US2497185A - Drill stem testing device - Google Patents

Description

Feb, M 1%@ c. E. REISTLE, JR 2,497,185

DRILL STEM TESTING DEVICE Filed Dec. 30, 1947 3 Sheets-Sheet 2 M as T I8 V Qnl $250725 f1, INVENTOR.

Feb, 14, 1950 7 g, R JR gfigzlg DRILL STEM TESTING DEVICE Filed Dec. 30, 194 3 Sheets-Sheet 3 ll Q I y F l G. 8. G/IZ X1 INVENTOR.

Patented Feb. 14, 1950 DRILL STEM TESTING DEVICE Carl E. Reistle, Jr., Houston, Tex., assignor, by

mesne assignments, to Standard Oil Development Company, Elizabeth, N. J a corporation of Delaware Application December 30, 1947, Serial No. 794,736

7 Claims.

This invention relates in general to sample taking methods and apparatus for use particularly in connection with the drilling of wells for the production of oil and other fluids. More particularly, this invention has reference to a method and means for taking samples of the fluid produced in the formation at the bottom of a drilled well.

It has been the practice in the past in the drilling of wells for the production of fluids, particularly, the production of petroleum, to make what is known as a drill stem test todetermine as nearly as possible just what kind of fluid a particular formation will produce when reached in drilling operations. The making of a drill stem test has in the past been a tedious, laborious and costly operation attendant with the usual dangers encountered in the drillin of the formations from which fluid flows under high pressure.

In the past the process of securing a sample of the fluid present in the bottom of the well has been attendant with many engineering difliculties. Chief among these difficulties is that of providing a means whereby the drilling mud used in the drilling operation is prevented from substantially filling the samplin device to the exclusion of the formation fluid which it is desired to secure. In order to minimize this particular difficulty various devices and methods have been developed, none of which are entirely satisfactory from an engineering or economic viewpoint. One method which has proved the most satisfactory from the engineering viewpoint but which is costly because of the excess amount of time consumed and large amount of labor required includes the steps of removing the drill stem'from the borehole, mounting a packer on the lower end of the drill stem, returning the drill stem to the bottom of the hole with the packer mounted thereon, distending the packer by mechanical means so as to seal off the fluid in the bottom of the hole against upward migration through the annular space between the drill stem and the borehole walls, lowering the sample taking device through the drill pipe by means of a wire line, taking a sample of the fluid in the bottom of the hole and recovering the sampling device through the drill stem by means of the wire line. Because the entire drill stem must be removed from the borehole and then reinserted after the packer has been aifixed, this method is costly in time and labor particularly when the formation being tested is at great depths below the surface. During this operation of removing the drill stem and running again with packer, the formation to be tested is exposed to the drilling mud having a hydrostatic pressure greater than the pressure of the fluids within the formation; and even though the drilling mud has good filtration characteristics, some of the liquid constituents of the drilling mud will enter the producing formation. The amount of fluids entering the formation is a function of the pressure differential, the filtration characteristics of the mud and the time of exposure. If an appreciable quantity of liquids enter the formation as a result of these conditions, it is often impossible to obtain anything but these fluids from the formation when a drill stem test is made. Obviously time is an important factor.

Since fluids such as petroleum are now being found at greater and greater depths, it has be come more and more important to develop a method and apparatus which will eliminate the necessity of removing the drill stem from the hole and reinserting it therein in order to take a sample of the fluids suspected to be present in a given formation penetrated by'a borehole.

It is an object of this invention to provide a method and means whereby a sample of the fluid produced in a formation penetrated bya borehole may be obtained without the removal of the drill stem from the borehole.

It is also'an object of this invention to provide a method and means whereby a sample of the 1 fluid product of a given formation penetrated by a borehole may be taken with the least possible contamination of the sample by substances normally present in a borehole, for example, drilling mud.

Other objects and advantages of the present invention will be evident from an examination of the following description, the accompanying drawing and the appended claims.

Referring now to the drawing on which like numerals indicate corresponding parts throughout: J

Fig. 1 is an elevation and cross-sectional view of an embodiment of the present invention, said drawing showing the various parts in their relative positions just prior to the time a sample of the fluid in the bottom of the borehole is to be taken;

Fig. 2 is the top portion of the embodiment shown in Fig. 1;

Fig. 3 is a cross-sectional view taken along line A-A of Fig. l;

Fig. 4 is a cross-sectional view taken along line BB of Fig. 1;

.F g. 5 is a view of the same embodiment-as shown in Fig. 1, the difference being that the various parts are shown in their relative positions while a sample of the fluid in the bottom of the borehole is being taken;

Fig. 6 is an elevation of the sample receiving assembly of the embodiment shown in Fig. 1 before the said assembly is lowered into the drill stem bore for the taking of a sample of the formation fluid;

Fig. 7 is a cross-sectional view taken along line -0 in Fig. 6; and

Fig. 8 is a view of the same embodiment as shown in Fig. 1, the difference being that only those parts are shown which are present in the borehole while normal drilling operations are being conducted.

Referring now specifically to the drawing, a tubular body member I having screw threads at its upper end adapted for securing said body member to the lower end of a drill stem 2 and having screw threads at its lower end adapted for securing said body to a cutter head 3 defines a port 4 fluidly connecting the exterior surface of said tubular body with the interior surface of said body. Port 4 terminates on the inside of tubular body I in a valve seat 5. Valve I3 is arranged to be seated in seat 5 and is biased upwardly against the said seat by valve spring I. Valve plug 8, defining a plurality of ports 9, supports and guides valve stem II] to which is affixed guide head II which projects into the central passage of tubular body I. A flexible formation packer I2 is mounted in a recess on the exterior surface of tubular body I in such a position along said body as to include the outer terminus of port 4 between its upper and lower edges. The upper edge of packer I 2 is rigidly affixed to and held in sealing contact with tubular body I by means of upper packer collar I3 and the lower edge of packer I2 is rigidly affixed to and held in sealing contact with tubular body I by means of lower packer collar I4.

Sample container assembly consists of sample container I5 which is removably aflixed to hooking ring guide body IS with gasket I'I providing a seal between the said two parts. Hooking ring guide body I6 is cylindrical in shape at its midsection and is tapered at both its upper and lower ends, I8 and I9 being the upper and lower tapered surfaces, respectively. Afiixed removably to the lower end of hooking ring guide body I6 is piston guide body 20. gasket 2I providing a seal between the said two parts. Piston 22 is mounted .on piston guide body 20 and is arranged to move longitudinally with respect to said piston guide body and slidably thereon and is further arranged to move longitudinally with respect to tubular body I and in slidable contact with the inner walls of said tubular body I. Mounted on the outside cylindrical surface of piston 22 and recessed between its upper and lower extremities is packing ring 23 which provides a seal against the passage of fluid between piston 22 and the inner walls of tubular body I. Mounted on the inner cylindrical surface of piston 22 and recessed therein between its upper and lower extremities is packing ring 24, the said ring providing a seal against the passage of fluid between piston 22 and piston guide body 20. Aflixed to the lower end of piston 22 is piston spring 25, the said piston spring 25 being seated at its lower end on spring seat 26 and biasing piston 22 away; from spring seat 26. Mounted slidably in the lower end of piston guide body 20 are a plurality of pins 27 which are arranged to be moved longitudinally with respect to the axis of said piston guide body by piston 22. Piston stop 28 prevents further downward movement of piston 22. Pins 21, at their lower end, are in contact with valve flange 29, the said flange containing ports 30. Valve stem guide 3I, defining a plurality of ports 32 and rigidly aifixed to piston guide body 20, supports valve 33 whose stem 34 passes slidably through valve stem guide 3|. Valve spring 35 is rigidly affixed at its lower end to valve stem guide 3I and biases valve 33 upwardly into seat 35. Piston guide body 20 is provided on its outer surface with shoulder 31 which, when the fluid container assembly is lowered through the drill stem, abuts against stops 38 in cutter head 3. The lower extension of guide body 20 contains fluid ports 39. Sample fluid port 40 begins at piston seat 36 and extends longitudinally through the center of piston guide body 20, gasket 2I, hooking ring guide body I6, gasket I1, and through the lower portion of sample container I5 terminating in tapered valve seat 4I.

Sample container valve 42 is mounted ver tically in sample container I5 and is normally held in the closed position in valve seat M by valve spring 43 which exerts pressure downwardly on valve 42 and upwardly against valve stem guide 44, the said valve stem guide being rigidly afiixed to the inner wall of sample container. I5. A plurality of ports 45 pass vertically through valve stem guide 44. Valve stem 46 moves slidably through valve stem guide 44.

Hooking ring 41 at its lower end is recessed in and rigidly affixed to the upper cylindrical walls of piston 22. Hooking ring 41 consists at its lower end of a cylindrical ring on which projects upwardly and longitudinally with re spect to the axis of piston 22 a series of closely spaced hooks radially arranged with respect to each other along the upper cylindrical edge of said ring, the aforesaid hooks constituting an integral part of said hooking ring 41, each terminating at their upper end in a hook projecting outwardly.

Having enumerated the parts constitutin the preferred embodiment of my invention as shown in the accompanying drawings, the relation of the various parts to each other will not be explained.

In the drawing formation packer I2 is positioned a short distance above cutter head 3. Preferably, packer I2 is positioned as close to cutter head 3 as is practical and consistent with good engineering design of the mechanism afflxed to the lower end of sample container 35 so that the volumetric capacity of said container may be kept to a minimum while still being of greater capacity than the volume of fluids, other than fluids produced from the formation, trapped in the bottom of the borehole when packer I2 is distended, as shown in Fig. 2. However, formation packer I2 and tubular body I may be positioned at any point above cutter head 3 along the drill stem but when it is positioned further from the cutter head 3 than the practical minimum, the mechanism affixed to the lower end of sample container I5 must necessarily be longer and sample container I5 must necessarily have a correspondingly greater volumetric capacity if the sample container is to have a greater capacity than the volume of fiuid, other than fluids produced from the formation, which are trapped in the bottom of the borehole when formation packer I2 is distended, as shown in Fig. 2.

As previously pointed out, hooking ring 41 terminates at its upper end in a series of closely spaced hooks. These hooks are designed to seat in springing contact at their upper, inner edge against tapered surface I8 of hooking ring guide body I 6 when piston 22 is pressed upwardly at the top of its stroke by piston spring 25 and are designed to firmly engage with guide head I I when piston 22 is driven downwardly.

The degree of taper of tapered surface 18 on hooking ring guide body 16 is designed to provide a recess for the hooks of hooking ring 41 when piston 2 is at the top of its stroke. On the other hand, tapered surface 3 must have sufficient taper to :cause the hooks of hookin ring 41 to engage with guide head II when fluid pressure is applied against the head of piston 22 to cause the said piston to move downwardly. Lower taper I9 on hooking ring guide body I6 is tapered in such a manner as to provide a minimum area of contact between the lower edge of hooking ring guide body l6 and the head of piston 22. The cylindrical mid-section of hooking ring guide body I6 is of sufficient vertical height to cause hooks of hooking ring 41 to be in engaging contact with guide head H during the entire time that fluid pressure is being applied to the head of piston 22 during sample taking operations.

In the apparatus of my invention, it will be obvious that the design and dimensions of the various parts mentioned herein and their relative distances from other parts may be varied as desired to suit the particular conditions encountered. For example, it is possible in the practice of my invention to employ only one slide valve in the tubular body member to permit the flow of fluid from the central passage of the body member to the annular space between the flexible formation packer and the recessed surface of the body member. Where only one such valve is employed, it will be desirable to employ a larger valve and a correspondingly larger port leading to the annular space between the flexible formation packer and the recesed surface of the tubular body member than if more than one valve is employed. However, I prefer to use more than one valve so that the said valves and the said ports leading to the annular space between the flexible formation packer and the recessed surface of the body member may be of relatively small size and diameter.

As a further possible modification in the practice of my invention, the effective area over which pressure is to be exerted by fluid in the annular space between the flexible formation packer and the recessed surface of the tubular body member may be greatly increased by cutting annular, longitudinal or spiral grooves in the recessed surface of the body member and fluidly connecting such grooves with the port or ports in the said body member. Such grooves permits of a more rapid inflation of the formation packer by the pressurized fluid when the valve or valves located in the tubular body member are opened and also reduce the possibility of an operational failure caused by adherence of the formation packer to the recessed surface of the tubular body member.

The hooking means employed for the purpose of opening valve 5 when fluid pressure is applied downwardly 0n the head of piston 22 may be of any desired design which will engage guide head II at the proper time, but I prefer to employ a hooking device which will result in positive engagement with the said guide head withall) out the necessity of positioning the entire sample taking assembly in the bore of the drill stem. Consequently, in the preferred practice of my invention, the hooking ring which I employ consists at its bottom end of a ring designed to fit around the upper cylindrical edge of piston 22, the said ring containing a series of radially spaced hooks forming an integral part of the aforementioned ring spaced sufficiently close to each other so that at least one of the said hooks will positively engage with guide head II irrespective of the radial position of the said assembly with respect to the bore of the drill stem. These hooks may be made of any material which has sufficient resilience to remain at all times in springing contact with hooking ring guide body IS. The material I prefer to use for this purpose is spring steel although any other suitable material may be used.

In the practice of my invention, flexible formation packer l2 may be constructed of any kind of material which is capable of being internally stretched by the application of a stretching force but which is capable of returning to its normal shape and dimensions when the aforementioned force is no longer applied. The material which I prefer to use for flexible formation packer I2 is natural rubber but such other materials as synthetic rubber, synthetic rubber containing fibrous threads such as cotton or nylon, natural rubber containing thread fibers, orother material possessing the above-mentioned property may be also used.

Having described the component parts of the apparatus of my invention, a mode in which this apparatus may be employed will now be described.

When employing the apparatus of my invention, a borehole is drilled into a formation in the usual manner employing cutter head 3, drill stem 2 with tubular body member I located between the said cutter head and the said drill stem. While the normal drilling operation'is being conducted, the sampling assembly shown in Fig. 6 is not present in the drill stem bore and drilling mud is normally being circulated down through the bore of the drill stem, around the cutter head 3 and up through the annular space between drill stem 2 and wall 48 of the borehole. While the normal drilling operation is being conducted, valve 5 is held closed by means of valve spring 1 thereby preventing fluid pressure from being applied to the inside face of formation packer l2 and consequently formation packer i2 is in the collapsed position shown in Fig. 8, that is, formation packer l2 lays substantially fiat against the recess in tubular body member l. Inthis position formation packer [2 offers no resistance to the flow of mud upwardly through the annular space between drill stem 2 and the walls of the borehole 48. When it is desired to take a sample of the fluid from a particular formation, the rotation of drill stem 2 is discontinued and the sampling assembly shown in Fig. 6 is lowered through the bore of the drill stem 2 by means of a wire line in the same manner as a conventional core barrel is lowered or by another satisfactory means. On reaching the bottom of the hole, the sampling assembly will assume the position shown in Fig. 1 since further downward movement of the sampling device will be prevented by the abutment of shoulder 3'! against shoulder stop 38 located in the cutter head. When the sampling assembly comes to rest in the above-described position, the 'bottom edge of the sampling device will be approximately even with or higher than the bottom edge of cutter head 3 since the distance between the lower edge of shoulder 31 and the lower edge of the sampling device is substantially equal to or may be less than the distance between the lower edge of the taper on shoulder stop 38 and the lower edge of cutter head 3. Furthermore, rings 23 and 24 prevent the passage of fluid from the upper part of the bore of the drill stem to the lower part since these rings form an effective seal against the passage of fluid. Having assumed the position above described, the sampling assembly is now properly positioned for the taking of a sample of the desired fluid from the bottom of the borehole.

At this stage of the sample taking operation, pressure is applied to the fluid located in the drill stem bore above rings 23 and 24 by means of a pump, not shown, at the surface of the earth. This fluid pressure will drive piston 22 downwardly moving the hooks of hooking ring 41 downwardly and outwardly into engaging contact with guide head It thus causing valve 6 to open and to permit the passage of fluid through port 4 into the annular space between the inside surface of formation packer I2 and the recessed surface of tubular body member I. The fluid, on entering the above-mentioned annular space, will rapidly expand formation packer l2 into sealing contact with the borehole walls 48 as shown in Fig. 2. Any fluid present in the borehole below the point of contact of formation packer l2 and borehole walls 48 is effectively prevented from moving upwardly past the said point of contact. After formation packer i2 has been forced outwardly into sealing contact with boreholewalls 48, piston 22 continues to move downwardly by reason of the fluid pressure applied and when the said piston approaches the bottom of its stroke, it will contact the upper ends of pins 21 which in turn will be driven downwardly into contact with flange 29 thereby causing valve 33 to open. Since the pressure inside sample container I is much lower than the pressure of the fluid trapped in the bottom of the hole, when valve 33 opens, fluid will flow from the formation through ports 39, 32, and into chamber l5 through sample container valve 42 which valve is forced open by the differential pressure existing between container l5 and the fluid in the bottom of the borehole. Fluid will continue to flow into sample container l5 until the said sample container is completely filled. When sample container i5 is filled, the pump pressure applied to the drilling fluid inside of the drill stem is relieved, piston 22 moves upward to its original starting position and valves 33 and 42 close. The sample assembly is removed from the bore of the drill stem by means of a wire line in the same manner as a conventional core barrel is removed. When the said pump pressure is relieved, the pressure existing in the annular space between the recess of tubular body member I and formation packer l2 will exceed the pressure inside the drill stem bore and consequently assumes its original collapsed position as shown in Fig. 8.

In the practice of my invention the sample chamber l5 can be made as long as desired so as to permit the taking of as much of the sample fluid at the bottom of the well as is required. I prefer to employ a sample chamber of sufficient length to take a sample of volume greater than the volume of fluid which is originally trapped in the bottom of the borehole when formation packer i2 is distended into sealing contact with the walls 48 of the borehole. When my invention is practiced in the preferred manner, and when the sample chamber is filled, it must necessarily contain fluid produced from the formation and thereby provides a positive method of securing such fluid.

It will be readily appreciated that there has, by this invention, been provided a method and apparatus capable of carrying out all the objects and advantages hereinbefore revealed. My invention is particularly advantageous in that it provides a method and apparatus which renders unnecessary the costly removal of the drill stem from the borehole and its reinsertion therein after a packer has been installed on the drill stem as was the practice before this invention was made. Furthermore, my invention provides a positive means for securing fluid produced from the formation to be tested. My invention also provides a safe and simple method for securing fluid produced from a formation by the use of a simple and effective apparatus.

Having described my invention, what I claim as new is:

l. A device adapted for obtaining a sample of fluid of an earth formation penetrated by a borehole Without removing the drill stem and drill bit therefrom comprising, in combination, a first tubular member having a port connecting the exterior with the interior, a flexible formation packer mounted on the exterior of said first tubular member in sealing contact at its upper and lower edges therewith and defining a cavity in communication with said port, a first valve mounted on said first tubular member to control the flow of fluid through the port and movable to an open position to allow the passage of fluid therethrough, an activating member mechanically connected to said first valve and projecting into the central passage defined by said first tubular member, an assembly freely slidable into the central passage of said first tubular member including a second tubular member defining a sample chamber with a passage communicating to the exterior thereof, a second valve carried by the assembly adapted to assume a first position preventing the flow of fluid into said passage and a second position permitting the flow of fluid into the passage, means slidable with respect to the second tubular member and cooperating therewith and with the interior wall of the first tubular member to form a fluid-tight seal and movable from a first position to a second position, from said second position to a third position and arranged to engage with the activating member of the first valve to move the first valve into open position upon movement of the said means from its first to its second position, and an activating member carried by the assembly adapted to move the second valve from its closed position to its open position upon movement of the said means from its second to its third position.

2. A device for obtaining a sample of the fluid production of an earth formation penetrated by a borehole drilled by the rotary drilling method without removing the drill stem and drill bit from said borehole, said drill bit carrying a shoulder stop therein, comprising, in combination, a tubular body member adapted to be secured to said drill stem above said drill bit and having a port fluidly connecting the exterior with the interior thereof, a flexible formation packer recessed in the outer surface of said tubular body member and rigidly affixed to and in sealing contact with the said tubular body member at its upper and lower edge and between itsupperand lower edges distensible radially with respect to said tubular body member defining an annular space in fluid communication with said port, at least one first normally closed spring pressed valve in the wall of said tubular body member arranged to permit the passage of fluid from the central passage of said tubular body member to the annular space between the flexible formation packer and the tubular member through the port fluidly connecting said central passage and said annular space, a container adapted to be lowered through the bore of said drill stem, a second spring pressed valve in the lower end of said container normally closing said container against the ingress of fluid under pressure, a first means connected with and below the said container including a piston longitudinally m'ovable with respect to the bore of the said drill stem in sealed slidable contact with the inner walls of said tubular member and the surface of a piston guide body, a spring biasing said piston upwardly, a second means aflixed to said piston arranged to open said first spring pressed valve, a third spring pressed valve adapted to be opened by downward movement of said piston slidably along said piston guide body after the said first spring pressed valve has been opened by said second means, said third spring pressed valve normally closing a port axially traversing said first means and fluidly connecting the seat of third spring pressed valve with the seat of said second spring pressed valve, a shoulder on the lower end of said first means adapted to seat on said shoulder stop in said cutter head to prevent further downward movement of said container and the non-movable parts of said first means.

3. A device for obtaining a sample of the fluid production of an earth formation penetrated by a borehole drilled by the rotary drilling method without removing the drill stem and drill bit from said borehole, said drill bit carrying a shoulder stop therein, comprising, in combination, a tubular member adapted to be secured to said drill stem above said drill bit and defining a port through its annular wall fluidly connecting the exterior with the interior thereof, a flexible formation packer recessed in the outer surface of said member and rigidly afilxed at its upper and lower edges to said tubular member in sealing contact therewith and distensible radially in its medial sector with respect to said tubular member and defining an annular space between its upper and lower edges in fluid communication with said port, at least one first normally closed spring pressed valve in the wall of said tubular member arranged to permit the passage of fluid from the central passage of said tubular member to the annular space between the said flexible formation packer and the said member through the said port, a sample container adapted to be lowered through the bore of said drill stem into the central passage of said tubular member, a second spring pressed valve in the lower end of said container normally closing said container against the ingress of fluid under pressure, a hooking ring guide body tapered at its upper and lower ends affixed at its upper end to the lower end of said container below the said second valve, a piston guide body aflixed at its upper end to the lower end of said hooking ring guide body, a piston mounted on said piston guide body longitudinally movable with respect to the bore of said drill stem and said piston guide body and in sealed slidable contact with the walls of said tubular member and said piston guide body, a

piston spring biased upwardly against said piston, a hooking ring mounted at its lower edge to the upper end of said piston the said hooking ring terminating at its upper edge in a plurality of closely spaced hooks arranged radially with respect to said piston to open the said first spring pressed valve, a third spring pressed valve in the lower end of said piston guide body normally preventing the passage of fluid upwardly through a fluid port extending from the seat of said third spring pressed valve axially and longitudinally through said piston guide body, said hooking ring guide body and the lowerend of said container terminating in the seat of said second spring pressed valve, a plurality of pins located in said piston guide body the said pins being actuated by the said piston subsequent to the actuation of the said first spring pressed valve and arranged to open the said third spring pressed valve to permit a sample of the fluid trapped in the bottom of the borehole including fluid produced from said formation to enter the said fluid port above said third spring pressed valve to open the said second spring pressed valve inside said container and to enter said container, a shoulder on said piston guide body below said piston arranged to rest on said shoulder stop in said cutter head and to hold the lower extremity of said piston guide body above the lower edge of said cutter head.

4. A device for obtaining a sample of the fluid production of an earth formation penetrated by a borehole drilled by the rotary drilling method without removing thedrill stem and drill bit from said borehole, said drill bit carrying a shoulder stop therein, comprising, in combination, a drill stem, a cutter head, a shoulder stop in said cutter head, a tubular body member defining screw threads at its upper end adapted for securing it to the lower end of a drill stem and defining screw threads at its lower end adapted for securing a drill bit thereto and having a port communicating between the interior and exterior thereof, a flexible formation packer recessed in the outer surface of said tubular body member and at its upper and lower edge rigidly affixed to and in sealing contact. with said member and distensible radially in its medial sector with respect-to said tubular member and defining an annular space between its upper and lower edges in fluid communication with said port, at least one first normally closed spring pressed valve in the wall of said member arranged to permit the passage of fluid from the central passage of said member to. the annular space between the said flexible formation packer and the said member through the port communicating between the interior and exterior of said member, a guide head secured to said first valve projecting into the central passage of said tubular body member, a sample container adapted to be lowered through the bore of said drill stem, a second spring pressed valve in the lower end of said container normally closing said container against the ingress of fluid under pressure, a hooking ring guide body tapered atits upper and lower ends affixed at its upper end to the lower end of said container below the said second valve, a piston guide body aflixed at its upper end to the lower end of said hooking ring guide body, a piston mounted on said piston guide body longitudinally movable with respect to the bore of said drill stem and said piston guide body and in sealed slidable contact with the inner walls of said tubular body member and with said piston guide body, a piston spring biased upwardly against said piston, a booking ring mounted at its lower edge to the upper end of said piston arranged to open the said first spring pressed valve when said piston is driven downwardly by the application of fluid pressure on the head of said piston after the said container with its appended parts is lowered into said drill stem to abut on the said shoulder stop, a third spring pressed valve in the lower end of said piston guide body normally preventing the passage of fluid upwardly through a fluid port extending axially and longitudinally from the seat of said third spring pressed valve through said piston guide body, said hooking ring guide body, and the lower end of said sample container terminating in the seat of the said second sprin pressed valve, a plurality of pins slidably mounted in said piston guide body arranged to be actuated by the said piston subsequent to its actuation of the said nrst spring pressed valve to open said third spring pressed valve to permit a sample of the fluid trapped in the bottom of the borehole including fluid produced from said formation to enter the said fluid port above said third valve to open the said second spring pressed valve inside said container and to enter said container, a shoulder on said piston guide body below said piston arranged to rest on said shoulder stop in said cutter head and to support the lower extremity of said piston guide body above the lower edge of said cutter head.

5. A device adapted for receiving a sample of fluid from a formation comprising, in combination, a body member defining a cavity adapted to receive a sample with a passage connecting said cavity with the exterior of the body member, a valve member carried by the body member adapted to assume a closed position preventing flow of fluid through the passage and movable from a closed position to an open position for admitting fluid therethrough, a piston member slidably mounted on the body member and adapted to be moved from a first position to a second position and from a second position to a third position, a hook member secured to said piston member said hook member including a plurality of hooks arranged to be moved radially on movement of said piston member from its first position to its second position, an activating member carried by the body member for moving the valve member from its closed to its open position upon movement of the piston from its second to its third position.

I 6. A device in accordance with claim 8 in which a second valve member is mounted on the body member for controlling the flow of fluid from the passage into the cavity and arranged to move from a closed position to an open position and a 12 spring arranged to bias the second valve member to its closed position.

7. A device adapted for obtaining a sample of fluid from an earth formation penetrated by a borehole without removing the drill stem and drill bit therefrom comprising, in combination, a tubular member having a central passage and adapted to be secured to said drill stem to form a part thereof, the walls of said tubular member defining at least one port therethrough fluidly connecting said central passage with the exterior of said tubular member, a flexible formation packer mounted on the exterior of said tubular member in sealing contact at its upper and lower edges with said tubular member and defining an annular space between said edges in communication with said at least one port, at least one first valve mounted on said tubular member to control the flow of fluid through said at least one port and movable to an open position to allow passage of fluid through said at least one port, a sample receiving assembly freely slidable through said drill stem into the central passage of said tubular member including a member defining a sample chamber with a fluid passage communicatin to the exterior thereof, a second valve carried by said assembly adapted to assume a first position preventing the flow of fluid through said fluid passage and to a second position permitting the flow of fluid through said fluid passage, 2, piston mounted on said sample receiving assembly arranged to be moved slidably in fluid tight relation with the interior wall of said tubular member, said piston being movable from a first position to a second position and from said second position to a third position, a first valve engaging member carried by said piston adapted to engage with said at least one first valve to move said valve into open position upon movement of said piston from its first position to its second position and a second valve engaging member carried by said sample receiving assembly adapted to be actuated by said piston to open said second valve when said piston moves from its second position to its third position.

CARL E. REISTLE, JR.

REFERENCES CITED The following references are of record in the Certificate of Correction Patent No. 2,497,185 February 14, 1950 CARL E. REISTLE, JR.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column 11, line 54, for the claim reference numeral 8 read 5; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Ofiice.

Signedand sealed this 18th day of July, A. D. 1950.

[SEAL] JOE E. DANIELS,

Assistant Oommzssioner of Patents.

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