CN212272153U - Separate-layer fracturing string - Google Patents

Abstract

The utility model provides a separate-layer fracturing string, which comprises a first fracturing assembly, a second fracturing assembly, a third fracturing assembly and a fracturing oil pipe which are arranged from bottom to top and are communicated with each other; the first fracturing component comprises a sieve tube, a check valve and a first sleeve spray gun which are sequentially arranged from bottom to top and are communicated with each other; the second fracturing component comprises a packer and a second sleeve spray gun which are sequentially arranged from bottom to top and are communicated with each other; the third fracturing assembly comprises a well completion sliding sleeve and a safety joint which are sequentially arranged from bottom to top and are communicated with each other; the first casing spray gun and the second casing spray gun are respectively positioned in different oil-gas layers in the casing completion section and are both used for spraying fracturing fluid. The embodiment of the utility model provides a separate layer fracturing tubular column is through connecting expanding packer between two sleeve spray guns, and control packer sits and seals the opportunity, makes the pump stopping pressure of first hydrocarbon reservoir fracturing not influence the construction of second hydrocarbon reservoir, finally realizes high-pressure oil gas well separate layer hydraulic jet fracturing.

Description

Separate-layer fracturing string

Technical Field

The utility model relates to an oil field fracturing technical field especially relates to a separate layer fracturing tubular column.

Background

The hydraulic jet fracturing is an important oil and gas well development mode at present, is a production increase transformation technology integrating sand jet perforation, fracturing and isolation, and is suitable for oil and gas wells with various well types and well completion types.

At present, the fracturing is widely carried out by adopting a hydraulic jet mode, the existing layered fracturing pipe column comprises an oil pipe, a sleeve spray gun and the like, when the fracturing is carried out, the sleeve spray gun is firstly put down to a first layer of fracturing position, fracturing fluid is pumped into the oil pipe, hydraulic jet perforation is carried out by the sleeve spray gun, fracturing front fluid is pumped after the perforation is finished, the oil sleeve annulus is rapidly pressurized to generate cracks, the first layer of fracturing is completed, then the well is closed and the jet is released, the pipe column is lifted to a second fracturing position, and the second layer of fracturing is carried out.

The pumping pressure of the stratum in some areas is high, generally exceeds 40Mpa, the pressure of the oil casing pipe is above 40Mpa after the first layer fracturing of the stratified hydraulic jet is finished, and when the second layer hydraulic jet perforation is prepared, the overpressure of the construction pressure of the oil pipe pumping is caused by the high throttling pressure of the casing pipe spray gun and the influence of the friction resistance of the fluid in the pipe column, and the pumping is difficult. Meanwhile, the casing pressure exceeds 40MPa, the casing back pressure control difficulty is high during hydraulic sand blasting perforation, the risk is high, and the implementation of the layered hydraulic jet fracturing process in a high-pressure area is severely limited, so that the layered hydraulic jet fracturing process needs to be improved when the high-pressure well is constructed.

SUMMERY OF THE UTILITY MODEL

The utility model provides a layering fracturing string realizes carrying out two-layer hydraulic jet fracturing transformation to high pressure oil gas well.

The utility model provides a separate layer fracturing string, include: the first fracturing assembly, the second fracturing assembly, the third fracturing assembly and the fracturing oil pipe are sequentially arranged from bottom to top and are communicated with each other;

the first fracturing component comprises a sieve tube, a check valve and a first sleeve spray gun which are sequentially arranged from bottom to top and are communicated with each other;

the second fracturing assembly comprises a packer and a second sleeve spray gun which are sequentially arranged from bottom to top and are communicated with each other;

the third fracturing assembly comprises a well completion sliding sleeve and a safety joint which are sequentially arranged from bottom to top and are communicated with each other;

the first casing spray gun is located first hydrocarbon reservoir, the second casing spray gun is located the second hydrocarbon reservoir, first casing spray gun with the second casing spray gun all is used for spraying fracturing fluid.

Further, still include the school dark nipple joint, the school dark nipple joint is located third fracturing unit spare top and with fracturing oil pipe intercommunication.

Further, the fracturing unit further comprises a first straddle oil pipe for connecting the first fracturing assembly and the second fracturing assembly and a second straddle oil pipe for connecting the second fracturing assembly and the third fracturing assembly, and the lengths of the first straddle oil pipe and the second straddle oil pipe are adjustable.

Further, the first fracturing assembly further comprises a guide head, and the guide head is located below the screen and connected with the screen.

Further, the first fracturing assembly further comprises an oil pipe nipple, and the oil pipe nipple is used for connecting the first casing spray gun and the check valve.

Furthermore, a plurality of evenly distributed holes are formed in the screen pipe wall of the screen pipe and are used for enabling the fracturing oil pipe to be communicated with the oil sleeve annulus.

Furthermore, the check valve comprises a check valve shell, a baffle, a return spring, a spring seat and a steel ball, wherein a liquid passing hole is formed in the baffle, the baffle is connected to the check valve shell through a screw thread, the return spring is sleeved on the spring seat, and the steel ball is pressed on the ball seat by the return spring.

Further, the first sleeve spray gun comprises a first main body, a first sealing ring and a first combined nozzle, wherein an opening is formed in the first main body, the first combined nozzle is installed in the opening of the first main body, and the first combined nozzle and the main body are sealed through the first sealing ring.

Further, the second sleeve spray gun comprises a first shear pin ring, a first shear pin, a second combined nozzle, a first sealing ring, a second sliding sleeve and a second main body, wherein the second main body is provided with an opening, the second combined nozzle is installed in the opening of the second main body, and the second combined nozzle and the main body are sealed through the second sealing ring; the first shear pin ring is connected with the second main body, the first shear pin is matched with the first shear pin ring for use and enables the first sliding sleeve to be hung on the inner side of the second main body, and the first sliding sleeve is sealed between the second main body through the first sealing ring and the second sealing ring.

Further, the packer is an expandable packer.

The embodiment of the utility model provides a separate zone fracturing tubular column is through connecting expanding packer between first sleeve spray gun and second sleeve spray gun, can sit through the mode control packer who opens the sliding sleeve and seal the opportunity, forces the packer to sit when second hydrocarbon reservoir fracturing and seals, seals oil jacket annular space, reaches the purpose that the pump stopping pressure of first hydrocarbon reservoir fracturing does not influence second hydrocarbon reservoir construction, finally realizes high-pressure oil gas well separate zone hydraulic jet fracturing.

Drawings

In order to illustrate the technical solutions of the present invention or the prior art more clearly, the drawings needed for the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without inventive labor.

Fig. 1 is a schematic structural diagram of a separate-layer fracturing string provided by an embodiment of the present invention;

fig. 2 is a structural cross-sectional view of a conduit head in a layered fracturing string provided by an embodiment of the present invention;

FIG. 3 is a cross-sectional structural view of a screen in a frac string in accordance with an embodiment of the present invention;

fig. 4 is a structural cross-sectional view of a check valve in a layered fracturing string provided by an embodiment of the present invention;

fig. 5 is a structural cross-sectional view of a first casing lance in a layered fracturing string provided by an embodiment of the present invention;

fig. 6 is a cross-sectional view of a second casing lance in a layered fracturing string in accordance with an embodiment of the present invention;

fig. 7 is a structural cross-sectional view of a packer in a zonal fracturing string provided by an embodiment of the present invention;

fig. 8 is a cross-sectional structural view of a completion sleeve in a zonal fracturing string provided by an embodiment of the present disclosure;

fig. 9 is a structural cross-sectional view of a safety joint in a separate zone fracturing string provided by an embodiment of the present invention.

Reference numerals:

1-a first fracturing assembly; 11-a guide head;

12-a screen; 121-eyelet;

13-a check valve; 131-a single flow valve housing;

132-a baffle; 133-a return spring;

134-spring seat; 135-steel ball;

14-tubing nipple; 15-a first sleeve lance;

151-a first body; 152-a first seal ring;

153-a first composite nozzle; 2-a second fracturing assembly;

21-a packer; 211-packer upper sub;

212-a third sealing ring; 213-upper rubber cylinder seat;

214-a glue cartridge; 215-lower rubber cylinder seat;

216-a central tube; 217-second shear pin;

218-a second runner; 219-movable baffle ring;

2110-set screw; 2111-a stop collar;

2112-fourth seal ring; 2113-packer lower sub;

22-a second sleeve lance; 221-a first shear pin ring;

222-a first shear pin; 223-a first sealing ring;

224-a second seal ring; 225-a second composite nozzle;

226-a first runner; 227-a second body;

228 — a second seal ring; 3-a third fracturing assembly;

31-a well completion sliding sleeve; 311-baffle ring;

312-a fifth seal ring; 313-a third shear pin;

314-a side hole; 315-a third slip sleeve;

316-a housing; 32-a safety joint;

321-an upper joint; 322-a second shear pin ring;

323-a fourth shear pin; 324-a sixth sealing ring;

325-a fourth slip sleeve; 326-seventh seal ring;

327-lower joint; 4-fracturing the oil pipe;

5-a first straddle oil pipe; 6-a second straddle oil pipe;

7-depth correcting short section; 8-hanging the oil pipe;

9-a sleeve; a-a first hydrocarbon reservoir;

b-a second hydrocarbon reservoir.

Detailed Description

To make the objects, technical solutions and advantages of the present invention clearer, the drawings of the present invention are combined to clearly and completely describe the technical solutions of the present invention, and obviously, the described embodiments are some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.

The invention is described below with reference to the accompanying drawings in conjunction with specific embodiments.

Example one

Fig. 1 is the utility model provides a structural schematic of layering fracturing tubular column, it is shown with reference to fig. 1 that the layering fracturing tubular column that this embodiment provided is a layering water jet fracturing tubular column step by step, include: the fracturing unit comprises a first fracturing assembly 1, a second fracturing assembly 2, a third fracturing assembly 3 and a fracturing oil pipe 4 which are sequentially arranged from bottom to top. The direction from bottom to top is along the direction from the bottom to the top of the well, namely the first fracturing assembly 1 is located at the lowest part of the separate-layer fracturing string, the upper part of the first fracturing assembly 1 is connected with the second fracturing assembly 2, the upper part of the second fracturing assembly 2 is connected with the third fracturing assembly 3, and the upper part of the third fracturing assembly 3 is connected with the fracturing oil pipe 4. And a depth correcting nipple 7 is further arranged on the fracturing oil pipe 4, is connected with the fracturing oil pipe 4 and is positioned above the third fracturing assembly, so that magnetic positioning and depth correction are facilitated, and the tool setting depth is determined. The wellhead is also provided with an oil pipe hanger 8, the upper part of the fracturing oil pipe 4 is connected with the oil pipe hanger 8, and the whole layered fracturing string is stably suspended in the well through the oil pipe hanger 8. First fracturing unit spare 1 and second fracturing unit spare 2 can be connected according to actual need between first stride oil pipe 5, and first length of striding oil pipe 5 can be adjusted according to the interval between first fracturing unit spare 1 and the second fracturing unit spare 2 to adapt to different operating modes. Similarly, a second cross-oil-separating pipe 6 can be connected between the second fracturing assembly 2 and the third fracturing assembly 3 according to actual needs, and the length of the second cross-oil-separating pipe 6 can be adjusted according to the distance between the second fracturing assembly 2 and the third fracturing assembly 3 so as to adapt to different working conditions.

Specifically, the first fracturing assembly 1 comprises a sieve tube 12, a check valve 13 and a first casing spray gun 15 which are sequentially arranged from bottom to top and are communicated with each other, the first casing spray gun 15 is located in an oil layer a and is used for spraying fracturing fluid, and the check valve 13 only allows fluid to flow from bottom to top, otherwise, the fluid does not flow. The first fracturing assembly 1 further comprises a guide head 11, wherein the guide head 11 is of an integral structure without a through hole in the middle and is positioned below the sieve tube 12 and connected with the sieve tube 12. The first fracturing assembly 1 can also be provided with an oil pipe nipple 14 between the check valve 13 and the first casing spray gun 15 as required, and the check valve 13 and the first casing spray gun 15 are communicated through the oil pipe nipple 14. The second fracturing assembly 2 comprises a packer 21 and a second casing spray gun 22 which are sequentially arranged from bottom to top and are communicated with each other, and the third fracturing assembly 3 comprises a completion sliding sleeve 31 and a safety joint 32 which are sequentially arranged from bottom to top and are communicated with each other.

Fig. 2 is a structural cross-sectional view of a conduit head in a separate-zone fracturing string provided by an embodiment of the present invention, and fig. 2 shows that the guide head 11 is an integral structure, and has an external cone with a certain angle and no through hole inside. The guide head 11 is used for preventing the separate layer fracturing string from being hung on the side wall of the sleeve 9 to be blocked in the process of descending the separate layer fracturing string.

Fig. 3 is the utility model provides a structural section of screen pipe in the separate stratum fracturing tubular column, refer to fig. 3 and show, in this embodiment, screen pipe 12 is overall structure, and inside cavity, a series of punchholes 121 of evenly distributed on the screen pipe wall, punchhole 121 are used for intercommunication fracturing oil pipe and oil jacket annular space, and the supplementary oil jacket pressure balance of income tubular column in-process also can regard as the circulation to wash the liquid passageway of crossing of oil pipe and oil jacket annular space when well.

Fig. 4 is a structural cross-sectional view of a check valve in a separate zone fracturing string provided by an embodiment of the present invention, and referring to fig. 4, the check valve 13 specifically includes a check valve housing 131, a baffle 132, a return spring 133, a spring seat 134, and a steel ball 135. The baffle plate 132 is provided with a liquid passing hole and is connected to the uniflow valve shell 11 by a screw thread, the return spring 133 is sleeved on the spring seat 134, the steel ball 135 is pressed on the ball seat by the return spring 133, the steel ball is seated on the ball seat in a sealing state when fluid flows from top to bottom, and the fluid is blocked. When fluid flows from bottom to top under the action of external force, the steel ball is forced to compress the return spring to leave the ball seat, the fluid can flow from bottom to top, and once the external force disappears, the fluid stops flowing, and then the steel ball is seated into the ball seat under the action of the return spring. This makes the fluid flow from bottom to top only, not from top to bottom.

Fig. 5 is a structural cross-sectional view of a first casing lance in a layered fracturing string according to an embodiment of the present invention, referring to fig. 5, in this embodiment, the first casing lance 15 includes a first main body 151, a first sealing ring 152, and a first combination nozzle 153. The first body 151 has openings, each of which is installed with a first combination nozzle 153, and the first combination nozzle 153 and the first body 151 are sealed by a first sealing ring 152. The working principle is that the fracturing fluid forms high-speed jet flow after passing through the first combined nozzle 18, and the high-speed jet flow is used for perforating on the wall of the casing and completing hydraulic jet fracturing.

The number of openings in the first body 151 and the number of first combination nozzles 153 may be increased or decreased according to actual conditions, and in an exemplary embodiment, 8 holes are uniformly arranged in the first body 151 in a spiral manner, and 1 first combination nozzle 153 is installed in each hole, where the number of openings in the first body 151 and the number of first combination nozzles 153 are not limited. The first combination nozzle 153 may be installed in the opening by a screw thread method, or other installation methods may be selected, and the aperture of the first combination nozzle 153 may be 6.3mm, or other sizes may be selected, which is not limited herein.

Fig. 6 is a structural cross-sectional view of a second casing lance in a layered fracturing string according to an embodiment of the present invention, and referring to fig. 6, in this embodiment, the second casing lance 22 includes a first shear pin ring 221, a first shear pin 222, a first sealing ring 223, a second sealing ring 224, a second combination nozzle 225, a first sliding sleeve 226, a second main body 227, and a second sealing ring 228. The second body 227 is provided with an opening, a second combined nozzle 225 is installed in the opening, the second combined nozzle 225 and the second body 227 are sealed through a second sealing ring 224, the second body 227 is internally connected with a first shear pin ring 221 through threads, the first shear pin 222 is matched with the first shear pin ring 221 for use, the first sliding sleeve 226 is hung on the inner side wall of the second body 227, and the first sliding sleeve 226 is kept sealed with the second body 227 by means of an upper sealing ring and a lower sealing ring, namely a first sealing ring 223 and a second sealing ring 228. The working principle is that when hydraulic sand blasting perforation fracturing of the second oil-gas layer b needs to be carried out, the first shearing pin 222 is sheared off by throwing balls and adding positive pressure, the first sliding sleeve 226 falls down to expose the liquid passing channel of the second combined nozzle, fracturing liquid forms high-speed jet flow after passing through the second combined nozzle, and perforation is carried out on the casing wall by means of the high-speed jet flow and hydraulic jet fracturing is completed.

The number of openings in the second body 227 and the number of the second combined nozzles 225 may be increased or decreased according to actual conditions, and in an exemplary embodiment, 8 holes are uniformly arranged in the second body 227 in a spiral manner, and 1 second combined nozzle 225 is installed in each hole, where the number of openings in the second body 227 and the number of the second combined nozzles 225 are not limited. The second combined nozzle 225 may be installed in the opening by a screw thread method, or may be installed in other manners, and the aperture of the second combined nozzle 225 may be 6.3mm, or may be selected in other sizes, which are not limited herein.

Fig. 7 is the structural section view of the packer in the zonal fracturing string provided by the embodiment of the present invention, referring to fig. 7, in this embodiment, the packer adopts K344 step-by-step expandable packer, specifically including packer upper joint 211, center tube 216, packer lower joint 2113, packing element assembly, second sliding sleeve 218, and the packing element assembly includes packing element 214, upper packing element seat 213, lower packing element seat 215. The packer upper joint 211 is connected to the top end of the center pipe 216, the packer lower joint 2113 is connected to the bottom end of the center pipe 216, the rubber sleeve assembly is sleeved outside the center pipe 216, the upper rubber sleeve seat 213 is connected with the packer upper joint 211, the upper rubber sleeve seat 213 and the packer upper joint 211 are sealed through a third sealing ring 212, the lower rubber sleeve seat 215 is connected with the packer lower joint 2113, a liquid inlet hole is formed in the pipe wall of the center pipe 216, the second sliding sleeve 218 is fixed on the inner wall of the center pipe through a second shearing pin 217 and keeps sealed with the inner wall of the center pipe 216 through a fourth sealing ring 2112, and the liquid inlet hole is sealed. The working principle is as follows: when carrying out the fracturing of first hydrocarbon reservoir a, because the feed liquor hole is sealed by second sliding sleeve 218, the packer can not set, when preparing fracturing second hydrocarbon reservoir b, through bowling to second sliding sleeve 218, through adding the malleation, open second sliding sleeve 218, pump the fracturing fluid in to fracturing oil pipe 4 this moment, liquid in the center tube 216 enters into the gap between center tube 216 and packing element 214 through the feed liquor hole, make packing element 214 outwards swell, thereby realize packing, the sealed oil jacket annulus is empty, when the interior pressure release of tubular column, when reaching oil jacket pressure balance, packing element 214 withdraws the deblocking promptly.

When the rubber barrel 214 expands or contracts, the lower rubber barrel holder 215 can move downwards or upwards, and in order to avoid an excessive range of movement, the movable stop ring 219 and the limiting ring 2111 can be arranged to limit the movement position, for example, the movable stop ring 219 can be a small iron ring, and the movable stop ring 219 is connected to the lower rubber barrel holder 215 to play a limiting role and limit the maximum upward movement position of the lower rubber barrel holder 215. Meanwhile, a limiting ring 2111 is arranged on a lower joint 2113 of the packer, the limiting ring 2111 is connected with the lower joint 2113 of the packer through a fixing screw 2110, and the limiting ring 2111 is used for limiting the downward maximum moving position of the lower rubber sleeve seat 215 and preventing external force from impacting the lower rubber sleeve seat 215 and the movable retaining ring 219 when the pipe string descends.

The fracturing fluid can adopt a sand carrying fluid with a certain sand ratio, and can also adopt other fracturing fluids, wherein the type of the fracturing fluid is not limited.

Fig. 8 is a structural sectional view of the completion sliding sleeve 31 in the separate zone fracturing string provided by the embodiment of the present invention, referring to fig. 8, in this embodiment, the completion sliding sleeve 31 specifically includes a stop ring 311, a fifth sealing ring 312, a third shear pin 313, a third sliding sleeve 315, and a housing 316. The completion sliding sleeve 31 is a hollow structure, three side holes 314 are formed in the side face of the shell 316, the baffle ring 311 is connected inside the shell 316 through threads, and the third sliding sleeve 315 is fixed inside the shell 316 through a group of third shear pins 313 and sealed through a fifth sealing ring 312. During specific work, balls with proper sizes are thrown to the upper part of the third sliding sleeve 315, the third shearing pin 313 is sheared by positive pressure, the third sliding sleeve 315 falls, the side hole 314 is exposed, and the tubular column and the oil sleeve annulus are communicated.

Fig. 9 is a cross-sectional view of a safety joint in a separate zone fracturing string provided by an embodiment of the present invention, and referring to fig. 9, in this embodiment, the safety joint 32 specifically includes an upper joint 321, a second shear pin ring 322, a fourth shear pin 323, a sixth sealing ring 324, a fourth sliding sleeve 325, a seventh sealing ring 326, and a lower joint 327, and the safety joint 32 is a hollow structure. The upper joint 321 is connected with the lower joint 327 through a locking claw and sealed by a seventh sealing ring 326, the fourth sliding sleeve 325 limits the upper joint and the lower joint, the fourth sliding sleeve 325 is connected with the upper joint 321 through a second shear pin ring 322 and a fourth shear pin 323, and the upper joint 321 and the lower joint 327 are in sawtooth structures matched with each other and can transmit torque. When the pipe column is blocked, a ball with proper size is thrown to the upper part of the fourth sliding sleeve 325, positive pressure is applied to cut the fourth shearing pin 323, the fourth sliding sleeve 325 falls down, the limit of the locking claw is released, the pipe column is lifted, the locking claw deforms and retracts, the locking is released, and the upper joint and the lower joint are separated.

The following describes a fracturing reconstruction process using the separate zone fracturing string provided in this embodiment by way of a specific example.

Illustratively, referring to FIG. 1, a zonal fracturing string is lowered into a well at a predetermined location, first fracturing a first section: and opening an injection gate of an oil pipe of a fracturing wellhead in the first oil-gas layer a, pumping fracturing fluid with designed discharge capacity from a fracturing oil pipe 4, properly controlling back pressure by using a throttling manifold for a sleeve 9, calculating the position of the perforating fracturing fluid reaching a spray gun, carrying out sand blasting for 7-9min, and perforating the sleeve and a cement ring to finish perforation. And (4) continuing the oil pipe pump to perform fracturing, generating high-speed jet flow at the position of the first sleeve spray gun 15 to form negative pressure, and simultaneously completing the fracturing of the first oil-gas reservoir a by sleeve fluid infusion.

After fracturing of the first oil-gas layer a is completed, a ball is thrown into the fracturing string from the wellhead to the second sliding sleeve 218 of the packer 21, positive pressure is applied to cut the second shearing pin 217, the second sliding sleeve 218 falls to the lower connector 2113 of the packer, and the liquid inlet hole of the central pipe 216 is exposed; then, the ball is thrown to the first sliding sleeve 226 of the second casing spray gun 22, the first shearing pin 222 is sheared off by applying positive pressure, the first sliding sleeve 226 falls to the upper part of the second sliding sleeve 218 of the packer 21, the jet hole of the second casing spray gun 22 is exposed, and the first casing spray gun 15 is plugged.

Then fracturing of the second hydrocarbon reservoir b is carried out, fracturing fluid is pumped from the ground, and because the first casing spray gun 15 is blocked, the fracturing fluid is sprayed out from the second casing spray gun 22 at high speed, and throttling differential pressure is generated. The packer 21 completes setting under the action of throttling pressure difference, seals and separates the annular space of the oil sleeve, the pumping stop pressure of the fracturing of the first oil-gas layer a is blocked, the fracturing of the second oil-gas layer b is not influenced, fracturing fluid continues to be pumped, sand blasting perforation is carried out for 7-9min, a casing and a cement ring are penetrated, and perforation is completed. And (4) continuing the oil pipe pump to perform fracturing, generating high-speed jet flow at the position of the second sleeve spray gun 22 to form negative pressure, and simultaneously completing fracturing of the second oil-gas layer b by sleeve fluid infusion.

After second hydrocarbon reservoir b fracturing, put the pressure through oil pipe, fracturing oil pipe and sleeve pipe internal pressure are balanced gradually, and packer 21 is because there is not inside and outside pressure differential, and packing element 214 is automatic to be retrieved, and packer 21 deblocking.

In the later production process, the ball can be thrown into the well completion sliding sleeve 31, the third sliding sleeve 315 is opened by adding positive pressure, the side hole 314 is exposed, the fracturing oil pipe and the casing annulus are communicated, and well washing and production can be completed.

If the pipe string is blocked in the process of lifting the pipe string, balls can be thrown to the fourth sliding sleeve 325 of the safety joint 32, the fourth sliding sleeve 325 is opened by adding positive pressure, the pipe string is lifted upwards, the safety joint 32 is disconnected, the upper pipe string can be recycled, and the process is prevented from being complicated.

In the description of the present invention, it is to be understood that the terms "center", "length", "width", "thickness", "top", "bottom", "upper", "lower", "left", "right", "front", "rear", "vertical", "horizontal", "inner", "outer", "axial", "circumferential", and the like, which are used to indicate the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for convenience of description and simplification of the description, and do not indicate or imply that the position or element referred to must have a particular orientation, be of particular construction and operation, and therefore should not be construed as limiting the present invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly, e.g., as meaning fixedly connected, detachably connected, or integrally formed; may be mechanically coupled, may be electrically coupled or may be in communication with each other; either directly or indirectly through intervening media, such as through internal communication or through an interaction between two elements. The specific meaning of the above terms in the present invention can be understood according to specific situations by those skilled in the art.

In the present disclosure, unless expressly stated or limited otherwise, the first feature "on" or "under" the second feature may comprise direct contact between the first and second features, or may comprise contact between the first and second features not directly. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly under and obliquely below the second feature, or simply meaning that the first feature is at a lesser elevation than the second feature.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the present invention.

Claims (10)

1. A layered fracturing string is characterized by comprising a first fracturing component, a second fracturing component, a third fracturing component and a fracturing oil pipe which are sequentially arranged from bottom to top and are communicated with each other;

the first fracturing component comprises a sieve tube, a check valve and a first sleeve spray gun which are sequentially arranged from bottom to top;

the second fracturing assembly comprises a packer and a second sleeve spray gun which are sequentially arranged from bottom to top;

the third fracturing assembly comprises a well completion sliding sleeve and a safety joint which are sequentially arranged from bottom to top;

the first casing spray gun is located first hydrocarbon reservoir, the second casing spray gun is located the second hydrocarbon reservoir, first casing spray gun with the second casing spray gun all is used for spraying fracturing fluid.

2. The fracturing string of claim 1, further comprising a depth stop nipple located above the third fracturing assembly and in communication with the fracturing tubing.

3. The layered fracturing string of claim 2, further comprising a first straddle tubing connecting the first and second fracturing assemblies and a second straddle tubing connecting the second and third fracturing assemblies, the first and second straddle tubing being adjustable in length.

4. The fracturing string of claim 1, wherein the first fracturing assembly further comprises a guide head positioned below the screen and connected to the screen.

5. The fracturing string of claim 1, wherein the first fracturing assembly further comprises a tubing nipple for connecting the first casing gun and the check valve.

6. The zonal fracturing string of claim 1, wherein the screen wall of the screen is provided with a plurality of evenly distributed perforations for providing communication between the frac tubing and the oil jacket annulus.

7. The layered fracturing string as claimed in claim 1, wherein the check valve comprises a check valve housing, a baffle, a return spring, a spring seat and a steel ball, the baffle is provided with a liquid through hole, the baffle is connected to the check valve housing through a screw thread, the return spring is sleeved on the spring seat, and the steel ball is pressed on the ball seat by the return spring.

8. The fracturing string of claim 1, wherein the first casing gun comprises a first body having an opening therein, a first seal ring, and a first composite nozzle mounted within the opening of the first body, the first composite nozzle and the body being sealed by the first seal ring.

9. The zonal fracturing string of claim 1, wherein the second casing lance comprises a first shear pin ring, a first shear pin, a second combination nozzle, a first seal ring, a second seal ring, a first sliding sleeve, and a second body, the second body having an opening therein, the second combination nozzle being mounted in the opening of the second body, the second combination nozzle and the body being sealed by the second seal ring; the first shear pin ring is connected with the second main body, the first shear pin is matched with the first shear pin ring for use and enables the first sliding sleeve to be hung on the inner side of the second main body, and the first sliding sleeve is sealed between the second main body through the first sealing ring and the second sealing ring.

10. The zonal fracturing string of claim 1, wherein the packer is an expandable packer.

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