US3396796A - Fluid-sampling apparatus - Google Patents

Description

Aug.

Filed Dec. 1, 1966 E. VOETTER 3,396,796

FLUID-SAMPLING APPARATUS 2 Sheets-Sheet 1 I (////c/$ 5 l oefzer INVENTOR.

Aug. 13, 1968 u. E. VOETTER 3,396,796

FLUID-SAMPLING APPARATUS Filed Dec. 1, 1966 2 Sheets-Sheet 2 BY /02 m0 M f Afro F United States Patent 3,396,796 FLUID-SAMPLING APPARATUS Ulrich E. Voetter, Houston, Tex., assignor to Schlumberger Technology Corporation, Houston, Tex., a corporation of Texas Filed Dec. 1, 1966, Ser. No. 598,447 6 Claims. (Cl. 166-100) ABSTRACT OF THE DISCLOSURE This application discloses fluid-sampling apparatus including a particularly arranged sealing member for taking fluid samples along an elongated interval of earth formations. More particularly, the sampling apparatus is described as including an elongated sealing member having a long recess in its forward face for isolating an elongated section of an earth formation. Spaced ports are formed through the sealing member so as to terminate in the long recess. By connecting sample-admitting means in the apparatus to these ports, fluid samples can be taken through either or both of the ports irrespective of which portion or portions of the isolated formation interval are producible.

Accordingly, as will become apparent, this invention relates to fluid-sampling apparatus; and, more particularly, this invention pertains to fluid-sampling apparatus employing new and improved sealing members with multiple fluid-sampling means for obtaining superior fluid contact with the exposed faces of earth formations to take fluid samples therefrom.

Heretofore, wireline formation fluid-sampling tools have been arranged to take fluid samples through either a single isolated point or two closely spaced isolated points on the wall of a well bore. Typical examples of these single-point sampling tools are shown in Patents 2,441,894, 2,821,256 and 2,965,176. Typical dual-point samplers are shown in Patents 3,104,712 and 3,261,402.

The supposed advantages of such dual-point samplers are that the possibilities of even obtaining fluid samples are significantly increased by using two spaced sampleadmitting means and that more representative samples are presumably obtained by taking samples from two points along a given formation interval. It is, however, not always possible to obtain representative fluid samples even when such dual-point samplers are used in uncased well bores which traverse earth formations having a significant number of closely spaced impervious formation layers, such as shale or the like. It will be appreciated that should the spaced sealing members happen to be straddling an impervious formation layer, the fluid sample obtained will be strictly dependent upon the flow through each of the two isolated points. Thus, should one of the sample-admitting ports be adjacent a fairly tight formation, whatever fluid sample that is recovered will represent only what can be produced from the formation adjacent to the other port. Similarly, should the producing formations be relatively thin and fairly well segregated by intervening imprevious layers, it is impossible to position the tool so precisely that the sample-admitting ports are known to be adjacent a producible formation rather than an impervious layer. Thus, a test might well give inconclusive or even negative results which often will cause a potentially producib-le formation to be overlooked. The same problems are, of course, recognized with respect to the above-mentioned single-point samplers.

Accordingly, it is an object of the present invention to provide new and improved sealing members that are capa- Patented Aug. 13, 1968 ble of making continuous sealing engagement along a significant length of an adjacent earth formation for recovering a fluid sample from all or any portion of the entire sealedoif interval. This and other objects of the present invention are obtained by arranging a sealing member with a longitudinal length that is substantially greater than its transverse width. By providing a recess of corresponding proportions in the forward face of the sealing member and arranging fluid-entry means at spaced intervals in this recess for connection to a fluid-sampling tool, an elongated and quite substantial area along a formation interval can be isolated and placed into fluid communication with the tool so that fluid samples can be taken from any point along the isolated area.

The novel features of the present invention are set forth with particularity in the appended claims. The operation together with further objects and advantages thereof, may best be understood byway of illustration and example of certain embodiments when taken in conjunction with the accompanying drawings, in which:

FIG. 1 depicts sample-taking apparatus employing the present invention as it might appear within a borehole;

FIG. 2 is a simplified, schematic representation of the sample-taking apparatus illustrated in FIG. 1;

FIG. 3 is -a cross-sectional view in elevation of a portion of the apparatus of FIG. 1 and illustrates a preferred embodiment of a sealing member arranged in accordance with the present invention;

FIG. 4 is a cross-sectional view taken along the lines 44 in FIG. 3; and

FIG. 5 is an elevational view of the forward face of the sealing member depicted in FIG. 3.

Turning now to FIG. 1, fluid-sampling apparatus 10 incorporating the principles of the present invention is shown suspended from a multi-conductor cable 11 in an uncased borehole 12. The fluid-sampling apparatus 10 has been positioned adjacent a shale-streaked earth formation 13 for collecting a sample of connate fluids therefrom. The cable 11 is spooled from a winch 14 at the earths surface, with some of its conductors being connected to a switch 15 for selective connection to a conventional power source 16 and others being connected to typical indicating-and-recording pressure-measurement apparatus 17. The fluid-sampling apparatus 10 is comprised of an elongated body 18 which, to facilitate its manufacture and assembly, may be arranged in tandemly connected sections as shown.

Sample-admitting means 19, including a sealing member 20 arranged in accordance with the principles of the present inveniton, are mounted along one side of the body 18 diametrically opposite'from extendible wall-engaging means 21. Inasmuch as the particular details of most of its various components are not necessary for fully understanding the present invention, the fluid-sampling apparatus 10 is shown only schematically in FIG. 2. Since these other components are fully disclosed in either the aforementioned Whitten Patent No. 3,261,402 or some of the other patents referred to above, it is necessary to only briefly explain their basic operation as well as their general relation to one another and to the present invention.

As illustrated in FIG. 2, the fluid-sampling apparatus 10 is basically comprised of a hydraulic system 22 which utilizes the hydrostatic pressure of the Well control fluids to develop an increased hydraulic pressure for actuating the apparatus, the sample-admitting means 19 employing the sealing member 20, and a sample-collecting system 23 for obtaining a sample of connate fluids.

Briefly stated, after the apparatus 10 has been positioned adjacent the formation 13, the hydraulic system 22 is first activated from the surface. In response thereto, the wall-engaging means 21 are extended to laterally shift the apparatus and sealingly engage the sealing member against the exposed face of the formation 13 in readiness for obtaining a fluid sample therefrom. Once it is believed that a good seal is made, the sample-admitting means 19 are employed to collect a fluid sample in the sample-collecting system 23. The pressure in the hydraulic system 22 is then relieved to disengage the wall-engaging means 21 and sample-admitting means 19 for retrieval of the apparatus 10'.

The hydraulic system 22 may, for example, be generally of the type described in the Desbrandes Patent No. 3,011,554 and includes a master piston 24 slidably mounted in a stepped cylinder 25. An electrically actuated mud valve 26 (such as shown in FIG. 4 of the Desbrandes patent) is selectively operable to admit well control fluids through a passage 27 into the cylinder above the piston 24. Thus, whenever the mud valve 26 is opened, the hydrostatic pressure of the well control fluids will drive the master piston 24 inwardly to develop a somewhat greater hydraulic pressure in that portion of the cylinder 25 below the piston. A pressure-regulating valve 28 (such as shown in FIGS. 8 and 8A of the Desbrandes patent) is responsive to the hydrostatic pressure of the well control fluids to maintain the hydraulic pressure in an outlet conduit 29 downstream of the valve 28 at a predetermined differential above the hydrostatic pressure.

The hydraulic system 22 also includes a dump" chamber 30 for the hydraulic fluid that is connected by a branch conduit 31 to a normally-closed, piston-actuated, pressureequalizing valve 32 and, via a normally-closed, electrically actuated valve 33 (such as shown in FIG. 7 of the Desbrandes patent), to the main hydraulic conduit 29. As illustrated in FIG. 2, the equalizing valve 32 normally blocks fluid communication between a conduit 34 leading to the sample-admitting means 19 and a conduit 35 opening to the exterior of the apparatus 19. Thus, whenever hydraulic fluid is admitted to the conduit 31, the equalizing valve 32 will shift outwardly to admit well control fluids into the conduit 34.

The dump chamber 30 is normally at atmospheric pressure and is divided into larger and smaller compartments 36 and 37 separated by a flow restriction or an orifice 38. When it is desired to retrieve the apparatus 10, the valve 33 is opened to simultaneously admit hydraulic fluid from the main conduit 29 to the smaller dump chamber compartment 37 and direct the fluid to the pressure-equalizing valve 32. Although the pressure of the hydraulic fluid will immediately drop when the valve 33 is opened, the lower compartment 37 and .orifice 38 are suitably sized to enable the equalizing valve 32 to be opened before the hydraulic pressure has dropped to its final level. Once the equalizing valve 32 opens, the hydrostatic pressure will be equalized across the sealing member 20.

The extendible wall-engaging means 21 on the opposite side of the body 18 from the sample-admitting means 19 are arranged to shift the apparatus 10 laterally and engage the sealing member 20 against the formation wall prior to taking fluid samples. The hydraulically actuated wall-engaging means 21 are comprised of an extendible back-up shoe 39 which is normally held in a retracted position against the body 18 by springs 40. A piston actuator 41 is connected by a branch conduit 42 to the main hydraulic conduit 29. Thus, whenever the mud valve 26 is opened, the increased pressure in the main hydraulic conduit 29 will urge the piston actuator 41 outwardly to extend the back-up shoe 39 against the adjacent wall of the formation 13.

The sample-admitting means 19 include a pair of Iongitudinally spaced lateral chambers 43 and 44 within the body 18 that are each open at one end, with the sealing member 20 being mounted outside of the body around these open ends to provide an elongated central opening or recess 45 for admitting a fluid sample into the chambers. The chambers 43 and 44 are interconnected by a conduit 46 and, via a normally-closed, electrically actuated valve 47 and another conduit 48, to the sample-collecting system 23.

Perforating means, such as a shaped charge 49, are disposed in the rear of the lower chamber 44, with a thinwalled closure member 50 being mounted in front of the shaped charge to fluidly seal it therein. The shaped charge 49 is connected to electrically responsive igniter means, such as a blasting cap 51, that is ignitable from the surface via a conductor 51a in the cable 11. Thus, so long as it has not been detonated, the shaped charge 49 will be isolated from the sample-collecting system 23 and fluid can enter the apparatus body 18 only by way of the forward end of the upper chamber 43 within the confines of the sealing member 20.

The sample-collecting system 23 includes a sample-receiving chamber 52 which has a normally-open, hydraulically actuated closure or seal valve 53 (such as shown in FIG. 10 of the Desbrandes patent) adapted for movement into engagement with a complementary valve seat 54 in the entrance of the chamber to block flow communication with the main fluid conduit 48. The seal valve 53 is normally held open but, once it has been actuated, it will become latched in a closed position. A normallyclosed, electrically actuated valve 55 connects the seal valve 53 to the main hydraulic conduit 29. Thus, to shut off fluid flow from the main fluid conduit 48, opening of the valve 55 will admit fluid from the hydraulic conduit 29 to shift the piston-actuated valve 53 downwardly into sealing engagement with the valve seat 54.

The sample-receiving chamber 52 generally includes upper and lower compartments 56 and 57 separated by a partition 58 having a flow restriction or orifice 59 therein. A liquid cushion 60, such as water, is disposed in the upper compartment 56 and isolated from the upper portion thereof by a floating piston 61 which is sealingly received within the upper compartment. Since the lower compartment 57 is initially empty, the connate fluids entering the sample-receiving chamber 52 from the conduit 48 will move the piston 61 downwardly at a rate regulated by the flow of the water cushion through the orifice 59.

Pressure transducers 62 and 63 are provided to continuously monitor the pressure in the hydraulic system 22 and sample-collecting system 23. These transducers 62 and 63 may, for example, be of the type shown in FIG. 9 of the Desbrandes patent and are connected by electrical leads 62a and 63a to the pressure indicatingand-recording apparatus 17 (FIG. 1) at the surface of the earth. Thus, by observing the variations of these pressure measurements, an operator will be advised of each step in the operating cycle of the fluid-sampling apparatus 10.

To operate the sample-taking apparatus 10 illustrated in FIGS. 1 and 2, the apparatus is positioned in the borehole 12 adjacent the formation 13 of interest. In the preferred manner of operation, the fiow-line valve 47 is opened first and then the mud valve 26 is opened immediately thereafter. As explained in greater detail in a co-pending application Ser. No. 365,328, now Patent No. 3,305,014, filed May 6, 1964, by Emmet F. Brieger, sequential operation of the valves 47 and 26 in quick succession will substantially equalize the pressures between the sample-collecting system 23 and the formation 13 so that the formation will not be subjected to shock that can disrupt the surface on which the sealing member 20 is to be seated. As pointed out in this co-pending application, corrections can be easily made to discount the effect of the minimal quantity of well control fluids that will enter the sample-receiving chamber 52.

By connecting the power source 16 through the switch 15 to the cable conductor 26a, the mud valve 26 will be opened to admit well control fluids from the passage 27 into the upper portion of the master cylinder 25. This will drive the piston 24 downwardly and develop a substantially greater hydraulic pressure in the lower, reduced-diameter portion of the cylinder 25. The pressureregulating valve 28 will operate to admit hydraulic fluid into the main hydraulic conduit 29 and maintain the pressure therein at a substantially constant differential above the hydrostatic pressure of the well control fluids.

Since the other normally-closed valves 33 and 55 are not yet opened, the hydraulic fluid will be admitted initially only to the branch conduit 42 leading to the wallengaging means 21. Thus, the piston actuator 41 will operate to extend the back-up shoe 39 against the adjacent wall of the formation 13 to shift the apparatus laterally in the opopsite direction. Once the apparatus 10 has been shifted laterally, the annular sealing member 20 will be sealingly engaged against the opposite inner wall of the formation. 13. It will be understood, of course, that by monitoring the pressure transducer 62, an operator can determine when the sealing member 20 has been engaged.

Once the sealing member 20 is set, it will be recognized that whatever recoverable connate fluids there are in the formation 13 will flow into the sample-receiving chamber 52. Although a small quantity of well control fluids will have entered the chamber 52 when the flowline valve 47 was opened, the pressure in the samplereceiving chamber will still be substantially at atmospheric pressure so as to induce flow of whatever producible connate fluids there may be in the formation 13.

It will be appreciated, however, that by virtue of the elongated central opening 45 in the sealing member 20, if there is only a small portion of the formation 13 that is capable of being produced, the connate fluids therein can flow into the sample-admitting means 19 if this portion is in communication with any part of the elongated opening 45. Thus, by employing the new and improved sealing member 20 of the present invention, the available sealed-off flow area will be extremely greater than has been possible heretofore with prior-art sealing members. It will be appreciated that with this increased flow area as well as the continuous contact with a long interval of the formation 13, the possibility of recovering fluid samples from potentially producible formationswill be significantly enhanced.

In the event that pressure measurements provided by the transducer 63 indicate that little or no connat fluids are entering the sam le-collecting system 23, the power switch 15 is operated to connect it to the cable conductor 51a to detonate the shaped charge 51. Upon detonation of the shaped charge 49, the thin-walled closure member 50 will be punctured and the perforating jet will perforate the adjacent formation 13. Accordingly, should there be recoverable connate fluids that can flow into the resultant perforation, they will enter the sample-admitting means 19 and flow into the sample-receiving chamber 52 by way of the conduit 48. It has been found, however, that the superior performance of the sealing member 20 makes it usually unnecessary to employ the shaped charge 51.

It should be noted that the elongated recess 45 effectively bypasses that portion of the fluid passage 34 between the chambers 43 and 44. Thus, should, perchance, the passage 46 by plugged by formation materials or even portions of the elastomeric material around the sealing member 20, the shaped charge 49 can be detonated (if not already) to open the flow passage in front of it. It is recognized by those skilled in the art that such plugging will most likely occur either right in a fluid entry port or in the flow passage 46 immediately adjacent thereto. Opening of this additional passage will permit connate fluids to flow through the recess 45 and into the tool 10 even though that part of the formation that is perforated is not itself producible. This additional flow passage will, therefore, oftentimes enable a successful test to be completed that might well have been a failure heretofore.

In any event, whenever pressure measurements from the transducer 63 indicate that the sample-receiving chamber 52 is most likely full, the power switch 15 is connected to the cable conductor 55a to open the valve 55. Opening of the valve 55 will admit fluid from the main hydraulic conduit 29 to the seal valve 53 and close off the sample-receiving chamber 52. The power switch 15 is then connected to the conductor 33a -to open the valve 33 and relieve the hydraulic pressure holding the wallengaging means 21 in position. Opening of the valve 33 will admit hydraulic fluid to the lower compartment 37 of the dump chamber 30 as well as to the pressureequalizing valve 32. As previously explained, however, the hydraulic pressure in the branch conduit 31 will decrease slowly so that the equalizing valve 32 will first shift outwardly from its flow-blocking position between conduits 34 and 35. Once the well control fluids are admitted through the conduit 34 into the chamber 43, any fluid pressure across the sealing member 20 will be equalized. Finally, as the pressure drops in the main hydraulic conduit 29, the hydrostatic pressure of the well control fluids will, with the assistance of the springs 40, retract the back-up shoe 39 to free the apparatus 10 and allow it to be retrieved.

Turning now to FIG. 3, a partial cross-sectional view in elevation is shown of a portion of the body 18 and a preferred embodiment of a sealing member arranged in accordance with the present invention. In FIG. 5, an eleva-tional view is also shown of the front of the sealing member 100. The sealing member 100 is comprised of an elongated block of a relatively stiff elastomeric material 101 having a recess in its forward face 102 in which a rigid insert member 103 of steel or the like is mounted. The insert member 103 has an elongated, shallow recess 104 formed in its forward face 105. Two holes 106 and 107 are formed through the elastomeric block 101 and insert member 103 that open into the recess 104. As best seen in FIG. 4, the forward face of the insert member 103 and forward face 102 of the elastomeric block 101 are curved along their transverse axes to accommodate the curvature of a borehole. The rear of the elastomeric block 101 is hollowed, as at 108, to insure that the hydrostatic pressure of the well bore fluids will be uniformly distributed along the entire back of the sealing member 100.

The front face 102 of the elastomeric block 101 is carried forwardly of the insert member 103 to provide a yieldable margin that completely surrounds the recess 104. It will also be noted that, as best seen in FIG. 4, the longitudinal edges of the elastomeric block 101 are projected laterally so as to provide a substantial thickness, as at 109, of the elastomeric material along both edges and slightly to the rear of the insert plate 103. Similarly, the upper and lower ends of the elastomeric block 101 are arranged to provide a sufiicient thickness of the elastomeric material above and below the insert 103 for making a fluid-tight seal. Thus, whenever the sealing member 100 is moved against the formation 13, the back-up shoe 39 will be urged with sufficient force to insure that the curved forward face 105 of the insert plate 103 is firmly against the exposed face of the formation as far as its surface irregularities will permit. The inherent resiliency of the elastomeric block 101 will, of course, insure that its forward face 102 will conform to the wall of the formation 13. In this way, the higher hydrostatic pressure of the formation fluids will urge the elastomeric block 101 into sealing engagement and the rigid insert member 103 will support the elastomeric material to prevent its extrusion into the now sealed-off recess 104 as a fluid sample is being obtained.

As best seen in FIG. 3, in the preferred embodiment of the tool 10, the chambers 43 and 44 are arranged to include means for supporting the sealing member 100 as generally shown in FIG. 4-of application Ser. No. 506,444, now Patent No. 3,295,615, filed 'Oct. 22, 1965,

by Emmet F. Brieger and Ulrich E. Voetter but, of course, without a shaped charge being in the upper chamber 43 for the reasons already explained. To support the seal ing member 100, the forward ends of sleeve members 110 and 111 are threadedly secured by complementary threads in those :portions of the holes 106 and 107 through the insert member 103. O-rings are respectively mounted within rings 112 and 113 within the holes 106 and 107 and bonded into the elastomeric block 101 fluidly seal the outer ends of the sleeves 110 and 111. The rearward portions of the sleeves 110 and 111 are slidably and somewhat loosely received in the central bores of annular closure members 114 and 115 that are coincidentally aligned and mounted in the forward ends of the chambers 43 and 44, with O-rings 116 and 117 sealing the sleeves in their respective bores. To limit forward travel of the sleeves 110 and 111, their rearward ends are upset or enlarged, as at 118 and 119, and arranged to engage the rear of the annular members 114 and 115.

The forward ends of the annular closure members 114 and 115 are enlarged, as at 120 and 121, and received in complementary counterbores 122 and 123 formed in the side of the body 18. O- rings 124 and 125 on the rear of their enlarged ends 120 and 121 and O- rings 126 and 127 around their midportions fluidly seal the annular closure members 114 and 115 relative to the body 18. Inasmuch as the transverse and longitudinal rearward edges of the elastomeric block 101 may sealingly engage the tool body 18, the forward faces of the enlarged ends 120 and 121 of the annular members 114 and 115 are provided with communication channels opening to the borehole, such as radial and concentric grooves 128 and 129 in each face, to insure that the full area of the rear of the sealing member 100 will be exposed to the well control fluids.

It will be noted that the sleeves 110 and 111 are appropriately proportioned so that their upset rearward ends 118 and 119 are normally abutted against the rear surfaces of the enlarged ends 120 and 121. In this manner, so long as the apparatus is not set in position, the sealing member 100 is held in its retracted position against the body 18. On the other hand, when the back-up shoe 39 is extended, the apparatus 10 will be moved laterally (to the right as viewed in FIGS. 3 and 4) in the borehole 12.

Thus, as best seen in FIG. 4, the forward longitudinal edges, as at 109, of the elastomeric block 101 will be sealingly engaged against the wall of the borehole 12. Then, as connate fluids are withdrawn from the formation 13, the differential pressure between the well control fluids and connate fluids will act on the rear of the sealing member 100 to further compress the elastomeric material 101 and bring the forward face 105 of the insert plate 103 against the face of the formation. When this occurs, the body 18 of the apparatus 10 will move still further (to the right as viewed in FIG. 4) but now relative to the sleeves 110 and 111 as far as the body can move. This relative movement will move the rear surface of the enlarged portions 120 and 121 of the annular members 114 and 115 away from the upset ends 118 and 119 of the sleeves 110 and 111. Thus, should the flow of connate fluids erode the surface of the formation 13, the insert member 103 can again move slightly forward as necessary to accommodate such erosion or sloughing of the formation material. Should the upper chamber 43 be, for example, the sole entry for connate fluids, the loose fit of the sleeves 110 and 111 within their respective supports 114 and 115 will permit the upper end of the sealing member 100 to move a limited distance further away from the body 18 than the lower end. Similarly, the sealing member 100 will be free to rock about its longitudinal axis a slight amount should this be necessary. In this manner, therefore, the sealing member 100 will be capable of accommodating itself to the borehole 12 as well as possible.

It should be understood as well that alternate forms of sample-admitting means can also be used with the sealing member 100. For example, the sample-admitting means 19 could just as well be arranged as shown in any one of FIGS. 3 and 5-9 shown in the aforementioned Brieger and Voetter application. By using hydraulically actuated sample-admitting means such as shown, for example, in FIG. 6 thereof, the sealing rnemebr would be moved outwardly as the back-up shoe 39 is set to better assure that the sealing member is tightly sealed.

It will be appreciated, therefore, that by employing the new and improved elongated sealing member of the present invention in conjunction with longitudinally spaced, separate, and, preferably, selectively operable sampleadmitting means, a substantial and continuous area of an earth formation can be isolated. With such a substantial area isolated, either one or both of the sampleadmitting means will be capable of withdrawing connate fluids from any point along that formation interval irrespective of whether the producible strata is immediately opposite of the sample-admitting means so long as the forward recess in the sealing member is in communication therewith.

Moreover, by mounting the sealing member in the manner shown and described, it can move Within certain limits to accommodate many irregularities in the formation wall as well as shift to best maintain sealing engagement with a sloughing formation. In the embodiment illustrated, the sealing member is moved into sealing engagement by lateral movement of the tool body and will thereafter shift as circumstances dictate. By employing the aforementioned hydraulically actuated sample-admitting means, however, the sealing member will be moved outwardly from the tool body as the tool is set and will then likewise shift as required to maintain a seal. In any event, by employing a sealing member arranged in accordance with the present invention, formation fluid samples can now be obtained under conditions which heretofore would have been impossible.

While a particular embodiment of the present invention has been shown and described, it is apparent that changes and modifications may be made Without departing from this invention in its broader aspects; and, therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of this invention.

What is claimed is:

1. Fluid-sampling apparatus adapted for use in a borehole to obtain samples of fluids from earth formations penetrated by the borehole and comprising: a support; a sealing member along one side of said support including an elongated elastomeric body having a forward face with an elongated hollow therein, an elongated rigid member disposed in said hollow and having a forward face with peripheral anti-extrusion walls thereon defining an elongated recess, and at least two longitudinally-spaced lateral ports extending through said elastomeric body and rigid member respectively opening into said recess; first and second sample-admitting means on said support including first and second conduit means connected to said spaced ports respetcively; and means for urging said sealing member against a wall of a borehole to sealingly engage said frow-ard face of said elastomeric body therewith and isolate said recess whereby any fluid flow from earth formations lying between said recess may flow into one or the other of said ports, said anti-extrusion walls preventing extrusion of said elastomeric body into said recess.

2. The apparatus of claim 1 wherein said first sampleadmitting means include perforating means directed along an axis passing through said first conduit means.

3. The apparatus of claim 1 wherein said first conduit means are an open tube.

4. The apparatus of claim 3 wherein said second sample-admitting means include perforating means directed along an axis passing through said second conduit means.

5. The apparatus of claim 1 Where one of said conduit means is normally open and one of said conduit means is normally closed.

6. The apparatus of claim 5 wherein perforating means are disposed in said support in alignment with said normally closed conduit, said perforating means being adapted, upon firing, to open said conduit and provide a perforation in said earth formations.

References Cited UNITED STATES PATENTS Boller 166-100 X Blood 166-100 Taylor et a1 166-100 Fox 166-100X Briggs et a1 166100 Reynolds 166--100 X Voetter 166-100 DAVID H. BROWN, Primary Examiner.

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