US3347314A

US3347314A - Methods for well completion

Info

Publication number: US3347314A
Application number: US451787A
Authority: US
Inventors: Nick A Schuster
Original assignee: Schlumberger Technology Corp
Current assignee: Schlumberger Technology Corp
Priority date: 1965-04-29
Filing date: 1965-04-29
Publication date: 1967-10-17
Anticipated expiration: 1984-10-17

Description

Oct. 17, 1967 N. A. scHUsTER 3,347,314

' METHODS FOR WELL COMPLETION Filed April 29, 1965 E 5 sheets-sheet 1 gg 63 i. 26 60 7; .'I 23 45" 55 I; L 25 i0 f 47 Y f f f f f i l l 32 I l I I JJ l 205 I I /l//C 0J ze/4 I INVENTOR.

. 1 l l /f/ l l Oct. 17, 1967 N A, SCHUSTER 3,347,314

METHODS FOR WELL COMPLETION Filed April 29, 1965 5 SheetS-Sheet 2 Z INVENTOR.

OC- 17, 1967 N. A. scHUsTER 3,347,314

METHODS FOR WELL COMPLETION Filed April 29, 1965 5 Sheets-Sheet 3 United States Patent O 3,347,314 METHDS FOR WELL CMPLETION Nick A. Schuster, Houston, Tex., assigner, by mesne assignments, to Schlumberger Technology Corporation, Houston, TeX., a corporation of Texas Filed Apr. 29, 1965, Ser. No. 451,737 17 Claims. (Cl. 16o-13) ABSTRACT F THE DISCLOSURE This application discloses methods for consolidating incompetent earth formations. More particularly, the disclosed methods are directed toward consolidating incompetent earth formations and providing iluid communication therewith of improved quality Without the attendant production of loose formation materials. These methods are accomplished yby first perforating the particular formation being completed in such a manner as to establish a circuitous flow passage therein. Suitable fluids are then successively injected into one end of the circuitous flow passage as communication is established at its other end with an enclosed chamber initially at a reduced or atmospheric chamber for flushing out debris in the ilow passage as well as loosened formation particles to develop the ilow passage into an enlarged cavity in the formation. Once the chamber is filled, the injected fluids permeate the formation adjacent to the enlarged cavity to stabilize or consolidate the formation and maintain the integrity of the cavity.

Accordingly, as will subsequently become more apparent, this invention relates to methods for completing wells; and, more particularly, to methods for inhibiting 'the production of sand from unconsolidated or incompetent subsurface formations.

The present trend in Well completion techniques is to rely upon only one or, at most, a very few perforations at each of carefully selected points in a well rather than indiscriminately scattering a large number of perforations along a wide interval. Where such perforations are made into aparticularly loose or unconsolidated formation, sand particles and the like will, however, 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 fill the well bore or be carried to the surface by the produced fluids and severely damage production equipment. Moreover, with only a few perforations affording limited entry into the formation, the production will be severely limited should any of these perforations 'become plugged.

Accordingly, to solve these problems, apparatus and methods have been devised whereby as soon as a loose formation is perforated, 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 pores spaces between -adjacent particles are left open in one Way or another so as to provide permeability. Thus, a portion of the formation surrounding the perforation is consolidated to serve as a porous support to prevent loose sand particles from entering the perforation as connate uids are produced from the formation.

Typical of such treating agents, apparatus and methods are those disclosed in Patent Nos. 3,153,449 granted to Maurice P. Lebourg and 3,174,547 granted to Roger Q. Fields. As described in those patents, a perforating and injection -tool is positioned adjacent a formation that is believed to be unconsolidated. An extendible Wall-engaging member is operated to shift the tool toward one wall of the casing and sealingly engage a sealing member on the opposite wall to isolate a portion of the well bore from the well control fluids. A perforator, such as a shaped charge, is then actuated to produce a perforation through the isolated portion into the adjacent earth formations.

Thereafter, a bonding agent is ejected from a cylinder in the tool by a displacing piston and ejected through the perforation into the formation.

The present invention is directed toward providing new and improved methods for injecting formation-consolidating materials into unconsolidated formations. In practicing the invention, shaped charges are employed to produce a circuitous flow passage within the formation. When the shaped charges are detonated, however, they will deposit low-permeability debris Within the perforations and on their walls. Examinations have shown that this low-permeability debris includes casing and cement particles as well as residue products of the shaped charges.

Thus, in the present invention, after the shaped charges are detonated, fluid communication is established through the circuitous ow passage between a low-pressure receiver and a source of treating agents at the hydrostatic pressure of the well control fluids. Connate fluids and the treating agents will then flush the debris from the ow passage into the receiver. When the receiver is filled, the formation-consolidating agent is injected through the cleaned passage into the formation.

Accordingly, it is an object of theI present invention to provide new and improved methods for obtaining flow passages into earth formations that are free of such obu jectionable low-permeability debris to increase the ow rate at which treating agents can be injected into the formations as Well as the iiow rate at which connate fluids may be subsequently produced.

This and other objects of the present invention are provided by rst isolating adjacent surfaces in a well bore from the well control fluids; perforating through these isolated surfaces to provide a circuitous iiuid passage from one surface through the formation to the other surface; flushing debris from the passage; and, thereafter, injecting treating .agents into the passage.

A preferred form of apparatus to be used in practicing the new and improved methods of the present invention is comprised of packing means that are selectively operable to isolate adjacent surfaces of an earth formation and cooperatively arranged with perforating means for producing a circuitous ilow passage through the formation from one surface to another as well as means for withdrawing debris from the passage either before or concurrently With the injection of treating agents into the passage.

The novel features of the present invention are set forth with particularity in the appended claims. The present invention7 both as to its organization vand manner of operation together with Afurther objects and advantages thereof, may best be understood by way of illustration and example of certain embodiments when taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a view of one embodiment of a well completion tool Within a well bore and in position to practice the present invention;

FIG. 2 is an elevational view, partially in cross-section, of a portion of the tool depicted in FIG. 1;

FIGS. 3-5 are views depicting in sequence the apparatus of FIG. 1 performing the methods of the present in- Ivention; and

FIGS. 6-8 are views depicting in sequence apparatus similar to that shown in FIG. l practicing a variation of the present invention.

Turning now to FIG. 1, a well completion tool 10 is shown suspended from a multi-conductor cable 11 in a casing 12 secured 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 conductors being arranged for selective connection to a conventional power source (not shown) and others being connected to conventional indicating-and-recording means (not shown) at the surface of the ground.

The well completion tool is comprised of an elongated body 15 which, to facilitate manufacture and assembly, may be arranged in tandemly connected sections. Longitudinally spaced, annular pack-off means or sealing

members

16 and 17 are disposed on one side of the body 15 and extendible and retractable wall-engaging means 18 on its opposite side.

The upper portion of the body 15 encloses a hydraulic system (not shown) for selectively actuating the extendible wall-engaging means 13. This hydraulic system may, for example, be of the type illustrated in Patent No. 3,011,554 granted to Robert Desbrandes which utilizes the hydrostatic pressure of the well control fluids or mud 19 to develop an increased pressure in the system for selectively actuating the wall-engaging means 18. Thus, upon command from the surface, the wall-engaging means 18 will be extended against one side of the casing 12 to shift the tool 10 laterally and sealingly engage the sealing

members

16 and 17 against the opposite side of the casing.

The hydraulically actuated wall-engaging means 18 are comprised of one or more extendible pistons 2f) that support a back-up shoe 21 that is normally held in a retracted position against the body 15 by springs 22. The pistons 20 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 20 outwardly to extend the back-up shoe 21 against the casing 12. Subsequently, the hydraulic system can be deactivated to relieve the hydraulic pressure in the pistons so that retraction of the shoe 21 can be effected. Inasmuch as the particular details of the hydraulic system and wall-engaging means 18 are not necessary for fully understanding the present invention, they have been shown only schematically in FIG. 1 to show their general functions during the practice of the present invention.

Separate treating

agent cylinders

23 and 24 are formed in the lower portion of the body 15 which may, for example, be arranged as disclosed in the aforementioned Lebourg and Fields patents. Thus, as described in the Fields patent, the upper cylinder 23 sealingly receives a slidable, annular, piston member 25 that is sealingly engaged around a concentrically positioned tubular 4member 26 that extends through the upper cylinder into the lower cylinder 24. The upper cylinder 23 is connected by a centrally located passage 27 to a normally-closed valve 28, such as that shown at 41 in Patent No. 3,121,459. A port 29 is provided below the annular piston member 25 so that well control fluids 19 can act upon the piston to displace a treating agent from the cylinder 23 through passage 27 whenever the valve 28 is opened.

The lower cylinder 24 is divided into separate compartments 30-32 by spaced, floating pistons 33-35 that are each fluidly sealed to the inner wall of the cylinder. As will be subsequently explained in greater detail,

normallyclosed valves

36 and 37 in the floating

pistons

33 and 34 remain closed to segregate the treating agents in the chambers 30-32 until each piston has reached its upper limit of travel. These

pistons

33 and 34 and

valves

36 and 37 may be, for example, of the type illustrated in FIG. 3 of the aforementioned Fields patent. A port 3S in the lower end of the cylinder 24 admits well control fluids 19 into the space below the lower piston 35. Thus, as described in greater detail in the Fields patent, the hydrostatic pressure of the well control fluids 19 acting on the lower piston will exert pressure on the treating agents in the chambers .3U-32 to sequentially discharge the treating agents from the chambers through the tubular member 26 and into a fluid passage 39 thereabove which has a normally-open valve 40, such as at 105, in the abovementioned Desbrandes patent.

The

passages

27 and 39 converge above their

respective valves

28 and 40 and are connected to a fluid passage 41 leading to the fluid discharge means 42. A pressure transducer 43 is -provided to continuously monitor the pressure in the fluid passage 41. This transducer 43 may, for example, be of the type shown in FIG. 9 of the Desbrandes patent and is connected by an electrical lead (not shown) via the cable 11 to the pressure indicatingand-recording apparatus at the surface of the earth. Thus, by observing the variations in pressure measurements, an operator can determine the occurrence of various functions of the operating cycle of the well completion tool 10.

The fluid discharge means 42 include a pair of

lateral chambers

44 and 45 within the body 15 that are each open at one end, with the

annular sealing members

16 and 17 being mounted around the open ends of these chambers to provide

central openings

46 and 47. The lower chamber 45 is connected to fluid passage 41; and thin-

walled closure members

48 and 49 are mounted in the chamber on each side of the open upper end of the passage to block the central opening 47 and the rearward portion of the chamber. A shaped charge 50 is received in the rearward portion of the chamber 45 and faces the

closure members

48 and 49 so that, upon detonation, the perforating jet will puncture the closure members and be directed through the central opening 47.

In a simil-ar manner, the upper chamber 44 is connected by a fluid passage 51 to an enclosed low pressure or atmospheric chamber 52 in the body 15. Thin-

walled closure members

53 and 54 are mounted in the upper chamber 44 on each side of the open lower end of the passage 51 to block the central opening 46 of the sealing member 16 and the rearward portion of the chamber. A shaped charge 55 is disposed in the rear of the chamber 44 and directed toward the

closure members

53 and 54 so that, upon detonation, the perforating jet will pierce the closure members and be directed through the central opening 46. Suitable electrically responsive igniter means 56 and 57 (FIG. 2) that are `ignitable from the surface of the earth via conductors in the cable 11, are connected to the shaped

charges

55 and 50.

It will be realized that when the shaped charge 50 is detonated to puncture the

closure members

48 and 49 and produce a perforation into an earth formation, fluid communication will be established from the fluid passage 41 through the central opening 47 and into the resultant perforation. Similarly, whenever the other shaped charge 55 is detonated, the

closure members

53 and 54 will be pierced and fluid communication will be established from the resultant perforation through the central opening 46 and into the low-pressure chamber 52. Accordingly, by detonating the shaped

charges

50 and 55, a circuitous passage (FIG. 3) will be produced in an adjacent earth formation that extends between the

central openings

46 and 47. Thus, debris that is deposited in the circuitous passage can be swept into the low-pressure chamber 52 and treating agents may be injected into the fluid passage either concurrently or shortly thereafter.

Turning now to FIG. 2, an elevational view, partially in cross-section, is shown of a preferred embodiment of the fluid discharge means 42, with reference numerals used in conjunction with FIG. 1 identifying the corresponding elements. The shaped

charge chambers

44 and 45 are formed in the body 15 by longitudinally spaced lateral bores that are tilted in such a manner that their

central axes

58 and 59 intersect a short distance in front of the forward ends of the bores. The shaped charges 5) and 55 are secured and fluidly sealed in their

chambers

45 and 44 behind threaded tubular members 60 and 61 having enlarged-

diameter flanges

62 and 63 on their forward ends. The

flanges

62 and 63 support metal back

plates

64 and 65 carrying the

elastomeric sealing members

16 and 17 and are received within forwardly facing

counterbores

66 and 67 in the body 15 and fluidly sealed therein by O-

rings

68 and 69. O-rings 70 and 71 around the central portions of the tubular members 60 and 61 provide fluid-tight annular spaces 72 and 73 in the forward ends of the

lateral chambers

45 and 44, with

radial bores

74 and 75 connecting these spaces to the central bores through the tubular members.

The thin-

walled closure members

53 and 54 are spaced apart and threadedly secured in the central bore through the upper tubular member 61 on opposite sides of the radial bores 75 to block the central opening 46 and isolate the shaped charge 55. The fluid passage 51 connects the space between the thin-walled closure members 53 and 544 to an enlarged bore thereabove that is closed at its upper end to provide the atmospheric chamber 52. To detonate the shaped charge 55, detonating means 56 are comprised of a short length of detonating cord 76 disposed on the rear of the shaped charge and coupled to a conventional electrical detonator 77 received within a transverse passage 78 extending upwardly from the shaped charge chamber 44.

The other thin-

walled closure members

48 and 49 are arranged in the same `manner and dene a space therebetween in the central bore of the lower tubular member 60 that is connected by the radial bores 74 to the main fluid passage 41. The shaped charge 50 is detonated by detonating means 57 comprised of a detonating cord 79 and electrical detonator 80. The hydraulically actuated pistons 2l) are mounted in hydraulic cylinders in the body with the back-up shoe 21 being normally retracted against the rear face of the body.

Turning now'to FIGS. 3-5, the successive steps of the method of the present invention are schematically illustrated as they would be performed by the well completion tool 10. Although the exact arrangement will be determined by the particular consolidating materials to be used, a pre-flush fluid 81, such as a saline solution, is contained in the upper chamber 30 of the lower treating cylinder 24. The intermediate chamber 31 contains a plastic consolidation agent 82, such as a `formaline-cresol mixture, while the lower chamber 32 contains an afterflush agent 83, such as kerosene. A suitable temporary plugging agent 84, such as Black Magic oil-base mud as supplied by Oil Base, Inc., of Compton, California, is deposited in the upper treating cylinder 23.

After the treating agents 81-84 have been deposited in the

cylinders

23 and 24, the tool 1t? is assembled and positioned in a well bore 13 adjacent a selected formation 85. By actuating the hydraulic system, the back-up shoe 21 is extended to shift the tool 1t) laterally and sealingly engage the sealing

members

16 and 17 against -the casing 12. Once the sealing

members

16 and 17 have been firmly seated, it will be appreciated that the

central openings

46 and 47 in front of the thin-

walled closure members

54 and 49 will be isolated from the well control fluids 19 in the well bore 13. By this time, the hydrostatic pressure of the well control fluids 19 will have displaced some of the pre-flush fluid 81 from the upper chamber 30 through the normally-open valve 39 and into the space between the thin-

walled closure members

53 and 54.

The lower shaped charge 5) is then detonated to puncture the thin-walled closure members 5.3 and 54 and produce a perforation S6 that is directed into the formation 85 in a slightly upward direction. As the perforating jet punctures the closure member 54, the hydrostatic pressure of the well control fluids 19 (which are at a higher pressure than the formation fluids) will immediately displace preflush fluid 81 into the perforation 86. Then, as best seen in FIG. 3, when the other shaped charge 55 is detonated to produce a second perforation 87 that either intersects the first perforation 86 or comes in close proximity thereto, flow communication will be established through the second perforation from the first perforation to the atmospheric chamber 52. Thus, by suddenly opening communication from the formation 35 to the atmospheric chamber 52, the formation pressure will displace connate fluids and adjacent sand particles into the perforations 86 and $7 and on into the atmospheric chamber along with the pre-flush fluid 81. This sudden in-rush of the fluids will flush the debris from within the perforations. It will be appreciated that the sudden in-rush of the pre-flush fluid 81 may enlarge the perforations 86 and 87, as at 88, to provide a still greater surface area for admitting other treating agents. Chamber 52 is preferably of less volume than the volume of the upper chamber 30 for the pre-flush fluid 81.

Thus, as best seen in FIG. 4, once the pre-flush fluid 81 has been expelled from the upper chamber 30, the upper floating piston 33 will have reached the top of the cylinder 24 to open the valve 36 therein. Then, the continued application of hydrostatic pressure on the lower piston 35 will displace the other treating

agents

82 and 83 in controlled sequence from the intermediate and

lower chambers

31 and 32 into the formation 35 where the consolidating plastic agent S2 will harden and, in time, consolidate the loose formation.

It should be understood that the detonation of the second shaped charge 55 and opening of the formations to the low pressure chamber 52 causes both the formation fluids and pressurized pre-flush agent 81 to flush any debris from the perforations. This flushing action which is precipitated by detonation of the second shaped charge 55 can be at any selected time during injection so long as the injection fluids are viscous enough to effect the desired removal of the aforementioned debris.

i After closing the normally-open valve 40 by command from the surface, the normally-closed valve 28 is then opened. The hydrostatic pressure of the well control fluids 19 acting through the port 29 will then urge the annular piston 25 upwardly to displace the temporary plugging agent 84 from the upper cylinder 23 into the perforations 86 and 87 or cavity 88. Agent 84 by filtration builds up a relatively impermeable surface which prevents contact of the well control fluids with plastics in the cavity 88 When the pack-off means 16 and 17 are removed.

Once all yof the treating agents 81-84 have been expelled from the tool 10, the hydraulic system is actuated to relieve the hydraulic pressure therein to retract the back-up shoe 21 and allow the tool to be withdrawn from the well bore 13. The pressure of the well control fluids 19 maintains the temporary plugging agent 84 in the cavity 88 while the plastic is setting.

The consolidation agents used in performing the present invention may be either porous-setting or solid-setting plastics. The invention is not limited, however, to any particular type of sand consolidating agent so long as it is capable of ultimately providing a porous barrier 89 within the formation around the perforation through which it is ejected. Typical types of sand-consolidation agents that may be used generally include (1) a poroussetting type of plastic wherein a phase separation takes place to leave hardened plastic around the sand grains and open pore spaces between the sand grains; (2) a porous-setting type of plastic that shrinks and cracks upon setting to form openings within the consolidating region to allow passage of connate fluids; (3) a solid-setting type of plastic wherein after the plastic is injected, after-flush fluids are injected to wash away the plastic from the pore spaces between sand particles to provide sufficient permeability for flow of connate fluids; and (4) a solid-setting type of plastic wherein at least two of its constituents are kept separated from one another within the treating agent cylinder 24 and are sucessively injected into the formation 85 to mix in situ. i

It will be further realized that the particular nature of the sand-consolidating agent employed will govern whether either a pre-flush or an after-Hush agent are required. Thus, the treating cylinder 24 needs only to contain whatever agents or constituents thereof and arranged in whatever sequence that are considered to be necessary to obtain a porous consolidated portion, as at 89, that is calculated to be sufficiently strong in time to prevent the collapse of the perforations 86 and S7 and cavity 88. Therefore, the present invention should neither be considered as being limited to any particular one or genus of sand-consolidating agents nor requiring pre-ii-ush or after-fiush fluids unless necessary to achieve the abovementioned consolidating reaction.

Accordingly, it will be seen that to practice the method of the present invention, the tool is positioned in the borehole 13 adjacent to the formation 85 of interest. The sealing means 16 and 17 are urged against the casing 12 to isolate a surface thereon from the well control fluids 19. Then, the formation 85 is perforated at spaced intervals, as at 86 and 87, to produce a circuitous flow passage from one portion of the isolated surface to the other and provide flow communications therethrough from a source of a owable substance, such as a treating agent, at an elevated pressure to a receiver at a lower pressure. Then, once the flowable substance has fiushed debris from the circuitous flow passage, treating agents are injected into the formation 85. Thereafter a temporary plugging agent may be injected into the circuitous ow passage to prevent entry of the well control fluids 19.

Turning now to FIGS. 6-8, the successive steps of the present invention are depicted las performed by a well completion tool 100 with a further operational function. Inasmuch as the well completion tool 100 may be arranged in the same manner as the well completion tool 10 but with only minor additions, the same reference numerals employed in FIGS. 1-3 have been used in FIGS. 6-8 with prime marks thereafter to designate the equivalent elements and simplify the description of tool 100. Accordingly, it will be appreciated by comparison of the two groups figures that well completion tool 100 differs essentially from well completion tool 10 only in that a second atmospheric chamber 101 is provided that is connected to atmospheric chamber 52 by way of a fluid passage 102 that is closed by a selectively-operable, normally-closed valve 103.

After treating agents 01-84 have been deposited in the chambers 23 and 24', thel tool 100 is assembled and positioned in a well bore 104 as seen in FIG. 6 adjacent a selected formation 105. `By actuating the hydraulic system, the back-up shoe 21 is extended to shift the tool 100 laterally and sealingly engage the sealing members 16l and 17 against the casing 106. Once the sealing

members

16 and 17 have been firmly seated, it will be appreciated that the central openings in front of the thin-

walled closure members

49 and 54 will be isolated from the well control fluids 107 in the well bore 104. At this time, the hydrostatic pressure of the well control fluids 107 will have displaced some of the pre-flush fiuids 81 from the upper chamber through the normally-open valve 40 and into the space between the thin-walled closure members 48' and 49.

The lower shaped charge 50 is then detonated to puncture the thin-walled closure members 118 and 49 and produce a perforation 108 that is directed into the formation 105 in a slightly upward direction. As the perforating jet punctures the closure member 49', the hydrostatic pressure of the well control `fiuids 107 (which are at a higher pressure than the formation fiuids) will immediately displace pre-flush fiuid 01 into the perforation 108. Then, when the other shaped charge is detonated to provide a second perforation 109 that either intersects the first perforation 108 or comes in close proximity thereto, uid communication will be established through the second perforation from the first perforation to the atmospheric chamber 52'. Thus, by suddenly opening communication from the formation 105 to the atmospheric chamber 52', the formation pressure will displace connate liuids and adjacent sand particles into the perforations 108, 109 and on into the atmospheric chamber 52 along with the pre-flush fluid 81. This sudden in-rush of fluids will flush the debris from Within the perforations. It will be appreciated that the sudden in-rush of the pre-fiush fiuid 81 may enlarge the perforations and 109, as at 110, to provide a still greater surface area for admission of treating agents.

Thus, as best seen in FIG. 7, once the pre-ush fluid 81 has been expelled fom the upper chamber 30', the upper floating piston 33 will have reached the top of the cylinder 24 to open the valve 36. Then, the continued application of the hydrostatic pressure on piston 3-5 will inject the other treating

agents

82 and 83 in controlled sequence from the intermediate and

lower chambers

31 and 32 and into the formation 105 where, in time, the consolidating plastic agent 82 will harden and consolidate the loose formation. Then, when the treating agents 82 and 83l have been exhausted, valve 40 may be closed if desired and valve 28' opened. Opening of valve 2S' will admit the plugging agent 84 into the cavity 110 and allow it to infiltrate the formation 105 until a relatively impermeable filtrate layer has been built up on the cavity walls.

To prevent collapse of the cavity 110, which might occur because of formation pressure equalization or of substantial overburden pressures in a particularly unconsolidated formation, as seen in FIG. 8, a valve 103 is then opened by command from the surface to exhaust the contents of chamber 52' into the other atmospheric Chamber 101. This sudden exhausting of the contents of chamber 52 will, of course, allow a quantity of the plugging agent 84 to fiow through the Cavity 110 and into the chamber 52. The flow of this final flushing will be maintained by hydrostatic pressure and the plugging agent 84 will again form an impermeable filtrate layer. When the tool is removed, the hydrostatic pressure -acting on the plugging agent 84' in the cavity 110 will support the cavity and prevent well control fluids 107 from invading the formation 105. It should be understood, of course, that a valve, such as at 103, could also be used to control fluid cornmunication through passage 51 (and passage 51 in FIG. 1.

Once all of the treating agents 81-84 have been expelled from the tool 100, the hydraulic system is actuated to relieve the hydraulic pressure therein to retract the back-up shoe 21 and allow the tool to be withdrawn from the well bore 104. After the porous support 111 about the cavity 110 has hardened, the pressure of the control fluids 19 can be removed and production can be commenced. The pressure of formation fiuids when greater than the pressure within the casing, causes the temporary plugging agent to be displaced into the casing 12.

Accordingly, it will be -seen that in the practice of the present invention, the tool 100 is positioned in the well bore 104 adjacent the formation 105. The sealing means 16 and 17 are urged against the casting 106 and isolated adjacent surfaces thereon. These adjacent surfaces are then perforated to provide a circuitous fiow passage through the formation 105 from one surface to the other and suddenly open the flow passage to a rst atmospheric chamber, such as 52. Then, as iiuids including a formation-consolidating agent, such as at 82', are injected into the passage, a cavity, such as at 110, will be cut in the formation 105 and the debris washed into the chamber 52'. The formation-consolidating agent 82' will be injected into the formation 105 where, in time, it will firm and provide a hardened but porous support, such as at 111, around the cavity 110. Thereafter, by opening valve 103, a second low-pressure chamber, such as at 101, is opened to flow the plugging agent, such as 84', through the cavity to form a fiow passage. The plugging agent 84 will form an impermeable filtrate layer on the flow passage thru cavity 110. Then, after the tool 1t) is withdrawn, the well control fluids lfi' will enter the cavity and, by virtue of the filtrate layer, keep the flow passage from collapsing.

Thus, it will be appreciated that the present invention has provided new and improved methods for obtaining fluid passages into earth formations that are free of objectionable low-permeability debris so that materials may be injected into the formations at reasonably high flow rates. It should be noted that although the foregoing description was primarily directed to the application of the methods of the present invention in sand consolidation operations, these methods will be equally successful in other completion operations where it is desired to inject flowable materials into an ea-rth formation at reasonably high flow rates.

While particular embodiments of the present invention have 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 of 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. A method of completing a well bore traversing an earth formation, comprising the rsteps of: forming a first passage from the well bore into the formation; forming a second passage from the well bore into the formation in a direction to intersect said first passage to be eectual for establishing fluid communication therebetween; and, thereafter, lowering the pressure in the well bore below that in said passages for withdrawing fluid through said passages to flush debris therefrom into the well bore and enlarge said passages.

2. A method of completing a well bore traversing an earth formation, comprising the steps of: forming a first passage extending from the well bore into the formation; forming a second passage directed from the well bore into the formation and -substantially intersecting said first passage to be effectual for establishing fluid communication therebetween; and, thereafter, discharging fluid under pressure through one of said passages while maintaining the other of said passages at a lower pressure for flushing debris therefrom into the well bore and enlarging said passages.

3. A method of completing a well bore containing a column of Well control fluids and traversing an earth formation, comprising the steps of: packing-off a portion of the well bore to isolate said portion from the well control fluids and from another portion of the well bore; perforating through one of said portions and into the formation to provide a rst passage therein; perforating through the other of said portions and into the formation to provide a second passage therein directed relative to said rst passage to be effectual for establishing fluid communication therebetween; and, prior to unpacking said isolated portion, discharging a fluid at one pressure from said other portion through said passages to said isolated portion while maintaining said isolated portion at a reduced pressure for flushing debris therefrom.

4. A method of completing a well bore containing a column of well cont-rol fluids and traversing an earth formation, comprising the steps of: packing-off a portion of the well bore to isolate said portion from the well control fluids and from another portion of the well bore; perforating through one of said portions and into the formation to provide a first passage therein; perforating through the other `of said portions and into the formation to provide a second passage therein in a direction relative to said first passage to be effectual for establishing fluid communication therebetween; and prior to unpacking said isolated portion, producing a pressure differential in the well bore between said passages; and passing fluid through said passages into said isolated portion.

5. A method of completinga well bore containing a column of well control fluids and traversing an earth formation, comp-rising the steps of packing-off a portion of the well bore to isolate said portion from the well control fluids and from another portion of the well bore, perforating through one of said portions and into the formation to provide a first passage therein, perforating through the other of said portions and into the formation to provide a second passage therein positioned relative to said first passage to be effectual for establishing fluid communication therebetween, and, prior to unpacking said isolated portion, coupling a receiver at a reduced pressure to said isolated portion, said receiver being at a pressure calculated to be sufficient to produce connate fluids from the formation, for flushing debris from at least one of said passages and into the receiver.

6. A method of completing a well bore containing a column of well control fluids and traversing an earth formation, comprising the steps of: packing-off a portion of the Well bore to isolate said portion of the well control fluids and from another portion of the Well bore; perforating through one of said portions and into the formation to provide a first passage therein; perfo-rating through the other of said portions and into the formation to provide a second passage therein positioned relative to said first passage to be effectual for establishing fluid communication therebetween; prior to unpacking said isolated portion, coupling a receiver vat a reduced pressure to said isolated portion; and discharging a fluid at a greater pressure from said other portion through said passages and into the receiver for flushing debris from said passages.

7. A method of completing a well bore containing a column of well control fluids and traversing an earth formation, comprising the steps of: packing-off first and second portions of the well bore to isolate said portions from the well control fluids and from one another; perforating through one of said isolated portions and into the formation to provide a rst passage therein; perforating through the other of said portions and into the formation to provide a second passage therein positioned relative to said first passage to be effectual for establishing fluid communication therebetween; prior to unpacking said isolated portion, coupling a receiver at a reduced pressure to one of said isolated portions; and, thereafter, passing fluid from at least one of said passages and into said receiver for flushing debris therefrom.

8. A method of completing a well bore containing a column of well control fluids and traversing `an earth formation, comprising the steps of: packing-off first and second portions of the well -bore to isolate said portions from the well control fluids and from one another; perforating through one of `said isolated portions and into the formation to provide a first passage therein; perforating through the other of said portions and into the formation to provide a second passage therein positioned relative to said first passage to be effectual for establishing fluid communication therebetween; coupling a receiver at a reduced pressure to one of said isolated portions and `a source containing a fluid at a greater pressure to the other of said isolated portions; and, thereafter, discharging said fluid from said source through said passages and into said receiver for flushing debris from said passages.

9. A method of completing a well bore containing a column of well control fluids and traversing an earth formation, comprising the steps of: packing-off first and second portions of the Well bore to isolate said portions from the well control fluids and from one another; perforating through one of said isolated portions and into the formation to provide a first passage therein; perforating through the other of said portions and into the formation to provide a second passage therein positioned relative to said first passage to be effectual for establishing fluid communication therebetween; prior to unpacking said isolated portion, coupling a receiver at a reduced pressure to one of said isolated portions and a source containing -a fluid at a greater pressure to the other of said isolated portions; discharging said fluid fromsaid source through said passages and into said receiver for flushing debris from said passages; and, thereafter, injecting a temporary plugging agent into said passages to isolate the exposed surfaces therein from the Well control fluids.

if). A method of completing a Well bore containing a column of Well control fluids and traversing an earth formation, comprising the steps of: packing-off first and second portions of the well bore to isolate said portions from the well control fluids and from one another; perfor-ating through one of said isolated portions and into the formation to provide a first passage therein; perforating through the other of said isolated portions and into the formation to provide a second passage therein positioned relative to said first passage to be effectual for establishing fluid communication therebetween; coupling a receiver at a reduced pressure to one of said isolated portions, said receiver being at a pressure calculated to be sufficient to produce connate fluids from the formation, for flushing debris from said passages and into said receiver; coupling a source containing a fluid at a greater pressure to the other of said isolated portions; discharging said fluid from said source through said passages and into said receiver for flushing debris from said passages; and, thereafter, injecting a temporaryV plugging agent into said passages for isolating the exposed surfaces therein from the well control fluids.

11. A method of completing a Well bore containing a column of Well control fluids and traversing an earth formation, comprising the steps of: packing-off first and second portions of the Well bore to isolate said portions from the well control fluids and from one another; perforating through one of said isolated portions and into the formation to provide va first passage therein; perforating through the other of said isolated portions and into the formation to provide a second passage therein positioned relative to said first passage to be effectual for establishing fluid communication therebetween; coupling a receiver at a reduced pressure to one of said isolated portions and a source containing a treating agent at a greater pressure to the other of said isolated portions; discharging said treating agent from said source through said passages for flushing debris from said passages and into said receiver and flowing into the formation when said receiver is filled; and, thereafter, injecting -a temporary plugging agent into said passages for isolating the exposed surfaces therein from the well control fluids.

12. A method of completing a cased Well bore containing a column of Well control fluids and traversing an earth formation believed to include unconsolidated particles comprising the steps of: packing-off first and second portions of the casing to isolate said portions from the Well control fluids and from one another; perforating through the casing at one of said isolated portions and into the formation to provide a first passage therein; perforating through the casing at the other of said isolated portions and into the formation adjacent to said first passage to provide a second passage therein effective for establishing fluid communication with said first passage; coupling a receiver at a reduced pressure to one of said isolated portions and a source containing at least a formation-consolidating fluid at a greater pressure to the other of said isolated portions; and, then, discharging said fluid from said source into said passages for flushing debris from said passages into said receiver and, thereafter, into the formation for consolidating the unconsolidated particles when said receiver is filled.

13. A method of completing a cased well bore containing a column of Well control fluids and traversing an earth formation believed to include unconsolidated particles comprising the steps of: packing-off first and second portions of the casing to isolate said portions from the Well control fluids and from one another; perforating through the casing at one of said isolated portions and into the formation to provide a first passage therein; 4perforating through the casing at the other of said isolated portions and into the formation in a direction relative to said first passage to provide a second passage therein effectual for establishing fluid communication with said first passage; coupling a receiver at a reduced pressure to one of said isolated portions and a source containing a formation consolidating fluid at a greater pressure to the other of said isolated portions; and, discharging said fluid from said source into said passages for flushing debris from said passages into said receiver and, When said receiver is filled, into the formation for consolidating the unconsolidated particles.

lld. A method of completing a cased well bore containing a column of well control fluids and traversing an earth formation believed to include unconsolidated particles, comprising the steps of: packing-off first and second portions of the casing to isolate said portions from the well control fluids and from one another; perforating through the casing at one of said isolated portions and into the formation to provide a first passage therein; perforating through the casing at the other of said isolated portions and into the formation in a direction calculated to approach an intersection with said first passage to provide a second passage therein in fluid communication with said first passage; prior to unpacking said isolated portion, coupling a receiver at a reduced pressure to one of said isolated portions and a source containing a fluid and a formation-consolidating agent at a greater pressure to the `other of said isolated portions; discharging said fluid from said source through said passages and into said receiver for flushing debris from said passages; and, then, discharging said formation-consolidating agent into said passages for consolidating the formation particles.

15. A method of completing a cased well bore containing a column of Well control fluids and traversing an earth formation believed to include unconsolidated particles, comprising the steps of: packing-off first and second portions of the casing to isolate said portions from the Well control fluids and from one another; perforating through the casing at one of said isolated portions and into the formation to provide a first passage therein; perforating through the casing at the other of said isolated portions and into the formation in a direction calculated to approach an intersection With said first passage to provide a second passage therein in fluid communication with said first passage; prior to unpacking said isolated portion, coupling a receiver at a reduced pressure to one of said isolated portions and a source containing a fluid and a formation consolidating agent at a greater pressure to the other of said isolated portions; discharging said fluid from said source through said passages and into said receiver for flushing debris from said passages; discharging said formation consolidating agent into said passages for consolidating the formation particles; and, then, injecting a temporary plugging agent into said passages to isolate the exposed surfaces therein from the Well control fluids.

16. A -rnethod of completing a well bore containing a column of Well control fluids and traversing an earth formation, comprising the steps of: positioning a source of treating fluid confined under pressure by a first closure member opposite a first portion of the Well bore and a receiver maintained at a reduced pressure by a second closure member opposite an adjacent second portion of the Well bore; packing-off rst and second portions of the Well bore to isolate said portions from the Well control fluids and from one another; perforating through said first closure member and first isolated portion and on into the formation for providing a first passage therein and releasing said treating fluid into said first passage; perforating through said second closure member and second isolated portion and on into the formation, in a direction calculated to approach an intersection with said first passage, for providing a second passage in the formation and opening fluid communication between said receiver and rst passage; and then, discharging said treating Huid from said source through said passages and into `said receiver for ushing debris from said passages.

17. A method of completing a well bore containing a Icolumn of well control uids and traversing an earth formation, comprising the steps of: positioning a source of treating uid confined under pressure by a first closure member opposite a rst portion of the well bore and a receiver maintained at a reduced pressure by a second closure member opposite an adjacent second portion of the Well bore; packing-off said rst and second portions of the Well bore to isolate said portions from the Well control fluids and from one another; perforating through said rst closure member and first isolated portion and on into the formation, in a direction calculated to approach the intersection with said rst passage, for providing a second passage in the formation and opening fluid communication between said receiver and rst passage; discharging said CTI treating duid from said source through said passages and into said receiver for flushing debris from said passages; and, then, injecting a temporary plugging agent into said passage to isolate the exposed surfaces therein from the Well control uids.

References Cited UNITED STATES PATENTS 2,237,313 4/1941 Pmaon 166-13 2,321,256 1/1958 Boiler 166- 100X 3,115,932 12/1963 Reynokis 166 23X 3,121,459 2/1964 van Ness et a1. 16623 X 3,182,722 5/1965 Reed 166w-25 3,212,576 10/1965 Lannion 175-4.52X 3,277,961 10/1966 Bohn 166 -35X 3,289,764 12/1966 santourian 166-42 CHARLES E. OCONNELL, Prim'ary Examiner. DAVID H. BROWN, Examiner.

Claims

1. A METHOD OF COMPLETING A WELL BORE TRAVERSING AN EARTH FORMATION, COMPRISING THE STEPS OF: FORMING A FIRST PASSAGE FROM THE WELL BORE INTO THE FORMATION; FORMING A SECOND PASSAGE FROM THE WELL BORE INTO THE FORMATION IN A DIRECTION TO INTERSECT SAID FIRST PASSAGE TO BE EFFECTUAL FOR ESTABLISHING FLUID COMMUNICATION THEREBETWEEN; AND, THEREAFTER, LOWERING THE PRESSURE IN THE WELL BORE BELOW THAT IN SAID PASSAGES FOR WITHDRAWING FLUID THROUGH SAID PASSAGE TO FLUSH DEBRIS THEREFROM INTO THE WELL BORE AND ENLARGE SAID PASSAGES.