Classifications

• • E—FIXED CONSTRUCTIONS
  • E21—EARTH OR ROCK DRILLING; MINING
  • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
  • E21B21/00—Methods or apparatus for flushing boreholes, e.g. by use of exhaust air from motor
  • E21B21/08—Controlling or monitoring pressure or flow of drilling fluid, e.g. automatic filling of boreholes, automatic control of bottom pressure

Definitions

• the present invention relates to the operation of installations used for drilling wells on land or at sea and of installations for carrying out maintenance operations on existing wells.
• Stavanger NORWAY entitled “New concepts for improved well control”
• Stavanger NORWAY includes a train of hollow rods whose lower end located at the bottom of the sea is provided with a drilling tool and the upper end located at the surface of the sea is coupled to rotary drive means.
• This drill string is surrounded in its upper part by an extension tube which extends from the bottom to the surface of the sea to form an annular space.
• One of the drilling operations consists in drilling a hole at the bottom of the sea using the drilling tool driven by the drill string. During this operation a drilling fluid is injected inside the drill string at its upper part to cool and lubricate the drilling tool.
• the drilling fluid After passing through the tool, the drilling fluid rises towards the surface of the sea in the annular space formed by the drill string and the extension tube.
• the drilling fluid also has the role of evacuating the cuttings produced during the drilling of the hole, of maintaining the walls of the hole and of balancing by its own weight the pressure of the fluids contained in the formations traversed in the drilling.
• the pressure at the bottom of the well exerted by the column of mud is proportional to the density of the mud and to the difference between the height of the ascent of the mud in the annular space and the bottom of the well.
• the installation used for drilling also comprises pumping means connected to the extension tube below sea level, which suck the drilling fluid into the annular space and discharge it to the surface of the sea in a tank. storage.
• One method for conducting such an installation consists in measuring the pressure at the bottom of the well by means of a suitable sensor and in regulating this pressure by varying the level of rise of the mud in the annular space.
• Another control method described in French patent application No. 98 10974 of 02/03/1998, consists in adjusting the pressure at the bottom of the well, from a calculated value of said pressure, by acting on the flow rate of liquid extracted by the pumping means connected to the extension tube.
• centrifugal pumps or positive displacement pumps driven by electric motors with variable speed For example centrifugal pumps or positive displacement pumps driven by electric motors with variable speed.
• Centrifugal pumps with fairly narrow optimal operating ranges are poorly suited to variable flow operations in large proportions. They also exhibit operating non-linearities which must be compensated for by complex control systems and which are manifested by variable response times with the operating flow and pressure.
• the maximum rate of increase of the level of liquid in the annular space is obtained by reducing as much as possible the rate of extraction of drilling liquid, if possible in l 'canceling.
• This maximum speed is determined for a given well, on the one hand by the flow of drilling liquid injected into the drill string which is itself fixed by the drilling conditions, for example the speed of rotation of the tool, the nature of the formation crossed and on the other hand possibly by the minimum flow rate of the pumping means of the extracted liquid.
• the means for pumping the extracted liquid must have a large reserve of power which is difficult to obtain with immersed equipment at great depth having a good reliability and at acceptable costs.
• the object of the present invention is precisely to remedy these drawbacks and in particular to provide a method and a device for adjusting the level of drilling fluid in an extension tube of a well drilling installation and an installation for producing maintenance operations on existing wells.
• This method is particularly well suited to the operation of underwater oil production wells, gas or water injection wells, waste injection wells and product storage wells.
• the present invention proposes a method for adjusting the level of drilling fluid in an extension tube of an installation for drilling a well to an objective value, installation in which said extension tube surrounds a train of hollow rods in which drilling fluid is injected, said drill string and said extension tube defining an annular space into which the drilling fluid rises after passing through a drilling tool mounted at the end of said drill string, said method consisting in extract drilling liquid from the annular space at an adjustable extraction rate and characterized in that it consists in addition of directly introducing into the annular space, drilling liquid at an adjustable introduction rate and act on said extraction rates and until the liquid level in the extension tube reaches the target value.
• the flow rate Qi of injecting mud into the drill string being determined by the conditions for carrying out the drilling, the flow rate for introducing drilling liquid directly into the annular space is between 0.2.Qi and 4.Q
• the flow rate Qi of injecting mud into the drill string being determined by the conditions for carrying out the drilling, the flow rate for extracting drilling liquid from the annular space is between 1, 2.Qi and 5.Q
• the introduction of drilling liquid directly into the annular space consists in pouring drilling liquid into the upper part of said annular space, above the drilling liquid contained in said space .
• the introduction of drilling liquid directly into the annular space consists in injecting drilling liquid into the part of said annular space containing drilling liquid.
• the subject of the invention is also a device for adjusting the level of drilling liquid to an objective value in an extension tube of a drilling installation for a well, installation in which said extension tube surrounds a train of hollow rods, means for injecting drilling fluid into said drill string, said drill string and said extension tube defining an annular space into which the drilling fluid rises after passing through a drilling tool mounted at the end of said train rods, said device comprising means for extracting drilling liquid from the annular space at an adjustable extraction rate and being characterized in that it further comprises means for direct introduction into the annular space, of drilling fluid at an adjustable introduction rate, said extraction and introduction means acting on said rates until the level of liquid in the extension tube reaches the va their objective.
• the flow rate Qi of injecting mud into the drill string being determined by the conditions for carrying out the drilling, the flow rate for introducing drilling liquid directly into the annular space is between 0.2.Qi and 4.QL
• the flow rate Qi of injecting mud into the drill string being determined by the conditions for carrying out the drilling, the extraction flow rate drilling fluid in the annular space is between 1, 2.Qi and 5.QL
• the means for direct introduction of drilling liquid into the annular space comprises means for pouring the drilling liquid into the upper part of said annular space, above the drilling liquid contained in said space.
• the means for directly introducing drilling liquid into the annular space comprise means for injecting the drilling liquid into the part of said annular space containing drilling liquid.
• FIG. 1 schematically shows a first embodiment according to the description of the invention usable for adjusting the level of drilling liquid in an extension tube of a drilling rig for an underwater oil well, by injecting drilling liquid into said extension tube.
• FIG. 2 schematically represents a second embodiment in accordance with the description of the invention which can be used to adjust the level of drilling liquid in an extension tube of a drilling installation for an underwater oil well, by pouring liquid from drilling in said extension tube.
• - Figure 3 shows schematically an installation for drilling a well on land equipped with a device according to the description of the invention usable for adjusting the level of drilling fluid in the extension tube of said installation, by pouring liquid from drilling in said extension tube.
• FIG. 1 schematically represents a first embodiment of the device of the invention which can be used to adjust a level of drilling liquid in an extension tube of an installation for drilling an oil well underwater.
• the device of the invention comprises: a train 2 of hollow cylindrical rods provided at its upper end with a head 3 for injecting drilling mud and at its lower end with a drilling tool 4,
• An extension tube 7 connected to the casing 6, which extends between the bottom 27 and the surface 8 of the sea and surrounds the train 2 with rods, which defines with the latter an annular space 9 and which includes a nozzle 10 of injection located at a depth Hr as well as an extraction connection 11 located at a depth He less than Hr,
• means for injecting drilling liquid into the drill string 2 comprising a pump 13 for injecting mud into the drill string 2 which has an inlet 14 and an outlet 15,
• a suction pipe 16 which connects the inlet 14 of the pump 13 for injecting mud into the train 2 of rods, to the tank 12 of mud,
• a discharge pipe 17 which connects the outlet 15 of the pump 13 for injecting mud into the train 2 of rods, at the injection head 3, through a control valve 18 comprising an input 19 for controlling ,
• - means for extracting drilling liquid from the annular space 9 comprising a pump 32 for extracting mud from the annular space 9 which has an inlet 33 and an outlet 34,
• a suction pipe 35 which connects the inlet 33 of the mud extraction pump 32 to the extraction nozzle 11, - a discharge pipe 36 which connects the outlet 34 of the mud extraction pump 32 in the annular space 9, to the mud tank 12, through a valve 37 for controlling the flow of sludge extracted from the annular space 9, comprising an inlet 38 for control and through means 39 for filtering the mud , a sensor 40 for measuring the flow rate of sludge extracted from the annular space 9, which delivers an electrical signal representative of this flow rate to an output 41, means for direct introduction of drilling liquid into the annular space 9 comprising a pump 22 for injecting mud into the annular space 9 which has an inlet 23 and an outlet 24,
• a suction pipe 25 which connects the inlet 23 of the pump 22 for injecting mud into the annular space 9, to the tank 12 of mud,
• a discharge pipe 26 which connects the outlet 24 of the pump 22 for injecting mud into the annular space 9, to the injection nozzle 10, through a valve 28 for controlling the flow rate of mud injected into the annular space 9, comprising a control input 29, a sensor 30 for measuring the flow rate of sludge injected directly into the annular space 9, which delivers an electrical signal representative of this flow rate to output 31,
• a regulation device 44 comprising inputs 45, 46, 47 and 48 respectively connected to outputs 21, 31 and 41 of the flow sensors 20, 30 and 40 and to output 43 of the pressure sensor 42 and outputs 49, 50 and 51 connected respectively to the inputs 19, 29 and 38 of the control valves 18, 28 and 37,
• the drilling operation of the well 1 at the bottom of the sea consists in making a hole in the formation by means of the tool 4 driven in rotation by the train of stems. During this operation, fresh drilling mud stored in the tank is sucked up by the pump 13 and injected inside the drill string via the injection head.
• the flow rate Qi of mud to be injected into the drill string is determined by the drilling conditions, in particular the nature of the rocks which constitute the formation crossed, the speed of rotation of the drilling tool 4, the pressure on the drilling tool. drilling by train 2 of rods. This flow rate value is introduced into the device 44 for regulation by an operator by means of the control and display means 52, as a reference value for the flow rate of injected sludge.
• This flow rate, measured by the sensor 20 is controlled by the set value Qi by the regulating device 44 which delivers on the output 49 an electrical signal representative of the position of the automatic valve 18.
• the mud injected into the drill string 2 flows from top to bottom and passes through the drilling tool 4 to cool and lubricate it. After passing through the tool, the mud is loaded with the rock cuttings produced by the action of the tool 4 on the formation and rises in the annular space 9 to a level Hl.
• the pressure at the bottom of the well must be maintained at a value Pm such that the equilibrium with the pressure of the fluids contained in the formation and maintenance of the wall of the hole being produced is simultaneously ensured.
• This pressure value Pm depends on the nature of the well and varies as the drilling progresses.
• the flow of mud injected into the train 2 of rods being regulated to the set value Qi, according to the method of the invention is injected into the annular space 9 at the depth Hr a flow Qint of mud by means of the pump 22
• This flow rate Qint is equal to k.Qi, k being between 0 and 4.
• the value of k is introduced into the regulation device 44 by an operator by means of the control and display means 52. This value k is used by the regulating device 44 to calculate the flow rate setpoint Qint, and to control the flow rate of directly injected sludge, measured by the sensor 30, at this value by delivering an electrical signal for controlling the valve to the output 50. 28 automatic.
• the regulating device 44 controls the pressure measured in the annular space 9 by means of the sensor 42 to a pressure reference value calculated by applying the following formula:
• Pc represents the pressure in the annular space 9 measured by the sensor 42
• Db represents the density of the mud
• g represents the terrestrial acceleration
• Hm represents the height to which the mud goes up in the annular space 9 measured from the bottom of the well
• Hf represents the depth of the well measured from the surface 8 of the sea
• Hp represents the depth at which the pressure sensor 42 is installed, measured from the surface 8 of the sea. and by delivering to the output 51 an electrical signal for controlling the position of the automatic valve 37.
• the set point Hm of mud level in the annular space is modified either automatically or by an operator which has the effect of very quickly bringing the flow of mud extracted to a zero value.
• the maximum speed of rise of the level of mud in the annular space can be easily obtained instantaneously, by stopping the flow of mud extraction by closing the automatic valve 37 and / or by stopping the pump 32 of mud extraction. .
• the operator can stop the pump 22 for injecting mud into the space 9 annular and / or close the valve 28 for injecting mud into the annular space, then instantly the difference between the mud extraction flow rate and the flow of mud injected into the extension tube 7 is equal to [(k + 1 ) .Qi - Qi] or k.Qi.
• FIG. 2 schematically represents a second embodiment of the device of the invention which can be used to regulate a level of drilling liquid in an extension tube 7 of a drilling installation for an underwater oil well, which comprises the same elements as the device according to the first embodiment shown in the figure, except the pipe 26, the end of which is no longer connected to the tap 10, but opens into the upper part of the space annular 9 above the mud level, in order to allow the pouring of drilling mud into this part of the annular space 9.
• the underwater mud extraction equipment operates in a narrow flow range, it can therefore be of a robust, reliable type, optimized for each drilling and controllable by simple control means.
• FIG. 3 schematically represents an installation for drilling an onshore oil well, which comprises an aerial extension tube 7 which extends the casing 6 and a device for adjusting the level of drilling liquid in this extension tube which comprises the same elements as the device according to the second embodiment of the invention shown in FIG. 2.

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• Engineering & Computer Science (AREA)
• Life Sciences & Earth Sciences (AREA)
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• Mining & Mineral Resources (AREA)
• Mechanical Engineering (AREA)
• Physics & Mathematics (AREA)
• Environmental & Geological Engineering (AREA)
• Fluid Mechanics (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Geochemistry & Mineralogy (AREA)
• Earth Drilling (AREA)

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• 1998
  • 1998-12-29 FR FR9816525A patent/FR2787827B1/fr not_active Expired - Fee Related
• 1999
  • 1999-12-28 WO PCT/FR1999/003296 patent/WO2000039431A1/fr not_active Application Discontinuation
  • 1999-12-28 EP EP99961177A patent/EP1144800A1/de not_active Withdrawn
• 2001
  • 2001-06-27 NO NO20013227A patent/NO20013227L/no not_active Application Discontinuation

Non-Patent Citations (1)

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