A preloaded ball fracturing device

Abstract

A pre-placed ball (8) fracturing device and fracturing method, the pre-placed ball (8) fracturing device includes a mandrel (1), a cone (2), a seal (3), an anchoring mechanism (4), a lower connector (5), a connecting rod (6), a shear pin (7), and a pre-placed ball (8). The mandrel (1) includes an upper part (11) and a lower part (12) of the mandrel, which are connected by a mandrel connecting part (13). The inner diameter of the upper part (11) is larger than the inner diameter of the lower part (12), and the outer surface of the mandrel connecting part (13) is a conical surface; the pre-placed ball (8) is also included. The ball (8) is pre-set inside the upper part (11) of the mandrel. The outer diameter of the pre-set ball (8) is larger than the inner diameter of the lower part (12) of the mandrel. The connecting rod (6) is connected to the upper part (11) of the mandrel through the shear pin (7). The connecting rod (6) is used to limit the pre-set ball (8) inside the upper part (11) of the mandrel so that the pre-set ball (8) blocks the inner diameter of the lower part (12) of the mandrel. The cone (2) is adapted to the outer side of the mandrel connecting part (13). The lower connector (5) is fixedly connected to the lower part (12) of the mandrel. The seal (3) and the anchoring mechanism (4) are located between the cone (2) and the lower connector (5).

Description

Technical Field

[0001] This utility model relates to the field of oil and gas development technology, and in particular to a pre-placed ball fracturing device and fracturing method. Background Technology

[0002] In unconventional well completion techniques, soluble bridge plugs are commonly used. These plugs require a fracturing ball to seal their inner diameter in order to guide the fracturing fluid to the wellbore. Typically, the fracturing ball is inserted into the wellhead after the soluble bridge plug has been seated but before fracturing operations. During fracturing, the fracturing ball settles at the tail of the bridge plug along with the fracturing fluid at the front, forming a temporary wellbore seal and guiding the fracturing fluid. This method is time-consuming for ball insertion and pumping, and carries the risk of ball misalignment, increasing both operation time and cost. Utility Model Content

[0003] The purpose of this invention is to address the problems of long time consumption for ball dropping and pumping in existing technologies, as well as the problem of fracturing ball displacement. This invention provides a pre-placed ball fracturing device and fracturing method, in which the fracturing ball is pre-placed in the ball seat and enters the well together with the ball seat to complete the setting and sealing, eliminating the time consumption of ball dropping and pumping, and reducing operation time and cost.

[0004] To achieve the above objectives, the technical solution adopted by this utility model is as follows: A pre-placed ball fracturing device includes a mandrel, a cone, a seal, an anchoring mechanism, a lower connector, a connecting rod, a shear pin, and a pre-placed ball. The mandrel includes an upper part and a lower part, which are connected by a mandrel connecting part. The inner diameter of the upper part is larger than the inner diameter of the lower part, and the outer surface of the mandrel connecting part is a conical surface. The pre-placed ball is pre-placed inside the upper part of the mandrel, and the outer diameter of the pre-placed ball is larger than the inner diameter of the lower part of the mandrel. The connecting rod is connected to the upper part of the mandrel through the shear pin. The connecting rod is used to limit the pre-placed ball inside the upper part of the mandrel, so that the pre-placed ball blocks the inner diameter of the lower part of the mandrel. The cone is adapted to the outer side of the mandrel connection, the lower connector is fixedly connected to the lower part of the mandrel, and the seal and the anchoring mechanism are located between the cone and the lower connector.

[0005] The pre-placed ball fracturing device of this invention pre-places the pre-placed balls (i.e., fracturing balls) inside a ball seat (typically including a mandrel, cone, seal, anchoring mechanism, and lower connector), and fixes the position of the pre-placed balls with a connecting rod. This allows the pre-placed balls to be sent downhole along with the ball seat, eliminating the time-consuming process of dropping and pumping balls, thus reducing operating time and costs. Furthermore, the pre-placed balls can seal the inner bore of the mandrel, allowing the tool string to be retrieved immediately after setting and perforation, further reducing operating time and costs. Simultaneously, the connecting rod of this invention is connected to the mandrel via shear pins, facilitating connection and allowing for easy control of shear strength by replacing different types of shear pins, ensuring smooth fracturing operations. Moreover, by setting different inner diameters for the upper and lower parts of the mandrel, this invention facilitates the placement of pre-placed balls and achieves effective sealing of the mandrel's inner bore.

[0006] As a preferred embodiment of this utility model, the outer diameter of the pre-placed ball is 70%-93% of the inner diameter of the upper part of the mandrel, which facilitates the arrangement of the pre-placed ball.

[0007] As a preferred embodiment of this utility model, the inner surface of the mandrel connecting part is a conical surface, and the pre-placed ball is arranged close to the inner surface of the mandrel connecting part to ensure that the pre-placed ball can seal the inner hole of the mandrel.

[0008] As a preferred embodiment of this utility model, the end of the connecting rod is provided with a concave conical surface, and the pre-placed ball is set close to the concave conical surface, which facilitates fixing the position of the pre-placed ball and ensures that the pre-placed ball can seal the inner hole of the mandrel.

[0009] As a preferred embodiment of this utility model, the pre-placed ball has a soluble metal structure, is automatically degradable, and leaves no clogging solid residue.

[0010] As a preferred embodiment of this utility model, the mandrel, the cone, the seal, the anchoring mechanism, and the lower connector are all soluble metal structures that can automatically degrade and leave no clogging solid residue.

[0011] As a preferred embodiment of this utility model, the soluble metal includes magnesium alloys, aluminum alloys, and magnesium-aluminum alloys, and other alloys that can meet the melting standard can also be used.

[0012] As a preferred embodiment of this utility model, the lower part of the mandrel and the lower connector are threadedly connected, the sealing element is fixedly connected to the end of the anchoring mechanism away from the lower connector, and both the sealing element and the anchoring mechanism are provided with an inner conical surface that is adapted to the cone.

[0013] As a preferred embodiment of this utility model, after the lower part of the mandrel and the lower connector are threadedly connected, the mandrel body has sufficient strength to ensure that the shear pin can still be sheared normally after the mandrel is soaked and dissolved before setting, and the mandrel body will not be pulled apart due to the shear pin not breaking because the mandrel is dissolved.

[0014] As a preferred embodiment of this utility model, after the lower part of the mandrel and the lower connector are threadedly connected, the threaded connection strength is sufficient to ensure that the shearing pin can still be normally sheared after the mandrel is soaked and dissolved before setting, and the threaded connection at the lower part of the mandrel will not be pulled apart.

[0015] As a preferred embodiment of this utility model, the upper part of the mandrel, the lower part of the mandrel, and the mandrel connecting part are integrally formed structural components.

[0016] As a preferred embodiment of this utility model, the entire pre-placed ball fracturing device is designed as a soluble metal structure. After the fracturing operation is completed, the ball fracturing device can be completely degraded and the well can be opened due to the action of temperature and mineralization of the liquid downhole.

[0017] In summary, due to the adoption of the above technical solution, the beneficial effects of this utility model are: 1. The pre-placed ball fracturing device of this utility model pre-places the pre-placed ball (i.e., fracturing ball) inside the ball seat (usually including a mandrel, cone, seal, anchoring mechanism, and lower connector), and fixes the position of the pre-placed ball through a connecting rod, so that the pre-placed ball can be sent downhole along with the ball seat, eliminating the time-consuming ball dropping and pumping, reducing operation time and cost; moreover, the pre-placed ball can seal the inner hole of the mandrel, so that after setting and perforation are completed, the tool string can be pulled out and fracturing operation can be started immediately, further reducing operation time and cost. At the same time, the connecting rod of this utility model is connected to the mandrel through a shear pin, which is convenient to connect, and by changing different types of shear pins, it is easy to control the shear strength, so that the setting and release operation can be carried out smoothly. Furthermore, this utility model, by setting the upper and lower parts of the mandrel with different inner diameters, facilitates the arrangement of pre-placed balls and can achieve good sealing of the inner hole of the mandrel.

[0018] 3. This utility model designs the entire pre-placed ball fracturing device as a soluble metal structure. After the fracturing operation is completed, the ball fracturing device can be completely degraded and formed into a well through the action of temperature and mineralization liquid downhole, without any blockage solid residue. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the pre-placed ball fracturing device during its insertion into the well.

[0020] Figure 2This is a schematic diagram of the pre-set ball fracturing device during setting.

[0021] Figure 3 This is a schematic diagram of the pre-placed ball fracturing device during pressurization.

[0022] Icons: 1-Mandrel, 11-Upper part of mandrel, 12-Lower part of mandrel, 13-Mandrel connecting part, 2-Cone, 3-Seal, 4-Anchoring mechanism, 5-Lower connector, 6-Connecting rod, 7-Shear pin, 8-Preset ball. Detailed Implementation

[0023] The present invention will now be described in detail with reference to the accompanying drawings.

[0024] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this utility model and are not intended to limit this utility model.

[0025] Example 1 like Figure 1 As shown, a pre-placed ball fracturing device has a pre-placed ball 8 pre-installed in a ball seat. Specifically, it includes a mandrel 1, a cone 2, a seal 3, an anchoring mechanism 4, a lower connector 5, a connecting rod 6, a shear pin 7, and the pre-placed ball 8.

[0026] To facilitate the placement of the pre-placed ball 8, the mandrel 1 is designed with a variable cross-section structure. Specifically, the mandrel 1 includes an upper mandrel 11 and a lower mandrel 12, which are connected by a mandrel connecting part 13. The upper mandrel 11, lower mandrel 12, and mandrel connecting part 13 are integrally formed structural components. The outer surface of the mandrel connecting part 13 is a conical surface. The outer diameter of the upper mandrel 11 is larger than the outer diameter of the lower mandrel 12, and the inner diameter of the upper mandrel 11 is larger than the inner diameter of the lower mandrel 12.

[0027] The preset ball 8 is preset inside the upper part 11 of the mandrel. The outer diameter of the preset ball 8 is 70%-93% of the inner diameter of the upper part 11 of the mandrel. The outer diameter of the preset ball 8 is larger than the inner diameter of the lower part 12 of the mandrel, so as to block the inner hole of the ball seat (the internal through hole of the lower part 12 of the mandrel).

[0028] In order to fix the position of the pre-placed ball 8, the connecting rod 6 is fixed inside the upper part 11 of the mandrel by the shear pin 7, and the connecting rod 6 is located at the end of the upper part 11 of the mandrel away from the lower part 12 of the mandrel. The end of the connecting rod 6 extends out of the mandrel 1, so as to facilitate connection with the setting tool.

[0029] Link 6 is used to confine the pre-placed ball 8 within the upper part 11 of the spindle, so that the pre-placed ball 8 blocks the inner diameter of the lower part 12 of the spindle.

[0030] To better secure the pre-placed ball 8, as a preferred solution, the end of the connecting rod 6 is provided with a concave conical surface, the inner side of the spindle connection part 13 is a conical surface, and the pre-placed ball 8 is set close to the concave conical surface and the inner side of the spindle connection part 13, thereby ensuring that the pre-placed ball 8 can block the inner hole of the ball seat.

[0031] The cone 2 is adapted to the outer surface of the mandrel connecting part 13, and the lower connector 5 is fixedly connected to the lower part 12 of the mandrel. Preferably, the lower part 12 of the mandrel and the lower connector 5 are threaded together.

[0032] The sealing element 3 and the anchoring mechanism 4 are located between the cone 2 and the lower connector 5. The sealing element 3 is fixedly connected to the end of the anchoring mechanism 4 away from the lower connector 5. Both the sealing element 3 and the anchoring mechanism 4 are provided with an inner conical surface that is compatible with the cone 2, so as to complete the anchoring and sealing functions.

[0033] As a preferred option, the entire pre-placed ball fracturing device is designed with a soluble metal structure. Specifically, the mandrel 1, cone 2, seal 3, anchoring mechanism 4, lower connector 5, and pre-placed ball 8 are all soluble metal structures, such as magnesium alloy, aluminum alloy, and magnesium-aluminum alloy structural components. This allows for automatic degradation without leaving any clogging solid residue.

[0034] For ease of understanding, the fracturing method of the pre-placed ball fracturing device in Example 1 will be introduced. The method includes the following steps: Step 1: As Figure 1 As shown, the pre-placed ball fracturing device is placed in the downhole working position along with the downhole tool string, and the connecting rod 6 is connected to the setting tool to maintain a fixed state. At this time, the connecting rod 6 and the mandrel 1 are fixed by the shear pin 7, while the other end of the mandrel 1 is fastened to the lower connector 5 to maintain a fixed state.

[0035] Step Two: As Figure 2 As shown, at the predetermined position, the setting operation is performed using the setting tool, with the connecting rod 6 remaining fixed, and the cone 2 moving from left to right ( Figure 2 The cone 2 moves axially towards the lower connector 5 along the spindle 1. Due to the conical surface fit between the cone 2, the seal 3, and the anchoring mechanism 4, and the lower connector 5 acting as a limit, the cone 2 pushes the seal 3 and the anchoring mechanism 4 up and down. Figure 2 The movement (in the center direction) involves the seal 3 and anchoring mechanism 4 gradually approaching the well wall radially along the mandrel 1, thus forming an anchoring and sealing structure on the well wall. Since the mandrel 1, lower connector 5, and connecting rod 6 remain relatively fixed after anchoring, when the cone 2 can no longer move to the right, the shearing force on the shear pin 7 gradually increases. When the shearing value of the shear pin 7 reaches the shear failure value, the shear pin 7 shears off. The connecting rod 6 is then brought out of the wellhead along with the downhole tool string, and the pre-placed ball 8 falls into the bottom of the well.

[0036] Step 3: As Figure 3 As shown, according to the operation procedure, after pressurization in the well, under the action of fracturing fluid, the pre-placed ball 8 re-enters the upper part 11 of the mandrel, still sealing the inner diameter of the lower part 12 of the mandrel. The pre-placed ball 8 plays a sealing role. After being subjected to force, the mandrel 1 moves from left to right ( Figure 3 (In the direction of movement). Because the anchoring mechanism 4 forms an anchoring effect with the inner wall of the casing during the setting process, the cone 2 and the sealing element 3 remain fixed; after the mandrel 1 contacts the cone 2, a sealing structure is formed; at this time, the sealing of the sealing element 3 and the cone 2 and the inner wall of the casing, the sealing of the mandrel 1 and the cone 2, and the sealing of the pre-placed ball 8 and the mandrel 1 are all completed, that is, the purpose of this pre-placed ball structure is achieved; it is not necessary to drop the ball from the well to the ball seat in the traditional way.

[0037] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A pre-placed ball fracturing device, characterized in that, It includes a mandrel (1), a cone (2), a seal (3), an anchoring mechanism (4), a lower connector (5), a connecting rod (6), a shear pin (7), and a pre-placed ball (8). The mandrel (1) includes an upper part (11) and a lower part (12). The upper part (11) and the lower part (12) are connected by a mandrel connecting part (13). The inner diameter of the upper part (11) is larger than the inner diameter of the lower part (12). The outer surface of the mandrel connecting part (13) is a conical surface. The pre-placed ball (8) is pre-placed inside the upper part (11) of the mandrel. The outer diameter of the pre-placed ball (8) is larger than the inner diameter of the lower part (12) of the mandrel. The connecting rod (6) is connected to the upper part (11) of the mandrel through the shear pin (7). The connecting rod (6) is used to limit the pre-placed ball (8) inside the upper part (11) of the mandrel, so that the pre-placed ball (8) blocks the inner diameter of the lower part (12) of the mandrel. The cone (2) is adapted to the outer side of the mandrel connection part (13), the lower connector (5) is fixedly connected to the lower part (12) of the mandrel, and the seal (3) and the anchoring mechanism (4) are located between the cone (2) and the lower connector (5).

2. The pre-placed ball fracturing device according to claim 1, characterized in that, The outer diameter of the pre-placed ball (8) is 70%-93% of the inner diameter of the upper part (11) of the mandrel.

3. The pre-placed ball fracturing device according to claim 1, characterized in that, The inner surface of the mandrel connecting part (13) is a conical surface, and the pre-placed ball (8) is set close to the inner surface of the mandrel connecting part (13).

4. The pre-placed ball fracturing device according to claim 3, characterized in that, The end of the connecting rod (6) is provided with a concave conical surface, and the pre-placed ball (8) is set close to the concave conical surface.

5. The pre-placed ball fracturing device according to claim 1, characterized in that, The pre-placed sphere (8) has a soluble metal structure.

6. The pre-placed ball fracturing device according to claim 5, characterized in that, The mandrel (1), the cone (2), the seal (3), the anchoring mechanism (4), and the lower connector (5) are all soluble metal structures.

7. The pre-placed ball fracturing device according to claim 6, characterized in that, The soluble metals include magnesium alloys, aluminum alloys, and magnesium-aluminum alloys.

8. A pre-placed ball fracturing device according to any one of claims 1-7, characterized in that, The lower part (12) of the mandrel and the lower connector (5) are threaded together. The seal (3) is fixedly connected to the end of the anchoring mechanism (4) away from the lower connector (5). Both the seal (3) and the anchoring mechanism (4) are provided with an inner conical surface that is compatible with the cone (2).

9. A pre-placed ball fracturing device according to any one of claims 1-7, characterized in that, The upper part (11), the lower part (12), and the connecting part (13) of the mandrel are integrally formed structural components.

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