US3507340A - Apparatus for well completion - Google Patents

Description

April 21, 1970 u. E. voETTER 3,507,340

APPARATUS FOR WELL COMPLETION Filed Feb. 5, 1968 2 Sheets-Sheet 1 April 21, 1970 u. E. voETTER APPARATUS FOR WELL COMPLETION 2 Sheets-Sheet 2 Filed Feb. 5, 1968 United States Patent() U.S. Cl. 175-4.52 14 Claims ABSTRACT OF THE DISCLOSURE This application discloses well-completion apparatus for injecting uids into earth formations. More particularly, the disclosed ap-paratus exemplifying the invention includes sealing means for isolating portions of a wall of a well bore, with these sealing means being appropriately arranged with means for perforating such isolated wall portions to form a flow passage in an earth formation. 'Fluid-discharge means are arranged for selectively injecting one or more uent substances contained in the apparatus into the formation passage. To provide a reliable indication of the progress of the uid injection, at least one of the uent substances is made radioactive so that radioactivity-responsive monitoring means on the apparatus will provide a surface indication as these radioactive substances are discharged.

Where perforations are made through a well casing into a particularly loose or unconsolidated formation, sand particles and the like will usually be displaced into the well bore as connate fluids are produced from the formation. Thus, unless preventative measures are taken, these sand particles will either settle out and eventually iill the well bore or be carried to the surface by the produced uids and severely damage production equipment. Moreover, where only a few perforations have been made, the production will be severely limited should any of these perforations become plugged.

To solve these problems, apparatus and methods have been devised whereby a loose formation is perforated and a suitable bonding or consolidating agent is injected through the perforation into the formation where, in time, it will react and harden. These agents or so-called plastics generally coat the sand particles and thereby cement them together. Although it will depend upon the particular agents employed, the pore spaces. between adjacent particles are left open in one way or another so as to provide permeability. Thus, that portion of the formation immediately surrounding the perforation is consolidated to serve as a porous support to prevent loose sand particles from entering the perforation as connate fluids are produced from the formation.

Typical of such treating agents, apparatus and methods are those disclosed in Patent Nos. 3,347,314 and 3,348,621 to Nick A. Schuster. As described in these patents, a perforating-and-injection tool is positioned adjacent a formation that is believed to be unconsolidated. An extendible wall-engaging member is voperated to shift the tool toward one wall of the casing and sealingly engage a sealing member on the oppositewall to isolate a portion of the well bore wall from the well control fluids. Shaped charges in the tool are then detonated to produce a circuitous flow passage within the formation. To remove the low-permeability debris typically left in such perforations, iiuid communication is established through the circuitous flow passage between a low-pressure receiver on one end of the tool and the treating agents in the other end of the tool. Connate fluids and a pre-flushing agent will then flush the debris from the flow passage into the receiver. Once the receiver 3,507,340' Patented Apr. 21, '1970 ICC is filled, the formation-consolidating agents are successively injected through the cleaned passage into the formation.

Heretofore, the progress of such consolidation operations has been estimated by monitoring the fluid pressure in the fluid-injection passage of the tool. Such pressure measurements, however, give an indication only of the beginning and completion of the fluid-injection operation. Thus, so long as the various treating agents are supposedly being injected, an observer at the surface can only speculate as to the progress of the injection operation. On the other hand, should the injection unknowingly stop for some reason, there is usually no detectable variation in these pressure measurements. Accordingly, the usual practice is to wait for a substantial time before recovering the tool tobe certain that the injection is not still slowly progressing. Thus, even if it is found that the operation had not actually failed, the tool must still be reconditioned and the consolidation operation repeated. This obviously results in many expensive delays and repeated operations that would otherwise not result with surface indications of the progress of the injection operation.

Accordingly, it is an object of the present invention to provide a formation-,injection tool having means therein for providing reliable surface indications in response to the progressive discharge of treating agents carried therein.

This and other objects of the present invention are attained by providing radioactivity-responsive monitoring means on a formation-injection tool adapted to contain one or more fluent substances that are to be injected into an earth formation. By using at least one uent substance with a detectable radioactivity characteristic, passage of this substance by the radioactivity-responsive means as the substance is being discharged into a formation will provide an indication at the surface that the tool is functioning properly.

The novel features of the present invention are set forth with particularity in the appended claims. The present invention, both as to its organization and manner of operation together with further objects and advantages thereof, may best be understood by way of illustration and example of an exemplary embodiment when taken in conjunction with the accompanying drawings, in which: v

FIGURE l is a view of an exemplary embodiment of a well-completion tool arranged in accordance with the present invention lwithin a well bore and in position to consolidate an earth formation; and

FIGURES 2-4 are sequential views depicting the apparatus of FIGURE l performing a typical formationconsolidating operation.

Turning now to FIGURE l, a well-completion tool 10 employing the principles of the present invention is shown suspended from a multi-conductor cable 11 in a casing 12 secured in the usual manner within a borehole 13 by a column of cement 14. The cable 11 is spooled from a winch (not shown) at the earths surface, with some of its electrical conductors being arranged for selective connection to a typical power source 15 and others being connected to typical pressure indicating-and-recording means 16 at the surface of the ground.

The well-completion tool 10 is comprised of an elongated body 17 which, to facilitate manufacture and assembly, may be arranged in tandemly connected sections. Pack-off means such as longitudinally spaced, annular sealing members 18 and 19 are disposed along the forward side of the body 17 and extendible and retractable wall-engaging means 20 are disposed on its opposite side.

The upper portion of the body 17 encloses a hydraulic system (not shown) for selectively actuating the extendable wall-engaging means 20. This hydraulic system may, for example, be of the type illustrated in Patent No. 3,011,554 to Robert Desbrandes which utilizes the hydrostatic pressure of the well control fluids or mud 21 to develop an increased pressure in the system for selectively actuating the wall-engaging means 20. Thus, upon command from the surface, the wall-engaging means 20 will be extended against one side of the casing 12 to shift the tool laterally and sealingly engage the sealing members 18 and 19 against the opposite side of the casing.

The hydraulically actuated wall-engaging means 20 are comprised of one or more extendible pistons 22 supporting a backup shoe 23 that is normally held in a retracted position against the body 17 by springs 24. The pistons 22 are sealingly received Within hydraulic cylinders (not shown) that are connected to the hydraulic system. Thus, whenever the hydraulic system is activated from the surface, the developed hydraulic pressure will urge the pistons 22 outwardly to extend the back-up shoe 23 against the casing 12. Subsequently, the hydraulic system can be de-activated to relieve the hydraulic pressure acting on the pistons so that retraction of the shoe 23 can be effected. Inasmuch as the particular details of the hydraulic system and wall-engaging means 20 are not necessary for fully understanding the present invention, they have been shown only schematically in FIGURE 1 to show their general relationship to the present invention.

Separate treating-agent receivers or cylinders 25 and 26 are formed in the lower portion of the body 17 which may, for example, be arranged as disclosed in Patent Nos. 3,153,449 and 3,348,621. As described in the latter patent, uid discharge means are provided such as a slidable, annular, piston member 27 that is sealingly disposed in the upper receiver or cylinder around a concentrically positioned tubular member 28 that extends through the upper cylinder 25 into the lower cylinder 26. The upper cylinder 25 is connected by a centrally located passage 29 to a normally-closed valve 30 such as the electrically-responsive valve shown at 41 in Patent No. 3,121,459. To selectively discharge a uent substance from the upper cylinder, a port 31 is provided below the annular piston member so that the pressure of well control fluids 21 acting upon the underside of the piston 27 will move the piston upwardly and displace a treating agent from the cylinder 25 through the passage 29 whenever the valve 30 is opened.

To discharge fluent substances from the lower receiver or cylinder 29, the cylinder is divided into a plurality of separate compartments 32-34 by spaced, floating pistons 35-37 that are each iluidly sealed to the inner wall of the cylinder. For bypassing uent substances around the piston in sequence, normally-closed valves 38 and 39 are arranged in the iloating pistons 35 and 36 and adapted to remain closed to segregate the treating agents in the chambers 32-34 until each piston has reached its upper limit of travel. These pistons 35 and 36 and their respective valves 38 and 39 may be, for example, of the type illustrated in FIGURE 3 of the aforementioned Patent No. 3,348,621. A port 40 in the lower end of the cylinder 26 admits well control uids 21 into the space below the lower piston 37. Thus, as will be subsequently described in greater detail, the hydrostatic pressure of the well control fluids 21 acting on the lower piston 37 will exert pressure on the treating agents in the chambers or compartments 32-34 to sequentially discharge the treating agents from the chambers through the tubular member 28 and into a fluid passage 41 thereabove which has a normally-open valve 42, such as the electrically-responsive valve shown at 105 in the abovementioned Desbrandes patent. It Will be appreciated, of course, that the fluid discharge means for the lower cylinder 26 can also be arranged in accordance with Patent No. 3,327,785 if it is desired to inject the treating agents at a pressure substantially greater than hydrostatic pressure.

The passages 29 and 41 converge above their respective valves 30 and 42 and are connected to a uid passage 43 leading to the uid-outlet portion 44 of the fluiddischarge means. A pressure transducer 45 is provided to continuously monitor the pressure in the fluid passage 43. This transducer 45 may, for example, be of the type shown in FIGURE 9 of the Desbrandes patent and is connected by an electrical lead (not shown) via the cable 11 to the pressure indicating-and-recording apparatus 16 at thesurface of the earth. Thus, by observing the variations Vin pressure measurements, an operator can determine .the occurrence of various functions of the operating cycle of the well-completion tool 10. y

The fluid-outlet portion 44 of the tool 10 is preferably arranged as shown in Patent No. 3,347,322. As disclosed there, the tool 10 is provided with a pair of lateral chambers 46 and 47 within the body 17 that are each open at one end, with the annular sealing members 18 and 19 being mounted around the open ends of these chambers to provide central openings 48 and 49. The lower chamber 47 is connected to fluid passage 43; and thin-walled closure members 50 and 51 are mounted in the chamber on each side of the open upper end of the passage to block the central opening 49 and the rearward portion of the cham-ber. Perforating means, such as a shaped charge 52, are arranged in the rearward portion of the chamber 47 and faced toward the closure members 50 and 51 so that, upon detonation, the perforating jet will puncture the closure members vand be directed through the central opening 49.

In a similar manner, the upper chamber 46 is connected by a fluid passage 53 to an enclosed low-pressure or atmospheric` chamber 54 in the body 17. Thin-walled closure members 55 and 56`are mounted in the upper chamber 46 on each side of the open lower end of the passage 53 to block the central opening 48 of the sealing member 18 and the rearward portion of the chamber. Perforating means, such as a second shaped charge 57, are disposed in the rear of the chamber 46 and directed toward the closure members 55 and 56 so that, upon detonation, the perforating jet will pierce the closure members and be directed through the central opening 48. Suitable electrically-responsive igniter means (as shown at 56 and 57 in FIGURE 2 of Patent No. 3,348,621) are connected to the shaped charges upon connection of selected ones of the conductors in the cable 11 to the power source 15.

For reasons that will subsequently become apparent, it will be noted that the shaped charges 52 and 57 are preferably directed so that the perforating axis of each approaches an intersection with the other at a distance in front of the tool 10. It will be realized, therefore, that when the shaped charge 52 is detonated to puncture the closure members 50 and 51 and produce an upwardly inclined perforation into an earth formation, fluid communication will be established from the fluid passage 43 through the central opening 49 and into the resultant perforation. Similarly, whenever the other shaped charge 57 is detonated, the closure members 55 and 56 will be pierced and fluid communication will be established from the resultant downwardly inclined perforation through the central opening 48 and into the low-pressure chamber 54.

In accordance with the present invention, radioactivityresponsive sensing means 58 are disposed in the body 17 and appropriately arranged in relation to the conduit 43 so that passage of a radioactive substance through the ow conduit will be monitored. The radioactivity detector 58 is connected by way of one or more electrical conductors in the suspension cable 11 to suitable indicating means 59 at the surface. Accordingly, in the operation of the tool 10 of the present invention, each of the various treating agents in the cylinders 25 and 26 will be monitored by the radioactivity detector 58 as they ow through the conduit 43; and, by previously preparing a selected one or ones of these agents to exhibit a radioactive characteristic, the passage of a radioactive agent will provide an unmistakeable indication at the surface that such an agent is flowing at that time through the conduit.-

It will, of course, be recognized that any one of several typical radioactivity-detecting devices can be used at 58. Similarly, various techniques can be employed to make a selected one or ones of the treating agents radioactive. It is preferred, however, to use a radioactivity-detecting device at 58 that employs a Geiger-Mueller tube in view of theirpmore-rugged construction as well as the recognized capability of such devices to operate in higher temperatures than, for example, a device employing a scintillation detector. Inasmuch as the consolidating agents that are customarily used for formation consolidation typically include one or more constituents with a petroleum or hydrocarbon base, it is preferred to use oil-soluble radioactive isotopes or tracers. Typical ones of such tracers are cobalt Co-60 (cobalt naphtenate in either a benzene or a xylene carrier), antimony Sb-l24 in a `benzene carrier, iridium Ir-192 in either a benzene or a Xylene carrier, or iodine I-131 either as `an elemental solution in benzene or as pure iodobenvzen'e (CSH5I). It will berecognized, of course, that each of `lthese tracers are stable even at the relatively high temperatures that might be encountered in a well bore.

Accordingly, it will be appreciated that the radioactivity detector 58 will be selectively responsive to the passage of only a'radioactive fluid through the conduit 43 to provide corresponding indications at the surface (by way of the associated measuring device 59). Thus, by adding a radioactive tracer to one or more of the various treating agents in the cylinders 2S and 26, discharge of these selected agents from the tool will be reliably signalled to the surface to advise an observer that the tool is continuing to` function as planned. On the other hand, should some otherwise undetectable malfunction halt the progress of the operation, the failure to receive expected indications on the measuring device 59 will indicate that the operation is not continuing as intended. This will, of course, allow the tool 10 to be retrieved much sooner than has-been possible heretofore so that the malfunction can be corrected and the tool quickly returned to repeat the operation.

It is of particular significance that the present invention provides more than just go-no go indications that the treating agents in the cylinders 25 and 26 are being discharged. Instead, by employing the present invention, a fairly accurate determination of the rate of injection can also be simply obtained. For example, assuming that radioactive tracers have been added to the treating agents in the compartments 32 and 34, discharge of the treating agent from the compartment 32 will provide a continuing indication on the measuring device 59 so long as this treating agent is being discharged. Thus, since the volumes of each of the various treating agents are known, the rate of dlow of the radioactive treating agent in the compartment 32 can be readily determined by noting the time interval between the first and the last indications of radioactivity on the measuring device 59. Once this flowrate determination is made, an accurate estimate can then be made of the length of time that it should require for the non-radioactive agent in the next compartment 33 to be discharged. An observer can, therefore,` predict with reasonable certainty when to expect the first reappearance of an increased indication on the measuring device 59 which will, of course, occur when the radioactive substance in the lower compartment 34 first passes the radioactivity sensor 58. Thus, if this second indication is not obtained by this anticipated time, it will be known that a malfunction has occurred during the discharge of the second substance and the tool 10 can be retrieved to correct the malfunction without waiting for an unduly long period.

It will also be appreciated that other arrangements can be used as well to make such flow-rate determinations.

6 For example, assuming that only the treating agent in the middle compartment .'33 exhibits a radioactive characteristic, the time required to empty the first compartment 32 can be used to estimate the flow rate from the middle compartment. Similarly, the anticipated flow rate of the agent in the lower compartment 34 can also be estimated once the time required to discharge either the first or the second agent is known. Thus, once either of these flow rates is ascertained, failure of the pressure indicated on the pressure-measuring device 16 to drop within the predicted time interval will indicate that the piston 37 has not reached its final position and that some malfunction has prevented the discharge of all of the treating agent in the lower compartment 34. Other variations will, of course, be possible.

Turning noW to FIGURES 2-4, the successive steps of a typical operation of the well-completion tool 10 are depicted, with the tool employing the principles of the present invention. Although the exact arrangement will be determined by the particular consolidating materials to be used, in a typical operation a preflush fluid such asfa saline solution is contained in the upper compartment 32 of the lower treating cylinder 26; the intermediate compartment 33 contains a plastic consolidation agent such as a formaline-cresol mixture; while the lower compartment 34 contains an after-flush agent such as kerosene. A suitable temporary plugging agent lsuch as Black Magic oil-base mud as supplied by Oil Base, Inc., of Compton, Calif., is deposited in the upper treating cylinder 25..

Although other sequences may be chosen as previously described, it is preferred to make every other one of the treating agents in the cylinder 26 radioactive. In this manner, frequent positive indications of the course of the injection operation will be obtained on the radioactivity indicator 59 at the surface. Thus, to describe an exemplary fluid-injection operation, it will be assumed that a suitable radioactive tracer has been incorporated with the preflush fluid in the upper compartment 32 as well as with the after-flush agent in the lower compartment 34. Similarly, the plugging agent in the cylinder 25 will also be assumed to be radioactive. It will be appreciated, of course, that where the consolidation agent is a two-component agent such as an epoxy requiring a separate catalyst, another piston (similar to the piston 35) will be used to separate the two fluid components. In this event, it would be preferred to make the pre-flush agent and the plastic component radioactive and leave the catalyst and the after-flush agent non-radioactive so that every other agent to be injected would be radioactive and the intervening agents would not be radioactive. If desired, the level of radioactivity in the radioactiveagents can be adjusted so that one of the agents will exhibit a greater level of radioactivity than the other.

Accordingly, as seen in FIGURE 2, after the treating agents have |been deposited in the cylinders 25 and 26, the tool 10 is positioned in the borehole 13 adjacent a selected formation `t'flf. By actuating the hydraulic system, the back-up shoe 23 is extended to shift the tool 10 laterally and sealingly engage the sealing members 18 and 19 against the casing 12. Once the sealing members 18 and 119 have been firmly seated, it will be appreciated that the central openings 48 and 49 in front of the thinwalled closure members 56 and 51 will be isolated from the well control fluids 21 in the borehole 13. By this time, the hydrostatic pressure of the well control fluids 21 will have displaced some of the radioactive pre-flush fluid from the upper compartment 32 through the normally-open valve 42 and into the space between the thinwalled closure members 50 and 51. The presence of the radioactive pre-ush -tluid in the conduit 43 will, of course, cause the radioactivity sensor 58 to respond and provide a corresponding indication on the indicator 59 at the surface.

The lower shaped charge S2 is then detonated to puncture the thin-walled closure members 50 and 51 and produce a perforation 61 that is directed into the formation 60 in a slightly upward direction. As the perforating jet punctures the closure member 51, the hydrostatic pressure of the well control uids 21 (which are at a higher pressure than the formation fluids) will immediately move the pistons 35-7 upwardup in unison to begin displacing the pre-flush fluid from the upper compartment 32 into the perforation 61. Then, when the other shaped charge 57 is detonated to produce a second perforation 62 that either intersects the rst perforation 61 or comes in close proximity thereto, ilow communication will be established through the second perforation from the rst perforation to the atmospheric chamber 54. Thus, as best seen in FIGURE 3, once communication is opened from the formation 60 to the atmospheric chamber 54, the formation pressure will displace connate fluids and adjacent sand particles into the perforations 61 and 62 and on into the atmospheric chamber along with the pre-flush agent. This sudden in-rush of the fluids will ush the debris from within the perforations 61 and 62. It will be appreciated that the sudden in-rush of the preush fluid may enlarge the perforations 61 and 62, as at 63, to provide a still greater surface area for admitting other treating agents. Chamber 54 is preferably of less volume than the volume of the upper compartment 32 containing the preflush agent so that enlargement of the cavity 63 will halt `before the pre-flush agent is exhausted. It will be understood, of course, that the shaped charges 52 and 57 may also be detonated simultaneously to achieve the desired formation cavity 63.

yDetonation of the shaped charges S2 and 57 will result in detectable variations in the fluid pressure in the conduit 43 which are readily observed on the indicator 16 at the surface. Moreover, once the upper shaped charge 57 is detonated and fluid communication is `iirst established between the perforations 61 and 62 and the atmospheric chamber 54, a detectable decrease in pressure will be indicated on the measuring apparatus 16 at the surface. Thus, the commencement of the injection operation will provide unmistakable variations in the measurements obtained on the pressure indicating-and-recording apparatus 16. This -change in pressure measurements will signal the commencement of the injection operation and provide a starting time from which the injection flow rate of the radioactive pre-flush agent from the upper compartment 32 can be determined once the radioactivity indicator 59 indicates that the last of the pre-flush agent has passed the detector 58. Accordingly, although the ow rate of the pre-flush agent may not necessarily be the same as for the other treating agents, an observer will at least have a reasonable basis on which to predict the injection rates of the other treating agents.

Thus, as further seen in FIGURE 3, once the preflush agent has been expelled from the upper compartment 32, the upper floating piston 35 will have reached the top of the cylinder 26 to open the valve 38 therein. Then, the continued application of hydrostatic pressure on the lower piston 37 will displace the other treating agents in controlled sequence from the intermediate and lower chambers 33 and 34 into the formation 60 where the consolidating plastic agent will harden and, in time, consolidate the loose formation.

The continued passage of the second treating agent in the intermediate compartment 33 will be signalled by the absence of the radioactivity measurement on the surface indicator 59. The previously calculated ow rate of the pre-flush agent will, of course, have provided a basis for predicting when to expect the conclusion of the injection of the non-radioactive agent in the compartment 33. Thus, if a renewed signal of radioactivity is obtained on the measuring device 59, it will be known that the expulsion of the radioactive after-flush agent has begun. On the other hand, if no renewed signal is obtained at about the expected time, it will be soon recognized that a malfunction of some nature has probably occurred and the tool 10 can be promptly retrieved for remedial repairs.

After closing the normally-open valve 42 by command from the surface, the normally-closed valve 30 is then opened as seen in FIGURE 4. The hydrostatic pressure of the well control fluids 21 acting through the port 31 will then urge the annular piston 27 upwardly to begin displacing the temporary plugging agent from the upper cylinder 25 into the perforations 61 and 62 or cavity 63. This plugging agent builds up a relatively impermeable surface which prevents contact of the well contro-l fluids 21 with the plastics in the cavity 63 when the tool 10 is removed.

-It is preferred to add one of the aforementioned tracers to the plugging agent in the upper cylinder 25 so that the injection of this substance can also be monitored from the surface. Thus, by observing the radioactivity monitor 59, it will be 4known that opening of the valve 42 was successful to begin the injection of the plugging agent. Reduction of the reading on the measuring device 59 will, of course, indicate the completion of the injection of the plugging agent.

IOnce all of the treating agents have been expelled from the cylinders 25 and 26, the hydraulic system is actuated to relieve the hydraulic pressure therein to retract the back-up shoe 23 and allow the tool 10 to be withdrawn from the borehole 13. The pressure of the well control uids 21 maintains the temporary plugging agent in the cavity 63 while the plastic is setting.

Once the tool 10 has been retrieved, it will also be appreciated that the injection of radioactive treating agents into the formation 60 will leave this portion of the formation radioactive. Thus, as an added feature resulting from the present invention, the perforated and treated formation interval can be subsequently located with typical radioactivity-detecting tools. This will, of course, aid in the accurate placement of other completion tools as well as enable a radioactivity log to be made to establish the location of the perforations 61 and 62 in relation to various formation intervals.

It will be appreciated, therefore, that the present invention has provided new and improved means for reliably monitoring from the surface the progress of the injection of one or more treating substances into subterranean earth formations. By making at least one of several treating substances radioactive, the radioactivity detector in the tool will provide an indication at the surface so long as a radioactive agent is being discharged past the detector. Thus, as described above, from these indications, determinations can be readily made to estimate the flow rate of the treating substances as well as the expected time at which each agent will be injected. In this manner, it will be reliably established when either a malfunction has occurred or the injection operation is continuing satisfactorily. Accordingly, the present invention will enable accurate determinations to be quickly made as to whether an injection operation is -being successfully conducted.

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. Apparatus for use in a well bore traversing earth formations and comprising: a support; sealing means on said support and adapted for isolating a surface in a well bore; means on said support for placing said sealing means into sealing engagement with a well bore surface; perforating means on said support and adapted, upon operation, for passing through said sealing means and such an isolated surface and producing a perforation in an earth formation in communication therewith; a receiver on said support and adapted for containing a uent substance having a detectable characteristic; means on said support and adapted for selectively discharging such a uent substance from said receiver through that isolated surface and into such a perforation; and means adapted for monitoring the passage of a fluent substance from said receiver and responsive to said detectable characteristic to provide indications signalling the discharge of a uent substance having said characteristic.

2. The apparatus of claim 1 wherein said detectable characteristic is radioactivity and said monitoring means include: a radioactivity detector operatively arranged on said support for measuring the radioactivity of tiuent substances passing from said receiver.

3. The apparatus of claim 1 wherein said monitoring means include: detecting means operatively arranged on said support for sensing the passage of a liuent substance having said detectable characteristic and providing signals indicative of said characteristics; and indicating means at the surface responsive to such signals.

4. The apparatus of claim 1 wherein said detectable characteristic is radioactivity and said monitoring means include: radioactivity-detecting means operatively arranged on said support for sensing the passage of radioactive fluent substances and providing signals indicative of such radioactivity; and indicating means at the surface responsive to such signals.

5. Apparatus for use in a well bore traversing earth formations and comprising: a support; sealing means on said support and adapted for isolating a surface in a Well bore; means on said support for placing said sealing means into sealing engagement with a well bore surface; perforating means on said support and adapted, upon operation, for passing through said sealing means and such an isolated surface and producing a perforation in an earth formation in communication therewith; a receiver on said support and adapted for containing a plurality of tiuent substances; pressure-developing means on said support and adapted for selectively discharging such uent substances in succession under pressure through that isolated surface and into such a perforation; first means on said support and adapted for monitoring the pressure at said isolated surface to provide rst signals indicative of the pressure of such fluent substances; and second means on said support and adapted for monitoring the passage of such uent substances from said receiver and responsive only to a detectable characteristic of less than all of such fluent substances to provide second signals indicative of the discharge of a tiuent substance having that characteristic from said receiver.

6. The apparatus of claim 5 wherein said second means include a radioactivity detector; and further including at least two uent substances disposed in said receiver, and less than all of said uent substances being radioactive whereby discharge of a radioactive one of said tluent substances will provide said second signals.

7. Apparatus for use in a well bore traversing earth formations and comprising: a support; sealing means on said support and adapted for isolating a surface in a well bore; means on said support for placing said sealing means into sealing engagement with a Well bore surface; perforating means on said support and adapted, upon operation, for passing through said sealing means and such an isolated surface and producing a perforation in an earth formataion in communication therewith; a receiver on said support and adapted for containing a plurality of fluent substances; means on said support and adapted for selectively discharging such uent substances in succession from said receiver through such an isolated surface and into such a perforation; and detecting means on said support and adapted for monitoring the passage of such fluent substances from said receiver and responsive only to a detectable property of less than all of such fluent substances to provide signals indicative of the discharge of a fluent substance having that property from said receiver.

8. The apparatus of claim 7 further including indicating means adapted for location at the surface of the earth and responsive to such signals to provide an indication of the discharge of a uent substance having that said property.

9. The -apparatus of claim 7 wherein said property is radioactivity.

10. The apparatus of claim 7 wherein said detecting means include: a radioactivity detector; and first and second fluent substances respectively disposed in said receiver, one of said fluent substances having detectable radioactivity.

11. Apparatus for use in a well bore containing fluids and traversing earth formations, said apparatus comprising: a support; an annular sealing member on one side of said support adapted for sealing engagement with a wall in a well bore and defining a central opening within said sealing member; means on said support and selectively operable for placing said sealing member into sealing engagement with a Well bore Wall to isolate said central opening from well bore fluids; perforating means on said. support and including a shaped charge having a perforating axis directed through said central opening and adapted, upon operation, to produce a perforation in an earth formation in communication with said central opening; a receiver on said support and adapted for containing fluent substances; a conduit between said receiver and said central opening; piston means in said receiver and adapted for segregating liuent substances therein from one another; duid-discharge means on said support and selectively operable for discharging such fluent substances under pressure in succession from said receiver and through said conduit to said central opening; pressuremeasuring means adapted for monitoring passage of fluent substances through said conduit. to providetirst signals representative of the pressure of such uent substances;

and radioactivity-detecting means adapted for monitoring passage of fluent substances through said conduit toy v provide second signals representative of the radioactivity of such fluent substances.

12. The lapparatus of claim 11 further including: indicating means adapted for location at the surface andv responsive to said first and second signals to provide corresponding irst and second indications thereof.

13. The apparatus of claim 12 further including: a`

suspension cable adapted to support said well bore apparatus and including electrical conductors operatively interconnecting said pressure-measuring means and said radioactivity-detecting means with said indicating means.

14. The apparatus of claim 13 further including:` first and second uent substances in said receiver, one of said fiuent substances being radioactive whereby discharge of said uent substances will produce said first signals and discharge of said one tiuentsubstance will produce said second signals References Cited UNITED STATES PATENTS DAVID H. BROWN,

U.S. Cl,

Primary Examiner

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