GB2436236A

GB2436236A - Perforating gun and dart

Info

Publication number: GB2436236A
Application number: GB0710479A
Authority: GB
Inventors: Jorge E Lopez De Cardenas; Gary L Rytlewski; Matthew R Hackworth; John R Whitsitt; Jose F Garcia
Original assignee: Gemalto Terminals Ltd; Schlumberger Holdings Ltd
Current assignee: Gemalto Terminals Ltd; Schlumberger Holdings Ltd
Priority date: 2004-12-30
Filing date: 2005-12-13
Publication date: 2007-09-19
Anticipated expiration: 2025-12-13
Also published as: GB2436237A; GB2436235A; GB2421745A; NO20056107L; US20060144590A1; GB2436235B; GB2436236B; GB0525276D0; GB0710478D0; RU2310066C2; RU2005141589A; GB0710481D0; GB2436237B; GB2421745B; NO337861B1; GB0710479D0

Abstract

A system for use in a wellbore intersecting a well zone 410, 412 comprises a tubular member 402 fixed in the wellbore; a polished bore receptacle (PBR) 420,422 arranged within the tubular member below the well zone and a dart for pumping down the wellbore. The dart comprising a sealing mechanism 442 adapted to seal with the PBR and a perforating gun 444 connected above the dart. A transmitter 430,432 may be located proximate the PBR and a receiver 446 connected to the dart so that the sealing mechanism is actuated between collapsed and expanded positions when the receiver detects a signal. The gun may de fired after a predetermined delay as the receiver detects the signal.

Description

68.0527D2 2436236

MULTIPLE ZONE COMPLETION SYSTEM AND METHOD

BACKGROUND OF THE INVENTION

The present invention relates generally to recovery of hydrocarbons in subterranean formations, and more particularly to a system and method for delivering treatment fluids to wells having multiple well zones.

In typical welibore operations, various treatment fluids may be pumped into the well and eventually into the formation to restore or enhance the productivity of the well. For example, a non-reactive "fracturing fluid" or a "frac fluid" may be pumped into the welibore to initiate and propagate fractures in the formation thus providing flow channels to facilitate movement of the hydrocarbons to the welibore so that the hydrocarbons may be produced from the well. In such fracturing operations, the fracturing fluid is hydraulically injected into a weilbore penetrating the subterranean formation and is forced against the formation strata by pressure. The formation strata is forced to crack and fracture, and a proppant is placed in the fracture by movement of a viscous-fluid containing proppant into the crack in the rock. The resulting fracture, with proppant in place, provides improved flow of the recoverable fluid (i.e., oil, gas or water) into the weilbore. In another example, a reactive stimulation fluid or "acid" may be injected into the formation. Acidizing treatment of the formation results in dissolving materials in the pore spaces of the formation to enhance production flow.

Currently, in wells with multiple production zones, it may be necessary to treat various formations in a multi-staged operation requiring many trips downhole. Each trip generally consists of isolating a single production zone and then delivering the treatment fluid to the isolated zone. Since several trips downhole are required to isolate and treat each zone, the complete operation may be very tune consuming and expensive.

Accordingly, there exists a need for systems and methods to deliver treatment fluids to multiple zones of a well in a single trip downhole.

SUMMARY

According to one aspect of the present invention, there is provided a system for use in a weilbore intersecting a well zone, the system comprising: a tubular member fixed in the weilbore; a polished bore receptacle arranged within the tubular member below the well zone; a dart for pumping down the weilbore, the dart comprising a

I

68.0527D2 sealing mechanism adapted to seal with the polished bore receptacle; and a perforating gun connected above the dart.

According to another aspect of the invention, there is provided a method for use in a welibore intersecting a well zone, the method comprising: providing a casing having a polished bore receptacle installed therein; installing the casing in the weilbore such that the polished bore receptacle is located below the well zone; providing a dart having a latching mechanism and a perforating gun attached thereto; pumping the dart in the weilbore until the sealing mechanism seals with the polished bore receptacle; perforating the well zone with the perforating gun; and delivering a treatment fluid to the well zone via the casing Other features of the invention will be apparent from the following description, from the drawings, and from the claims.

BRIEF DESCRIPTION OF THE DRAWiNGS

The manner in which these objectives and other desirable characteristics can be obtained is explained in the following description and attached drawings in which: Figure 1 illustrates a profile vie of an embodiment of the multi-zonal well completion system of the present invention having polished bore receptacles installed in a weilbore.

Figure 2 illustrates a profile view of an embodiment of the multi-zonal well completion system of the present invention having polished bore receptacles installed in a weilbore for isolating perforated well zones and a fluid delivery tool having a sealing assembly arranged thereon for delivering a fluid to a selected perforated well zone.

Figures 3A-3F illustrate profile views of an embodiment of the multi-zonal well completion system of the present invention depicting a perforating gun and seal assembly arranged below a fluid delivery tool being run in a wellbore having polished bore receptacles for isolating multiple well zones.

Figures 4A-4B illustrate profile views of an embodiment of the multi-zonal well completion system of the present invention depicting a string of perforating guns being run in a welibore having polished bore receptacles for isolating multiple well zones and detonated simultaneously.

Figures 5A-5D illustrate profile views of an embodiment of the multi-zonal well completion system of the present invention depicting a fluid delivery tool with seal assemblies arranged above and below the fluid delivery tool, the fluid delivery tool 68.0527D2 being run in a weilbore having polished bore receptacles for isolating multiple well zones.

Figure 6 illustrates a profiLe view of an embodiment of the multi-zonal well completion system of the present invention depicting concentric inner and outer strings having one or more seals formed on the outer surface of the outer string for bypassing particular well zones of a weilbore having polished bore receptacles and a diverter tool connected to the bottom of the concentric strings for directing flow between inner string, the annulus defined between the outer string and inner string, and the well annulus outside the outer string.

Figures 7A-7D illustrate profile views of an embodiment of the multi-zonal well completion system of the present invention depicting a actuatable seal dart with a perforating gun connected above the dart, the dart being run in a welibore having polished bore receptacles for isolating multiple well zones.

It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.

DETAILED DESCRIPTION

In the specification and appended claims: the terms "connect", "connection", "connected", "in connection with", and "connecting" are used to mean "in direct connection with" or "in connection with via another element"; and the term "set" is used to mean "one element" or "more than one element". As used herein, the terms "up" and "down", "upper" and "lower", "upwardly" and downwardly", "upstream" and "downstream"; "above" and "below"; and other like terms indicating relative positions above or below a given point or element are used in this description to more clearly describe some embodiments of the invention. Moreover, the term "sealing mechanism" includes: 0-ring, chevron seal, V-packed seal, bonded elastomer seal, compression seal element, inflatable seal element, face seal, and all other methods and devices for engaging a polished bore receptacle and temporarily blocking the flow of fluids through the weilbore. Furthermore, the term "treatment fluid" includes any fluid delivered to a formation to stimulate production including, but not limited to, fracing fluid, acid, gel, foam or other stimulating fluid. Still furthermore, the terms "tubular member", "casing", and "liner" may be used interchangeably (e.g., any embodiment described herein for use with a casing may also be used with a liner or other tubular member).

Yet furthennore, the term "polished bore receptacle'1 or "PBR" includes a smooth, 68.0527D2 polished, or honed bore formed on the inner surface of a tubular member (e.g., casing or liner) having a predetermined diameter for sealing or mating with a sealing mechanism.

Generally, this invention relates to a system and method for completing multi-zone wells by delivering a treatment fluid to achieve, facilitate, and/or improve productivity. Typically, such welts are completed in stages that result in very long completion times (e.g., on the order of four to six weeks). The present invention may reduce such completion thne (e.g., to a few days) by facilitating multiple operations, previously done one trip at a time, in a single trip. Moreover, some embodiments of this invention provide a system and method for completing a well without the use of inflatable packers, which may need to be set and reset to facilitate multiple zonal isolations in a single run.

Figures 1 and 2 illustrate an embodiment of the well completion system of the present invention for use in a weilbore 10. The wellbore 10 may include a plurality of well zones (e.g., formation, production, injection, hydrocarbon, oil, gas, or water zones or intervals) 12A, 12B. The wellbore 10 includes a tubular member 15 such as a casing, liner, production string, and so forth defining an axial bore therethrough with a selected diameter Dl. At least one polished bore receptacle (PBR) 20A, 20B, 22A, 228 is installed in the tubular member 15 to facilitate isolating a well zone 12A, 12B.

A PBR 20A, 20B, 22A, 22B may be a tubular element formed or installed along the inner wall of the tubular member 15 having an axial bore with a diameter D2 less than the diameter Dl of the axial bore of the tubular member. Moreover, each PBR 20A, 20B, 22A, 22B may include a smooth and/or honed inner surface to provide a sealing surface for a sealing mechanism 30 to engage and seal to restrict access to the axial bore of the tubular member 15 below the PBR.

In one embodiment, PBRs 20A, 20B are installed only below the well zones 12A, 12B respectively. In this embodiment, the lower well zone 12B is perforated first Then a sealing mechanism 30 is used to seal the tubular member 15 at PBR 20B. The well zone 12B is then treated via a fluid delivery device 40 on a tubing string 50. Next the upper well zone 12A is perforated. The sealing mechanism 30 is used to seal the tubular member 15 at PBR 20A and isolate well zone 12A from well zone 12B. The well zone 1 2A is then treated via a fluid delivery device 40.

In another embodiment, PBRs 20A, 20B are installed below the well zones 12A, 12B respectively and PBRs 22A, 22B are installed above the well zones 12A, 12B 68.0527D2 respectively. In this embodiment, the well zones 12A, 12B may both be perforated before any well zone l2A, 12B is treated. Once the well zones 12A, 12B are perforated, a straddling sealing mechanism (such as shown in Figure 5A) may be used to isolate a particular well zone and treat the well zone via a fluid delivery device. For example, the straddling sealing mechanism may include seals for engaging PBRs 20B and 22B and isolating well zone 12B. A fluid delivery device being arranged between the seals is then used to treat the perforated well zone 12B via a tubular string 50.

Figures 3A-3F illustrate another embodiment of the present invention for isolating and treating a well zone. In this embodiment, a wellbore 100 having well zones 120, 130 is drilled and a tubular member 101 is fixed therein with cement 102. A PBR 110 is installed between the well zones 120, 130. The lower well zone 120 is perforated and treated thus the well zone may be referred to as a "finished well zone." A completion tool 140 is provided having a perforating gun 142, a sealing mechanism 144, and a fluid delivery device 146. In one embodiment, the sealing mechanism 144 may be arranged above the perforating gun 142 and below the fluid delivery device 146. The completion tool 140 may be suspended in the tubular member 101 on a tubing string 150 having an axial bore therethrough. The fluid delivery device 146 may include at least one port 148 formed therein for establishing communication between the axial bore of the tubing string 150 and the annulus within the tubular member 101.

With reference to Figures 3A-3F, in operation, once the well zone 120 is perforated and treated, the completion tool 140 is pulled upward by the tubing string (Figure 3A). The perforating gun 142 is aligned pmximate the next well zone 130 and the gun is detonated thereby perforating the well zone 130 (Figure 3B). The completion tool 140 is then lowered until the sealing mechanism 144 engages and seals with the PBR 110 (Figure 3C). In this arrangement, the sealing mechanism isolates the well zone 130 from the finished well zone 120 and the fluid delivery device is proximate the new target zone 130 such that a treatment fluid may be delivered to the target zone 130 via the at least one port 148 of the fluid delivery device (Figure 3D). If circulation is required (e.g., as to circulate out sand), then fluid pressure may be increased to circulate fluid upward through the at least one port 148 of the fluid delivery device (Figure 3E). Once the well zone 130 is finished, the completion tool may be moved upward again to the next target well zone (Figure 3F).

In other embodiments of the present invention, instead of perforating and treating one well zone at a time, all well zones may be perforated before any well zone 68.0527D2 is treated. With respect to Figures 4A-4B, each well zone 202, 204 of a wellbore 200 may be perforated by a perforating gun 210 on a line 220 (e.g., wireline, slickline, or tubing string) one at a time (as shown in Figure 4A), or each well zone 202, 204 may be perforated by a perforating gun string 212 simultaneously on a line 220 (as shown in Figure 4B). In either case, a plurality of PBRs 231, 232, 233 are installed in or formed on the casing 205 of the weilbore 200 such that a PBR is located above and below each respective well zone 202,204.

In one embodiment, once the well zones are perforated, a well completion tool is provided to isolate and deliver a treatment fluid to each well zone. With respect to Figures 5A-5D, an embodiment of the well completion tool 250 includes a fluid delivery device 252 and sealing mechanisms 254, 255 arranged above and below the fluid delivery device or "straddling" the device. The well completion tool 250 is suspended in the wellbore 200 on a tubing string 260 and defines an axial bore therethrough for communication with the tubing string. The fluid delivery device 252 includes at least one port 253 formed therein for establishing hydraulic communication between the perforated well zones 202,204 and the tubing string 260.

In operation, the well completion tool is run in the casing 205 of a welibore 200 to a target well zone 204 (Figure 5A). At this position, the fluid delivery device is proximate the target well zone 204 and the sealing mechanisms 254, 255 engage and seal with the PBRs 231, 230 respectively to isolate the target well zone. Once the well zone 204 is isolated, a treatment fluid may be pumped or otherwise delivered down the tubing string 260 and into the formation of the target well zone 204 via the port 253 of the fluid delivery device 252 (Figure 5B). After' treating the well zone 204, the well completion tool 250 may be lifted upward to break the seals between the sealing mechanisms 254, 255 and the PBRs 231, 230 respectively. Next, hydraulic pressure in the well completion tool 250 may be increased to circulate out any excess sand from the annulus between the tool and the casing 205 (Figure 5C). The tool 250 may then be lifted further upwards to the next target well zone 202 where the sealing mechanisms 254, 255 engage and seal with PBRs 232, 231 respectively to isolate the well zone 202 for treatment.

In an alternative embodiment of the present invention, a well completion tool is provided to deliver treatment fluid to isolated well zones, each of which have been perforated as shown in Figures 4A, 4B. In this embodiment, a well completion tool 270 having: (1) an inner string 272 and outer string 274 arranged concentrically to 68.0527D2 define a first annulus within the inner string 272, a second annulus within the outer string 274 but outside the inner sIring 272, and a third annulus within the casing 205 and outside the outer string 274; (2) a diverter tool 280 connected to the lower end of the inner string 272 and having at least one port 282 formed therein for establishing hydraulic communication between the axial bore of the inner string 272 and the annulus inside the casing 205; and (3) a sealing mechanism 276 formed on the outer surface of the diverter tool 280 and a plurality of sealing mechanisms 277, 278 formed on the outer surfice of the outer string 274 to engage and seal with PBRs 230, 231,232 in the casing 205. The lower end of the outer string 274 is open to the annulus within the casing 205. This embodiment provides circulation to a target well zone 204 via both the annulus between the inner string 272 and outer string 274 and the annulus within the inner string 272 without flowing past open formations of well zone 202 (or any other well zone above or below the target well zone 204 for that matter).

Still with respect to Figure 6, in operation, the well completion tool 270 is run in a casing 205 of a weilbore 200 to a target formation 204. In this position, the diverter tool 280 is proximate the target w1l zone 204 and the sealing mechanisms 276, 277, 278 engage and seal with the PBRs 230, 231, 232 thus isolating well zone 204 from other zones. A treating fluid may then be delivered through the inner string 272 to the formation of the target well zone 204 via the port 282 of the diverter tool 280.

Alternatively, a treatment fluid may be delivered via the outer string 274 alone or both the inner string 272 and the outer string 274 simultaneously. Furthermore, the outer string 274 may be used to circulate excess sand once the well completion tool 270 is pulled out of engagement with the PBRs 276, 277, 278 and moved to another target well zone. Alternatively, circulation may be achieved through the inner string 272 alone or both the inner string 272 and the outer string 274 simultaneously.

With respect to Figures 7A-7D, yet another embodiment of the present invention is provided for selectively perforating and isolating a target well zone for delivery of a treatment fluid to the underlying formation. Figure 7A illustrates a casing 402 being fixed to a welibore 400 by cement 404. The welibore 400 intersects a plurality of well zones 410, 412 and the casing 402 includes a plurality of PBRs 420, 422 arranged below the well zones 410, 412 respectively. Transmitters 430, 432 are arranged proximate to the well zones 410, 412 respectively. In one embodiment, the transmitters 430, 432 are attached to the PBRs 420, 422. In other embodiments, the transmitters 430, 432 may be embedded in the cement 404 or attached to the casing 68.0527D2 402. Each transmitter 430, 432 emits a particular or unique signal (e.g., a radio frequency "RF" signal, an acoustic signal, a radioactive signal, a magnetic signal, or other signal). A dart 440 having a sealing mechanism 442, perforating gun 444, and receiver 446 is provided. Certain embodiments of the dart 440 may include a centralizer 448 (e.g., guiding fins) for maintaining the alignment of the dart being pumped downhole. Other embodiments of the dart 440 may include a fishing profile 450 such that the dart may be retrieved after the treatment fluid is delivered and before the well is produced. The sealing mechanism 442 of the dart is moveable between a collapsed position wherein the dart 440 does not engage and seal with a PBR 420, 422 (as shown in Figures 7A, 7D) and a biased position wherein (as shown in Figures 7B, 7C). The receiver 446 controls (e.g., by means of a controller, PLC, or other similar device) the position of the sealing mechanism 442 based on detection of a signal from a transmitter 430,432.

Still with respect to Figures 7A-7D, in operation, the dart 440 is initially run downhole with the sealing mechanism 442 collapsed and is programmed to bias radially outward upon coming into proxiiity of a predetermined target well zone 432.

Particularly, the receiver 446 of the dart 440 is programmed to take an action upon receiving the particular signal being emitted by transmitter 432. Thus, no action is taken as the dart 440 passes transmitter 430, which is emitting a different signal (Figure 7A). Once the receiver 446 of the dart 440 is proximate to the transmitter 432, the sealing mechanism 442 moves radially outward into the biased position (Figure 78).

The biased sealing mechanism 442 then engages and seals with the PBR 422. The perforating gun 444 is then in a position proximate the target well zone 412. In some embodiments, the perforating gun 444 is set to detonate after a predetermined delay once the sealing mechanism 442 is actuated to bias radially outwards as by a counter or timer. In other embodiments, the perforating gun 444 may be actuated from the surface to detonate via pressure pulses, pressure changes, or other signaling in the welibore.

Either way, the perforating gun 444 detonates to penetrate the casing, cement, and the underlying formation of the well zone 412 (Figure 7C). Once the target well zone 412 is perforated, a treatment fluid may be delivered down the annulus of the casing 402 to the target well zone 412. The sealing mechanism 442 of the dart 440 effectively seals and isolates the target well zone 412 from any previously perforated and treated well zones below. After treatment of the target well zone 412, the sealing mechanism 442 moves back into the collapsed position and the dart 440 is freed from sealing 68.0527D2 engagement with the PBR 422. The dart 440 may then be pumped to the bottom of the welibore 400 (Figure 7D). Another dart (not shown) keyed to the frequency of the signal emitted by transmitter 430 may be used to seal with PBR 420, perforate, and treat the next target well zone 410. In some embodiments, the darts may include a fishing profile such that the darts may be retrieved after zonal operations are complete (e.g., isolate, perforate, and treat) and before the well is produced.

In some alternative embodiments of the present invention using PBRs to achieve zonal isolation in a weilbore, an anchoring device may be installed proximate to each PBR for the purpose of providing a positive location for depth control. The anchoring device may also support the weight of any dart or fluid delivery tools or applied forces produced from differential pressure across the seals of the PBRs and sealing mechanisms. I Although only a few exemplary embodiments of this invention have been described in detail above, those sidlied in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantags of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention as defined in the following claims. In the claims, means-plus-function clauses are intended to cover the structures described herein as perfonning the recited function and not only structural equivalents, but also equivalent structures. Thus, although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface, in the environment of fastening wooden parts, a nail and a screw may be equivalent structures.

Claims

68.0527D2

CLAIMS

I. A system for use in a welibore intersecting a well zone, the system comprising: a tubular member fixed in the weilbore; a polished bore receptacle arranged within the tubular member below the well zone; a dart for pumping down the weilbore, the dart comprising a sealing mechanism adapted to seal with the polished bore receptacle; and a perforating gun connected above the dart.

2. The system of claim 1, further comprising: a transmitter arranged proximate the polished bore receptacle, the transmitter being adapted to emit a particular signal; and a receiver connected to the dart, the receiver adapted to detect the signal from the transmitter; wherein the sealing mechanism is actuated between a collapsed and radially biased position as the receiver detects the signal.

3. The system of claim 2, wherein the perforating gun is fired after a predetermined delay as the receiver detects the signal.

4. The system of claim 2, wherein the sealing mechanism is selected from a group consisting of 0-ring, chevron seal, V-packed seal, bonded elastomer seal, compression seal element, inflatable seal element, and face seal.

5. The system of claim 2, wherein the signal is selected from a group consisting of RF signal, radioactive signal, and magnetic signal.

6. The system of claim 1, wherein the dart further comprises: a fishing profile fonned on the dart adapted to facilitate retrieval of the dart by a fishing tool.

7. The system of claim 1, wherein the dart further comprises a centralizer adapted to maintain the alignment of the dart.

68.0527D2 8. A method for use in a weilbore intersecting a well zone, the method comprising: providing a casing having a polished bore receptacle installed therein; installing the casing in the weilbore such that the polished bore receptacle is located below the well zone; providing a dart having a latching mechanism and a perforating gun attached thereto; pumping the dart in the weilbore until the sealing mechanism seals with the polished bore receptacle; perforating the well zone with the perforating gun; and delivering a treatment fluid to the well zone via the casing.

9. The method of claim 8, further comprising actuating the sealing mechanism of the dart to expand radially outward to seal with the polished bore receptacle.

10. The method of claim 8, further comprising actuating the sealing mechanism of the dart to collapse to disengage from the r1si bore receptacle; 11. The method of claim 9, wherein actuating the sealing mechanism is achieved by sending a signal to the dart.

12. The method of claim 10, wherein actuating the sealing mechanism is achieved by sending a signal to the dart.