrictor (33) near the bottom of the drill string to cause a high fluid pressure area (25) and a low fluid pressure area (60), a valve (40) interposed between these zones, a sensor (101) for detecting the value of a sampling hole parameter, a generator (102) for producing a succession of sensor pulses, this succession being representative of said value, an electronic circuit (103) ) responsive to the sensor pulses to produce first and second electrical pulses in response to each of the sensor pulses, the first of the electrical pulses (104b) capable of causing a sudden opening of the valve in a relatively short time. t short, and the second electrical pulse (104c) can cause a quick closing of the valve in a relatively short time, means (P77-P78) to maintain the valve, once opened, in the open state during a relatively long duration, means (P77-P84) for maintaining the valve, when closed, in the closed state for a relatively long time, the openings and closures of the valve producing sudden pulses of pressure of the drilling fluid each pressure pulse having a steep rising edge, a steep descent edge and a relatively progressive pressure variation between fronts, the distribution state in the pulse pressure range being representative of the value of the parameter.  Apparatus according to claim 15, characterized in that a transient pressure pulse is generated within the circulation system at each opening of the valve and wherein a detector (51) can be placed at the ground surface to detect the transient pressure pulse.  15 - Apparatus according to claim 15, characterized in that a means (302,304,306) is provided to maintain the valve in the open state in the absence of an electrical pulse to open the valve.  18 - Apparatus according to claim 15, characterized in that a means (302, 304, 306) is provided to maintain the valve in the closed state in the absence of an electrical pulse to close the valve.