A secondary fracture creation device for volume fracturing of tight reservoirs

Abstract

The present invention discloses a secondary seam-making device for volume fracturing of a tight reservoir, which is placed in a pre-drilled hole and comprises a seam-making tube, a first sealing disk, a second sealing disk and a suction tube, wherein a seam-making hole is opened on the seam-making tube, and a first sealing disk and a second sealing disk fixed to the outside of the seam-making tube are respectively arranged on both sides of the seam-making hole, the seam-making tube is controlled by a seam-making control tube, and the seam-making control tube is configured as follows: firstly, a first volume of fracturing fluid is injected into the seam-making tube at a first flow rate and a first pressure, and then a part of the fracturing fluid is slowly extracted, and then a secondary seam-making process is performed.

Description

Technical Field

[0001] The invention relates to the technical field of volume fracturing and seam-making, in particular to a device for secondary seam-making by volume fracturing of a dense reservoir. Background Art

[0002] With the advancement of transformation technologies in unconventional oil and gas fields such as shale gas and tight oil, the use of volume fracturing technology to improve tight reservoirs by creating fractures has become the mainstream method of transformation. However, the current volume fracturing technology often uses a one-time fracturing method, and its fracture creation effect is average, which is specifically reflected in the poor elongation of the fracture. In addition, it cannot provide effective support for the fracture body.

[0003] Therefore, it is necessary to provide a secondary fracture creation device for volume fracturing of a tight reservoir to solve the problems raised in the above background technology. Summary of the invention

[0004] To achieve the above-mentioned objectives, the present invention provides the following technical solutions: a secondary seam-making device for volume fracturing of a tight reservoir, which is placed in a pre-drilled hole, and comprises a seam-making tube, a first sealing disk, a second sealing disk and a suction tube, wherein a seam-making hole is opened on the seam-making tube, and a first sealing disk and a second sealing disk fixed to the outside of the seam-making tube are respectively arranged on both sides of the seam-making hole, the seam-making tube is controlled by a seam-making control tube, and the seam-making control tube is configured as follows: first, a first volume of fracturing fluid is injected into the seam-making tube at a first flow rate and a first pressure, and then a portion of it is slowly extracted, and then a secondary seam-making process is performed.

[0005] Furthermore, preferably, an annular capsule is fixed to the outer surface of the first sealing disk and the second sealing disk, and the expansion and contraction of the annular capsule is controlled by an external hydraulic control tube.

[0006] Further, as a preference, when the slit control tube controls the slit tube to perform secondary slit making, a second volume of fracturing fluid is first injected into the slit tube at a second flow rate and a second pressure, and then a portion of the fracturing fluid is slowly extracted, and then a third volume of fracturing fluid is injected into the slit tube at a third flow rate and a third pressure.

[0007] Further, preferably, the second volume is 3 / 2 of the first volume; and the third volume is 7 / 4 of the first volume.

[0008] Furthermore, preferably, one end of the slit-making tube away from the hole body is connected to an expansion tube, a straight tube and a tightening tube in sequence, and the other end of the tightening tube is also connected to the slit-making control tube by a sealing connection seat.

[0009] Further, as a preference, the sealing connection seat is also sealingly connected to a blocking seat, and the blocking seat can block the pre-drilled hole.

[0010] Furthermore, preferably, the straight pipe is also fixedly connected to a feed pipe, a control valve is provided at the bottom of the feed pipe, a feed port is connected to one side of the feed pipe, and a powered piston is provided on the inner side of the feed pipe in a sealing and sliding manner.

[0011] Furthermore, as a preference, a suction tube is also provided inside the suturing tube, one end of the suction tube extends out of the suturing tube, and the extended portion has a suction head, and the other end of the suction tube is fixedly connected to a suction seat passing through the suturing tube.

[0012] Further, as a preference, the suction pipe is divided into two parts, and a guide pipe and an arc-shaped connector are connected between the two parts in sequence from left to right, wherein the outer diameter of the guide pipe gradually increases from left to right, and the guide pipe is arranged corresponding to the discharge pipe.

[0013] Further, as a preference, the suction tube is controlled by a suction control tube, and the suction control tube is configured to continuously perform suction on the suction tube during the suturing process using the suturing tube.

[0014] Compared with the prior art, the present invention provides a device for secondary fracture creation by volume fracturing of a tight reservoir, which has the following beneficial effects:

[0015] In the present invention, the secondary slit-making treatment technology is adopted, which can effectively increase the extension length of the crack, and the slit-making control tube is configured as follows: first, a first volume of fracturing fluid is injected into the slit-making tube at a first flow rate and a first pressure, and then a portion of it is slowly extracted, and then a secondary slit-making treatment is performed. When the fracturing fluid of the initial injection is partially extracted slowly, the support particles in the fracturing fluid can be retained in the crack for continuous support, and the extracted part of the fracturing fluid can make room for the next injection of fracturing fluid, thereby injecting more support particles in a limited space, improving the stability of the crack, and facilitating effective slit-making in dense reservoirs. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of a secondary fracture-making device for volume fracturing of a tight reservoir;

[0017] Figure 2 for Figure 1 An enlarged schematic diagram of the right side structure;

[0018] Figure 3 Schematic diagram of the change of fracturing fluid injection volume, where L is the injection volume and T is the time;

[0019] In the figure: 1, slit tube; 2, first plugging disk; 3, second plugging disk; 4, slit hole; 5, suction tube; 6, suction head; 7, suction seat; 8, plugging seat; 9, sealing connection seat; 10, slit control tube; 11, suction control tube; 12, tightening tube; 13, expansion tube; 14, feeding tube; 15, feeding port; 16, arc connector; 17, guide tube;

[0020] M1, first line body; M2, second line body; M3, third line body; M4, fourth line body; M5, fifth line body. DETAILED DESCRIPTION

[0021] Example: Please refer to Figure 1-3 In an embodiment of the present invention, a secondary seam-making device for volume fracturing of a tight reservoir is placed in a pre-drilled hole, and comprises a seam-making pipe 1, a first sealing disk 2, a second sealing disk 3 and a suction pipe 5, wherein a seam-making hole 4 is opened on the seam-making pipe 1, and a first sealing disk 2 and a second sealing disk 3 fixed to the outside of the seam-making pipe 1 are respectively arranged on both sides of the seam-making hole 4, and the seam-making pipe 1 is controlled by a seam-making control pipe 10, and the seam-making control pipe 10 is configured as follows: first, a first volume of fracturing fluid is injected into the seam-making pipe 1 at a first flow rate and a first pressure, and then a portion of the fracturing fluid is slowly extracted, and then a secondary seam-making process is performed.

[0022] It should be noted that in this embodiment, the secondary slit-making treatment technology is used to effectively increase the extension length of the crack, and the slit-making control tube 10 is configured as follows: first, a first volume of fracturing fluid is injected into the slit-making tube 1 at a first flow rate and a first pressure, and then a portion of it is slowly extracted, and then a secondary slit-making treatment is performed. When the portion of the fracturing fluid injected initially is slowly extracted, the support particles in the fracturing fluid can be retained in the crack for continuous support, and the extracted portion of the fracturing fluid can make room for the next injection of fracturing fluid, thereby injecting more support particles in a limited space.

[0023] As a preferred embodiment, an annular capsule is fixed to the outer surface of the first sealing disk 2 and the second sealing disk 3, and the expansion and contraction of the annular capsule is controlled by an external hydraulic control tube.

[0024] The annular capsule can effectively improve the sealing effect of the first sealing disk 2 and the second sealing disk 3;

[0025] A sealed injection space can be formed between the first sealing disk 2 and the second sealing disk 3, thereby achieving regional directional injection and improving the specificity of fracturing.

[0026] In this embodiment, when the slit control tube 10 controls the slit tube 1 to perform secondary slit making, a second volume of fracturing fluid is first injected into the slit tube at a second flow rate and a second pressure, and then a portion of the fracturing fluid is slowly extracted, and then a third volume of fracturing fluid is injected into the slit tube at a third flow rate and a third pressure.

[0027] Furthermore, the second volume is 3 / 2 of the first volume; and the third volume is 7 / 4 of the first volume.

[0028] like Figure 3 , Figure 3 Schematic diagram of the change of injection volume of fracturing fluid, where L is the injection volume and T is the time; the secondary fracture creation adopts the method of injecting fracturing fluid three times, and the three injections of fracturing fluid can be the first fracturing fluid, the second fracturing fluid and the third fracturing fluid respectively;

[0029] When the first injection of fracturing fluid is performed, such as the first line body M1, the first fracturing fluid is quickly injected into the area to be fractured. Afterwards, such as the second line body M2, part of the fracturing fluid is slowly extracted, and a large number of supporting particles are retained. When the second injection of fracturing fluid is performed, such as the third line body M3, the second fracturing fluid is quickly injected into the area to be fractured. Afterwards, such as the fourth line body M4, part of the fracturing fluid is slowly extracted, and more supporting particles are retained. Finally, the third injection of fracturing fluid can be performed, such as the fifth line body M5, and the third fracturing fluid is quickly injected into the area to be fractured, and the pressure is maintained.

[0030] It should also be explained that the support particles contained in the three injections of fracturing fluid are first support particles, second support particles and third support particles, respectively, wherein the particle size of the first support particles is larger than the particle size of the second support particles which is larger than the particle size of the third support particles.

[0031] In this embodiment, the end of the suturing tube 1 away from the hole body is connected with the expansion tube 13, the straight tube and the tightening tube 12 in sequence, and the other end of the tightening tube 12 is also connected with the suturing control tube 10 through a sealing connection seat 9.

[0032] In addition, the straight pipe is fixedly connected to a feed pipe 14, the bottom of which is provided with a control valve, one side of which is connected to a feed port 15, and the inner side of the feed pipe 14 is sealed and slidably provided with a powered piston.

[0033] When the fracturing fluid flows through the tightening tube 12, the straight tube and the expansion tube 13, a certain suction force will be generated in the straight tube part, so that the supporting particles in the feeding tube 14 can be sucked, so that the supporting particles can evenly enter the slit-making tube 1, which is convenient for subsequent fracturing and support.

[0034] In addition, the piston can also provide pulse force to the fracturing fluid, thereby improving the fracturing effect.

[0035] In this embodiment, the sealing connection seat 9 is also sealingly connected to the blocking seat 8, and the blocking seat 8 can block the pre-drilled hole.

[0036] In this embodiment, a suction tube 5 is further provided inside the suturing tube 1, one end of the suction tube 5 extends out of the suturing tube 1, and the extended part has a suction head 6, and the other end of the suction tube 5 is fixedly connected to a suction seat 7 that passes through the suturing tube 1.

[0037] Furthermore, the suction tube 5 is controlled by a suction control tube 11 , and the suction control tube 11 is configured to continuously perform suction on the suction tube 5 during the suture making process using the suture making tube 1 .

[0038] In fact, the sealed space formed between the first sealing disk 2 and the second sealing disk 3 corresponds to the area to be sutured, and suction is performed on both sides of the area to be sutured, which can guide the gas in the area to be sutured to penetrate to both sides, which is highly safe and convenient for subsequent direct suture creation.

[0039] As a preferred embodiment, the suction pipe 5 is divided into two parts, and the two parts are connected with a guide pipe 17 and an arc-shaped connecting head 16 from left to right in sequence, wherein the outer diameter of the guide pipe 17 gradually increases from left to right, and the guide pipe 17 is arranged corresponding to the discharge pipe 14.

[0040] What has been described above are only preferred specific implementations of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, can make equivalent replacements or changes based on the technical solutions and inventive concepts of the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A secondary fracture creation device for volume fracturing of a tight reservoir, which is placed in a pre-drilled hole, characterized in that: The invention comprises a slit-making tube (1), a first plugging disk (2), a second plugging disk (3) and a suction tube (5), wherein a slit-making hole (4) is opened on the slit-making tube (1), and the first plugging disk (2) and the second plugging disk (3) fixed to the outside of the slit-making tube (1) are respectively arranged on both sides of the slit-making hole (4); the slit-making tube (1) is controlled by a slit-making control tube (10), and the slit-making control tube (10) is configured to: firstly inject a first volume of fracturing fluid into the slit-making tube (1) at a first flow rate and a first pressure, and then slowly extract a part of the fluid, and then perform a secondary slit-making process; When the slit control pipe (10) controls the slit pipe (1) to perform secondary slit making, a second volume of fracturing fluid is first injected into the slit pipe at a second flow rate and a second pressure, and then a portion of the fracturing fluid is slowly withdrawn, and then a third volume of fracturing fluid is injected into the slit pipe at a third flow rate and a third pressure; The end of the slit-making tube (1) away from the hole body is connected in sequence to an expansion tube (13), a straight tube and a tightening tube (12), and the other end of the tightening tube (12) is also connected to the slit-making control tube (10) by a sealing connection seat (9); The straight pipe is also fixedly connected to a feed pipe (14), the bottom of the feed pipe (14) is provided with a control valve, one side of the feed pipe (14) is connected to a feed port (15), and a piston with power is provided on the inner side of the feed pipe (14) in a sealing and sliding manner; A suction tube (5) is also provided inside the suturing tube (1), one end of the suction tube (5) extends out of the suturing tube (1), and the extended portion has a suction head (6), and the other end of the suction tube (5) is fixedly connected to a suction seat (7) that passes through the suturing tube (1); The suction pipe (5) is divided into two parts, and a flow guide pipe (17) and an arc-shaped connector (16) are connected between the two parts from left to right in sequence, wherein the outer diameter of the flow guide pipe (17) gradually increases from left to right, and the flow guide pipe (17) is arranged corresponding to the discharge pipe (14).

2. A device for secondary fracture creation in volume fracturing of a tight reservoir according to claim 1, characterized in that: An annular sac is fixed to the outer surface of the first blocking disc (2) and the second blocking disc (3), and the expansion and contraction of the annular sac is controlled by an external hydraulic control pipe.

3. A device for secondary fracture creation in volume fracturing of a tight reservoir according to claim 1, characterized in that: The second volume is 3 / 2 of the first volume; and the third volume is 7 / 4 of the first volume.

4. A device for secondary fracture creation in volume fracturing of a tight reservoir according to claim 1, characterized in that: The sealing connection seat (9) is also sealingly connected to the blocking seat (8), and the blocking seat (8) is capable of blocking the pre-drilled hole.

5. A device for secondary fracture creation in volume fracturing of a tight reservoir according to claim 1, characterized in that: The suction tube (5) is controlled by a suction control tube (11), and the suction control tube (11) is configured to continuously perform a suction action on the suction tube (5) during the suturing process using the suturing tube (1).

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