US3527298A - Bottom hole sampler - Google Patents

Description

Sept, 8, 1970 w. M. VARTY ET AL 3,527,298

BOTTOM HOLE SAMPLER Filed Feb. 11, 1969 I2 I l. l r M 1 v ill J T w i? W 5 m m 4 l 2 INVENTORS:

WILLIAM M. VARTY DONALD L. ZERB F nl- United States Patent 3,527,298 BOTTOM HOLE SAMPLER William M. Varty and Donald L. Zerb, Edmonton, Alberta, Canada, assignors to Drill Stem Testing & Coring Ltd., Edmonton, Alberta, Canada Filed Feb. 11, 1969, Ser. No. 798,418 Int. Cl. E21b 27/00; F21b 25/00 US. Cl. 166-162 Claims ABSTRACT OF THE DISCLOSURE This invention relates to new and useful improvements in bottom hole samplers for oil wells.

Conventional samplers are usually attached to a line by which they are lowered into the drill hole. However, the principal object of the invention is to provide a sampler which exists as a removable component of a drill pipe string and which is separably connectable to a drill rod so that by relative movement of the drill pipe and drill rod the sampler may be conveniently actuated to trap a sample of fluid therein, whereupon the sampler may be removed from the drill pipe string and transported in a sealed condition to suitable testing facilities.

More particularly, the sampler of the invention comprises a tubular casing which is adapted to be removably interposed in a drill pipe string and contains a pair of longitudinally spaced valve passages with a sampler chamber therebetween. A valve stem equipped with a pair of valve members for cooperation with the valve passages, is separably connectable to a drill rod and may be moved axially relative to the casing between a valveopen position which permits free flow of fluid through the valve passages and sampler chamber, and a valveclosed position in which the valve passages are blocked by the valve members and a sample of fluid is trapped in the sampler chamber. An important feature of the invention is that, in the valve-open position of the stem, free flow of fluid through the casing is facilitated as aforesaid, and the device may be readily flushed out, if it is suspected that a proper sample has not been obtained.

Also, the sampler of the invention embodies means for discharging fluid from the sampler chamber for test purposes while the sampler is still in the valve-closed position, this being of particular significance when, as often happens, the kuid is under considerable pressure.

Other advantages of the invention reside in its simple construction, efficient operation, and in its adaptability to economical manufacture.

With the foregoing more important object and features in view and such other objects and features as may become apparent as this specification proceeds, the invention will be understood from the following description taken in conjunction with the accompanying drawings, wherein like characters of reference are used to designate like parts, and wherein:

FIG. 1 is a view, partly in vertical section and partly 3,527,298 Patented Sept. 8, 1970 in elevation, showing the sampler of the invention in its valve-open position;

FIG. 2 is a fragmentary view, similar to that in FIG. 1, but showing the sampler in the valve-closed position; and

FIG. 3 is an elevational view of the valve stem and valve members.

Referring now to the accompanying drawings in detail, the bottom hole sampler of the invention is designated generally by the reference numeral 10 and is adapted to be removably interposed in a string of drill pipe so as to constitute a component of the drill pipe string. The sampler 10* comprises a tubular casing 11 having screw-threaded end portions 12, 13 for separable connection to adjacent components of the drill pipe string, including a short pipe portion or component 14 which may be provided at the lower end of the casing 11 for a purpose hereinafter described.

The casing 11 may be in one piece, although preferably it is composed of a plurality of assembled sections 11a, 1117, 110, so as to facilitate internal machining.

In any event, the casing 11 is provided at longitudinally spaced points at the inside thereof with a pair of axial valve passages 15, 16, and a portion of the casing between these passages defines a sampler chamber 17 with which the passages communicate. In the sectional arrangement of the casing as shown, the passages 15, 16 may be conviently located within the casing sections 11a, 11c, respectively, while the chamber 17 is located mainly in the intermediate casing section 11b.

A valve stem 18 extends axially through the passages 15, 16 and through the chamber 17, the upper end of the stem being threaded as at 19 for separable connection to a drill rod (not shown). The stem 18 carries a pair of longitudinally spaced valve members 20, 21 equipped with suitable packing rings 22, such as Viton O-rings, for example, the longitudinal spacing of the valve members on the stem corresponding substantially to the longitudinal spacing of the valve passages in the casing.

The valve stem 18 is movable axially relative to the casing 11, or vice versa, between a valve-open position shown in FIG. 1 in which the valve members 20, 21 are disposed outside of the valve passages 15, 16, and a valve-closed position shown in FIG. 2 in which the valve members 20, 21 have entered and are blocking the respective valve passages 15, 16, as will be clearly apparent. It is to be particularly noted that in the valveopen position of FIG. 1, free flow of fluid through the casing is facilitated, but in the valve-closed position of FIG. 2 the valve passages 15 and 16 are blocked and a sample of fluid is trapped in the chamber 17.

The valve stem 18 has a diametrically enlarged lower end portion 23 and is provided with an axial bore 24 which extends upwardly through the stem and communicates at its inner or upper end through laterial openings 25 with the interior of the chamber 17. The lower end of the bore opens into a counterbore 26 having lateral orifices 27 in communication therewith, and the counterbore 26 accommodates a screw-threaded closure plug 28. When the plug 28 is screwed in, the bore 24 is blocked, but when the plug is screwed out to some extent, communication is established between the bore 24 and the orifices 27 so that sample fluid may be delivered from the chamber 17 to appropriate testing equipment, without moving the valve stem 18 from the valveclosed to the valve-open position. Ordinarily, the orifices 27 may be blocked by screw-threaded plugs 29, and a stop pin or screw 30 may be provided in the lower end of the counterbore 26 to limit the extent to which the closure plug 28 may be screwed outwardly.

Finally, it is to be noted that one of the valve passages, for example, the passage 15, "is provided at its upper end with an annular shoulder 31 which is engageable by the valve member 20 in the valve-closed position of the stem 18, thus limiting the extent to which the stem 18 may be moved upwardly relative to the casing 11.

In operation, the sampler as a whole is installed in a string of drill pipe as a component thereof, the drill pipe below the sampler being perforated to permit flow of fluid into and through the sampler which at this stage is in the valve-open position so that free flow of fluid through the sampler casing 11 is facilitated. At the upper end of the perforated drill pipe, and still below the sampler, a packer is installed, which is expanded to fill the drill hole, the sampler of the invention being located at any suitable point along the length of the drill pipe between the packer and the top of the drill hole, with the upper end of the valve stem 18 of the sampler being connected to the drill rod. Conveniently, the sampler may be located immediately adjacent the usual mandrel at the top of the drill hole.

Fluid is then pumped from the top of the drill hole until the bottom hole fluid starts flowing on its own. As soon as this flow commences, the drill pipe mandrel is rotated and this causes the drill rod to move the valve stem 18 of the sampler from its valve-open to a partially valve-closed position, but full flow of fluid through the sampler is still permitted for a few moments, after which the drill pipe mandrel is rotated further so that the drill rod moves the stem 18 of the sampler to the full valve-closed position, thus trapping a sample of fluid in the chamber 18.

The sampler thus retains a sample of the bottom hole fluid or gas at actual bottom hole temperature, pressure and consistency, with all other characteristics pertainingg thereto, as required for test purposes.

With the sampler in the valve-closed position and fluid trapped in the chamber 17 thereof, the entire sampler 10 may be removed from the drill pipe and transported to appropriate testing facilities, it being noted in this regard that the contents of the sampler are sealed at the time of its removal from the drill pipe string and the sampler contents are thus unknown to persons at the site of the well. In this manner a safeguard is provided against leakage of information concerning the fluid sample at the well site, and the sampler is transmitted to test facilities with the desired amount of secrecy.

In the valve-closed position of the sampler as shown in FIG. 2, further upward movement of the stem 18 relative to the casing 11 is prevented by engagement of the valve member 20 with the shoulder 31. As a practical matter, the sampler remains in the valve-closed position without the stem 18 having any tendency to move downwardly, inasmuch as the pressure of fluidin the chamber 17 acts equally in all directions. Nevertheless, when the device is being transported, a cap may be applied to the bottom end portion 13 of the casing 11 as indicated at 32 in FIG. 2. Such a cap engages the lower end of the valve stem 18 and thereby positively prevents any possible downward movement thereof relative to the casing.

When the fluid trapped in the sampler is to be tested, the aforementioned plugs 29 are removed and appropriate testing equipment is connected to one of the orifices 27, while pressure is equalized by connecting a mercury pump, or the like, to the other of the orifices 27. The closure plug 28 is then unscrewed to establish communication from the chamber 17 through the bore 24 to the orifices 27, and appropriate tests may then be conducted while the stem 18 of the sampler still remains in the valve-closed position. Adjustment of the closure plug 28 affords a variable discharge of the sample fluid, which is particularly useful when, as often happens, the sample fluid is under considerable pressure.

When the device is not in use for either sampling or testing purposes, the aforementioned pipe portion 14 may be applied to the lower end 13 of the casing 11 so as to protect the downwardly projecting portion of the valve stem 18 against possible damage. The pipe portion 14, so applied, is shown in FIG. 1 and, although this pipe portion is not a part of the sampler itself, it may remain attached thereto as another drill pipe component when the sampler is interposed in a drill pipe string. When the sampling operation is completed, the pipe portion 14 may be removed from the sampler and substituted by the aforementioned cap 32 which serves to prevent downward movement of the valve stem 18 in a positive manner, it such prevention of movement should be desired or necessary.

What is claimed as new is:

1. A bottom hole sampler for oil wells, said sampler comprising a tubular casing adapted to be removably interposed in a string of drill pipe so as to constitute a removable component of the drill pipe string, said casing being provided at longitudinally spaced points therein with a pair of axial valve passages and defining a sampler chamber between and in communication with said passages, a valve stem extending axially through said passages and through said chamber, said stem having an upper end adapted to be separably connected to a drill rod and being movable axially relative to said casing between a valve-open and a valve-closed position, and a pair of valve members provided at longitudinally spaced points on said stem for cooperation with the respective passages said valve members being disposed out of said passages to permit free flow of fluid through the passages and through said chamber when said stem is in the valve-open position, but being sealingly received in said passages to block flow therethrough and to retain a fluid sample in said chamber when the stem is moved to the valve-closed position.

2. The device as defined in claim 1 wherein said stem is moved upwardly relative to said casing to the valveclosed position and is moved downwardly to the valveopen position, together with stop means provided in the casing for limiting upward movement of the valve stem.

3. The device as defined in claim 2 wherein said stop means comprise an annular shoulder provided at the upper end of one of said valve passages, said shoulder being engageable by the adjacent valve member when said stem is moved to the valve-closed position.

4. The device as defined in claim 1 wherein the lower end portion of said valve stem is provided with an axial bore having an outer end and also having an inner end communicating with said sampler chamber whereby fluid may be discharged from said chamber through said bore while the valve stem remains in the valve-closed position, and openable closure means for the outer end of said bore.

5. The device as defined in claim 4 wherein said lower end portion of said stem is provided with a counterbore at the outer end of said bore and with lateral orifice means communicating with said counterbore, said closure means comprising a screw-threaded plug adjustable in the counterbore to selectively block and establish communication between said bore and said orifice means.

References Cited UNITED STATES PATENTS 1,818,981 8/1931 Anderson 235 1,888,814 11/1932 Abercrombie 175-235 2,855,050 10/1958 Smith 175235 2,978,046 4/1961 True 166l62 JAMES A. LEPPINK, Primary Examiner US. Cl. X.R. 175-233, 235

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