CN116752931A - Multi-stage fracturing string of offshore horizontal well and well cementation and completion integrated method - Google Patents
Multi-stage fracturing string of offshore horizontal well and well cementation and completion integrated method Download PDFInfo
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- CN116752931A CN116752931A CN202310918043.7A CN202310918043A CN116752931A CN 116752931 A CN116752931 A CN 116752931A CN 202310918043 A CN202310918043 A CN 202310918043A CN 116752931 A CN116752931 A CN 116752931A
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- 238000000034 method Methods 0.000 title claims abstract description 23
- 238000005553 drilling Methods 0.000 claims abstract description 45
- 239000003129 oil well Substances 0.000 claims abstract description 23
- 238000004519 manufacturing process Methods 0.000 claims description 35
- 238000005086 pumping Methods 0.000 claims description 31
- 239000004568 cement Substances 0.000 claims description 23
- 239000012530 fluid Substances 0.000 claims description 19
- 238000002347 injection Methods 0.000 claims description 9
- 239000007924 injection Substances 0.000 claims description 9
- 238000007789 sealing Methods 0.000 claims description 8
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B33/00—Sealing or packing boreholes or wells
- E21B33/10—Sealing or packing boreholes or wells in the borehole
- E21B33/13—Methods or devices for cementing, for plugging holes, crevices or the like
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/25—Methods for stimulating production
- E21B43/26—Methods for stimulating production by forming crevices or fractures
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Abstract
The invention belongs to the technical field of offshore oil well exploitation, and discloses an offshore horizontal well multistage fracturing string and well cementation and completion integrated method, wherein the offshore horizontal well multistage fracturing string comprises a liner cementation structure and a tieback string structure, the liner cementation structure comprises a tieback tube, the tieback string structure is detachably connected with the liner cementation structure through the tieback tube, and when the horizontal well performs well cementation operation, one end of the liner cementation structure is positioned in the horizontal well, and the other end of the liner cementation structure is connected with a drilling tool; when the horizontal well performs well completion operation, one end of the tie-back tubular column structure is connected with the liner cementing structure, and the other end of the tie-back tubular column structure is arranged at the wellhead. According to the invention, through the detachable connection of the liner cementing structure and the tie-back tubular column structure in the offshore horizontal well multistage fracturing tubular column, the integrated operation of cementing and completing can be realized, the occupied space of ground equipment can be effectively reduced, the operation risk is further reduced, the fracturing and completion efficiency is improved, and the cementing and fracturing periods are reduced, so that the engineering cost is reduced.
Description
Technical Field
The invention relates to the technical field of offshore oil well exploitation, in particular to a multistage fracturing string of an offshore horizontal well and a well cementation and completion integrated method.
Background
With the continuous progress of oil and gas exploration and development equipment and technology, the exploration and development of marine oil and gas resources are gradually developing from the shallow water field to the deep water open sea field. Compared with the development of land oil and gas resource exploration, the marine oil and gas resource exploration often needs higher investment and has higher risk, is particularly limited and influenced by an operation platform and a marine environment, and has higher requirements on development space and operation period.
Specifically, in the exploitation process of the offshore horizontal well, due to the problems of small annulus, irregular borehole shape and the like, when the conventional casing perforation completion method is adopted for carrying out operations such as fracturing and the like, accidents such as lost circulation and gas channeling are easy to occur, and the problems of high requirements on borehole cleaning, early-stage well cementation quality and drilling machine load and difficulty in putting a casing into place frequently occur. Likewise, when the bridge plug perforation combined operation mode is utilized to perform staged fracturing in the prior art, a continuous oil pipe is generally adopted to carry a cable, a lower incident hole gun and the bridge plug are used for performing first stage fracturing at the toe end of the continuous oil pipe, the problems of drill sticking, collapse and the like easily occur in the mode, when some stratum weak positions are used for operation, a large operation risk exists, and the continuous oil pipe device and the operation with the perforating gun all need a long installation period and occupy a large amount of ground space.
Disclosure of Invention
The invention aims to provide a multistage fracturing string for an offshore horizontal well and a well cementation and completion integrated method, which realize fixed well completion integrated operation, effectively reduce occupation of ground equipment space, reduce operation risks, improve fracturing efficiency, reduce well cementation and fracturing cycles and reduce engineering cost.
To achieve the purpose, the invention adopts the following technical scheme:
an offshore horizontal well multistage fracturing string for cementing and completion operations of a horizontal well, comprising:
the drilling device comprises a liner well cementation structure and a tie-back tubular column structure, wherein the liner well cementation structure comprises a tie-back tube, the tie-back tubular column structure is detachably connected to the liner well cementation structure through the tie-back tube, and when the horizontal well performs well cementation operation, one end of the liner well cementation structure is positioned in the horizontal well, and the other end of the liner well cementation structure is connected to a drilling tool; when the horizontal well performs well completion operation, one end of the tieback tubular column structure is connected with the liner cementing structure, and the other end of the tieback tubular column structure is arranged at a wellhead.
Optionally, the liner cementing structure further comprises a liner hanger, a liner string and a liner string, wherein one end of the liner hanger is connected to the tieback tube, the other end is connected to the liner string, and the liner string is connected to an end of the liner string away from the liner hanger.
Optionally, a fracturing sliding sleeve is arranged in the tail pipe string, and the fracturing sliding sleeve is arranged at the toe end of the tail pipe string far away from the tail pipe string.
Optionally, the fracturing device further comprises a pumping pipe string, wherein the pumping pipe string is arranged in the tail pipe string and is arranged at a distance from the fracturing sliding sleeve.
Optionally, the tieback tubular column structure comprises a casing hanger, a casing string and a tieback plug, wherein one end of the casing hanger is arranged at the wellhead, the other end of the casing hanger is connected with the casing string, and the tieback plug is connected with the casing string and is detachably connected with the tieback barrel.
Alternatively, wherein the liner cementing structure and the tieback string structure are both disposed in an oil well casing of the horizontal well.
In another aspect, a method of integrating well cementation and completion comprises:
s1, drilling is completed;
s2, connecting a drilling tool and a liner cementing structure of the offshore horizontal well multistage fracturing string, performing cementing operation, enabling the liner cementing structure to be hung on the upper section of an oil well casing in the horizontal well, and completing manufacturing of a cement sheath;
s3, well dredging operation is carried out, so that a fracturing sliding sleeve in a liner pipe column in the liner well cementation structure extends out;
s4, connecting a tieback tubular column structure of the offshore horizontal well multistage fracturing tubular column to a tieback tube of a liner cementing structure, and completing multistage fracturing operation through a fracturing sliding sleeve and a pumping pipe string;
s5, lifting the tieback pipe column structure, taking out tieback plugs of the tieback pipe column structure, and performing self-injection production or gas lift production.
Alternatively, the step S2 includes:
s2.1, a drilling tool and a liner cementing structure of the offshore horizontal well multistage fracturing string are connected, and the liner cementing structure is lowered to a first fracturing position;
s2.2, ball throwing is carried out on a ball seat of the liner cementing structure for first pressurization so as to hang the liner cementing structure on the upper section of an oil well casing in the horizontal well;
s2.3, performing second pressurization until the ball seat is blocked, and then circulating drilling fluid;
s2.4, injecting cement paste, taking out the drilling tool, and waiting for the cement paste to self-harden to finish the manufacture of the cement sheath.
Alternatively, the step S4 includes:
s4.1, connecting a tieback tubular column structure of the offshore horizontal well multistage fracturing tubular column to a tieback cylinder of a liner cementing structure;
s4.2, after the sealing of the multi-stage fracturing string of the offshore horizontal well is confirmed to be normal, injecting fracturing fluid until the fracturing sliding sleeve is opened;
s4.3, pumping and pressurizing are continued until the cement sheath is opened, and the fracturing operation at the first fracturing position is completed;
s4.4, sequentially lowering the pumping pipe string into the tail pipe string to finish fracturing operation of the rest multiple fracturing positions;
s4.5, performing a flowback test, and adding a dissolving agent.
Optionally, the step S4.4 further includes:
s4.4.1 running the pumping string into the tailpipe string such that the soluble bridge plug in the pumping string is at the next fracturing location;
s4.4.2, taking out the perforating device after the perforating device lifting the pumping pipe string completes perforation;
s4.4.3, pitching to the soluble bridge plug to finish the fracturing operation;
s4.4.4, repeating steps S4.4.1 to S4.4.3 until the fracturing operation of all fracturing locations is completed.
The invention has the beneficial effects that:
according to the invention, through the detachable connection of the liner cementing structure and the tie-back pipe column structure in the multi-stage fracturing pipe column of the offshore horizontal well, the integrated operation of well cementation and completion can be realized, namely, the fixing operation in the horizontal well can be completed by connecting a drilling tool to the liner cementing structure, and the fracturing and completion operation in the horizontal well can be realized by connecting the tie-back pipe column structure to the liner cementing structure under the condition of only dismantling the drilling tool. Therefore, under the integrated operation mode of the offshore horizontal well multi-stage fracturing string, the occupied space of ground equipment can be effectively reduced, the operation risk is further reduced, the fracturing completion efficiency is improved, the well cementation and fracturing period is reduced, and the engineering cost is reduced. On the other hand, the invention also provides an integrated well cementation and completion method, namely, the split arrangement of the multi-stage fracturing string of the offshore horizontal well is utilized to respectively complete well cementation operation and well completion operation after well drilling, and the tieback string structure is removed after well completion, so that oil well production can be realized, and the self-injection production of the optical sleeve can be carried out according to the requirement, or the gas lift production is carried out by lowering the gas lift production string, so that the method is suitable for different production conditions, and the production efficiency is improved.
Drawings
FIG. 1 is a schematic diagram of the overall structure of a multi-stage fracturing string of an offshore horizontal well according to an embodiment of the invention;
fig. 2 is a schematic diagram of a multi-stage fracturing string for an offshore horizontal well according to an embodiment of the invention when fracturing.
In the figure:
10-casing hanger; 20-casing string; 30-tieback plugs; 40-tieback cylinder; 50-liner hanger; 60-tail pipe strings; 70-tail pipe string; 71-fracturing a sliding sleeve; 80-pumping string; 81-soluble bridge plugs; 82-perforating means;
100-wellhead; 200-oil well casing; 300-upper casing; 401-first frac location.
Detailed Description
Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar parts throughout, or parts having like or similar functions. The embodiments described below by referring to the drawings are illustrative and intended to explain the present invention and should not be construed as limiting the invention.
In the description of the present invention, unless explicitly stated and limited otherwise, the terms "connected," "connected," and "fixed" are to be interpreted broadly, as for example, they may be fixedly connected, or may be detachably connected, or may be electrically connected, or may be directly connected, or may be indirectly connected through an intermediary, or may be in communication with one another in two elements or in an interaction relationship between two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.
In the description of the present invention, unless explicitly stated and limited otherwise, a first feature "above" or "below" a second feature may include the first feature and the second feature being in direct contact, or may include the first feature and the second feature not being in direct contact but being in contact by another feature therebetween. Moreover, a first feature being "above," "over" and "on" a second feature includes the first feature being directly above and obliquely above the second feature, or simply indicating that the first feature is higher in level than the second feature. The first feature being "under", "below" and "beneath" the second feature includes the first feature being directly under and obliquely below the second feature, or simply means that the first feature is less level than the second feature.
With the continuous progress of oil and gas exploration and development equipment and technology, the exploration and development of marine oil and gas resources are gradually developing from the shallow water field to the deep water open sea field. Compared with the development of land oil and gas resource exploration, the marine oil and gas resource exploration often needs higher investment and has higher risk, is particularly limited and influenced by an operation platform and a marine environment, and has higher requirements on development space and operation period.
Specifically, in the exploitation process of the offshore horizontal well, due to the problems of small annulus, irregular borehole shape and the like, when the conventional casing perforation completion method is adopted for carrying out operations such as fracturing and the like, accidents such as lost circulation and gas channeling are easy to occur, and the problems of high requirements on borehole cleaning, early-stage well cementation quality and drilling machine load and difficulty in putting a casing into place frequently occur. Likewise, when the bridge plug perforation combined operation mode is utilized to perform staged fracturing in the prior art, a continuous oil pipe is generally adopted to carry a cable, a lower incident hole gun and the bridge plug are used for performing first stage fracturing at the toe end of the continuous oil pipe, the problems of drill sticking, collapse and the like easily occur in the mode, when some stratum weak positions are used for operation, a large operation risk exists, and the continuous oil pipe device and the operation with the perforating gun all need a long installation period and occupy a large amount of ground space.
The technical solution of the present embodiment is further described below by way of specific embodiments with reference to the accompanying drawings.
As shown in fig. 1-2, the embodiment provides a multi-stage fracturing string of an offshore horizontal well and a well cementation and completion integrated method, in the embodiment, the multi-stage fracturing string of the offshore horizontal well comprises a liner cementation structure and a tieback string structure, the liner cementation structure comprises a tieback tube 40, the tieback string structure is detachably connected with the liner cementation structure through the tieback tube 40, and when the horizontal well performs well cementation operation, one end of the liner cementation structure is positioned in the horizontal well, and the other end of the liner cementation structure is connected with a drilling tool; when the horizontal well performs well completion operation, one end of the tie-back tubular string structure is connected to the liner cementing structure, and the other end is arranged at the wellhead 100. On the other hand, the well cementation and completion integrated method in the embodiment comprises the following steps:
s1, drilling is completed;
s2, connecting a drilling tool and a liner cementing structure of a multi-stage fracturing string of the offshore horizontal well, performing cementing operation, enabling the liner cementing structure to be hung on the upper section of an oil well sleeve 200 in the horizontal well, and completing manufacturing of a cement sheath;
s3, performing well dredging operation to enable a fracturing sliding sleeve 71 in a liner string 70 in a liner cementing structure to extend out;
s4, connecting a tieback tubular column structure of the offshore horizontal well multistage fracturing tubular column to a tieback tube 40 of a liner cementing structure, and completing multistage fracturing operation through a fracturing sliding sleeve 71 and a pumping tubular string 80;
s5, lifting the tieback pipe column structure, taking out the tieback plug 30 of the tieback pipe column structure, and performing self-injection production or gas lift production.
Specifically, the embodiment can realize the integrated operation of well cementation and well completion through the detachable connection of the liner cementation structure and the tie-back pipe structure in the multi-stage fracturing pipe column of the offshore horizontal well, namely, the fixing operation in the horizontal well can be completed by connecting a drilling tool to the liner cementation structure, and the fracturing well completion operation in the horizontal well can be realized by connecting the tie-back pipe column structure to the liner cementation structure under the condition of only dismantling the drilling tool. Therefore, under the integrated operation mode of the offshore horizontal well multi-stage fracturing string, the occupied space of ground equipment can be effectively reduced, the operation risk is further reduced, the fracturing completion efficiency is improved, the well cementation and fracturing period is reduced, and the engineering cost is reduced. On the other hand, the embodiment also provides an integrated well cementation and completion method, namely, the split arrangement of the multi-stage fracturing string of the offshore horizontal well is used for respectively completing well cementation operation and well completion operation after well drilling, and the tieback string structure is removed after well completion, so that oil well production can be realized, and the self-injection production of the optical sleeve can be carried out according to the requirement, or the gas lift production can be carried out by the lower gas lift production string, so that the method is suitable for different production conditions, and the production efficiency is improved.
The following describes a specific structure of the multi-stage fracturing string of the offshore horizontal well in this embodiment.
As shown in fig. 1 and 2, the multi-stage fracturing string of the offshore horizontal well in this embodiment includes a liner cementing structure, a tieback string structure, and a pumping string 80. Optionally, the tieback tubular column structure is detachably connected to the liner cementing structure through the tieback tube 40, and when the horizontal well performs cementing operation, one end of the liner cementing structure is positioned in the horizontal well, and the other end of the liner cementing structure is connected to the drilling tool, so that the drilling tool can drive the liner cementing structure to enter the horizontal well and move to a preset position in the oil well casing 200 of the horizontal well; when the horizontal well is in well completion operation, one end of the tie-back pipe column structure is connected with the liner cementing structure, and the other end of the tie-back pipe column structure is arranged at the wellhead 100 so as to complete integral connection of the multi-stage fracturing pipe columns of the offshore horizontal well, and therefore the multi-stage fracturing well completion operation can be achieved after the pumping pipe string 80 is sent into the liner cementing structure.
Specifically, the tieback string structure comprises a casing hanger 10, a casing string 20 and a tieback plug 30, the liner cementing structure comprises a tieback barrel 40, a liner hanger 50, a liner string 60 and a liner string 70, wherein a fracturing sliding sleeve 71 is arranged in the liner string 70, and a pumping string 80 comprises a soluble bridge plug 81 and a perforating device 82.
As shown in fig. 1, when the multi-stage fracturing string of the offshore horizontal well is integrally installed, the liner cementing structure and the tieback string structure are both arranged in the oil well casing 200 of the horizontal well, specifically, one end of the casing hanger 10 is arranged at the wellhead 100, the other end is connected to the casing string 20, the tieback plug 30 is connected to the casing string 20 and is detachably connected to the tieback tube 40, so that the integral connection of the tieback string structure is realized, and the tieback string structure is connected to the liner cementing structure through the tieback tube 40. Illustratively, the casing hanger 10 in this embodiment is configured as a mandrel casing hanger and the casing string 20 employs 139.7mm.
Further, one end of the liner hanger 50 is connected to the tieback tube 40, the other end is connected to the liner string 60, the liner string 70 is connected to the liner string 60 at the end far away from the liner hanger 50, and the fracturing sliding sleeve 71 is arranged at the toe end of the liner string 70 far away from the liner string 60, so that after well cementation, the first-stage fracturing can be realized at the toe end of the liner string 70 through the fracturing sliding sleeve 71, and the problems of drill clamping and collapse caused by an incident hole gun and a bridge plug in the prior art are avoided. Optionally, when performing a fracturing completion, a pumping string 80 is disposed in the tailpipe string 70 and spaced from the fracturing sleeve 71 to complete the multi-stage fracturing operation. Illustratively, the soluble bridge plug 81 of the pumping string 80 in this embodiment can perform the function of a conventional bridge plug and can also be dissolved in a dissolving agent, so that after fracturing, the soluble bridge plug 81 can be dissolved by injecting the dissolving agent, the fracturing period is reduced, and the complex operation of taking and placing the bridge plug is avoided. Illustratively, 139.7mm liner string 70, 244.475mm 139.7mm liner hanger 50 is employed.
The following describes the method of integrating well cementation and completion in this example.
Specifically, the well cementation and completion integrated method in the embodiment comprises the following steps:
s1, drilling is completed;
s2, connecting a drilling tool and a liner cementing structure of a multi-stage fracturing string of the offshore horizontal well, performing cementing operation, enabling the liner cementing structure to be hung on the upper section of an oil well sleeve 200 in the horizontal well, and completing manufacturing of a cement sheath;
s3, performing well dredging operation to enable a fracturing sliding sleeve 71 in a liner string 70 in a liner cementing structure to extend out;
s4, connecting a tieback tubular column structure of the offshore horizontal well multistage fracturing tubular column to a tieback tube 40 of a liner cementing structure, and completing multistage fracturing operation through a fracturing sliding sleeve 71 and a pumping tubular string 80;
s5, lifting the tieback pipe column structure, taking out the tieback plug 30 of the tieback pipe column structure, and performing self-injection production or gas lift production.
Specifically, in step S1, drilling is performed by using a drilling tool to ensure that the horizontal well is smooth, and the offshore horizontal well multi-stage fracturing string is conveniently placed. Illustratively, well casing 200 is placed in a horizontal well to ensure well cementing quality and smooth running into subsequent casing. Illustratively, in this embodiment, the mining uses a 215.9mm drill bit to drill, and after the drilling is completed, the pre-operations such as well completion and well flushing are performed, so that the subsequent operation is performed after the well bore meets the operation requirements.
Further, step S2 includes:
s2.1, a liner cementing structure for connecting a drilling tool and a multi-stage fracturing string of an offshore horizontal well is lowered to a first fracturing position 401;
s2.2, ball throwing is carried out on a ball seat of the liner cementing structure for first pressurization so as to hang the liner cementing structure on the upper section of the oil well casing 200 in the horizontal well;
s2.3, performing second pressurization until the ball seat is blocked, and then circulating drilling fluid;
s2.4, injecting cement paste, taking out the drilling tool, and waiting for the cement paste to self-harden to finish the manufacture of the cement sheath.
As shown in fig. 2, specifically, in this embodiment, a liner string 70 including a fracturing sliding sleeve 71, a liner string 60, a liner hanger 50 and a tieback tube 40 are sequentially lowered into an oil well casing 200 by a drilling tool, and the fracturing sliding sleeve 71 is lowered to a first fracturing position 401 designed in advance, so that the first-stage fracturing is conveniently and directly implemented by the fracturing sliding sleeve 71. Further, the ball is thrown from the wellhead 100 into the liner running tool of the liner cementing structure, so that the ball is fed into the ball seat in the liner hanger 50, the first pressurization is performed, the first ball seat is pressed, the liner hanger 50 is further hung on the upper casing 300 of the upper section of the oil well casing 200, the ball seat is in a closed state, and no circulation passage exists in the oil well casing 200. Further, the methodAnd continuing the second pressurization until the ball seat is blocked, so that a circulation passage exists in the oil well casing 200, and the subsequent cement sheath manufacturing is facilitated. Illustratively, the pressure of the wellhead 100 is predicted according to the pressed target point and the end target point, the construction pressure is limited to 80MPa, the construction pressure of the wellhead 100 is controlled to be below 70MPa, a safe pressure space of 10MPa is reserved, and the discharge capacity can reach 9-9.5 m at most 3 And/min. The liner hanger 50 with the strength of internal pressure resistance and external extrusion resistance reaching 90MPa and 85MPa at the weak points is selected, and the integral sealing capacity of the liner hanger 50 and the tieback tube 40 after being connected is 80MPa.
Optionally, step S2.3 includes:
s2.3.1, pressurizing for the second time until the ball seat is closed;
s2.3.2, clamping a wellhead drilling tool by using a drill pipe slip, and reversely buckling by rotating a rotating disc positively;
s2.3.3, lifting the drilling tool after back-off for inspection, and placing the drilling tool back to the original position after verification is successful;
s2.3.4, injecting drilling fluid for circulation.
Thereby opening the circulation passage through the ball seat, so that the drilling fluid can circulate in the annular space between the oil well casing 200 and the well wall, and the subsequent cement slurry introduction is facilitated. Further, after the drilling fluid is circulated, cement slurry is injected and the drilling tool is taken out, so that cement is automatically solidified in the annular space between the oil well casing 200 and the well wall, the annular space is sealed, the oil-gas-water layer is sealed, the oil well casing 200 becomes a main channel for oil gas to enter the well, and the well cementation operation of the horizontal well is completed. Optionally, in step S3, the cement plugs therein are cleaned using a drilling tool, the tieback cylinder 40 is milled, and the fracturing slide sleeve 71 is left exposed in preparation for the first fracturing.
Optionally, step S4 includes:
s4.1, connecting a tieback tubular column structure of the offshore horizontal well multistage fracturing tubular column to a tieback tube 40 of the liner cementing structure;
s4.2, after the sealing of the multi-stage fracturing string of the offshore horizontal well is confirmed to be normal, the fracturing fluid is injected until the fracturing sliding sleeve 71 is opened;
s4.3, pumping and pressurizing are continued until the cement sheath is opened, and the fracturing operation at the first fracturing position 401 is completed;
s4.4, sequentially lowering the pumping pipe string 80 into the tail pipe string 70 to finish fracturing operation of the rest multiple fracturing positions;
s4.5, performing a flowback test, and adding a dissolving agent.
Specifically, the tieback plug 30 is connected with the casing string 20, and is sequentially pressed down into the horizontal well, so that the tieback plug 30 is connected with the tieback cylinder 40, thereby tightly connecting the casing string 20 with the liner hanger 50 and the liner string 70, and then connecting the casing string 20 with the wellhead 100 through the casing hanger 10, thereby completing the installation of the integral wellbore in the multi-stage fracturing string of the offshore horizontal well. Further, in step S4.2, pressure test and stabilization are performed on the whole shaft, and pressure drop is observed, and if no pressure drop exists, it is proved that the whole shaft is sealed normally, and the condition of staged fracturing operation is provided. Illustratively, the pressure inside and outside the pipe is respectively tested for 40MPa, the pressure is stabilized for 45min, the pressure is stable, the construction requirement is met, and the staged fracturing operation is carried out after the pressure test. After the fracturing fluid is injected into the embodiment, the pressure of the whole shaft is tested, the pressure test pressure is gradually increased, and when the pressure of the ground fracturing truck reaches 67MPa, the fracturing sliding sleeve 71 can be opened, so that the subsequent fracturing by penetrating the cement sheath is facilitated. Specifically, in step S4.3, after the fracturing sliding sleeve 71 is opened, pumping and pressurizing are continuously performed, so as to open the cement sheath, thereby establishing a channel for the flow of the whole shaft and the stratum, and further realizing the first stage fracturing operation at the first fracturing position 401 under the action of the fracturing sliding sleeve 71, wherein the preferred displacement is 8.0-9.5m 3 Preferably, the sand-carrying fluid is injected into 395m 3 The preferred proppant types employ 70/140 mesh and 40/70 mesh low density high strength ceramsite.
Optionally, step S4.4 includes:
s4.4.1 running the pumping string 80 into the tailpipe string 70 such that the soluble bridge plug 81 in the pumping string 80 is at the next fracturing location;
s4.4.2, taking out the perforating device 82 after the perforating device 82 of the pumping string 80 is lifted up to complete perforation;
s4.4.3, pitching to the soluble bridge plug 81 to complete the fracturing operation here;
s4.4.4, repeating steps S4.4.1 to S4.4.3 until the fracturing operation of all fracturing locations is completed.
Specifically, after the first stage fracturing is completed, the pumping string 80 is lowered through the cable into its soluble bridge plug 81 and perforating device 82 to pump it to the next fracturing location where the soluble bridge plug 81 was pre-designed. And then, the soluble bridge plug 81 is subjected to seat sealing at the position by using a seat sealing tool, the perforating device 82 is lifted up to carry out perforation, the cable, the perforating device 82 and the seat sealing tool are lifted out to the wellhead lubricator after perforation, the well is closed for pressure relief, the lower operation pipe string is assembled after the pipe string is disassembled for checking the pipe string, and then the ball is thrown to the soluble bridge plug 81 so as to complete the fracturing operation at the second fracturing position. Illustratively, a displacement of 8.0-9.5m is preferred 3 Preferably, the sand-carrying fluid is injected into 395m 3 The preferred proppant types employ 70/140 mesh and 40/70 mesh low density high strength ceramsite. Further, according to the setting of the fracturing operation, repeating steps S4.4.1 to S4.4.3, putting a plurality of soluble bridge plugs 81 at the corresponding fracturing positions, sequentially performing seat sealing, perforation, ball injection and fracturing to complete the fracturing operation of all the fracturing positions, and dissolving all the soluble bridge plugs 81 by using a dissolving agent in step S4.5 to complete the fracturing completion operation. Further, after the tieback pipe column structure is lifted up, the tieback plug 30 of the tieback pipe column structure is taken out, so that self-injection production or gas lift production can be performed, and the specific production mode can be set according to the needs. Illustratively, three-dimensional fracturing software is utilized to simulate the post-fracturing productivity under different fracture lengths, and the relation between the sand ratio and dimensionless diversion capacity of a well reservoir is analyzed and calculated, so that the fracture lengths of 150-160m and the sand ratio of 15-16% are optimized and optimized. And optimizing and calculating the relation between the front fluid proportion and the fluid efficiency according to the front-stage offshore fracturing construction experience, wherein the optimized front fluid proportion is 38% -48%.
The multi-stage fracturing string of the offshore horizontal well in the embodiment can realize well cementation operation and multi-stage fracturing during well completion operation, specifically, the first stage fracturing operation is realized through the fracturing sliding sleeve 71, then the residual multi-stage fracturing is realized under the action of the soluble bridge plugs 81, and the production operation can be realized through dissolving the plurality of soluble bridge plugs 81 by using a dissolving agent, so that the well cementation and well completion integrated process is realized, the occupied space of equipment on the ground is effectively reduced, the operation risk is reduced, the fracturing efficiency is improved, the well cementation and fracturing period is reduced, the engineering cost is reduced, and space is provided for self-injection or gas lift production, so that the large-scale multi-stage cluster horizontal well fracturing production can be still carried out under the condition that the ground space is limited, and the fracturing strategy of the horizontal well can be flexibly adjusted according to the underground condition.
Further, in this embodiment, firstly, data such as logging, earthquake, logging, core experiment, etc. are utilized to analyze geological and mechanical characteristics such as mineral content, porosity, permeability, etc. of the gas reservoir, and describe brittle characteristics, natural fracture characteristics, ground stress characteristics, temperature and pressure characteristics, dessert distribution, fracture network volume fracturing feasibility analysis, etc. And then analyzing the main control factors of the gas reservoir, which influence the fracturing effect, according to the data of logging, earthquake, geomechanics, fracturing construction, production and the like of the fractured well of the gas reservoir, and aiming at the main control factors, so that the fracturing design is optimized, and the fracturing quality and efficiency are improved. Furthermore, according to the condition of the gas reservoir (the well completion and fracturing construction operation is limited by the space and the period of the offshore platform, and the fracturing stratum has a weak layer) and the main control factors (factors such as the horizontal section length, the fracturing series, the natural cracks and the like) influencing the fracturing effect of the area, the multi-stage fracturing is carried out by adopting the multi-stage fracturing tubular column of the offshore horizontal well in the embodiment to reduce the fracturing construction risk and according to the characteristics that the sea is limited by the space and the period of the platform, so that the fracturing efficiency is improved.
Similarly, in the change characteristics of longitudinal physical parameters, ground stress, rock mechanical parameters and the like of different small layers, well sections with similar geological and engineering parameters are divided into the same section, so that uneven and insufficient fracturing caused by overlarge parameter difference in the same section is avoided. Preferably, perforation is carried out at the position where the crack is initiated and expanded, brittleness and stress parameters are kept close to each cluster in the section, uniform initiation and extension of each cluster crack are ensured, the perforation cluster position avoids lithology interfaces, casing joints and positions with poor well cementation quality, influences of different fracturing fluid systems on the form of a fracture network are researched according to the rock mineral composition, the reservoir sensitivity, the reservoir fluid properties and the reservoir temperature and pressure characteristics of a reservoir, and the characteristics of offshore fracturing construction technology are combined, and a guar gum fracturing fluid system with good compatibility with the reservoir is selected according to the compatibility, the temperature resistance, the sand carrying property, the fluid loss property, the resistance reducing property, the drainage assisting property and the gel breaking property of the fracturing fluid.
It is to be understood that the above examples of the present invention are provided for clarity of illustration only and are not limiting of the embodiments of the present invention. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. Any modification, equivalent replacement, improvement, etc. which come within the spirit and principles of the invention are desired to be protected by the following claims.
Claims (10)
1. An offshore horizontal well multistage fracturing string for cementing and completion operations of a horizontal well, comprising:
the drilling device comprises a liner cementing structure and a tie-back tubular column structure, wherein the liner cementing structure comprises a tie-back tube (40), the tie-back tubular column structure is detachably connected with the liner cementing structure through the tie-back tube (40), and when the horizontal well performs cementing operation, one end of the liner cementing structure is positioned in the horizontal well, and the other end of the liner cementing structure is connected with a drilling tool; when the horizontal well performs well completion operation, one end of the tie-back tubular column structure is connected with the liner cementing structure, and the other end of the tie-back tubular column structure is arranged at a wellhead (100).
2. The offshore horizontal well multistage fracturing string according to claim 1, wherein the liner cementing structure further comprises a liner hanger (50), a liner string (60) and a liner string (70), wherein the liner hanger (50) is connected at one end to the tieback tube (40) and at the other end to the liner string (60), and wherein the liner string (70) is connected at an end of the liner string (60) remote from the liner hanger (50).
3. The offshore horizontal well multistage fracturing string according to claim 2, wherein a fracturing sliding sleeve (71) is arranged in the tail pipe string (70), and the fracturing sliding sleeve (71) is arranged at the toe end of the tail pipe string (70) far away from the tail pipe string (60).
4. An offshore horizontal well multistage fracturing string according to claim 3, further comprising a pumping string (80), said pumping string (80) being arranged in said tailpipe string (70) at a distance from said fracturing sleeve (71).
5. The offshore horizontal well multistage fracturing string according to claim 1, wherein the tieback string structure comprises a casing hanger (10), a casing string (20) and a tieback plug (30), wherein one end of the casing hanger (10) is arranged at the wellhead (100) and the other end is connected to the casing string (20), and the tieback plug (30) is connected to the casing string (20) and is detachably connected to the tieback barrel (40).
6. The offshore horizontal well multistage fracturing string according to any of claims 1-5, wherein said liner cementing structure and said tieback string structure are both disposed in an oil well casing (200) of said horizontal well.
7. The well cementation and completion integrated method is characterized by comprising the following steps of:
s1, drilling is completed;
s2, connecting a drilling tool and the liner cementing structure of the offshore horizontal well multistage fracturing string according to any one of claims 1-6, performing cementing operation, enabling the liner cementing structure to be hung on the upper section of an oil well sleeve (200) in the horizontal well, and completing manufacturing of a cement sheath;
s3, well dredging operation is carried out, so that a fracturing sliding sleeve (71) in a liner pipe column (70) in the liner cementing structure extends out;
s4, connecting the tieback tubular column structure of the offshore horizontal well multistage fracturing tubular column according to any one of claims 1-6 to a tieback cylinder (40) of a liner cementing structure, and completing multistage fracturing operation through a fracturing sliding sleeve (71) and a pumping pipe string (80);
s5, lifting the tieback pipe column structure, taking out a tieback plug (30) of the tieback pipe column structure, and performing self-injection production or gas lift production.
8. The method according to claim 7, wherein the step S2 comprises:
s2.1, a liner cementing structure connecting a drilling tool and the multi-stage fracturing string of the offshore horizontal well as claimed in any one of claims 1-6 is lowered to a first fracturing position (401);
s2.2, ball throwing is carried out on a ball seat of the liner cementing structure for first pressurization so as to hang the liner cementing structure on the upper section of an oil well casing (200) in the horizontal well;
s2.3, performing second pressurization until the ball seat is blocked, and then circulating drilling fluid;
s2.4, injecting cement paste, taking out the drilling tool, and waiting for the cement paste to self-harden to finish the manufacture of the cement sheath.
9. The method of integrating well cementation and completion according to claim 7, wherein the step S4 comprises:
s4.1, connecting a tieback tubular column structure of the offshore horizontal well multistage fracturing tubular column according to any one of claims 1-6 to a tieback cylinder (40) of a liner cementing structure;
s4.2, after the sealing of the multi-stage fracturing string of the offshore horizontal well is confirmed to be normal, the fracturing fluid is injected until the fracturing sliding sleeve (71) is opened;
s4.3, continuing pumping and pressurizing until the cement sheath is opened, and completing fracturing operation at the first fracturing position (401);
s4.4, sequentially lowering the pumping pipe string (80) into the tail pipe string (70) to finish fracturing operation of the rest multiple fracturing positions;
s4.5, performing a flowback test, and adding a dissolving agent.
10. The method of integrating well cementation and completion according to claim 9, wherein the step S4.4 further comprises:
s4.4.1 running the pumping string (80) into the tailpipe string (70) such that a soluble bridge plug (81) in the pumping string (80) is located at the next fracturing location;
s4.4.2, taking out the perforating device (82) after the perforating device (82) lifting the pumping pipe string (80) completes perforation;
s4.4.3, pitching to the soluble bridge plug (81) to complete the fracturing operation;
s4.4.4, repeating steps S4.4.1 to S4.4.3 until the fracturing operation of all fracturing locations is completed.
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