NO337861B1 - Multi-zone completion system - Google Patents

Description

The field of invention

The present invention generally relates to the extraction of hydrocarbons in underground formations and more particularly relates to a system and a method for supplying treatment fluids to wells with several well zones.

BACKGROUND OF THE INVENTION

In typical well operations, various treatment fluids may be pumped into the well and ultimately into the formation to restore or improve the productivity of the well. For example, a non-reactive fracturing fluid or a "frac fluid" may be pumped into the wellbore to initiate and propagate fractures in the formation, so that flow channels are provided to facilitate the movement of the hydrocarbons to the wellbore, so that the hydrocarbons can be produced from the well. In such fracturing operations, the fracturing fluid is hydraulically injected into a borehole that penetrates the subsurface formation and is forced against the formation layers by means of pressure. The formation layers are 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 for the recoverable fluid (i.e., oil, gas, or water) into the borehole. In a further example, a reactive simulation fluid or "acid" may be injected into the formation. Acidizing the formation results in dissolution of materials in the pore spaces of the formation to improve production flow.

GB 2381281 describes a well assembly for extracting production fluids from at least one production zone (139) which includes a production pipe (112), a packing (146) for delimiting the production zone, and a fiber optic sensor package (10) arranged adjacent to a downstream side of the packing . The fiber optic sensor package (10) measures parameters in the production fluid and communicates these parameters to the surface to determine the composition of the production fluid into the production pipe through each production zone. The production pipe has a zone opening (151) to allow production fluid to enter the production pipe, and a control valve (150) to control the amount of production fluid flowing downstream from each production zone. The production pipe control valve is regulated to optimize fluid production from the specific production zone in the well on the basis of fluid parameters measured using the fiber optic sensor package (10).

In wells with several production zones, it may now often be necessary to process different formations in an operation with several steps that require many trips down the well. Each trip generally consists of isolating a single production zone and then supplying the treatment fluid to the isolated zone. Since several trips down the well are necessary to isolate and treat each zone, the complete operation can often be very time-consuming and expensive.

Consequently, there is a need for systems and methods to supply treatment fluids to several zones in a well in a single trip down the well.

The present invention relates to a system and a method for supplying a treatment fluid to a well with several well zones. According to some embodiments of the present invention, a well completion system is provided that includes one or more polished wellbore containers (PBB) installed in a casing and a fluid supply device with at least one seal assembly to selectively isolate a selected well zone and to supply a fluid to the selected zone.

The present invention is particularly suitable for providing a system for use in a borehole that intersects a well zone, comprising a pipe element fixed in the borehole; a first polished drilling container arranged inside the pipe element above the well zone and a second polished drilling container arranged inside the pipe element below the well zone; an outer tubing string having an upper end, a lower end, and an axial bore therethrough, the lower end of the outer tubing string being open to establish communication between the axial bore of the tubing string and the borehole; an inner tube string with an upper end, and a lower end, and an axial bore therethrough, the inner tube string bearing inside the axial bore of the outer tube string; a diverter tool in connection with the lower end of the inner pipe string, the diverter tool having a port formed therein to establish hydraulic communication between the axial bore in the inner pipe string and the borehole; a first sealing mechanism arranged on the outer pipe string, the first sealing mechanism being adapted to seal with the first polished bore container and a second sealing mechanism arranged below the port in the diverter tool, the second sealing mechanism being adapted to seal with the second polished bore container.

Other or alternative embodiments of the present invention will be apparent from the following description, from the drawings and from the patent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The manner in which these objects and other desirable properties can be achieved is explained in the following description and in the attached drawings, in which: Fig. 1 shows a profile view of an embodiment of a multi-zone well completion system according to the present invention with polished borehole containers (PBB) installed in a borehole. Fig. 2 illustrates a profile view of one embodiment of a multi-zone well completion system according to the present invention with polished borehole containers (PBB) installed in a wellbore to isolate perforated well zones and a fluid supply tool with a seal assembly arranged thereon to supply a fluid to a selected perforated well zone . Figs. 3A-3F illustrate profile views of one embodiment of the multi-zone well completion system according to the present invention and depict an assembly with a perforating firing device and seal arranged below a fluid delivery tool for insertion into a wellbore with polished borehole containers (PBB) to isolate multiple well zones. Figs. 4A-4B illustrate profile views of an embodiment of

the multi-zone well completion system of the present invention and depicts a string of perforating firing devices that are inserted into a wellbore with polished bore containers (PBB) to isolate multiple well zones and which are detonated simultaneously.

Figs. 5A-5D illustrate profile views of an embodiment of the multi-zone well completion system according to the present invention and show a fluid delivery tool with seal assemblies arranged above and below the fluid delivery tool, the fluid delivery tool being introduced into a borehole with polished borehole containers (PBB) to isolate multiple well zones.

Fig. 6 illustrates a profile view of an embodiment of

the multi-zone well completion system of the present invention and showing concentric inner and outer strings with one or more seals formed on the outer surface of the outer string for bypassing particular well zones in a borehole with polished borehole containers (PBB) and a diversion tool connected to the base of the concentric strings to direct flow between the inner string, the annulus defined between the outer string and the inner string, and the well annulus outside the outer string.

Figs. 7A-7D illustrate profile views of an embodiment of

the multi-zone well completion system according to the present invention and shows an activatable sealing plug with a perforating firing device connected to the plug, the plug being introduced into a borehole with polished borehole containers (PBB) to isolate several well zones.

DETAILED DESCRIPTION

In the following description, numerous details are set forth to provide an understanding of the present invention. However, it should be understood by those skilled in the art that the present invention can be practiced without these details and that numerous variations or modifications from the described embodiments may be possible.

In the description and subsequent patent claims, the terms "connect", "connection", "connected", "in connection with" and "connecting" are used to indicate

"in direct connection with" or "in connection with via a further element"; and the term "set" is used to indicate "one element" or "more than one element". As used herein, the terms "up" and "down", "upper" and "lower", "upwards" and "downwards", "upstream" and "downstream" are used; "over and under"; and other similar designations indicating relative positions above or below a given point or element in this description to more clearly describe some embodiments of the invention. Furthermore, the term "sealing mechanism" includes: O-ring

Chevron Seal, V-Packed Seal, Bonded Elastomer Seal,

compression seal element, inflatable seal element, surface seal, and all other methods and devices to bring a polished borehole container (PBB) into contact with each other and temporarily block the flow of fluids through the borehole. Furthermore, the term "processing fluid" includes any fluid supplied to a formation to stimulate production and includes but is not limited to fracturing fluid, acid fluid, gel fluid, foam fluid or other stimulating fluid. Even further, the terms "tubing element", "casing", and "extension pipe" may be used interchangeably (for example, any embodiment described herein for use with a casing may also be used with an extension pipe or other pipe element). Still further, the term polished bore container or "PBB" includes a smooth, polished or honed bore formed on the inner surface of a tubular member (eg casing or extension pipe) of a predetermined diameter for sealing or fitting with a sealing mechanism.

In general, this invention relates to a system and method for completing multi-zone wells by adding a treatment fluid to achieve, facilitate, and/or improve productivity. Typically, such wells are completed in stages resulting in very long completion times (for example, approximately four to six weeks). The present invention can reduce such completion time (for example to a few days) by facilitating several operations, previously carried out one trip at a time, in the form of a single trip. Furthermore, some embodiments of this invention provide a system and method for completing a well without the use of inflatable packings, which might otherwise be required for attachment and reattachment to facilitate multiple operations, which have previously been performed one step at a time, in a only trip. Furthermore, some embodiments of this invention provide a system and method for completing a well without the use of inflatable packings, which might otherwise be required for fixing and re-fixing to facilitate multiple zone isolations in a single trip.

Figs. 1 and 2 illustrate an embodiment of the well completion system according to the present invention for use in a borehole 10. The borehole 10 can include a plurality of well zones (for example formation, production, injection, hydrocarbon

, oil, gas or water zones or intervals) 12A, 12B. The borehole 10 includes a pipe element 15 such as a casing pipe, an extension pipe, a production string, etc. and which defines an axial bore therethrough with a selected diameter D1.1 at least one polished borehole container (PBB) 20A, 20B, 22A, 22B is installed in the pipe member 15 to facilitate isolation of a well zone 12A, 12B. A PBB 20A, 20B, 22A, 22B can be a pipe element formed or installed along the inner wall of the pipe element 15 with an axial bore with a diameter D2 smaller than the diameter D1 of the axial bore of the pipe element. Furthermore, each PBB 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 said PBB.

In one embodiment, PBB 20A, 20B are installed only under the well zones 12A and 12B, respectively. In this embodiment, the lower well zone 12B is perforated first. A sealing mechanism 30 is then used to seal the pipe element 15 at PNN 20B. The well zone 12B is then treated via a fluid supply device 40 on a production pipe 50. The upper well zone 12A is then perforated. The sealing mechanism 30 is used to seal the pipe element 15 at the PBB 20A and isolate the well zone 12A from the well zone 12B. The well zone 12A is then treated via a fluid supply device 40.

In a further embodiment, PBB 20A, 20B are installed below the well zones 12A and 12B, respectively, and PBB 22A, 22B are installed above the well zones 12A and 12B, respectively. In this embodiment, both well zones 12A, 12B can be perforated before any well zone 12A, 12B is treated. Once the well zones 12A, 12B have been perforated, a portal sealing mechanism (as for example shown in Fig. 5A) can be used to isolate a particular well zone and treat the well zone via a fluid supply device. For example, portal sealing mechanisms may include seals for engagement with PBBs 20B and 22B and isolating the well zone 12B. A fluid delivery device arranged between the seals is then used to treat the perforated well zone 12B via a production pipe 50.

Figs. 3A-3F illustrate a further embodiment of the present invention for isolating and treating a well zone. In this embodiment, a borehole 100 is drilled with well zones 120, 130 and a pipe element 101 is fixed therein by means of cement 102. A PBB 110 is installed between the well zones 120, 130. The lower well zone 120 is perforated and treated so that the well zone can be referred to as a " finished well zone". A completion tool 140 is arranged with a perforating firing device 142, a sealing mechanism 144, and a fluid supply device 146. In one embodiment, the sealing mechanism 144 can be arranged above the perforating firing device 142 and below

the fluid supply device 146. The completion tool 140 can be suspended in a pipe element 101 in a production pipe 150 with an axial bore through it. The fluid supply device 146 may include at least one port 148 formed therein to establish communication between the axial bore in the production pipe 150 and the annulus within the pipe member 101.

With reference to fig. 3A-3F, the completion tool 140 in operation, as soon as the well zone 120 is perforated and treated, is pulled upward by the pipe string 150 (Fig. 3A). The perforating firing device 142 is aligned near the next well zone 130 and the firing device is detonated and thereby perforates the well zone 130 (Fig. 3B). The completion tool 140 is then lowered until the sealing mechanism 144 engages and seals with the PBB 110 (Fig. 3C). In this arrangement, the sealing mechanism isolates the well zone 130 from the finished well zone 120 and the fluid supply device is then outside the new measurement zone 130, so that treatment fluid can be supplied to the target zone 130 via said at least one port 148 of the fluid supply device (Fig. 3D). If circulation is required (for example to circulate out sand), then the fluid pressure can be increased to circulate fluid upwards through said at least one port 148 of the fluid supply device (Fig. 3E). Once the well zone 130 has been completed, the completion tool 140 can again be moved upwards to the next target well zone (Fig. 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 zones are treated. In connection with fig. 4A-4B, each well zone 202, 204 in a wellbore 200 may be perforated using a perforating firing device 210 on a cable 220 (for example, cable, smooth steel wire cable, or production pipe) one at a time (as shown in FIG. 4A), or each well zone 202, 204 may be perforated by a perforating gun string 212 simultaneously on a wireline 220 (as shown in Fig. 4B). In any case, a plurality of PBBs 231, 232, 233 are installed in or formed on the casing 205 in the borehole 200, so that a PBB is located above and below each respective well zone 202, 204.

In one embodiment, once the well zone is perforated, the well completion tool is deployed to isolate and supply a treatment fluid to each well zone. In connection with fig. 5A-5D, one embodiment of the well completion tool 250 includes a fluid delivery device 252 and sealing mechanism 254, 255 arranged above and below the fluid delivery device or as a "portal" above the device. The well completion tool 250 hangs down in the wellbore 200 of a production pipe 260 and defines an axial bore therethrough for communication with the production pipe. The fluid supply device 252 includes at least one opening 253 formed therein to establish hydraulic communication between the perforated well zones 202, 204 and the production pipe 260.

In operation, the well completion tool is introduced into the casing 205 in the borehole 200 to a target well zone 204 (Fig. 5A). In this position, the fluid supply device is located close to the target well zone 204 and the sealing mechanisms 254, 255 engage and seal with PBB 231 and 230 respectively to isolate the target well zone. When the well zone 204 is first isolated, a treatment fluid can be pumped or otherwise supplied down through the production pipe 260 and into the formation of the target well zone 204 via the port 253 in the fluid supply device 252 (Fig. 5B). After treatment of the well zone 204, the well completion tool 250 can be lifted upwards to break the seals between the sealing mechanisms 254, 255 and PBB 231 and 230 respectively. Then, hydraulic pressure in the well completion tool 250 can be increased to circulate out any excess sand from the annulus between the tool and the casing 205 (Fig. 5C ). The tool 250 can then be lifted further upwards to the next target well zone 202 where the sealing mechanisms 254, 255 engage and seal with PBB 232 and 231 respectively to isolate the well zone 202 for treatment.

In an alternative embodiment of the present invention, a well completion tool is arranged to supply treatment fluid to isolated well zones, each of which has been perforated as shown in fig. 4A, 4B. In this embodiment, a well completion tool 270 having: (1) an inner string 272 and an outer string 274 arranged concentrically to define a first annulus within the inner string 272, a second annulus within the outer string 274 but outside the inner string 272, and a third annulus inside 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 to establish hydraulic communication between the axial bore of the inner string 272 and the annulus within the casing 205; and (3) a sealing mechanism 276 formed on the outer surface of the diverter tool 280 and having a plurality of sealing mechanisms 277, 278 formed on the outer surface of the outer strand 274 to engage and seal the PBB 230, 231, 232 in casing 205. The lower end of outer string 274 is open to the annulus within casing 205. This embodiment provides circulation to a target well zone 204 via both the annulus between inner string 272 and outer string 274 and the annulus within inner string 272 without to flow past open formations in the well zone 202 (or any other well zone above or below the target well zone 204 for that matter).

With continued reference to fig. 6, the well completion tool 270 is inserted into a casing 205 in a borehole 200 to a target formation 204. In this position, the diverter tool 280 is located close to the target well zone 204 and the sealing mechanisms 276, 277, 278 engage and seal with the PBB 230, 231, 232, so that the well zone 204 is isolated from other zones. A treatment fluid can then be supplied through the inner string 272 to the formation of the target well zone 204 via the port 282 and the diverter tool 280. Alternatively, a treatment fluid can be supplied via the outer string 274 alone or via both the inner string 272 and the outer string 274 simultaneously. Furthermore, the outer string 274 can be used to circulate excess sand once the well completion tool 270 has been pulled out of engagement with the PBB 276, 277, 278 and moved to a further target well zone. Alternatively, circulation can be achieved through the inner strand 272 alone or through both the inner strand 272 and the outer strand 274 simultaneously.

With reference to fig. 7A-7D, yet another embodiment of the present invention is provided for selectively perforating and isolating a measurement well zone for supplying a treatment fluid to the underlying formation. Fig. 7A illustrates a casing 402 that is attached to a wellbore 400 by means of cement 404. The wellbore 400 intersects a plurality of well zones 410, 412 and the casing 402 includes a plurality of PBBs 420, 422 arranged below the well zones 410 and 412, respectively. Transmitters 430, 432 are arranged near the well zones 410 and 412, respectively. In one embodiment, the transmitters 430, 432 are attached to the PBB 420, 422, respectively. In other embodiments, the transmitters 430, 432 may be embedded in the cement 404 or attached to the casing 402. Each transmitter 430, 432 emits a particular or distinctive signal (for example, a radio frequency "RF" signal, an acoustic signal, a radioactive signal, a magnetic signal, or other signal. A plug 440 with a sealing mechanism 442, perforating firing device 444 and receiver 446 is provided. Certain embodiments of The plug 440 may include a centralizer 448 (eg, guide fins) to maintain the alignment of the plug as it is pumped down the well. Forms of the plug 440 can include a fishing profile 450, so that the plug can be retrieved after the treatment fluid has been dispensed and before the well is produced. The plug sealing mechanism 442 is movable between a collapsed position in which the plug 440 does not engage and seals with the PBB 420, 422 (as shown in Figs. 7A, 7D) and an extended position (as shown in Figs. 7B, 7C). The receiver 446 controls (for example, using a controller, a programmable logic controller PLC, or other similar device) the position of the sealing mechanism 442 based on the detection of a signal from a transmitter 430, 432.

With continued reference to fig. 7A-7D, the plug 440 in operation is initially guided down the well with the sealing mechanism 442 collapsed and is programmed to push radially outward after approaching a predetermined target well zone 432. In particular, the receiver 446 in the plug 440 is programmed to act upon to have received the special signal emitted by the transmitter 432. No action is thus taken when the plug 440 passes the transmitter 430, which emits a different signal (fig, 7A). As soon as the receiver 446 in the plug 440 is close to the transmitter 432, the sealing mechanism 442 moves radially outwards to the extended position

(Fig. 7B). The extended sealing mechanism 442 then engages and seals with the PBB 422. The perforating firing device 444 is then in a position near the target well zone 412. In some embodiments, the perforating firing device 444 is set to detonate after a predetermined delay as soon as the sealing mechanism 442 is activated. to press radially outwards, such as with the help of a counter or timer. In further embodiments, the perforating firing device 444 may be activated from the surface to detonate via pressure pulses, pressure changes, or other downhole signaling. Either way, the perforating firing device 444 detonates to penetrate the casing, cement, and underlying formation of the well zone 412 (Fig. 7C). As soon as the target well zone 412 is perforated, a treatment fluid can be supplied down through the annulus in the casing 402 to the target well zone 412. The sealing mechanism 442 in the plug 440 effectively seals and isolates the target well zone 412 from all other 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 plug 440 is freed from sealing engagement with the PBB 422. The plug 440 can then be pumped to the bottom of the borehole 400 (Fig. 7D). An additional plug (not shown) keyed to the frequency of the signal emitted by the transmitter 430 may be used to seal with the PBB 420, perforate and process the next target well zone 410. In some embodiments, the plugs may include a fishing profile so that the plugs may be retrieved again after zone operations are completed (for example isolate, perforate and process) and before the well is produced.

In some alternative embodiments of the present invention using PBBs to achieve zone isolation in a borehole, an anchoring device may be installed near each PBB for the purpose of providing a positive location for depth control. The anchoring device can also support the weight of any plug or fluid delivery tools or impact forces produced from differential pressure across the seals of the PBB and the sealing mechanisms.

Although only a few exemplary embodiments of this invention have been described in detail above, those skilled in the art will readily realize that many modifications are possible in the exemplary embodiments without significantly deviating from the new teachings and advantages 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, mean-plus-function statements are intended to cover the structures described herein as performing the stated function and not only structural equivalents, but also equivalent structures. Thus, although a nail and a screw need not be structural equivalents in that the nail uses a cylindrical surface to fasten wooden parts together, while a screw uses a helical surface, in the area of fastening wooden parts to each other a nail and a screw can be equivalent structures. It is the applicant's express intent not to invoke 35 U.S.C. § 112, section 6 for some limitations for some of the patent claims herein, with the exception of those in which the patent claim expressly uses the words "devices for" together with an associated function.

Claims (9)

1. System for use in a borehole (10) intersecting a well zone (12A, 12B), characterized in that it comprises: a pipe element (15) fixed in the borehole (10); a first polished borehole container (PBB) (20A, 20B, 22A, 22B) arranged inside the pipe element (15) above the well zone (12A, 12B) and a second polished borehole container (PBB) (20A, 20B, 22A, 22B) arranged inside the pipe element (15) below the well zone (12A, 12B); an outer pipe string (274) having an upper end, a lower end, and an axial bore therethrough, the lower end of the outer pipe string (274) being open to establish communication between the axial bore of the pipe string and the borehole (10); an inner tube string (272) with an upper end, and a lower end, and an axial bore therethrough, the inner tube string (272) resting inside the axial bore of the outer tube string (274); a diverter tool (280) in connection with the lower end of the inner pipe string (272), the diverter tool (280) having a port (282) formed therein to establish hydraulic communication between the axial bore in the inner pipe string (272) and the borehole (10); a first sealing mechanism (277) arranged on the outer tubing string (274), the first sealing mechanism (277) being adapted to seal with the first polished bore container (PBB) (20A, 20B, 22A, 22B); and a second sealing mechanism (278) arranged below the port in the diverter tool (280), the second sealing mechanism (278) being adapted to seal with the second polished bore container (PBB). 2. System according to claim 1, characterized in that the sealing mechanism is selected from a group consisting of O-ring, Chevron seal, V-filled seal, bonded elastomer seal, compression sealing element, inflatable sealing element, and flat seal. 3. System according to claim 1, characterized in that it further comprises: a plug (440) to be pumped down through the borehole, the plug comprising a sealing mechanism (442) adapted to seal with the second polished borehole container (PBB); and a perforating firing device (444) connected above the plug (440). 4. System according to claim 3, characterized in that it further comprises: a transmitter (430, 432) arranged near the polished drilling container (PBB), the transmitter (430, 432) being adapted to emit a special signal; and a receiver (446) connected to the plug (440), the receiver (446) being arranged to detect the signal from the transmitter (430), 432); and wherein the sealing mechanism (442) is actuated between a collapsed and a radially extended position when the receiver (446) detects the signal. 5. System according to claim 4, characterized in that the perforating firing device (440) is fired after a predetermined delay when the receiver (446) detects the signal. 6. System according to claim 4, characterized in that the sealing mechanism is selected from a group consisting of an O-ring, a Chevron seal, a V-packed seal, bonded elastomer seal, compression sealing element, inflatable sealing element, and a flat seal. 7. System according to claim 4, characterized in that the signal is selected from a group consisting of a radio frequency RF signal, a radioactive signal and a magnetic signal. 8. System according to claim 3, characterized in that the plug (440) further comprises: a fishing-up profile formed on the plug (440) and arranged to facilitate retrieval of the plug (440) by means of a fishing-up tool. 9. System according to claim 3, characterized in that the plug (440) further comprises: a centralizer (448) arranged to maintain the alignment of the plug (440).