US3610335A

US3610335A - Apparatus for testing well formations

Info

Publication number: US3610335A
Application number: US50162A
Authority: US
Inventors: Orville Roland Smith
Original assignee: Halliburton Co
Current assignee: Halliburton Co
Priority date: 1970-06-26
Filing date: 1970-06-26
Publication date: 1971-10-05
Anticipated expiration: 1988-10-05
Also published as: CA931071A

Abstract

An apparatus is provided for obtaining a test sample of formation fluids from a well bore formation. An elongated tool is lowered into a well bore and is provided with explosive means for perforating the casing and formation at a desired production site. Sealing means is incorporated on the tool to define an isolated, relatively large diameter fluid flow path from the perforated formation site to a formation fluid receiving, test sampler chamber disposed within the tool. A unitary slide valve arrangement is provided within the tool for sequentially closing the fluid sample test chamber and equalizing the pressure differential across the sealing means to release the sealing means from the formation and permit the overall tool to be withdrawn from the well bore. The slide valve is powered by pressures existing in well bore fluid ambient to the tool.

Description

United States Patent [72] Inventor Orville Roland Smith 3,385,364 5/1968 Whitten 166/100 Houston, Tex. 3,530,933 9/1970 Whitten I66] 100 1970 Primary Examiner.lames A. Leppink M Ill Patented d. 1971 Attorney Burns, Doane, Benedict, Swecker & a [73] Assignee Halliburton Company nunumokh ABSTRACT: An apparatus is provided for obtaining a test sample of formation fluids from a well bore formation. An [54] APPARATUS FOR TBS-"N6 WELL FORMATIONS elongated tool is lowered into a well bore and is provided with 12 Claims 10 Drawing 8% explosive means for perforat ng the cas ng and formation at a desired production site. Sealing means is incorporated on the [52] US. Cl 166/55.l, too] to d fi an isohed relative, use diameter fl id fl 166/100 path from the perforated formation site to a formation fluid [51] lnt.Cl E21b33/l2 receiving test chamber disposed within he tool A Field of Search 166/100, unitary Slide valve arrangement is Provided within the tool f sequentially closing the fluid sample test chamber and equalizing the pressure differential across the sealing means to [56] References CM release the sealing means from the formation and permit the UNlTED STATES PATENTS overall tool to be withdrawn from the well bore. The slide 3,253,654 5/1966 Briggs, Jr. et a]. 166/100 valve is powered by pressures existing in well bore fluid am- 3,430,i8l 2/1969 Urbanoskv 166/100 bient to the tool.

10 -14 I r I6 .2 1 Ii 1 9" i x x a i ,3,

PATENTED OCT 5 ISH SHEET 1 OF 4 INVENTOR ORVILLE ROLAND SMITH Rams, 180m, Puum'at, [Ia/awn MRI/:8

ATTORNEYS APPARATUS FOR TESTING WELL FORMATIONS BACKGROUND OF THE INVENTION The invention relates generally to the testing of earth formations intersected by a well bore and more specifically relates to a new and improved apparatus for conducting such testing operations from a hoisting cable or "wire line."

Currently, formation testing tools are being employed having at least one sealing member or "pad" which is urged into engagement with a well casing or formation face and which functions to define an isolated flow path from a formation perforation developed adjacent the sealing means to a formation fluid receiving chamber within the tool. The perforation within the formation may be formed by an explosive charge carried by the tool and electrically detonated. The perforating action of the charge may be augmented by providing a metallic man to be propelled into the fonnation or, alternatively, the perforation may be developed merely by the blast effect of a shaped charge.

Once the formation fluid seal is set, fluid flows through an isolated path from the formation perforation site to the sample receiving chamber which may be located anywhere within the tool but is preferably disposed at the top or bottom thereof. After a desired volume of formation fluid has been obtained, the sample receiving chamber is closed off from the isolated flow path and the sealing member is released so that the overall tool may be withdrawn from the well bore by a cable and taken to the surface of the well site so that the sample may be removed from the tool to be measured and analyzed.

While complex and multiple valve arrangements in tester tools have been proposed to effect the sequence of operations above described, such arrangements have, in general, lacked the desired structural simplicity and operational reliability.

A common problem associated with perforation type, fluid sampling operations involves the fact that well formations are many times poorly consolidated. Thus, formation fluid comprising a sample may contain large amounts of detritus and/or sand. Such detritus and/or sand, once within a tester tool, tends to block the various flow passageways within the tool, erode various parts thereof, and jam the members, the movement of which may be necessary to the proper functioning of a cable-hoisted testing apparatus.

Additionally, prior attempts to incorporate the several necessary functions of a sample tester tool within one device have often resulted in complicated and expensive equipment. Many prior testing tools have been characterized by an excessive number of moving parts and undesirable bulk.

OBJECTS AND SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a new and improved apparatus for testing the production fluids of earth formations.

It is another object of the present invention to provide an apparatus for obtaining a sample of a formation fluid, which apparatus reduces the detrimental effects of any sand or detritus entrained within such fluid.

It is still another object of the present invention to provide an apparatus for testing formation fluids, which apparatus is less complicated than prior apparatus.

It is yet another object of the present invention to provide an apparatus for testing formation fluids wherein the single movement of a single member results in the sequentially controlled performance of a plurality of vital functions within a tester tool.

It is a further object of the present invention, in the context of the foregoing objects, to provide an apparatus for testing formation fluids wherein well bore fluid pressure is utilized as a power source so that only minimal stored energy need by carried by the tester tool itself.

It is still a further object of the present invention to provide an apparatus for solving many of the problems encountered in obtaining samples of formation fluids using cable-hoisted testing tools.

The objects of the present invention may be achieved by providing a formation testing tool having means carried therein for perforating the side of a well and the formation adjacent thereto. Sealing means is provided for defining an isolated flow path leading from the perforation site to the interior of the tool wherein a formation fluid sample receiving chamber may be disposed. A single, unitary valve means is provided within the tool to sequentially seal the formation fluid sample receiving chamber and release the sealing means from the bore casing so that the tool may be withdrawn from the well bore.

Ambient, well bore fluid pressure may be utilized to power the movement of the valve means in a unique, two-stage manner.

Additional means may ing the valve means.

BRIEF DESCRIPTION OF THE DRAWINGS While the invention is particularly pointed out and distinctly claimed in the concluding portion of the specification, preferred and alternative embodiments of the present invention are described in the following specification. which may be best understood when read in connection with the accompartying drawings in which:

FIG. 1 shows an elevation pictorial view of a preferred embodiment of the present invention disposed within a well bore;

FIG. 2 is a partial sectional view of a tool decentralizing spring assembly taken along the longitudinal axis thereof, with reference to section line 2-2 of FIG. 3;

FIG. 3 is a sectional view of the decentralizing spring shown in FIG. 2 taken along the line 3-3;

FIG. 4 is a detailed, partial sectional view of the apparatus shown in FIG. 1 taken along the longitudinal axis thereof, with tool portions shown in axially spaced relation;

FIG. 5 is a sectional view of a formation fluid sample chamber closing and pressure equalizing valve portion of the apparatus shown in FIG. 4 wherein the sample chamber is in fluid flow communicating relation with a formation perforation;

FIG. 6 is a sectional view of the apparatus shown in FIG. 5 immediately after actuation of the sample chamber closing and equalizing valve mechanism, wherein the sample chamber has been sealed but the pressure differential between the inside and outside of the overall tool has not yet been equalized;

FIG. 7 shows the valve mechanism of FIGS. 5 and 6 sequentially alter the valve mechanism has traveled the full stroke wherein the sample receiving chamber has been sealed and the pressure outside the tool has been communicated to the space within the tool so as to equalize the two pressures;

FIG. 8 is a sectional view of the apparatus shown in FIG. 4 taken along the line 8-8;

FIG. 9 is a sectional view of the apparatus shown in FIG. 4 talten along the line 9-9, and

FIG. 10 is a cross-sectional view of an alternative embodiment of the valve mechanism of the present invention shown in FIGS. 5, 6 and 7 taken along the longitudinal axis thereof.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT OVERALL TOOL Referring now to the drawings in which like numerals are used to indicate like parts throughout the various thereof, FIG. I shows a pictorial view of a formation testing tool which may be lowered on a cable (not shown). The tool is inserted within a well bore 10, which may be defined by a well casing 12. The cylindrical interior surface of the casing 12 is designated by the numeral l3.

The upper end of the tool is provided with a fitting 16 which serves as a "wire line" or cable connector. A formation fluid sample receiving chamber section 18 may be disposed immediately beneath and adjacent the cable connector. As

he provided for hydraulically openshown in FIG. I, an upper adapter section 17 may be used to connect the fitting 16 with the fluid receiving chamber section 18. An explosively actuated valve section 20 is disposed between the sample receiving chamber 18 and a lower, perforator and sealing pad carrier section 22.

Sealing pads 24 are mounted on the outer surface of the carrier section 22 adjacent the explosive charges (not shown) which may be electrically actuated to perforate the formation 14 through the well casing 12. The tool shown in FIG. 1 has two such sealing devices aligned with a common longitudinal plane such that two perforations will be blasted into the formation 14. it should be understood, however, that any number of perforations may be formed using the apparatus of the preferred embodiment.

LOWER END OF TOOL A tool decentralizing, spring apparatus 26 is attached to the lower end of the tool and operates to urge the sealing members 24 into sliding engagement with the surface 13 of the well casing I2.

The operation and detailed structure of the operating spring 26 may best be understood when described in connection with FIG. 2. The function of the decentralizing spring 26 is to bias the sealing pads 24 shown in FIG. 1, against the side 13 of the casing 12 so as to position a perforating shaped explosive charge in proper alignment with a site to be perforated. In order to bias the overall tool toward one side of the internal surface 13 of the casing 12, two bowed leaf springs 30 are mounted on a shaft 32 and extend in a generally longitudinal direction with respect to the tool. Leaf springs 30 are circumferentially spaced 120 from each other and from the longitudinal median plane of sealing pads 24. The upper end of the shaft 32 is formed with male threading 34 which engages within female threading 35 (see FIG. 4) formed on the lower portion of the carrier section 22 of the main body of the overall testing tool. A collar member 36 is also threadedly mounted on the male threads 34 of the axial shaft 32 and provides an anchoring point at which the upper ends of the leaf springs 30 are connected to the axial shaft 32 by means of threaded fasteners 38.

The decentralizing apparatus shown in FIG. 2 is adapted to bias the tool connected thereto to the right, as shown in FIG. I.

The lower end of the leaf springs 30 are connected to a slidable collar member 42 by means of threaded fasteners 44. When the tool is in a well bore, the center, bowed portion of springs 30 will thus yieldably flatten or radially contract and assume the phantom line configuration shown in FIG. 2. This flattening will be permitted by the slidable collar 42. Phantom lines 46 indicate the contracted configuration of the bowed leaf springs 30 and phantom line 48 indicates the position of the collar member 42 when the leaf spring is forced into a configuration indicated by the aforementioned phantom lines 46.

A bull plug 54 may be threadedly engaged on male threads 56 formed on the lower end of the decentralizing spring shaft 32. The purpose of the bull plug 54 is to present a generally pointed leading edge for the overall tool so as to facilitate movement of the tool into and through the well bore.

MAIN BODY OF TOOL Referring now to FIG. 4, details of the main body of the tool are shown in three axially separated views of tool body portions. As will be understood, the length of the tool may vary, depending on the length of tool cylinder walls connecting the portions shown in these views.

The Iefimost portion of FIG. 4 shows the threaded end 34 of the axial shaft 32 of the decentralizing spring arrangement 26. As can be seen, the threaded portion 34 engages within female threading 35 formed within a lower portion of the carrier section 22 of the overall tester tool. Shaped charges 60, each one associated with each pad 24, are disposed within the lower section of the carrier member 22. Each charge 60 is provided with a rearwardly extending conical projection 62. The conical projection 62 fits within a recess 64 which corresponds in configuration to the surface shape of projection 62 and is formed within the interior wall 66 of the carrier section 22. The forward end of the shaped charge is provided with a gun barrel-like stud 68 which extends through the wall of the carrier section 22 and is provided with a wide head portion 70 for impingingly securing a sealing member 24 against the outer surface 71 of the carrier section 22 of the overall tool.

Each sealing member or pad 24 consists of a flexible elastomeric substance such as natural or synthetic rubber and is generally configured as an annular body, curved about the exterior of the carrier section 22. Each pad 24 slides along surface I3 when inserted within the well bore 10.

A rigid metallic disc 72 may be embedded within each sealing member 24 as shown in FIG. 4. A frustoconical sealing nose portion 70 of a studlike, barrel member 68 of the shaped charge 60 engages the disc 72 as shown in FIG. 4. Pin members 74 are mounted within the metallic plate 72 and extend normally therefrom into recesses 76 formed within the wall of the carrier section 22. The pin members 74 function to ensure the proper positioning of the seal member 24 and cooperate with the rearwardly extending conical projection 62, which fits within the recess 64, to properly align the shaped charge and barrel-like stud 68.

OPERATION OF THE PERFORATION AND SEALING MEANS The overall tool is lowered into the well bore I0 by means of a cable (not shown). Upon the proper vertical positioning of the shaped charges 60 and sealing members 24 adjacent a site to be perforated, a conventional firing mechanism shown generally in FIG. 4, is actuated and the shaped charges are detonated. The shaped charges 60 may be detonated by means of an electrical system of which electrical conductors 75 comprise a portion. Upon detonation of the charges 60. the nose portions '70 of the barrel-like studs 68 are punctured by shaped charge blasts. The products of the explosion then puncture the well casing I2 and penetrate deeply into the for mation adjacent thereto.

The well bore fluids in the annulus surrounding the overall tool and the sealing member 24 are under a much higher pressure than are the formation fluids. Consequently, a pressure differential develops which urges the carrier 22 against the perforation site, causing the pads 24 to form seals encircling the formation perforation sites.

The formation fluids are than permitted to flow out from the formation and through the central apertures formed in the nose portions 70 by the detonation of the shaped charges. Since the charge explosions demolish all the structures designated as 60, the formation fluids will flow through the barrel-like stud members 68 and into the space 82 within the carrier section 22 of the too].

As can be seen by a perusal of the central drawing of FIG. 4, more than one perforating charge and sealing member combination may be provided in each testing tool. Since it is important to develop a pressure differential vector operating in a single general direction to obtain proper sealing, it is important that all the sealing members 24 be arranged on a generally vertical line. Likewise, since the differential pressure draws the sealing means and the tool closer to the casing along a vertical line, it is preferred, although not absolutely necessary. that the shaped charges be simultaneously detonated to get the greatest simultaneous impact obtainable.

Tracing the valve section of overall tool now from the lower carrier section 22 into the sampling receiving chamber sealing and pressure equalizing valve section 20, it will be noted that a rough filter member 86 is provided at the juncture between the

sections

22 and 20. The upper end of the carrier section 22 is formed with female threading 88 and the lower portion of the valve section 20 is formed with male threading 90. Threadings 90 and 88 are matingly engageable to provide a rigid connection between

sections

20 and 22. The rough filter member 86 is formed with a male threading 92 at the upper end thereof for threaded engagement within female threading 94 formed within the lower end of the valve member section 20.

A relatively thin walled, slidable hollow valve stem 100 is disposed within an axial passageway 102 of the valve section 20. Axial passageway 102 provides communication through relatively large passageway 103, defined by the hollow stern 100, between the space within the carrier section 22 and the formation fluid receiving sampler chamber 104. This communication is achieved through radial ports 106 formed near the upper end of the valve stem member 100 and communicating with passage 103. When the stem 100 is in the raised position shown in FIG. 4, the ports 106 are disposed in and communicate with the interior of chamber 104.

The passageway 102 is widened along a portion thereof intermediate of its length to form cylindrical surface 110 which defines an annular space 111 about the valve stem 100, It is apparent that, with the valve stem 100 in the position shown in FIG. 4 the formation fluids entering the space 82 defined by the casing of the carrier section 22 will flow from the formation (which is at a higher pressure than the atmospheric pressure within the tool) through the rough filter 86, through the axial fluid passageway 102 of the valve section 20, through the axial fluid passageway 103 of the valve stem member 100 and radially through the ports 106 thereof into the reservoir space 105 defined by the formation fluid sampler receiving chamber 104.

The portion of FIG. 4 at the far right-hand side of the sheet shows the upper portion of the formation fluid receiving chamber 104 which is provided at an upper end thereof with a second rough filter member 113. The upper axial portion of the chamber 104 is formed with female threads 117 which matingly engage with male threads 119 formed on the lower axial end of the upper adapter section 17. The filter 1 13 is provided with threads 121 to engage with threads 170 formed in the lower axial end of section 17. A passageway 123 is defined within the upper adapter section 17 from the filter member 1 13 to the outside surface 1 15 of the upper adapter section 17 at an outlet site 125. A plug member 116 is threadedly secured within the passageway 123 and may be removed from the passageway by a conventional tool to permit the formation fluids to be removed from the sampler chamber after releasing and withdrawing the overall tool from the well bore 10.

The outer cylindrical surface of the stern 100 is formed with a stepped-up or radially enlarged cylindrical portion 108 which fits within the annular space 11 formed intermediate the axial ends of the passageway 102. The valve body for housing the valve stem 100 comprises a cylindrical mandrel 112. Mandrel 112 may be connected at its lowermost end with an adapter member 114 by means of female threads 116 on the lower end of the mandrel and male threads 118 on the upper end of the adapter member 114. The adapter member 114 defines the lower end of section 20 and is connected with carrier section 22 as previously described.

It will be noted, that the composite axial passageway formed through the mandrel member 112, being of reduced diameter near the upper end thereof, forms an internal annular shoulder 120. The reduced diameter of the mandrel corresponds to the outside diameter of the nonstepped-up, or main cylinder wall portion of the valve stem 100. The adapter portion 114 is similarly formed with an axial passageway having a diameter corresponding to the outside diameter of the lower, nonstepped-up portion of the valve stem 100.

OPERATION OF THE SAMPLER RESERVOIR SEALING AND PRESSURE EQUALIZING VALVE With the above-described configuration of valve stem 100 within the mandrel 112 and adapter member 114, it is apparent that, when the valve stem is in the FIG. 4 position, to expose the radial ports 106 to the interior of the sample receiving chamber 104 of the overall tool, the upper radial surface 122 of the stepped-up portion of the valve stem is in abutting relationship with the annular shoulder of the mandrel member 112. The portion of the axial passageway 102 through the mandrel member 112 extending downwardly from the annular shoulder 120 to adjacent the upper end of the adapter member 114 is of a diameter corresponding to the outside diameter of the cylindrical stepped-up portion 108 of the valve stem 100. Therefore, it is apparent that, when a sufficient, downwardly directed, axial, hydraulic force is applied to the radial surface 122 of the stepped-up portion 108 of the valve stem 100, the overall valve stem may be axially moved downward until the lower radial surface 124 of the built-up portion 108 comes into abutting relationship with an upper radial surface 126 of the adapter member 114.

The force necessary to move the valve stem 100 downwardly, so as to seal off the passageway 103 defined therethrough from the interior of the sample receiving chamber 104 by withdrawing radial ports 106 to within the upper axial passageway 102 of the mandrel member 112, may be provided by directing high-pressure annular fluids from outside the tool and through a generally axially extending passageway 128 against the upper radially extending surface 122 of the built-up portion 108 of the valve stem 100. In order to supply the high-pressure annular fluid to the generally axially extending passageway 128 a second passageway 132, shown in FIGS. 1 and 8 is formed in the body of the mandrel member 112 and extends in a radial plane thereof from the up per-most end of the passageway 128 through the outer surface 130 of the mandrel member 112.

FIG. 8 is a cross sectional view of the mandrel member 112 taken along radial line 8-8 of FIG. 4 which lies in the plane containing the above-mentioned second passageway 132. It can be seen from this view that a plug member 134 is threadedly engaged within the passageway 132 by means of male threads 136 on the plug member 134 and female threads 138 formed within the passageway 132. An explosive squib member 140 is retained within a cylindrical recess 142 formed within the plug member 134. Electrical detonating wires 142a lead from the rear portion of the explosive squib 140 through a passageway 144 also extending in the radial plane containing the passageway 132 and defined by the sectional line 8-8 of FIG. 4. An electrical junction 146 is connected to the other end of the detonating wires 1420, which electrical junction is retained within a radially extending recess 148 formed in the outer surface 130 of the mandrel member 112. Wires 1S0 lead from the electrical junction 146 axially upward along the outside of the overall tool up through passageway 151 formed in upper adapter member 117 (see FIG. 4) and through the well bore 10 to an operator's position on the surface of the bore site (not shown).

Upon of the explosive squib 140, the plug member 134 is ruptured and well annulus fluid surrounding the outer surface 130 of the mandrel portion 112 of the overall tool rushes into the passageway 132 and down vertically through the connecting passageway 128 to encounter and act upon the upper radially extending surface 122 of the stepped-up portion 108 of the valve stem 100.

The sequence of operation of the valve stem may be best understood by reference to FIGS. 5, 6, and 7. FIG. 5 shows the valve stem 100 in the uppermost position corresponding to the position of the stem in FIG. 4. The ports 106 are exposed to the internal space defined by the formation fluid sampling chamber 104 so that formation fluids may flow upwardly through the central passageway 103 of the stern 100 and radially outward through the ports 106 into the space defined by the sample receiving chamber 104.

When the squib 140 is detonated, the passageway 132 is opened and the high-pressure annular fluid flows through this passageway axially downwardly through the passageway 128 to act upon the surface 122 of the stepped-up portion of the valve stem 100. The force developed by the pressure of the annular fluids on the area of the radially extending surface 122 forces the stem 100 away from the formation fluid receiving sampling chamber so that the ports 106 of the stem I become blocked by the internal surface 153 of the axial passageway formed through the mandrel 112. At this point, the flow path of formation fluids to the sample receiving chamber is sealed closed and the fluids retained within the formation fluid sampler chamber become isolated. This point in the sequence of valve operation is illustrated in FIG. 6 of the drawing.

As the higlrpressure annular fluids continue to flow through the explosively opened passageways I32 and 128 and continue act upon the area of the radial surface 122 of the stepped-up portion 108 of the valve stem 100, a second passageway 152 formed in the mandrel member 112 of the valve body communicates the high-pressure annular fluids with the annular space I 1 I adjacent the area defining the radially extending surface 122 of the built-up portion 108 of the valve stem 100. This is shown in FIG. 6 of drawings.

As the outer cylindrical surface 154 of the built-up or radially enlarged cylindrical portion 108 of the valve stem I00 clears the radially extending passageway I52, additional annular fluids are permitted to flow through passageway 152 into the annular space 111 adjacent the radially extending surface 122. While passage means 128 and 132 are somewhat small due to their location in the tool, and might be vulnerable to partial plugging, passage 152 is relatively large, continuously open, and not likely to become clogged. In the preferred embodiment of the present invention the radially extending port I52 is several times larger in cross-sectional area than either of the ports I28 or 132 and provides a relatively unobstructed, high-capacity communication path between the well bore and the space I] I. The pressure drop across port 152 should thus not be as great as the pressure drop across port means 128-132.

In efl'ect, the detonation of the squib I40 and the direction of the high-pressure annular fluids through the mandrel I12 and against the area of the radial surface 122 of the valve stem I00 is a starting operation which begins the movement of the valve stem I00 away from the formation fluid sampler chamber 104. The force applied to the surface 122 only need be great enough to move the outer cylindrical surface 154 of the stepped-up portion I08 of the valve stem 100 to a position clear of the large axially extending port I52 formed in the mandrel member 112 of the valve body.

As shown in FIGS. 4, 5, 6, and 7. an additional radially extending port 156 is formed through the valve stem I00 and is positioned to communicate with the annular space 111 when the radial extending surface 124 of the stepped-up portion 108 of the valve stem 100 is in abutting relationship with the radially extending surface I26 of the adapter member at substantially the full stroke of the valve stem 100. Although the preferred embodiment shown in FIG. 7, shows the port 156 aligned with the radially extending passageway I52 at the full stroke of the stem 100, it is only necessary that the port 156 is moved sufficiently away from the formation fluid receiving sampler chamber 104 so as to clear the internal shoulder I24 and communicate with the annular space 111. In this manner, high-pressure, hydrostatic-Le. annulus, fluid rushed in through the radial passageway 152 in the mandrel I12 as the cylindrical surface 154 of the stepped-up portion of the valve stem I00 clears the port 152. Then the high-pressure well annulus fluid rushes into the annular space I11 defined by the cylindrical surface 158 of the nonstepped-up portion of the valve stem I00 and the internal surface 110 of the axial passage I02 within the mandrel member In which cylindrical surface 158 has a diameter corresponding to the diameter of the stepped-up portion I08 of the valve stem I00.

With the valve stem in FIG. 7 position, the high-pressure annulus fluid is then free to flow through the additional port 156 formed within the valve stem 100. Since the terminal portion of the upper axial end of the stern passageway I03 is blocked by a radially extending wall 157, the hydrostatic fluid can only flow downwardly through the axial passageway I03 of the valve stem into the axial passageway 102 formed through the adapter member I14. Therefore. the movement of the valve stem 100 to a position where the upper radial ports I06 become blocked by the internal cylindrical surface 153 results in the flow of hydrostatic fluid being directed to the carrier section 22 end of the tool.

Referring back to FIG. 3 of the drawings, it will be understood that the high-pressure annular fluids will flow through carrier 22 toward the perforation sites. It will be remembered, that the sealing members 24 are forced against the perforation sites by the difi'erential pressure acting across the tool, which diflerential pressure is a resultant of the high-pressure annular fluids on the tool side of the sealing pads and the low-pressure formation fluids on the other side of the pads. However, as the high-pressure annulus fluid flows down through the interior of the tool and out through the isolated flow paths and into the formation perforations, the presure differentials across the sealing pads 24 are eliminated so that the sealing effect of the sealing pads around the perforation sites is released. The overall tool may then be cable hoisted out from the well bore I0 to the surface of the well site. Once the tool is recovered, the formation fluid sample may be withdrawn from the formation fluid sampler reservoir 104 in a manner which will now be described.

Still referring to FIG. 4 and in particular to the portion of the figure representing the uppermost end of the overall tool, the passageway 123 will be noted to extending from the upper end of the formation fluid sampler reservoir I04 and through the outer surface of an upper adapter member 17 upon which a cable coupler member 16 may be mounted. The plug 116, which is threadedly engaged within the passageway 123 so as to block the passage of fluids therethrough. may be removed by a tool so that the formation fluid sample within the reservoir I04 may be removed from within the reservoir.

BRIEF SUMMARY OF THE OVERALL OPERATION OF THE PREFERRED EMBODIMENT OF THE PRESENT INVENTION In operation, the overall tester tool is lowered into the well bore 10 by means of a hoisting cable. When the sealing pads 24 become disposed adjacent a formation site to be perforated, the explosive charges within the tool and behind each sealing pad are detonated. The detonation perforates the well casing I2 and penetrates deeply into the formation. The fluids in the formation being at a substantially lower pressure than the high-pressure hydrostatic annular fluids surrounding the tool, a pressure differential is developed which causes sealing members 24 to sealingly engage the casing while encircling the perforation sites. This pressure differential secures each sealing member around each perforation so that an isolated flow path is formed between the formation fluid and the interior of the overall tester tool.

The formation fluid then flows upwardly through the axial path I02 defined through the various members comprising the overall tool and into the passageway 103 defined by the axially aligned valve stem 100. The formation fluid flows through the axial path 103 of the valve stem to the upper end thereof. This upper end extends into the formation fluid sampling reservoir 104 and is formed with radially extending ports 106. The formation fluids flow radially outwardly through the ports 106 and fill the formation fluid sample receiving reservoir I04.

When the sample receiving reservoir 104 has been filled a desired amount, the explosive squib may be actuated from above so as to open the overall passageway defined by the passageway segments I32 and 128. Upon explosively opening this passageway, the radially extending surface 122 on the valve stem 100 is acted upon by the high-pressure hydrostatic fluids flowing through the passageways I28 and 132. The force resulting from the hydrostatic pressures acting on the ef fective area of the annular surface I22 forces the stem I00 downwardly so that the ports 106 are covered by the surface 153 of the mandrel 112 and, thereby, the sample receiving chamber 104 becomes sealed.

As the cylindrical surface 154 clears the large radially extending port 152 formed in the mandrel 112, an additional, relatively unobstructed and high-capacity flow of high-pressure hydrostatic or well bore annulus fluid enters the space 111 adjacent the radially extending surface 122. This additional flow through port 152 insures reliable actuation of the slide valve means 100, 108, 106.

As the additional port 156 of the valve stem becomes aligned with the annular space 111, the hydrostatic fluids rush through port 152 and space 111 to the interior valve stem passageway 103. The hydrostatic fluids then flow downwardly, away from the sample receiving reservoir 104, through the adapter member 114 and into the sealing means carrier section 22 of the tool. This continues such that fluids build up in the interior of member 114 and flow outwardly from the tool and into the perforations within the well casing 12 and formation 14 adjacent thereto.

As the high-pressure hydrostatic fluids flow to the outside of the sealing pads 24 and into the adjacent perforations, the existing pressure differential between the hydrostatic fluids on one side of the sealing pads 24 and the formation fluids on the other side of the pads is eliminated so as to release each seal and enable it to detach from the side 13 of the casing 12.

At this point, the overall tool is free to be hoisted to the surface of the well site where the plug 1 16 may be threadedly disengaged from within the fluid passageway [23 leading from the upper portion of the sampler reservoir 104 and the formation sample trapped therein may be removed.

ALTERNATIVE VALVE EMBODIMENT Referring now to FIG. of the drawings, an alternative embodiment of the sample chamber closing and differential pressure equalizing valve of the present invention is shown. This unit would be substituted for the slide valve mechanism 100-108 previously discussed.

From top to bottom, the housing construction comprises a sample receiving reservoir 200 threadedly engaged with an adapter member 202 by means of male threads 204 formed on the upper portion of the adapter member and female threads 206 formed on the lower portion of the formation sample reservoir. A valve body section 208 corresponding to the mandrel 112 of the preferred embodiment is threadedly connected with the lower end of the adapter member 202 by means of male threading 210 on the lower end of the valve body section 208. The lower portion of the valve body section 208 is connected with an adapter section 214 of the overall tool, which adapter section 214 corresponds to theadapter portion 114 of the preferred embodiment of the present invention. The valve body section 208 is connected to the carrier section 214 by means of male threads 216 on the lower portion of the valve body and female threads 218 formed within the upper portion of the carrier section 214. A valve stem 220, preferably cylindrical in nature, is disposed axially within the overall tool in a passageway 221 defined generally throughout the various aforementioned sections of the overall tool.

The valve stem 220 has a configuration similar to that of the corresponding valve 100 of the preferred embodiment. The valve stem 220 is a generally hollow elongated cylindrical member having radially extending ports 240 formed at the upper end thereof. A central axial flow path 242 is defined by the internal cylindrical wall 244 of the stem 220, which passageway 242 extends through the lower axial end of the stem 220 but is blocked at the upper axial end thereof by radially extending wall 243 so that fluid flowing upwardly through the lower axial end of the passageway 242 of the stem 220 can only escape out through the radial ports 240 at the upper end thereof.

A stepped-up, or radially outwardly enlarged, cylindrical portion 246 is formed on the stem 220. The stepped-up portion 246 is formed with an upper radially extending surface 248, a lower radially extending surface 250, and a cylindrical outer surface 252.

The valve body section 208 is formed with an axial passageway 254 having a diameter corresponding to the outside diameter of the built-up portion 246 of the valve stem 220. The axial passageway 254 of the valve body section 208 near the lower end thereof, is of decreased diameter which corresponds with the outside diameter of the nonstepped-up portion of the valve stem 220. In this manner, an internal, radially extending, and upwardly facing shoulder 256 is provided which is in abutting relationship with the lower radially extending surface 250 on the built-up portion 246 of the valve stem 220 when the valve stem is moved to its lowermost position at its full length of travel. When the valve stem is in its upward position, as shown in FIG. 10, with the radial ports 240 thereof extending into the fonnation fluid sampling reservoir 200, the upper radially extending surface 248 of the steppedup portion 246 of the valve stem 220 is in abutting relationship with the lower radially extending and downwardly facing portion 258 of the adapter member 202. Thus it can be seen, that the distance of travel of the valve stem 220 has an upper limit defined by the radial surface 248 and a lower limit defined by the surface 256.

The adapter member 202 may be provided with a passageway 260 leading from an outside port 261 of the tool, adjacent the high-pressure well bore fluids downwardly to the upper radially extending surface 248 of the built-up portion 246 of the valve stem 220. This passage arrangement is somewhat similar to the arrangement 128/132 shown in the preferred embodiment of the present invention. In FIG. 10, the passageway 160 leads from ports 261, outside the tool, to the upper radial surface 248 and is blocked by a plug indicated as numeral 262. When an explosive charge, not shown, is detonated, the plug 262 is removed from the flow path defined by passageway 260 and high-pressure hydrostatic, well bore fluid flows therethrough to assert a force against the upper radially extending surface 248 of the built-up portion 246 of the valve stem 220.

This explosive charge may be associated with plug 262 in somewhat the same manner that charge of the FIG. 8 embodiment is associated with plug 134. An electrical function 264, schematically shown in FIG. 10, is associated with the charge which ruptures plug 262 in much the same manner that junction 146 of the FIG. 8 embodiment is associated with charge 140.

The force asserted by the pressure of the hydrostatic well bore fluid on the area of the radially extending surface 248 is sufi'tcient to move the cylindrical surface 252 of the builtup portion 246 of the step valve 220 downwardly and clear of a plurality of radially extending, supplemental, continuously open ports 266, formed circumferentially about the valve body section 208. As the high-pressure hydrostatic fluid flows inwardly through the radial extending ports 266, which are uniquely resistant to clogging, and acts downwardly upon the upper radially extending surface 248 of the valve stem 220, the movement of the valve stem is more reliably actuated and the upper radially extending ports 240 are withdrawn from within the formation fluid receiving chamber 200. The ports 240 are thereby sealed against the internal cylindrical surface 268 of the adapter member 202. The formation fluid sample receiving chamber is thereby sealed against the invasion of well bore fluid and the cylindrical surface of the stepped-up portion 246 of the valve stem 220 is forced downwardly until the lower radially extending surface 250 of the stepped-up portion 246 of the valve stem 220 comes into abutting engagement with the internal shoulder surface 256 at the lower end of the axial passageway of the valve body 208.

The sequential two stage" actuation of port means 260 and 266 affords reliability in operation and minimizes port clogging problems, in a manner akin to the "two stage operation of port means 128/132 and 152.

A cushioning member (not shown) may be disposed between the abutting

surfaces

250 and 256 of the alternative embodiment and surfaces 124 and 126 of the preferred embodiment. The cushioning member may comprise an elastomeric bumper or the like. As will be understood, the space between

surfaces

250 and 256 will be substantially free of liquid.

A generally axially extending flow path 268 may be formed in the valve body section 208 to extend from the lowermost terminal portions thereof to an inwardly directed port 270 adjacent the cylindrically extending surface 252 of the built-up portion 246 of the valve stem 220, when the valve is in the raised position of FIG. 10. When the lower radially extending surface 250 of the built-up portion 246 is in abutting relationship with the internal shoulder 256 of the valve body 208, the port 270 communicates with the radial ports 266 through an annular space left as the upper portion of the cylindrical surface 252 clears the port 270.

As the built-up portion 246 of the valve stem 220 moves to its lowennost position under the influence of hydrostatic fluids entering through the radial port 266, an equalizing flow path is formed for the well fluids, extending through the radial ports 266 of the valve body and into the generally axially extending flow path 268 leading out to the lower terminal end of the valve body. In this manner, high-pressure hydrostatic fluid is directed through the member 214 and into the carrier member 22 upon which sealing pads are mounted and adiacent which the perforation sites are disposed. The high-pressure hydrostatic annular fluids then pass into the perforation site and operate to eliminate the pressure differential across the sealing pads so as to release the sealing cup effect on each sealing pad in the same manner as discussed with respect to preferred embodiment of the present invention. Upon release of the sealing pads, the alternative embodiment of the tester tool of the present invention may be cable or wire line hoisted out from the well bore.

A generally axially extending passageway 272 may be formed in the upper adapter member 202 to extend downwardly from the interior of the hydraulic fluid sampler chamber 200 to a radially extending port 274 formed from the lower end of the generally axially extending passageway 272 to the outer surface of the adapter member 202. A plug member 276 may be threadedly engaged within the radially extending passageway 274 and may be removed by any appropriate tool at the surface of the well site or a laboratory so as to permit the withdrawal of the formation fluid trapped within the formation sampler reservoir 200.

It may be found, that under adverse conditions a pressure buildup may occur in the carrier section and force the stem 120 upward, as a piston would be moved in a cylinder, so as to reexpose the radial extending ports 240 to the interior of the formation fluid sampler reservoir 200. This piston effect may be avoided by the provision of an automatic latch means feature in which a spring loaded latch member 278 may be provided within the valve body. This latch would operate to engage an annular groove 280 formed on the lower axial end of the valve stem 220 when the stem is moved to its lowermost position under the influence of the high-pressure annular hydrostatic fluid.

For example, if the perforated portion 70 of stud 68 and flow path 268 where to become clogged, gas pressure might be generated in the carrier section 22 as a result of detonation of the shaped charges. This pressure might be such that, lacking the restraining influence of the hydrostatic or well bore pressure acting on piston 146, would be sufficient to induce upward or reopening movement of the valve stem 220. Under such circumstances, valve opening movement of stem 220 would occur as the tool was raised through the well bore, since the hydrostatic well bore pressure would progressively diminish to zero during the raising operation. Thus, the latch mechanism 2'78 would tend to act to prevent such upward valve stem movement.

ADDITIONAL FEATURES Referring briefly now to FIGS. 4 and 9, an additional feature is shown which may be incorporated in either the preferred or alternative embodiment of the present invention.

Referring to the preferred embodiment, if for any reason it should be desired at the well head or at a laboratory to move the valve stem I00 of FIG. 4 upwardly, this may be accomplished by pumping a hydrostatic fluid through passageway 300 which extends in a radial plane containing cross-sectional line 9-9. As shown in FIGS. 4 and 9, a generally axially extending passageway 302 extends from the inner terminal end of passageway 300 and into the annular space 111. A plug member 304 may be threadedly engaged within the passageway 300 to block the flow of any fluid therethrough.

in order to force the stem upwardly, the plug 304 is threadedly disengaged from within the passageway 300 and hydrostatic fluids are pumped in through the passageway 300, up through the passageway 302, and against the lower radially extending surface 124 of the built-up portion 108 of the valve stem 100.

SUMMARY OF THE ADVANTAGES OF THE INVENTION It can thus be seen that a formation fluid testing tool has been herein provided, which tool is compact and may be hoist lowered into a well bore.

The operation of slide valve mechanism housed within the tool may be initiated by a very small explosive charge or even by an impulse of energy applied to the tool either hydraulically or pneumatically. The slide valve mechanism sequentially and under positive control, performs the functions of sealing the formation fluid receiving chamber and eliminating the pressure differential between the interior of the tool and the ambient hydrostatic annular fluids surrounding the tool.

As a result of the dual function capacity of the single acting slide valve, the overall tool is less complicated and has fewer moving parts than prior equipment.

As a corollary to the noncomplicated nature of the preferred embodiment, tester tools embodying the present invention are less expensive to build and have a reduced chance of jamming due to the infiltration of sand or detritus into the moving parts thereof. Only a minimal charge need be used as an energy source for moving the valve mechanism as the ambient hydrostatic annular fluid pressure is utilized as the main power source for operating the valve.

The internal flow path configuration made possible by the efficient nature of the present invention, and particularly the preferred embodiment, permits the incorporation of formation fluid passageways having larger diameters than currently possible. These large diameter flow paths. in turn, further reduce the chances of the formation fluid passageway being blocked by sand and detritus.

The simple and reliable operation of the slide valve made possible by the sequentially operable or "two stage" porting, is virtually foolproof so as to insure that the sample retained within the sample receiving chamber is uncontaminated by the annular fluids surrounding the tool and release of the sealing pads occurs.

The cumulative effect of all the aforementioned advantages is that tester tools made in accordance with the present invention are more versatile, and more reliable than prior devices which have heretofore been known.

While what has been shown in the drawing and described in the detailed description is a preferred embodiment and an alternative embodiment of the present invention, it is of course understood that various modifications and changes may be made therein without departing from the invention and it is therefore intended to cover in the appended claims all such modifications and changes as may fall within the true spirit and scope of the present invention.

What I claim is:

1. Apparatus for obtaining formation fluids from well bores comprising:

formation fluid receiving means;

formation perforating means;

fluid passageway means operable to define a flow path leading from a formation perforation to said formation fluid receiving means;

sealing means for isolating said flow path; and

unitary valve means for sequentially closing said isolated flow path to said formation fluid receiving means and for releasing said sealing means in response to a continued, unidirectional valving movement of said valve means; and

said valve means being movable centrally and longitudinally of said apparatus and contains a relatively large, longitudinally extending passageway defining a portion of said fluid passageway means leading from said formation perforation to said formation fluid receiving means.

2. An apparatus according to claim 1 wherein said valve means is powered by pressure applied thereto by well bore fluid dispose the well and ambient to said apparatus, with said pressure being transmitted, in sequence. through larger passage means during movement of said valve means.

3. An apparatus according to claim I:

wherein said valve an elongated valve stem having said longitudinally extending passageway; and

wherein said apparatus includes a plurality of sequentially openable passage means operable to transmit well bore pressure to said valve means and induce movement thereof.

4. An apparatus according to claim 3 with:

said valve stem being generally cylindrical in configuration and having a cylindrical wall portion;

a first axial end of said valve stem being formed with a wall extending radially across said longitudinally extending passageway;

said radially extending wall being operable to prevent the passage of fluids through said first axial end of said valve stem;

a second axial end of said valve stem being open so as to permit the flow of fluids into or out from said longitudinally extending passageway of said valve stem through said second axial end;

first generally radially extending port means being formed in said cylindrical wall portion of said valve stem adjacent said first axial end of said stern, said port means being adapted to transmit well bore fluid to said formation fluid receiving means; and

second generally radially extending, equaling port means formed in said cylindrical wall portion and in continuous communication with said longitudinally extending passageway, said second port means being adapted to transmit the pressure of well bore fluid to said sealing means to effect the release thereof.

5. An apparatus according to claim 4 wherein:

said first generally radially extending port means in said valve stem is disposed in fluid flow communicating relation with the interior of said formation fluid receiving means for the filling of said formation fluid receiving means with formation fluids;

said valve stem is formed with an outer, radially outwardly enlarged cylindrical portion having first and second radially extending surface areas formed at each axial end thereof;

said apparatus is provided with a valve body for supporting said valve stem;

a first fluid passageway means in said valve body extends from well bore fluid surrounding the overall apparatus to said first radially extending surface area formed on said outer cylindrical portion of said valve stem;

a plug means is disposed within said first valve body fluid passageway means;

said apparatus includes means for imparting an impulse of energy to said plug means to rupture said plug means;

the rupturing of said plug member is operable to direct said well bore fluid to said first radially extending surface of said outer cylindrical portion of said valve stem through said first fluid passageway means; and

an axial force is developed on said valve stem by said well bore fluid acting on said first radially extending surface of said stepped-up portion, said axial force being operable to slide said valve stem axially away from said formation fluid receiving means whereby said first radially extending port means formed in said valve stem is withdrawn from fluid flow communicating relation with the interior of said formation fluid receiving means, and said formation fluid receiving means is sealed from said isolated flow path to said formation perforation by said radially extending wall disposed across said first axial end of said longitudinally extending passageway through said valve stem.

6. An apparatus according to claim 5 wherein:

said valve body is formed with second fluid passageway means in said valve body and operable to extend from the well bore fluid surrounding the overall apparatus to said cylinder portion formed on said valve stem;

said second fluid passageway means is spaced longitudinally of said stem from the said first fluid passageway means by an increment of axial distance;

the movement of said valve stem through said last mentioned increment of axial distance in response to the well bore fluid passing through said first fluid passageway means and acting against said first radially extending surface on said cylindrical portion of said stern being operable to expose said first radially extending surface on said cylindrical portion of said valve stem to said second fluid passageway means to direct additional well bore fluid against said first radially extending surface.

7. An apparatus according to claim 6 wherein:

said second radially extending port means is operable to place said well bore fluid in fluid flow communicating relation with said longitudinally extending fluid passageway defined through the interior of said stem when said stem is moved a sufficient axial distance to withdraw said first port means from flow communicating relation with said formation fluid receiving chamber 8. An apparatus according to claim 7 wherein:

an annular space is formed in said valve body about said stem when said cylindrical portion of said stem is moved in a direction away from said formation fluid receiving means; and

one axial end of said annular space is defined by said first radially extending surface of said cylindrical portion of said valve stem.

9. An apparatus according to claim 3 with:

at second axial end of said valve stem being open so as to permit the flow of fluids into or out from said longitudinally extending passageway of said valve stem through said second axial end;

equalizing port means formed in a valve body surrounding said valve stem and in continuous communication with said longitudinally extending passageway, said equalizing port means being adapted to transmit the pressure of well bore fluid to said sealing means in response to a terminal movement of said valve stem; and latch means operable to engage and secure said valve stem subsequent to said terminal movement.

10. Apparatus for obtaining formation fluids from well bores comprising:

formation fluid receiving means;

formation perforating means;

fluid passageway means for defining a flow path from a for mation perforation to said formation fluid receiving means;

sealing means for isolating said flow path; unitary valve means for sequentially closing said isolated flow path to said formation fluid receiving means and for releasing said sealing means in response to a continued, unidirectional valving movement of said valve means; said valve means comprising an elongated valve stem having a longitudinally extending passageway formed therethrough; said londtudinally extending passageway formed in said stem comprising a portion of said fluid passageway means leading from said formation perforation to said formation fluid receiving means; and a plurality of sequentially openable passage means operable to transmit well bore pressure to said valve means and induce movement thereof, with the first operable one of said passage means being opened in response to the detonation of explosive means, and a later operable one of said passage means being larger in flow capacity than said first operable one of said passage means and continuously in communication with the exterior of said tool.

11. An apparatus according to claim 10 wherein an additional passageway is provided which communicates with said valve means and is operable to be connected with a source of pressurized fluid whereby hydraulic fluid may be forced inwardly through said additional passageway and be directed against said stem to force said stem toward said formation fluid receiving chamber and cause said stem to open a portion of said isolated flow path and permit fluid to move out of said formation fluid receiving means.

12. An apparatus according to claim 10 with the addition of latch means;

said latch means operable to lock said valve means in a position where said isolated flow path is closed and said sealing means are released.

Claims

1. Apparatus for obtaining formation fluids from well bores comprising: formation fluid receiving means; formation perforating means; fluid passageway means operable to define a flow path leading from a formation perforation to said formation fluid receiving means; sealing means for isolating said flow path; and unitary valve means for sequentially closing said isolated flow path to said formation fluid receiving means and for releasing said sealing means in response to a continued, unidirectional valving movement of said valve means; and said valve means being movable centrally and longitudinally of said apparatus and contains a relatively large, longitudinally extending passageway defining a portion of said fluid passageway means leading from said formation perforation to said formation fluid receiving means.

2. An apparatus according to claim 1 wherein said valve means is powered by pressure applied thereto by well bore fluid dispose the well and ambient to said apparatus, with said pressure being transmitted, in sequence, through larger passage means during movement of said valve means.

3. An apparatus according to claim 1: wherein said valve an elongated valve stem having said longitudinally extending passageway; and wherein said apparatus includes a plurality of sequentially openable passage means operable to transmit well bore pressure to said valve means and induce movement thereof.

4. An apparatus according to claim 3 with: said valve stem being generally cylindrical in configuration and having a cylindrical wall portion; a first axial end of said valve stem being formed with a wall extending radially across said longitudinally extending passageway; said radially extending wall being operable to prevent the passage of fluids through said first axial end of said valve stem; a second axial end of said valve stem being open so as to permit the flow of fluids into or out from said longitudinally extending passageway of said valve stem through said second axial end; first generally radially extending port means being formed in said cylindrical wall portIon of said valve stem adjacent said first axial end of said stem, said port means being adapted to transmit well bore fluid to said formation fluid receiving means; and second generally radially extending, equaling port means formed in said cylindrical wall portion and in continuous communication with said longitudinally extending passageway, said second port means being adapted to transmit the pressure of well bore fluid to said sealing means to effect the release thereof.

5. An apparatus according to claim 4 wherein: said first generally radially extending port means in said valve stem is disposed in fluid flow communicating relation with the interior of said formation fluid receiving means for the filling of said formation fluid receiving means with formation fluids; said valve stem is formed with an outer, radially outwardly enlarged cylindrical portion having first and second radially extending surface areas formed at each axial end thereof; said apparatus is provided with a valve body for supporting said valve stem; a first fluid passageway means in said valve body extends from well bore fluid surrounding the overall apparatus to said first radially extending surface area formed on said outer cylindrical portion of said valve stem; a plug means is disposed within said first valve body fluid passageway means; said apparatus includes means for imparting an impulse of energy to said plug means to rupture said plug means; the rupturing of said plug member is operable to direct said well bore fluid to said first radially extending surface of said outer cylindrical portion of said valve stem through said first fluid passageway means; and an axial force is developed on said valve stem by said well bore fluid acting on said first radially extending surface of said stepped-up portion, said axial force being operable to slide said valve stem axially away from said formation fluid receiving means whereby said first radially extending port means formed in said valve stem is withdrawn from fluid flow communicating relation with the interior of said formation fluid receiving means, and said formation fluid receiving means is sealed from said isolated flow path to said formation perforation by said radially extending wall disposed across said first axial end of said longitudinally extending passageway through said valve stem.

6. An apparatus according to claim 5 wherein: said valve body is formed with second fluid passageway means in said valve body and operable to extend from the well bore fluid surrounding the overall apparatus to said cylinder portion formed on said valve stem; said second fluid passageway means is spaced longitudinally of said stem from the said first fluid passageway means by an increment of axial distance; the movement of said valve stem through said last mentioned increment of axial distance in response to the well bore fluid passing through said first fluid passageway means and acting against said first radially extending surface on said cylindrical portion of said stem being operable to expose said first radially extending surface on said cylindrical portion of said valve stem to said second fluid passageway means to direct additional well bore fluid against said first radially extending surface.

7. An apparatus according to claim 6 wherein: said second radially extending port means is operable to place said well bore fluid in fluid flow communicating relation with said longitudinally extending fluid passageway defined through the interior of said stem when said stem is moved a sufficient axial distance to withdraw said first port means from flow communicating relation with said formation fluid receiving chamber.

8. An apparatus according to claim 7 wherein: an annular space is formed in said valve body about said stem when said cylindrical portion of said stem is moved in a direction away from said formation fluid receiving means; and one axial end of said annular space is defined by said first radially extending surface of said cylindrical portion of said valve stem.

9. An apparatus according to claim 3 with: said valve stem being generally cylindrical in configuration and having a cylindrical wall portion; a first axial end of said valve stem being formed with a wall extending radially across said longitudinally extending passageway; said radially extending wall being operable to prevent the passage of fluids through said first axial end of said valve stem; a second axial end of said valve stem being open so as to permit the flow of fluids into or out from said longitudinally extending passageway of said valve stem through said second axial end; first generally radially extending port means being formed in said cylindrical wall portion of said valve stem adjacent said first axial end of said stem, said port means being adapted to transmit well bore fluid to said formation fluid receiving means; and equalizing port means formed in a valve body surrounding said valve stem and in continuous communication with said longitudinally extending passageway, said equalizing port means being adapted to transmit the pressure of well bore fluid to said sealing means in response to a terminal movement of said valve stem; and latch means operable to engage and secure said valve stem subsequent to said terminal movement.

10. Apparatus for obtaining formation fluids from well bores comprising: formation fluid receiving means; formation perforating means; fluid passageway means for defining a flow path from a formation perforation to said formation fluid receiving means; sealing means for isolating said flow path; unitary valve means for sequentially closing said isolated flow path to said formation fluid receiving means and for releasing said sealing means in response to a continued, unidirectional valving movement of said valve means; said valve means comprising an elongated valve stem having a longitudinally extending passageway formed therethrough; said longitudinally extending passageway formed in said stem comprising a portion of said fluid passageway means leading from said formation perforation to said formation fluid receiving means; and a plurality of sequentially openable passage means operable to transmit well bore pressure to said valve means and induce movement thereof, with the first operable one of said passage means being opened in response to the detonation of explosive means, and a later operable one of said passage means being larger in flow capacity than said first operable one of said passage means and continuously in communication with the exterior of said tool.

12. An apparatus according to claim 10 with the addition of latch means; said latch means operable to lock said valve means in a position where said isolated flow path is closed and said sealing means are released.