A rotatable and salvageable ball-throwing fracturing sleeve and its use method

Abstract

The present invention relates to the field of oil completion tools. A rotatable ball-throwing fracturing sleeve and a method of use are provided. The sleeve comprises an upper joint, a lower joint, an outer cylinder and a fracturing hole, an inner sleeve and a locking block, an opening sleeve and a ball seat, and a salvaging anchor, wherein: a plurality of fracturing holes and locking block slots are arranged on the outer cylinder, and the inner sleeve can be fixed on the outer cylinder; the inner sleeve is connected to the outer cylinder by a locking block, and the top is a spline structure, and the inner sleeve and the outer cylinder are separated by rotating the spline by an inner tube tool; the bottom thread of the inner sleeve is connected to the docking anchor, and three sliders with slips are evenly distributed on the docking anchor, which is convenient for entering and salvaging the next-level fracturing inner sleeve, thereby realizing the one-time salvage of the multi-stage fracturing sleeve; the opening sleeve assembly comprises a sealing ring, an opening hole, a pin and a ball seat, and the ball seat is connected to the bottom thread of the opening sleeve, and the ball seat and the fracturing ball are matched in a step-by-step manner. The sleeve is suitable for multi-stage fracturing operations in horizontal wells, realizing the normal opening of the fracturing hole and the removal of the inner sleeve, thereby improving the efficiency of the fracturing operation.

Description

Technical Field

[0001] The present invention relates to a rotatable and salvageable ball-dropping fracturing sleeve and a use method in the field of petroleum completion tools. The present invention is suitable for multi-stage fracturing operations in horizontal wells. The inner sleeve of the fracturing sleeve is rotated and salvaged out of the well by using a fishing anchor. No drilling plug is required and the full bore can be achieved, thereby ensuring the successful implementation of the fracturing process, improving the efficiency of the fracturing operation and reducing the cost of the fracturing operation. Background Art

[0002] With the development of domestic oil and gas resources, low-permeability reservoirs with rich reserves have received more and more attention and have become the main battlefield for increasing reserves and production in major oil fields. Low-permeability reservoirs are affected by their porosity and permeability characteristics and seepage laws. How to effectively mobilize reserves and significantly increase single-well production is an urgent problem to be solved in the development of low-permeability reservoirs. Horizontal well multi-stage fracturing technology has become an effective technical means to develop unconventional and low-permeability oil and gas reservoirs. Among them, the ball-dropping fracturing process has become a key process in horizontal well multi-stage fracturing technology due to its high tool reliability and simple process.

[0003] At present, the commonly used technologies of ball-throwing fracturing process are mainly the following: First, the fracturing ball and the fracturing sleeve are matched in a step-by-step manner, the inner sleeve cannot be salvaged, the inner diameter is relatively small, or a plug drill is required to remove the inner sleeve to establish a larger inner diameter. Second, use a fracturing ball of one specification to open multiple fracturing sleeves at the same time, reduce the step-by-step, increase the inner diameter, and the sleeve and fracturing ball cannot be salvaged. Third, some parts of the tool are made of soluble materials, which can dissolve by themselves after fracturing. Fourth, use special tools to separate the inner sleeve from the outer cylinder to achieve the salvage of the inner sleeve out of the well.

[0004] For example, a multi-cluster unlimited-stage cementing segmented fracturing string and fracturing method (application number: 201510725756.7), wherein the multi-cluster fracturing sleeves are opened one by one by deploying a special opening tool, and the number of fracturing stages is not limited, and any stage fracturing can be achieved, but the fracturing sleeves and the special opening tool cannot be salvaged. A full-diameter fracturing sleeve without step difference (application number: 201820245163.X), wherein the fracturing ball and the ball seat have no step difference, and the elastic claw structure is used to open all fracturing sleeves by only deploying fracturing balls of the same size. A rotationally controlled stepless ball-throwing fracturing sleeve (patent number: CN201621073148.9), which controls the rotating sleeve to pull the petal claws to rotate different grooves, allowing the pressure ball to pass through, thereby achieving the purpose of steplessness. The ball-dropping sliding sleeve with a salvageable ball seat (application number: CN201810567984) is connected in sequence according to the ball seat classification and is lowered into the designed position of the ball-dropping sliding sleeve along with the horizontal section completion string. The balls are dropped in sequence for fracturing construction. The threaded fish-top fishing tool is lowered into the well to lift and untie the uppermost ball seat and the sliding sleeve, and push it down to the next level. The lower end of the upper ball seat unlocks the lower ball seat and salvages it until all the ball seats are unlocked and salvaged.

[0005] In comparison, in order to increase the internal diameter of the completion well, increase the production fluid and operating channels, and meet the needs of repeated fracturing and inner pipe operations in low permeability reservoirs, the best fracturing method is to salvage the inner casing with special tools. Summary of the invention

[0006] The purpose of the present invention is to overcome the deficiencies of the prior art and to provide a fracturing sleeve having a reliable connection between an inner sleeve and an outer cylinder and capable of being rotated and salvaged, and a method for using the same.

[0007] The technical solution is as follows:

[0008] A rotatable and salvageable ball-throwing fracturing sleeve comprises an outer tube, an inner tube, an opening sleeve, a ball seat, a docking anchor and a ball. The inner tube and the docking anchor are threadedly connected and sleeved in the outer tube. The opening sleeve and the ball seat are threadedly connected and sleeved in the inner tube. The inner tube is fixed to the outer tube by a locking block and a locking block slot arranged on the inner wall of the outer tube. A plurality of fracturing holes are arranged on the outer tube, and the ball is placed in the ball seat.

[0009] Furthermore, the top of the inner sleeve is a spline structure.

[0010] Furthermore, three sliding blocks with slips are evenly distributed circumferentially on the docking anchor.

[0011] Furthermore, the ball seat and the fracturing ball are matched in steps.

[0012] Furthermore, three sliding blocks with slips are provided at the end of the docking anchor.

[0013] Furthermore, the docking anchor can be screwed together with the spline on the top of the inner sleeve.

[0014] Furthermore, the fracturing hole is arranged on the outer cylinder section corresponding to the ball seat and the opening sliding sleeve connection section.

[0015] Furthermore, an upper joint is provided at the upper end of the outer cylinder.

[0016] Furthermore, a lower joint is provided at the lower end of the outer cylinder.

[0017] Furthermore, a method for using a rotatable and salvageable ball-dropping fracturing sleeve comprises: according to the well condition requirements, connecting multiple sets of rotatable and salvageable ball-dropping fracturing sleeves by rotating the docking anchor and the inner tube.

[0018] The present invention is different from other head ball fracturing sleeves. It is a new type of fracturing tool that can be salvaged and has a large inner diameter. Compared with the existing technology, the advantages of the present invention are as follows:

[0019] ① The inner sleeve and the outer cylinder are connected by a locking block, and the top is a spline structure. The inner sleeve and the outer cylinder are separated by rotating the spline using an inner tube tool;

[0020] ② The tool has a simple structure and a feasible principle, which is a useful supplement to the existing types of ball-throwing fracturing tools;

[0021] ③The tool’s action switch is reliable, reducing the risks of operations such as circulation, fracturing, and salvage. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of a rotatably salvageable ball-throwing fracturing sleeve;

[0023] In the figure: 1-upper joint, 2-lower joint, 3-butt anchor slider, 4-inner sleeve spline, 5-fixed lock block and slot, 6-inner sleeve, 7-sealing ring, 8-opening sleeve, 9-outer cylinder fracturing hole, 10-pin, 11-outer cylinder, 12-butt anchor, 13-opening sleeve opening, 14-fracturing ball, 15-ball seat;

[0024] Figure 2 It is a schematic diagram of a special tool for salvaging the inner sleeve;

[0025] In the figure: 16-fishing tool body, 17-fishing anchor slider, 18-spline rotation bar;

[0026] Figure 3 It is a schematic diagram of the spline structure. DETAILED DESCRIPTION

[0027] The present invention will be further described in detail below with reference to specific embodiments.

[0028] Embodiment 1:

[0029] A rotatable and salvageable ball-throwing fracturing sleeve and a method of use. The sleeve comprises an upper joint, a lower joint, an outer cylinder and a fracturing hole, an inner sleeve and a locking block, an opening sleeve and a ball seat, and a salvaging anchor, wherein: a plurality of fracturing holes and locking block slots are arranged on the outer cylinder, and the inner sleeve can be fixed on the outer cylinder; the inner sleeve is connected to the outer cylinder by a locking block, and the top is a spline structure, and the inner sleeve and the outer cylinder are separated by rotating the spline by an inner tube tool; the bottom thread of the inner sleeve is connected to the docking anchor, and three sliders with slips are evenly distributed on the docking anchor, which is convenient for entering and salvaging the next-level fracturing inner sleeve, thereby realizing the one-time salvage of the multi-stage fracturing sleeve; the opening sleeve assembly comprises a sealing ring, an opening hole, a pin and a ball seat, and the ball seat is connected to the bottom thread of the opening sleeve, and the ball seat and the fracturing ball are matched in a step-by-step manner. The present invention is suitable for multi-stage fracturing operations in horizontal wells, realizing the normal opening of the fracturing hole and the removal of the inner sleeve, ensuring the successful implementation of the fracturing process, and thus improving the efficiency of the fracturing operation. Its advantages: the fracturing ball and the ball seat are matched in a stepped manner; the inner sleeve of the fracturing sleeve can be completely salvaged out of the well by using the fishing anchor, without the need for drilling plugs, and the full diameter can be achieved.

[0030] The above scheme further comprises:

[0031] The ball-dropping fracturing sleeve can be used in multiple groups to improve the operational efficiency of staged fracturing in horizontal wells and extended-reach wells and reduce fracturing costs.

[0032] In order to achieve the purpose of staged fracturing, the opening diameters of the ball seats of each level of fracturing sleeve are different, which can be matched with fracturing balls of different sizes.

[0033] After the internal accessories of the sliding sleeve are salvaged out of the well, the inner diameter of the tool can be made consistent with the inner diameter of the casing, thereby greatly improving the success rate of subsequent operations.

[0034] Embodiment 2:

[0035] like Figure 1 As shown, a rotatable and salvageable ball-throwing fracturing sleeve and a method of use thereof include 1-upper joint, 2-lower joint, 3-butt anchor slider, 4-inner sleeve spline, 5-fixed locking block and slot, 6-inner sleeve, 7-sealing ring, 8-opening sleeve, 9-outer cylinder fracturing hole, 10-pin, 11-outer cylinder, 12-butt anchor, 13-opening sleeve opening, 14-fracturing ball, and 15-ball seat. Among them: multiple fracturing holes 9 and locking block slots 5 are arranged on the outer cylinder 11, and the inner sleeve 6 can be fixed on the outer cylinder 11; the inner sleeve 6 is connected to the outer cylinder 11 through the locking block 5, and the top is a spline structure 4, and the inner sleeve 6 is separated from the outer cylinder 11 by rotating the spline 4 using an inner tube tool; the bottom of the inner sleeve 6 is threadedly connected to the docking anchor, and three sliders 3 with slips are evenly distributed on the docking anchor, which is convenient for entering and salvaging the next-level fracturing inner sleeve, thereby realizing the one-time salvage of the multi-stage fracturing sleeve.

[0036] like Figure 2 As shown, the special tool for salvaging the inner sleeve includes a salvaging tool body 16, an anchor catching slider 17, and a spline rotating bar 18. The anchor catching slider 17 can move along the slideway to ensure that the inner sleeve is tightened after salvaging; the spline rotating bar 18 cooperates with the inner sleeve spline 4 to unlock the inner sleeve by rotation.

[0037] like Figure 3 As shown, the spline structure 19 is located in the inner sleeve 6 , and the 6 inner groove structures cooperate with the spline rotating bar 18 .

[0038] During the construction process, according to Figure 1 The rotatable fishing ball-dropping fracturing sliding sleeve shown in the figure can be combined with the multi-stage fracturing according to the well conditions and technical requirements. Multiple sets of rotatable fishing ball-dropping fracturing sliding sleeves are connected and the casing string is lowered. After the casing string is lowered into place, it is operated according to the procedure of cementing, ball-dropping, fracturing, next-stage ball-dropping, and next-stage fracturing.

[0039] The embodiments disclosed herein are to be considered in all respects as illustrative and non-restrictive. The embodiments described above may be omitted, replaced, or modified in various forms without departing from the appended claims and the gist thereof.

Claims

1. A rotatable and salvageable ball fracturing sleeve. It is characterized in that It includes an outer tube, an inner sleeve, an open sliding sleeve, a ball seat, a docking anchor, and a pitching ball. The inner sleeve and the docking anchor are threadedly connected and then sleeved in the outer tube. The open sliding sleeve and the ball seat are threadedly connected and then sleeved in the inner sleeve. The inner sleeve is fixed to the outer tube by a locking block and a locking block slot arranged on the inner wall of the outer tube. The outer tube is provided with a plurality of fracturing holes, and the pitching ball is placed in the ball seat. The top of the inner sleeve is a spline structure. Three sliding blocks with slips are evenly distributed circumferentially on the docking anchor. The docking anchor can be screwed together with the spline on the top of the inner sleeve.

2. A rotatably salvageable ball-throwing fracturing sleeve according to claim 1, It is characterized in that The ball seat and the fracturing ball are matched in a stepped manner.

3. A rotatably salvageable ball-throwing fracturing sleeve according to claim 2, It is characterized in that The end of the docking anchor is provided with three sliding blocks with slips.

4. A rotatably salvageable ball-throwing fracturing sleeve according to claim 3, It is characterized in that The fracturing hole is arranged on the outer cylinder section corresponding to the ball seat and the opening sliding sleeve connecting section.

5. A rotatably salvageable ball-throwing fracturing sleeve according to any one of claims 1 to 4, It is characterized in that An upper joint is arranged at the upper end of the outer cylinder.

6. A rotatably salvageable ball-throwing fracturing sleeve according to any one of claims 1 to 4, It is characterized in that A lower joint is arranged at the lower end of the outer cylinder.

7. A method for using a rotatably salvageable ball-throwing fracturing sleeve according to any one of claims 1 to 4, It is characterized in that include: According to the well conditions, multiple sets of rotatable and salvageable ball-dropping fracturing sleeves are connected by rotating the docking anchor and the inner tube.

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