Device and method for multistage pitching temporary plugging fracturing of deep shale gas

Abstract

The invention provides a deep shale gas multi-stage pitching temporary plugging fracturing device and method.The device comprises a high-pressure injection device, a plurality of high-pressure pump trucks, a plurality of high-pressure pipelines and a plurality of high-pressure pipelines, the high-pressure pump trucks are all connected with a high-pressure manifold, and the high-pressure manifold is connected with a wellhead through a high-pressure pipeline; and the multi-stage ball throwing device is connected with the well mouth and can conduct multi-stage ball throwing in sequence. The method is realized by using the device. A set of temporary plugging balls with different diameters and different densities is designed, multi-stage ball throwing can be achieved, the temporary plugging balls move in a pipeline at the same time, meanwhile, perforation holes are achieved, and the plugging pressure and the plugging efficiency are improved.

Description

Technical Field

[0001] The present invention relates to a device and method for multi-stage ball dropping and temporary plugging fracturing of deep shale gas, belonging to the field of deep shale gas development. Background Art

[0002] In China, there is a very rich resource volume of deep shale gas. Usually, large-scale fracturing volume transformation of horizontal wells is required to form a complex fracture network to provide a high-conductivity seepage channel to increase production for profitable development. Currently, multi-cluster perforating fracturing technology is usually adopted for deep shale gas wells. Each section is perforated with 3 to 6 clusters, the perforation density is 16 to 20 holes / m, and the total number of perforations is 50 to 60 holes. After sand addition for a period of time during the fracturing process, a ball is dropped to plug the perforation holes that have been fractured and filled with fluid, so that some unfractured holes can initiate fractures, extend the fractures and add sand for support. After adding sand to the designed sand volume, another ball is dropped to plug the perforation holes that have been filled with fluid, so that other unfractured holes can initiate fractures and be filled with sand, so as to open all the perforation holes and add sand for support, achieving the purpose of uniform transformation of each perforating cluster.

[0003] Currently, a ball dropper is generally installed on the high-pressure pipeline. The plugging ball is previously placed in the ball dropper. When a ball needs to be dropped, the ball dropper is first opened, and the plugging ball falls from the ball dropper to the high-pressure pipeline, and then is carried by the fracturing fluid from the high-pressure pipeline to the wellbore to plug the perforation holes. Since it takes 20 to 30 seconds for the ball dropper to be fully opened, there is a time interval for the plugging ball to fall from the ball dropper to the high-pressure pipeline. At a displacement of 8m 3 / min, the distance between the first ball and the last ball reaching the perforation holes in the Φ139.7mm casing is 220 to 330m, and the higher the displacement, the greater the distance.

[0004] This ball dropping method brings the following four adverse results: (1) The size of the ball dropper does not match the diameter of the temporary plugging ball, and it is difficult for the temporary plugging ball to fall to the high-pressure pipeline during the ball dropping process, failing to plug the perforation holes; (2) The falling time is long, and each ball cannot reach the perforation holes simultaneously. The wellhead pressure often does not rise significantly, or does not exceed 1MPa, making it impossible to judge whether the dropped plugging ball has successfully plugged and evaluate the plugging efficiency; (3) To observe the rise of the ball dropping pressure, generally, an additional wellbore fluid is pumped, resulting in liquid waste and increasing the fracturing cost; (4) The transformation is uneven, some clusters are over-transformed, and some clusters are not transformed, affecting the post-fracturing effect.

[0005] The current fracturing ball dropping device mainly considers single ball dropping, without considering multi-stage ball dropping and the simultaneous movement of temporary plugging balls in the pipeline to reach the perforation holes simultaneously, improving the plugging pressure and plugging efficiency, etc. Summary of the Invention

[0006] In view of the above technical problems existing in the prior art, the present invention provides a device and method for staged ball-drop temporary plugging fracturing of deep shale gas, designing a set of devices that can accommodate temporary plugging balls with different diameters and densities, and can perform staged ball-drop. The temporary plugging balls move in the pipeline simultaneously and reach the perforation holes at the same time, improving the plugging pressure and efficiency.

[0007] According to one aspect of the present invention, there is provided a device for staged ball-drop temporary plugging fracturing of deep shale gas, comprising:

[0008] A high-pressure injection device, the high-pressure injection device includes a number of high-pressure pump trucks, the high-pressure pump trucks are all connected to a high-pressure manifold, and the high-pressure manifold is connected to the wellhead through a high-pressure pipeline; and

[0009] A multi-stage ball-drop device, the multi-stage ball-drop device is connected to the wellhead and can perform multi-stage ball-drop in sequence.

[0010] A further improvement of the present invention is that the multi-stage ball-drop device includes a ball-drop pipeline, the inlet end of the ball-drop pipeline is connected to a ball-drop liquid supply tank and a ball-drop high-pressure pump truck, and the outlet end is connected to the wellhead;

[0011] A number of ball-drop devices are provided on the ball-drop pipeline.

[0012] A further improvement of the present invention is that a number of globe valves are provided on the ball-drop pipeline to divide the ball-drop pipeline into several sections.

[0013] A further improvement of the present invention is that the ball-drop pipeline includes a first section, a number of first-stage temporary plugging balls are placed in the first section, and the first section is connected to a first ball-drop device, and a second-stage temporary plugging ball is placed in the first ball-drop device;

[0014] The other sections of the ball-drop pipeline are respectively connected to a group of ball-drop devices.

[0015] A further improvement of the present invention is that the inner diameter of the outlet of the ball-drop device is larger than the sum of the diameters of the two largest temporary plugging balls.

[0016] According to another aspect of the present invention, there is also provided a method for staged ball-drop temporary plugging fracturing of deep shale gas, comprising:

[0017] Determine the drilling plan and perform drilling and casing cementing completion;

[0018] Design the horizontal section perforation plan and fracturing plan, prepare the fracturing fluid, and assemble the device for staged ball-drop temporary plugging fracturing of deep shale gas according to any one of claims 1 to 5;

[0019] Carry out the first-stage fracturing construction, perform multi-stage ball-drop respectively until the ball-drop of the first-stage fracturing well section is completed;

[0020] The subsequent stage fracturing construction is carried out in the same manner as the first stage fracturing construction.

[0021] A further improvement of the present invention lies in that the multi-stage ball injection includes:

[0022] For the first-stage ball injection, first pump the preflush fluid and then pump the proppant-carrying fluid;

[0023] Open the plug valve and drop all the first-stage temporary plugging balls in the ball injection pipeline into the wellbore.

[0024] A further improvement of the present invention lies in that after the first-stage ball injection, the second-stage ball injection is carried out:

[0025] After the first-stage ball injection is completed, the ball injection device stops supplying fluid, closes the plug valve, opens the first ball injector, allows the second-stage temporary plugging balls to enter the ball injection pipeline. After all the temporary plugging balls fall into the ball injection pipeline, close the ball injector;

[0026] Pump the preflush fluid and proppant-carrying fluid in the second stage;

[0027] Open the plug valve and drop all the second-stage temporary plugging balls in the ball injection pipeline into the wellbore.

[0028] A further improvement of the present invention lies in that the third-stage and subsequent stages of ball injection are carried out in the same manner as the second-stage ball injection; until the multi-stage ball injection of the first-stage fractured well section is completed.

[0029] A further improvement of the present invention lies in that after the pumping of the preflush fluid and proppant-carrying fluid is completed, displace 10 - 15 m 3 of fluid volume, then reduce the displacement to the designed ball injection displacement, and then carry out ball injection.

[0030] Compared with the prior art, the advantages of the present invention are as follows:

[0031] According to the device and method for multi-stage ball injection and temporary plugging fracturing of deep shale gas of the present invention, a set of devices is designed that can accommodate temporary plugging balls with different diameters and different densities, and can carry out multi-stage ball injection. The temporary plugging balls move in the pipeline simultaneously, reach the perforation holes at the same time, improve the plugging pressure and plugging efficiency.

[0032] According to the device and method for multi-stage ball injection and temporary plugging fracturing of deep shale gas of the present invention, by using the ball injection device, string and method, the temporary plugging balls move in the pipeline simultaneously, almost reach the perforation holes at the same time, plug the perforation holes that have been fractured, prevent the situation of unable to drop the temporary plugging balls, the temporary plugging balls moving dispersedly, low plugging efficiency, small increase in pressure, and difficult judgment of whether the plugging is successful, etc., and provide technical support for improving all perforation clusters and enhancing the production effect.

[0033] The device and method for multi-stage ball-drop temporary plugging and fracturing of deep shale gas according to the present invention are provided with a ball-drop device that can accommodate temporary plugging balls of different diameters and different densities. The inner diameter of the outlet of the ball-drop device is larger than the sum of the diameters of two temporary plugging balls, avoiding congestion of the temporary plugging balls together, which affects the ball-drop speed or makes it difficult to fall into the ball-drop pipeline. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In the drawings:

[0035] Figure 1 Shown is a schematic structural diagram of a device for multi-stage ball-drop temporary plugging and fracturing of deep shale gas according to an embodiment of the present invention.

[0036] The meanings of the reference numerals in the drawings are as follows:

[0037] 1. High-pressure injection device, 2. Multi-stage ball-drop device, 3. Horizontal well, 11. High-pressure pump truck, 12. High-pressure manifold, 13. High-pressure pipeline, 21. Ball-drop pipeline, 22. Ball-drop liquid supply tank, 23. Ball-drop high-pressure pump truck, 24. Ball-drop device, 25. Cock valve, 26. Temporary plugging ball, 31. Wellhead. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0038] In order to make the technical solutions and advantages of the present invention clearer, the exemplary embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than an exhaustive list of all embodiments. And without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0039] Currently, generally, a ball-drop device is installed on the high-pressure manifold. The plugging balls are previously placed in the ball-drop device. When ball dropping is required, the ball-drop device is first opened, and the plugging balls fall from the ball-drop device to the high-pressure manifold, and then are carried by the fracturing fluid from the high-pressure manifold to the wellbore to plug the perforation holes. Since it takes 20 - 30 seconds for the ball-drop device to be fully opened, there is a time interval for the plugging balls to fall from the ball-drop device to the high-pressure manifold. At a displacement of 8 m³ / min, the distance between the first ball and the last ball reaching the perforation holes in a Φ139.7 mm casing is 220 - 330 m, and the higher the displacement, the greater the distance.

[0040] This ball-drop method brings the following four adverse results:

[0041] (1) The size of the ball-drop device does not match the diameter of the temporary plugging balls, and it is difficult for the temporary plugging balls to fall into the high-pressure manifold during the ball-drop process, failing to plug the perforation holes.

[0042] (2) The falling time is long, and the balls cannot reach the perforation holes simultaneously. The wellhead pressure often does not rise significantly, or does not exceed 1 MPa, making it impossible to judge whether the dropped plugging balls have successfully plugged and evaluate the plugging efficiency.

[0043] (3) To observe the increase in ball - throwing pressure, generally, one more wellbore fluid is pumped, resulting in fluid waste and increased fracturing costs.

[0044] (4) The transformation is uneven. Some clusters are over - transformed while some are not, affecting the post - fracturing effect.

[0045] The current ball - throwing device for fracturing mainly considers single ball - throwing and does not consider multi - stage ball - throwing and the simultaneous movement of temporary plugging balls in the pipeline to reach the perforation holes simultaneously, improve the plugging pressure and plugging efficiency, etc.

[0046] To solve the above problems, the present invention proposes a device for multi - stage ball - throwing and temporary plugging fracturing of deep shale gas.

[0047] In the embodiment as Figure 1 shown, a device for multi - stage ball - throwing and temporary plugging fracturing of deep shale gas includes:

[0048] A high - pressure injection device 1, the high - pressure injection device 1 includes a number of high - pressure pump trucks 11, the high - pressure pump trucks 11 are all connected to a high - pressure manifold 12, and the high - pressure manifold 12 is connected to a wellhead 31 through a high - pressure pipeline 13;

[0049] The high - pressure injection device 1 is used to inject pre - flush fluid, sand - carrying fluid, etc. The pre - flush fluid, sand - carrying fluid, etc. are placed in the high - pressure pump trucks 11 according to the operation requirements, and the corresponding fluid in the high - pressure pump trucks 11 is pumped as needed during the operation process.

[0050] The device for multi - stage ball - throwing and temporary plugging fracturing of deep shale gas further includes a multi - stage ball - throwing device 2. The multi - stage ball - throwing device 2 is connected to the wellhead 31 and can perform multi - stage ball - throwing in sequence.

[0051] In one embodiment, the multi - stage ball - throwing device 2 includes a ball - throwing pipeline 21. The inlet end of the ball - throwing pipeline 21 is connected to a ball - throwing liquid supply tank 22 and a ball - throwing high - pressure pump truck 23, and the outlet end is connected to the wellhead 31. Liquid is placed in the ball - throwing liquid supply tank 22, and the ball - throwing high - pressure pump truck 23 injects the liquid in the ball - throwing liquid storage tank into the wellhead 31 through the ball - throwing pipeline 21. During the injection process, multi - stage balls enter the wellhead 31 along with the liquid by being put into the ball - throwing pipeline 21.

[0052] In one embodiment, a number of plug valves 25 are provided on the ball - throwing pipeline 21, dividing the ball - throwing pipeline 21 into several sections.

[0053] Several plug valves 25 are arranged inside the ball - throwing pipeline 21. Each section formed between the plug valves 25 is used to connect a group of ball - throwers.

[0054] In a preferred embodiment, the ball injection pipeline 21 includes a first section, in which a number of first-stage temporary plugging balls 26 are stored, and the first section is connected to a first ball injector, in which second-stage temporary plugging balls 26 are stored.

[0055] The other sections of the ball injection pipeline 21 are respectively connected to a set of ball injectors.

[0056] The first ball injector and the other ball injectors are in a closed state at the beginning. When ball injection is required during the ball injection process, the switch of the ball injector is opened, and the temporary plugging balls 26 in the ball injector fall into the ball injection pipeline 21.

[0057] In one embodiment, the inner diameter of the outlet of the ball injector is greater than the sum of the diameters of the two largest temporary plugging balls 26.

[0058] In this embodiment, the device is provided with a ball injection device that can accommodate temporary plugging balls 26 with different diameters and different densities. The inner diameter of the outlet of the ball injector is greater than the sum of the diameters of the two temporary plugging balls 26, avoiding congestion of the temporary plugging balls 26 together, affecting the ball injection speed or making it difficult to fall into the ball injection pipeline 21.

[0059] According to the device for multi-stage ball injection and temporary plugging fracturing of deep shale gas described in this embodiment, a set of devices is designed that can accommodate temporary plugging balls 26 with different diameters and different densities, and can perform multi-stage ball injection. The temporary plugging balls 26 move in the pipeline at the same time and reach the perforation holes simultaneously, improving the plugging pressure and plugging efficiency.

[0060] According to the device for multi-stage ball injection and temporary plugging fracturing of deep shale gas described in this embodiment, by using the ball injection device, string and method, the temporary plugging balls 26 move in the pipeline at the same time and almost reach the perforation holes simultaneously, plugging the perforation holes that have been fractured, preventing situations such as difficulty in injecting the temporary plugging balls 26, scattered movement of the temporary plugging balls 26, low plugging efficiency, small increase in pressure, and difficulty in judging whether the plugging is successful, providing technical support for improving all perforation clusters and enhancing the production effect.

[0061] According to another aspect of the present invention, a method for multi-stage ball injection and temporary plugging fracturing of deep shale gas is also proposed, including the following steps:

[0062] Determine the drilling plan and conduct drilling and casing cementing and completion;

[0063] Design the horizontal section perforation plan and fracturing plan, prepare the fracturing fluid, and assemble the device for multi-stage ball injection and temporary plugging fracturing of deep shale gas described in the above embodiment;

[0064] Conduct the first-stage fracturing construction, perform multi-stage ball injection respectively until the ball injection of the first-stage fracturing well section is completed;

[0065] Perform subsequent stage fracturing construction in the same manner as the first-stage fracturing construction.

[0066] In a preferred embodiment, performing multi-stage ball dropping includes:

[0067] For the first-stage ball dropping, first pump the preflush fluid and then pump the proppant-carrying fluid;

[0068] Open the plug valve 25 and drop all the first-stage temporary plugging balls 26 in the ball dropping pipeline 21 into the wellbore.

[0069] In one embodiment, after the first-stage ball dropping, perform the second-stage ball dropping:

[0070] After the first-stage ball dropping, the ball dropping device stops supplying fluid, close the plug valve 25, open the first ball dropper, let the second-stage temporary plugging balls 26 enter the ball dropping pipeline 21. After all the temporary plugging balls 26 have dropped to the ball dropping pipeline 21, close the ball dropper;

[0071] Pump the preflush fluid and proppant-carrying fluid in the second stage;

[0072] Open the plug valve 25 and drop all the second-stage temporary plugging balls 26 in the ball dropping pipeline 21 into the wellbore.

[0073] Perform the third-stage and subsequent-stage ball dropping in the same way as the second-stage ball dropping; until the multi-stage ball dropping of the first fractured well section is completed.

[0074] After the pumping of the preflush fluid and proppant-carrying fluid is completed, displace 10 - 15 m 3 of fluid volume, then reduce the displacement to the designed ball dropping displacement, and then perform ball dropping.

[0075] In one embodiment, the method for multi-stage ball dropping and temporary plugging fracturing of deep shale gas includes:

[0076] Determine the drilling plan and perform drilling and casing cementing and completion;

[0077] Design the horizontal section perforation plan and fracturing plan, prepare the fracturing fluid, and assemble the multi-stage ball dropping and temporary plugging fracturing device for deep shale gas according to the above embodiments.

[0078] Perform the first-stage fracturing construction, inject the first-stage preflush fluid and proppant-carrying fluid, start the ball dropping device, open the plug valve 25, and start the first-stage ball dropping;

[0079] After the first-stage ball dropping, the ball dropping device stops supplying fluid, close the plug valve 25, open the first ball dropper, let the second-stage temporary plugging balls 26 enter the ball dropping pipeline 21. After all the temporary plugging balls 26 have dropped to the ball dropping pipeline 21, close the ball dropper; pump the preflush fluid and proppant-carrying fluid in the second stage according to the design.

[0080] Start the second-stage ball dropping;

[0081] After the second-stage ball injection is completed, the ball injection device stops supplying liquid, closes the stop valve 25, opens the second ball injector, and allows the third-stage temporary plugging ball 26 to enter the ball injection pipeline 21. After all the temporary plugging balls 26 have fallen into the ball injection pipeline 21, close the ball injector; pump the preflush fluid and proppant-carrying fluid in the third stage according to the design.

[0082] Carry out ball injection for the third stage and subsequent stages according to the above steps; until the multi-stage ball injection for the first fracturing interval is completed.

[0083] According to the method described in this embodiment, the following technical effects are achieved: First, the ball injection speed is fast. The ball injection system injects balls directly after being opened without waiting for the temporary plugging ball 26 to fall from the ball injector; Second, the temporary plugging pressure rises significantly, which is convenient for judging the plugging effect. The temporary plugging balls 26 move in the pipeline simultaneously and reach the perforation holes almost simultaneously, and the temporary plugging pressure rises by more than 3 MPa; Third, the amount of fracturing fluid used and the cost are reduced. The fast ball injection and significant pressure rise can reduce the amount of fluid for sending balls and the amount of plugging fluid for judging the arrival of the temporary plugging ball 26, thus reducing the fracturing cost; Fourth, the uniformity of stimulation and the post-fracture effect are improved. The temporary plugging balls 26 reach the plugged intervals simultaneously to avoid over-stimulation of some intervals, thereby improving the stimulation uniformity and the productivity contribution rate of each cluster.

[0084] Embodiment 1

[0085] A device for multi-stage ball injection and temporary plugging fracturing of deep shale gas described in this embodiment includes:

[0086] A high-pressure injection device 1, the high-pressure injection device 1 includes a number of high-pressure pump trucks 11, the high-pressure pump trucks 11 are all connected to a high-pressure manifold 12, and the high-pressure manifold 12 is connected to the wellhead 31 through a high-pressure pipeline 13;

[0087] The high-pressure injection device 1 is used to inject preflush fluid, proppant-carrying fluid, etc. The preflush fluid, proppant-carrying fluid, etc. are stored in the high-pressure pump trucks 11 according to the operation requirements, and the liquid in the corresponding high-pressure pump trucks 11 is pumped as needed during the operation.

[0088] The deep shale gas multi-stage ball injection and temporary plugging fracturing device further includes a multi-stage ball injection device 2. The multi-stage ball injection device 2 is connected to the wellhead 31 and can perform multi-stage ball injection in sequence.

[0089] The multi-stage ball injection device 2 includes a ball injection pipeline 21. The inlet end of the ball injection pipeline 21 is connected to a ball injection supply tank 22 and a ball injection high-pressure pump truck 23, and the outlet end is connected to the wellhead 31. The ball injection supply tank 22 contains liquid, and the ball injection high-pressure pump truck 23 injects the liquid in the ball injection storage tank into the wellhead 31 through the ball injection pipeline 21. During the injection process, multi-stage balls enter the wellhead 31 along with the liquid by being put into the ball injection pipeline 21.

[0090] Four groups of stop valves 25 are provided on the ball injection pipeline 21, dividing the ball injection pipeline 21 into three sections.

[0091] The ball injection pipeline 21 includes a first section, a second section, and a third section. The first section contains a number of first-stage temporary plugging balls 26, and the first section is connected to a first ball injector which contains second-stage temporary plugging balls 26.

[0092] The second section is connected to a second ball injector which contains third temporary plugging balls 26.

[0093] The third section is connected to a third ball injector which contains fourth temporary plugging balls 26.

[0094] The first ball injector and other ball injectors are in a closed state at the beginning. When ball injection is required during the ball injection process, the switch of the ball injector is opened, and the temporary plugging balls 26 in the ball injector fall into the ball injection pipeline 21.

[0095] The inner diameter of the outlet of the ball injector is greater than the sum of the diameters of the two largest temporary plugging balls 26.

[0096] In this embodiment, the device is provided with a ball injection device that can accommodate temporary plugging balls 26 of different diameters and different densities. The inner diameter of the outlet of the ball injector is greater than the sum of the diameters of the two temporary plugging balls 26, avoiding the congestion of the temporary plugging balls 26 together, which affects the ball injection speed or makes it difficult to fall into the ball injection pipeline 21.

[0097] Embodiment 2

[0098] A device for multi-stage ball injection and temporary plugging fracturing of deep shale gas according to this embodiment includes:

[0099] A high-pressure injection device 1, which includes a number of high-pressure pump trucks 11. The high-pressure pump trucks 11 are all connected to a high-pressure manifold 12, and the high-pressure manifold 12 is connected to a wellhead 31 through a high-pressure pipeline 13;

[0100] The high-pressure injection device 1 is used to inject preflush fluid, sand-carrying fluid, etc. The high-pressure pump trucks 11 contain preflush fluid, sand-carrying fluid, etc. according to the operation requirements, and pump the corresponding liquid in the high-pressure pump trucks 11 as needed during the operation process.

[0101] The deep shale gas multi-stage ball injection and temporary plugging fracturing device further includes a multi-stage ball injection device 2. The multi-stage ball injection device 2 is connected to the wellhead 31 and can perform multi-stage ball injection in sequence.

[0102] The multi-stage ball injection device 2 includes a ball injection pipeline 21. The inlet end of the ball injection pipeline 21 is connected to a ball injection supply tank 22 and a ball injection high-pressure pump truck 23, and the outlet end is connected to the wellhead 31. The ball injection supply tank 22 contains liquid, and the ball injection high-pressure pump truck 23 injects the liquid in the ball injection storage tank into the wellhead 31 through the ball injection pipeline 21. During the injection process, multi-stage balls enter the wellhead 31 along with the liquid by being put into the ball injection pipeline 21.

[0103] There are five groups of stop valves 25 provided on the ball injection pipeline 21, dividing the ball injection pipeline 21 into four sections.

[0104] The ball injection pipeline 21 includes a first section, a second section, a third section and a fourth section. A number of first-stage temporary plugging balls 26 are placed in the first section, and the first section is connected to a first ball injector which contains second-stage temporary plugging balls 26.

[0105] The second section is connected to a second ball injector which contains third temporary plugging balls 26.

[0106] The third section is connected to a third ball injector which contains fourth temporary plugging balls 26.

[0107] The fourth section is connected to a fourth ball injector which contains fourth temporary plugging balls 26.

[0108] The first ball injector and other ball injectors are in a closed state at the beginning. When ball injection is required during the ball injection process, the switch of the ball injector is opened, and the temporary plugging balls 26 in the ball injector fall into the ball injection pipeline 21.

[0109] The inner diameter of the outlet of the ball injector is larger than the sum of the diameters of the two largest temporary plugging balls 26.

[0110] In this embodiment, the device is provided with a ball injection device that can accommodate temporary plugging balls 26 of different diameters and different densities. The inner diameter of the outlet of the ball injector is larger than the sum of the diameters of the two temporary plugging balls 26, avoiding the congestion of the temporary plugging balls 26 together, which affects the ball injection speed or makes it difficult to fall into the ball injection pipeline 21.

[0111] Embodiment 3

[0112] A method for multi-stage ball injection and temporary plugging fracturing of deep shale gas includes the following steps:

[0113] Conduct a comprehensive geological and engineering evaluation of the deep shale gas area to determine the horizontal well drilling plan.

[0114] Drill and complete the casing cementing according to the horizontal well drilling plan, and design the perforation plan and fracturing plan for the horizontal section according to the design; prepare fracturing fluid, proppant, fracturing equipment, manifolds, ball injection device, temporary plugging balls 26, pipelines, etc.

[0115] Connect the fracturing manifold with the ball injection device and the pipeline. The ball injection device and the pipeline are independent systems, connected to the wellhead 31. Different numbers and diameters of temporary plugging balls 26 are installed in the ball injection pipeline 21 and the ball injector according to the designed ball injection stages. The fracturing pipeline is another independent system, connected to the wellhead 31.

[0116] The first stage of fracturing operation. The first stage of fracturing operation is carried out according to the perforation plan and the single-well fracturing design plan. First, the preflush fluid is pumped, and then the proppant-carrying fluid is pumped.

[0117] The first stage of ball dropping. When the designed stage fluid volume and sand volume in the first stage are pumped out, 10 m of fluid volume is displaced, the displacement is reduced to the designed ball-dropping displacement, and at the same time, the ball-dropping system is started. The electric control opens the plug valve 25, and the first stage of ball dropping begins. After the first stage of ball dropping is completed, the ball-dropping system stops supplying fluid, closes the plug valve 25, the electric control opens the ball dropper, and the temporary plugging ball 26 of the second stage falls into the ball-dropping pipeline 21. After all the temporary plugging balls 26 fall into the ball-dropping pipeline 21, the ball dropper is closed. Pump the preflush fluid and proppant-carrying fluid of the second stage according to the design. 3 The first stage of ball dropping. When the designed stage fluid volume and sand volume in the first stage are pumped out, 10 m of fluid volume is displaced, the displacement is reduced to the designed ball-dropping displacement, and at the same time, the ball-dropping system is started. The electric control opens the plug valve 25, and the first stage of ball dropping begins. After the first stage of ball dropping is completed, the ball-dropping system stops supplying fluid, closes the plug valve 25, the electric control opens the ball dropper, and the temporary plugging ball 26 of the second stage falls into the ball-dropping pipeline 21. After all the temporary plugging balls 26 fall into the ball-dropping pipeline 21, the ball dropper is closed. Pump the preflush fluid and proppant-carrying fluid of the second stage according to the design.

[0118] The second stage of ball dropping. When the preflush fluid and proppant-carrying fluid of the second stage are pumped out, 10 m of fluid volume is displaced, the displacement is reduced to the designed ball-dropping displacement, and at the same time, the ball-dropping system is started. The electric control opens the plug valve 25, and the second stage of ball dropping begins. After the second stage of ball dropping is completed, the ball-dropping system stops supplying fluid, closes the plug valve 25, the electric control opens the ball dropper, and the temporary plugging ball 26 of the third stage falls into the ball-dropping pipeline 21. After all the temporary plugging balls 26 fall into the ball-dropping pipeline 21, the ball dropper is closed. Pump the preflush fluid and proppant-carrying fluid of the third stage according to the design. 3 The second stage of ball dropping. When the preflush fluid and proppant-carrying fluid of the second stage are pumped out, 10 m of fluid volume is displaced, the displacement is reduced to the designed ball-dropping displacement, and at the same time, the ball-dropping system is started. The electric control opens the plug valve 25, and the second stage of ball dropping begins. After the second stage of ball dropping is completed, the ball-dropping system stops supplying fluid, closes the plug valve 25, the electric control opens the ball dropper, and the temporary plugging ball 26 of the third stage falls into the ball-dropping pipeline 21. After all the temporary plugging balls 26 fall into the ball-dropping pipeline 21, the ball dropper is closed. Pump the preflush fluid and proppant-carrying fluid of the third stage according to the design.

[0119] The third stage of ball dropping. When the preflush fluid and proppant-carrying fluid of the third stage are pumped out, 10 m of fluid volume is displaced, the displacement is reduced to the designed ball-dropping displacement, and at the same time, the ball-dropping system is started. The electric control opens the plug valve 25, and the third stage of ball dropping begins. After the third stage of ball dropping is completed, the ball-dropping system stops supplying fluid, closes the plug valve 25, the electric control opens the ball dropper, and the temporary plugging ball 26 of the fourth stage falls into the ball-dropping pipeline 21. After all the temporary plugging balls 26 fall into the ball-dropping pipeline 21, the ball dropper is closed. Pump the preflush fluid and proppant-carrying fluid of the fourth stage according to the design. 3 The third stage of ball dropping. When the preflush fluid and proppant-carrying fluid of the third stage are pumped out, 10 m of fluid volume is displaced, the displacement is reduced to the designed ball-dropping displacement, and at the same time, the ball-dropping system is started. The electric control opens the plug valve 25, and the third stage of ball dropping begins. After the third stage of ball dropping is completed, the ball-dropping system stops supplying fluid, closes the plug valve 25, the electric control opens the ball dropper, and the temporary plugging ball 26 of the fourth stage falls into the ball-dropping pipeline 21. After all the temporary plugging balls 26 fall into the ball-dropping pipeline 21, the ball dropper is closed. Pump the preflush fluid and proppant-carrying fluid of the fourth stage according to the design.

[0120] Carry out the next stage of ball dropping. The ball-dropping method is the same as that of the second stage and the third stage of ball dropping. Repeat the process until the multi-stage ball dropping of a fracturing well section is completed.

[0121] Example 4

[0122] A method for multi-stage ball dropping and temporary plugging fracturing of deep shale gas includes the following steps:

[0123] Conduct a comprehensive geological and engineering evaluation of the deep shale gas area to determine the horizontal well drilling plan.

[0124] Drill and complete the casing cementing according to the horizontal well drilling plan. Design the perforation plan and fracturing plan for the horizontal section according to the design; prepare fracturing fluid, proppant, fracturing equipment, manifolds, ball-dropping devices, temporary plugging balls 26, pipelines, etc.

[0125] Connect the fracturing manifold to the ball injection device and the pipeline. The ball injection device and the pipeline are independent systems, connected to the wellhead 31. Different numbers and diameters of temporary plugging balls 26 are installed in the ball injection pipeline 21 and the ball injector according to the designed ball injection stages. The fracturing pipeline is another independent system, connected to the wellhead 31.

[0126] The first-stage fracturing construction. The first-stage fracturing construction is carried out according to the perforation plan and the single-well fracturing design plan. First, pump the preflush fluid, and then pump the sand-carrying fluid.

[0127] The first-stage ball injection. When the designed stage fluid volume and sand volume in the first stage are pumped out, displace 15 m 3 of fluid volume, reduce the displacement to the designed ball injection displacement. At the same time, the ball injection system is started, the electric control opens the plug valve 25, and the first-stage ball injection begins. After the first-stage ball injection is completed, the ball injection system stops supplying fluid, closes the plug valve 25, the electric control opens the ball injector, and allows the temporary plugging balls 26 of the second stage to fall into the ball injection pipeline 21. After all the temporary plugging balls 26 have fallen into the ball injection pipeline 21, close the ball injector. Pump the preflush fluid and sand-carrying fluid of the second stage according to the design.

[0128] The second-stage ball injection. When the preflush fluid and sand-carrying fluid of the second stage are pumped out, displace 15 m 3 of fluid volume, reduce the displacement to the designed ball injection displacement. At the same time, the ball injection system is started, the electric control opens the plug valve 25, and the second-stage ball injection begins. After the second-stage ball injection is completed, the ball injection system stops supplying fluid, closes the plug valve 25, the electric control opens the ball injector, and allows the temporary plugging balls 26 of the third stage to fall into the ball injection pipeline 21. After all the temporary plugging balls 26 have fallen into the ball injection pipeline 21, close the ball injector. Pump the preflush fluid and sand-carrying fluid of the third stage according to the design.

[0129] The third-stage ball injection. When the preflush fluid and sand-carrying fluid of the third stage are pumped out, displace 15 m 3 of fluid volume, reduce the displacement to the designed ball injection displacement. At the same time, the ball injection system is started, the electric control opens the plug valve 25, and the third-stage ball injection begins. After the third-stage ball injection is completed, the ball injection system stops supplying fluid, closes the plug valve 25, the electric control opens the ball injector, and allows the temporary plugging balls 26 of the fourth stage to fall into the ball injection pipeline 21. After all the temporary plugging balls 26 have fallen into the ball injection pipeline 21, close the ball injector. Pump the preflush fluid and sand-carrying fluid of the fourth stage according to the design.

[0130] Carry out the next-stage ball injection. The ball injection method is the same as that of the second-stage and third-stage ball injections. Repeat the process until the multi-stage ball injection of a fracturing interval is completed.

[0131] It should be understood that the embodiments disclosed in the present invention are not limited to the specific structures, processing steps or materials disclosed herein, but should extend to equivalent alternatives of these features understood by those of ordinary skill in the relevant art. It should also be understood that the terms used herein are for the purpose of describing specific embodiments only and do not imply limitation.

[0132] In the description of the present invention, unless otherwise specified, "a plurality of" means two or more; the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "inner", "outer", "front end", "rear end", "head", "tail", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0133] In the description of the present invention, it should be noted that, unless otherwise clearly defined and limited, the terms "connected" and "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0134] Certain terms are used throughout this application to refer to particular system components. As those skilled in the art will recognize, the same components may generally be referred to by different names, and thus this application is not intended to distinguish between components that differ only in name and not in function. The phrase "an embodiment" or "embodiments" as used in the specification means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the phrase "an embodiment" or "embodiments" that appears throughout the specification does not necessarily all refer to the same embodiment.

[0135] The embodiments of the present invention are given for purposes of illustration and description, and are not exhaustive or limiting of the invention to the disclosed form. Many modifications and variations will be apparent to those of ordinary skill in the art. The embodiments are chosen and described in order to better illustrate the principles of the present invention and its practical application, and to enable those of ordinary skill in the art to understand the present invention and design various embodiments with various modifications suitable for a particular purpose.

[0136] Although the preferred embodiments of the present invention have been described, additional changes and modifications can be made to these embodiments by those skilled in the art once they learn the basic creative concept. Therefore, the appended claims are intended to be construed to include the preferred embodiments as well as all changes and / or modifications that fall within the scope of the present invention. Any changes and / or modifications made in accordance with the embodiments of the present invention should be covered by the protection scope of the present invention.

Claims

1. A device for multi-stage ball-drop temporary plugging and fracturing of deep shale gas, characterized in that Including: A high-pressure injection device (1), the high-pressure injection device (1) includes a number of high-pressure pump trucks (11), the high-pressure pump trucks (11) are all connected to a high-pressure manifold (12), and the high-pressure manifold (12) is connected to a wellhead (31) through a high-pressure pipeline (13); and A multi-stage ball injection device (2) is connected to the wellhead (31) and can perform multi-stage ball injection in sequence.

2. The device for multi-stage ball-drop temporary plugging and fracturing of deep shale gas according to claim 1, characterized in that The multi-stage ball injection device (2) includes a ball injection pipeline (21), the inlet end of the ball injection pipeline (21) is connected to a ball injection liquid supply tank (22) and a ball injection high-pressure pump truck (23), and the outlet end is connected to the wellhead (31); A number of ball injectors are provided on the ball injection pipeline (21).

3. The device for multi-stage ball-drop temporary plugging and fracturing of deep shale gas according to claim 2, wherein A number of plug valves (25) are provided on the ball injection pipeline (21), dividing the ball injection pipeline (21) into several sections.

4. The device for multi-stage ball-drop temporary plugging and fracturing of deep shale gas according to claim 3, wherein The ball injection pipeline (21) includes a first section, a number of first-stage temporary plugging balls (26) are placed in the first section, and the first section is connected to a first ball injector, and a second-stage temporary plugging ball (26) is placed in the first ball injector; The other sections of the ball injection pipeline (21) are respectively connected to a group of ball injectors.

5. The device for multi-stage ball-drop temporary plugging and fracturing of deep shale gas according to claim 4, wherein, The inner diameter of the outlet of the ball injector is larger than the sum of the diameters of the two largest temporary plugging balls (26).

6. A method for multi-stage ball-drop temporary plugging fracturing of deep shale gas, characterized in that, Including: Determine the drilling plan and conduct drilling and casing cementing completion; Design a horizontal section perforation plan and a fracturing plan, prepare fracturing fluid, and assemble the deep shale gas multi-stage ball injection temporary plugging fracturing device according to any one of claims 1 to 5; Carry out the first-stage fracturing construction, perform multi-stage ball injection respectively until the ball injection of the first-stage fracturing well section is completed; Carry out subsequent-stage fracturing construction in the same manner as the first-stage fracturing construction.

7. The method for multi-stage ball-drop temporary plugging and fracturing of deep shale gas according to claim 6, characterized in that, Performing multi-stage ball injection includes: First-stage ball injection, first pump the preflush fluid, and then pump the sand-carrying fluid; Open the plug valve (25) and put all the first-stage temporary plugging balls (26) in the ball injection pipeline (21) into the well.

8. The method for multi-stage ball-drop temporary plugging and fracturing of deep shale gas according to claim 7, wherein After the first-stage ball injection, perform the second-stage ball injection: After the first-stage ball injection, the ball injection device stops supplying liquid, closes the plug valve (25), opens the first ball injector, allows the second-stage temporary plugging balls (26) to enter the ball injection pipeline (21), and after all the temporary plugging balls (26) fall into the ball injection pipeline (21), close the ball injector; Pump the preflush fluid and sand-carrying fluid in the second stage; Open the plug valve (25) and put all the second-stage temporary plugging balls (26) in the ball injection pipeline (21) into the well.

9. The method for multi-stage ball-drop temporary plugging fracturing of deep shale gas according to claim 8, characterized in that Perform the third-stage and subsequent-stage ball injection in the same manner as the second-stage ball injection; until the multi-stage ball injection of the first-stage fracturing well section is completed.

10. The method for multi-stage ball-drop temporary plugging and fracturing of deep shale gas according to claim 9, characterized in that, After the preflush fluid and proppant-carrying fluid are pumped, displace 10 - 15 m 3 of fluid, then reduce the displacement to the designed ball-drop displacement, and then conduct ball dropping.

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