Soluble bridge plug and preparation method therefor

Abstract

A soluble bridge plug and a preparation method therefor. The soluble bridge plug comprises a bridge plug main body and a rubber cylinder sleeved on the bridge plug main body, wherein the outer surface of the rubber cylinder is provided with an organic silicon coating. The soluble bridge plug comprises the organic silicon coating, such that during a fracturing operation, the organic silicon coating can effectively slow down the dissolution rate of the rubber cylinder and allow the soluble bridge plug to effectively bear pressure. After the fracturing operation, the organic silicon coating will fall off the rubber cylinder so as not to hinder the dissolution of the rubber cylinder.

Description

Soluble bridge plug and method of making the same

[0001] Cross-reference to Related Applications

[0002] This application claims the benefit of Chinese Patent Application No. 202411370407.3, filed September 29, 2024, the contents of which are incorporated by reference herein. TECHNICAL FIELD

[0003] The present application relates to the technical field of bridge plugs, and in particular to a soluble bridge plug for fracturing of oil and gas fields and a method of making the same. BACKGROUND

[0004] A soluble bridge plug is a kind of temporary wellbore isolation segmented tool for horizontal well fracturing reconstruction made of a new material, which integrates the advantages of conventional fast-drilling composite bridge plugs and large-diameter bridge plugs. The soluble bridge plug can provide stable interlayer isolation during fracturing operations and can dissolve in the liquid environment in the well after the operation is completed without the need for removal operations, which can significantly improve the operation efficiency, has partially replaced drillable composite bridge plugs, and is widely used in the production of unconventional oil and gas.

[0005] A qualified soluble bridge plug needs to meet the following two conditions: first, it can maintain good elasticity during fracturing operations, i.e., within a certain period of time, such as 24 hours; second, it can quickly dissolve itself after fracturing operations. The soluble bridge plug generally includes a bridge plug main body and a rubber sleeve sleeved on the bridge plug main body. The bridge plug main body is mainly made of high-strength magnesium-aluminum alloy or high-molecular material, and the rubber sleeve is mainly made of soluble rubber. Currently, the soluble rubber on the market has poor high-temperature resistance and dissolves quickly during fracturing operations, making it difficult for the soluble bridge plug to meet the above two conditions at the same time.

[0006] CN114907683A discloses a preparation method of a soluble bridge plug rubber compound for shale gas exploitation, comprising the following steps: S1: material selection: mixing type polyurethane rubber 60-80 parts, acrylic ester rubber 20-40 parts, vulcanization system 4-12 parts, filling and reinforcing system 50-80 parts, cosolvent 5-8 parts, water absorbing resin 3-5 parts, softening agent 3-5 parts. S2: mixing: put the mixing type polyurethane rubber, acrylic ester rubber, vulcanization system, filling and reinforcing system, cosolvent, water absorbing resin and softening agent into a mixer for stirring to fully mix the raw materials. S3: mixing: put the fully mixed mixture obtained in S2 step into a mixing mill for mixing, after mixing, the mixed raw materials are placed for a period of time. S4: vulcanization: put the raw materials placed for a period of time after S3 mixing into a vulcanizing machine for vulcanization. S5: molding: first preheat the mold to a vulcanization temperature of 150±1℃, then add the mixed raw materials into the preheated mold, vulcanize and form the finished product. The physical and mechanical properties of the soluble rubber cylinder compound prepared by the method meet the harsh pressure and pressure retention requirements in fracturing operation, but the dissolution speed during fracturing operation needs to be further slowed down.

[0007] CN110017117A discloses a soluble bridge plug, comprising a central pipe, a rubber cylinder, a protection ring, an upper opening ring, a lower opening ring, a threaded ring, a cone, a snap ring, a slip, wear-resistant particles, slip teeth, a lower body, and a lower positioning block. The central pipe is a hollow pipe, a step is arranged on the right end of the outer wall of the central pipe, an external thread for connection is arranged on the left end of the outer wall of the central pipe, the rubber cylinder, the protection ring, the upper opening ring and the lower opening ring are sequentially sleeved on the outer wall of the central pipe from right to left, a hollow cavity is arranged on the side of the rubber cylinder close to the outer wall of the central pipe, the left end of the central pipe is tightly connected through the threaded ring, the threaded ring is connected with the cone through threads, the cone is a hollow boss with a small left end and a large right end, the snap ring is sleeved on the left end of the cone, the slip is sleeved on the left end of the cone close to the snap ring, the main body of the slip is a columnar shape and has a hollow cavity with a small left end and a large right end, the left end of the slip is connected with the lower body, the lower positioning block is arranged in the step hole of the left end of the lower body, through holes are arranged in the lower body and the lower positioning block and penetrate the slip, a step is uniformly arranged on the right end surface of the lower body in the circumferential direction, a groove is arranged on the left end of the slip and matched with the step, wear-resistant particles are uniformly arranged on the outer wall of the right end of the slip, and slip teeth are uniformly arranged on the outer wall of the left end of the slip. The materials of the central pipe, the protection ring, the upper opening ring, the lower opening ring, the threaded ring, the cone, the snap ring, the slip, the lower body and the lower positioning block are all soluble magnesium alloy, and the rubber cylinder is soluble rubber. Compared with the conventional bridge plug structure, the soluble bridge plug has a simple structure, fewer parts and smaller size, which greatly reduces the dissolution time. However, the pressure bearing performance of the soluble bridge plug still needs to be further improved.

[0008] CN109339737A discloses a controllable dissolving bridge plug, which comprises a quick-dissolving bridge plug body and a slow-dissolving layer attached to the inner and outer surfaces of the quick-dissolving bridge plug body. The slow-dissolving layer is destroyed, and the quick-dissolving bridge plug body inside the slow-dissolving layer is exposed and starts to dissolve. The slow-dissolving layer is provided with a mechanical destruction structure for destroying the slow-dissolving layer. The slow-dissolving layer comprises several regional slow-dissolving layers according to the attachment position of the slow-dissolving layer on the quick-dissolving bridge plug body. The several regional slow-dissolving layers comprise a first regional slow-dissolving layer attached to the ball seat, a second regional slow-dissolving layer attached to the inner wall of the passage in the quick-dissolving bridge plug body, a third regional slow-dissolving layer attached to the outer wall of the quick-dissolving bridge plug body and located above the sealing element, and a fourth regional slow-dissolving layer attached to the outer wall of the quick-dissolving bridge plug body and located below the sealing ring. The second regional slow-dissolving layer is provided with a mechanical destruction structure, and the second regional slow-dissolving layer is torn off or torn open from the quick-dissolving bridge plug body by the action of the mechanical destruction structure. In the invention, the inner and outer surfaces of the quick-dissolving bridge plug body are attached with the slow-dissolving layer, which protects the bridge plug from starting to dissolve quickly after being put into the well, and cannot maintain until the fracturing is completed. In addition, the slow-dissolving layer is provided with a mechanical destruction structure to destroy the slow-dissolving layer, thereby exposing the quick-dissolving bridge plug body for dissolution. The pressure of the fracturing ball is used as a trigger signal to realize the synchronization of fracturing construction and dissolution, thereby avoiding the premature dissolution of the bridge plug before the completion of the fracturing construction, and saving the cost of implanting a new bridge plug. However, the structure of the soluble bridge plug is complex, and the production cost is high.

[0009] Therefore, it is urgent to provide a soluble bridge plug with simple structure, which can be delayed to dissolve during fracturing operation and quickly dissolve after fracturing operation. SUMMARY

[0010] The purpose of the present application is to solve the problem of the existing technology that the soluble bridge plug dissolves too quickly during fracturing operation, and to provide a soluble bridge plug with the advantages of being able to delay dissolution during fracturing operation and being able to quickly dissolve after fracturing operation, and a preparation method thereof.

[0011] In order to achieve the above-mentioned purpose, the first aspect of the present application provides a soluble bridge plug, which comprises a bridge plug body and a rubber sleeve sleeved on the bridge plug body; wherein the outer surface of the rubber sleeve is provided with a silicone coating.

[0012] Preferably, the silicone coating is formed by curing a silicone coating liquid.

[0013] Preferably, the silicone coating liquid is selected from Chemtronics CTSR-12, Chemtronics CTSR-5, Chemtronics CTSR-1, DuPont TMone or more of Silicone-Surface Safe Lubricant Aerosol, 3M Spray Silicone Lubricant-Low VOC, Clarion M Silicone Spray.

[0014] Preferably, the thickness of the silicone coating is 1-200 μm.

[0015] Preferably, the thickness of the silicone coating is 30-70 μm.

[0016] Preferably, the surface of the bridge plug body is provided with the silicone coating.

[0017] The second aspect of the present application provides a preparation method of a soluble bridge plug, wherein the method comprises: first spraying a silicone coating liquid on a rubber rubber cylinder for curing to obtain a rubber rubber cylinder provided with a silicone coating; and then sleeving the rubber rubber cylinder provided with the silicone coating on a bridge plug body to obtain a soluble bridge plug.

[0018] Preferably, the rubber rubber cylinder is subjected to cleaning treatment before the silicone coating liquid is sprayed.

[0019] Preferably, the silicone coating liquid is selected from Chemtronics CTSR-12, Chemtronics CTSR-5, Chemtronics CTSR-1, DuPont TM one or more of Silicone-Surface Safe Lubricant Aerosol, 3M Spray Silicone Lubricant-Low VOC, Clarion M Silicone Spray.

[0020] Preferably, the spraying operation condition comprises: a spraying temperature is room temperature, an ambient humidity is 40-60%, and a spraying distance is 10-100 cm.

[0021] Preferably, the spraying frequency is N, 1≤N≤15, and N is an integer.

[0022] Preferably, an operation interval between adjacent spraying operations is 5-30 min.

[0023] Preferably, the curing operation condition comprises: a curing temperature is room temperature-100℃, and a curing time is 10 min-48 h.

[0024] By the technical scheme, the application has the following beneficial technical effects:

[0025] 1) The soluble bridge plug provided by the application comprises a silicone coating arranged on the rubber rubber cylinder, which can effectively slow down the dissolution rate of the rubber rubber cylinder during fracturing operation and realize effective pressure bearing of the soluble bridge plug, and on the other hand, the silicone coating can fall off from the rubber rubber cylinder after fracturing operation, without hindering the dissolution of the rubber rubber cylinder;

[0026] 2) The soluble bridge plug provided by the application has an optimal thickness of the silicone coating, so that the pressure bearing capacity and dissolution effect of the soluble bridge plug are both better;

[0027] 3) In the preparation method of the soluble bridge plug provided by the application, the quality of the silicone coating can be further improved by controlling the operation conditions of spraying, so as to enhance the slow dissolution effect of the silicone coating on the rubber rubber cylinder;

[0028] 4) In the preparation method of the soluble bridge plug provided by the application, compared with one-time spraying, multiple spraying can avoid the appearance of pores or bubbles in the silicone coating when the thickness of the silicone coating is the same, so as to further improve the slow dissolution effect of the silicone coating on the rubber rubber cylinder;

[0029] 5) In the preparation method of the soluble bridge plug provided by the application, after each spraying operation of the silicone coating liquid is completed, the silicone coating liquid can be left to stand for a period of time to ensure that the silicone coating liquid that has been sprayed can first form a relatively firm film layer, so as to prevent the film layer formed by the silicone coating liquid of the previous spraying operation from being wrinkled during the next spraying operation; in addition, the next spraying operation can cover or fill the gaps generated on the film layer due to solvent volatilization during the previous spraying operation, so as to help improve the density of the silicone coating;

[0030] 6) The preparation method of the soluble bridge plug provided by the application is simple in operation, easy to process, and suitable for industrial promotion. BRIEF DESCRIPTION OF DRAWINGS

[0031] Fig. 1 is an optical microscope image of the cross section of the rubber element C;

[0032] Fig. 2 is a change diagram of the soluble bridge plug prepared in Example 3 during the dissolution process.

[0033] Fig. 3 shows the dissolution results of the rubber base material without silicone coating (upper side picture) and the soluble bridge plug prepared in Example 1 (lower side picture).

[0034] Fig. 4 shows the dissolution results of the DR-127 rubber base material without silicone coating (upper side picture) and the rubber element H prepared (lower side picture). DETAILED DESCRIPTION

[0035] The endpoints of the ranges and any values disclosed herein are not limited to the precise values recited as the exact dimensions are not critical to the invention. Any numeric range recited is intended to include all values from the lower value to the upper value. For numeric ranges recited as "from X to Y," the range is intended to include X and Y unless otherwise indicated. For numeric ranges recited as "X or greater," the range is intended to include X unless otherwise indicated. For numeric ranges recited as "less than X," the range is intended to include X unless otherwise indicated. Numeric ranges can be combined with other qualifiers unless otherwise indicated. For example, "less than or equal to 10" can be combined with "greater than 5" to include numeric values between 5 and 10, but not 10.

[0036] The first aspect of the present application provides a dissolvable bridge plug, comprising a bridge plug body and a rubber sleeve sleeved on the bridge plug body; wherein an outer surface of the rubber sleeve is provided with a silicone coating.

[0037] In the present application, the silicone coating is closely combined with the rubber sleeve, and there is substantially no gap between the two. Since the silicone coating has hydrophobicity and a low diffusion coefficient for water molecules. Therefore, when performing a fracturing operation, the silicone coating can prolong the time for water molecules in the fracturing fluid to contact the rubber sleeve, thereby delaying the dissolution rate of the rubber sleeve during the fracturing operation, and achieving effective pressure bearing. As the fracturing operation proceeds, water molecules slowly penetrate the silicone coating and contact the rubber sleeve. After the rubber sleeve contacts water, hydrolysis occurs, and separation begins between the silicone coating and the rubber sleeve, thereby enabling the bridge plug body and the rubber sleeve to be rapidly dissolved in the next link.

[0038] The present application does not make special limitations on the structure and material of the bridge plug body, and any publicly known dissolvable bridge plug body can be used in the present application. Preferably, the material of the bridge plug body is a dissolvable magnesium-aluminum alloy, which can be a commonly used dissolvable magnesium-aluminum alloy in the art and can be obtained by self-preparation or commercial purchase.

[0039] The present application does not make special limitations on the structure and material of the rubber sleeve, and any publicly known rubber sleeve can be used in the present application.

[0040] In an embodiment of the present application, the material of the rubber sleeve is a dissolvable rubber, such as a dissolvable polyurethane rubber. The dissolvable polyurethane rubber can be a commercially available product in the art, or can be prepared according to a publicly known method. For example, the dissolvable polyurethane rubber can be a dissolvable rubber disclosed in US11566097B2.

[0041] In an embodiment of the present application, the silicone coating is formed by curing a silicone coating liquid.

[0042] In an embodiment of the present application, the silicone coating liquid is selected from Chemtronics CTSR-12, Chemtronics CTSR-5, Chemtronics CTSR-1, DuPont TM One or more of Silicone-Surface Safe Lubricant Aerosol, 3M Spray Silicone Lubricant - Low VOC, Clarion M Silicone Spray.

[0043] wherein Chemtronics CTSR-12, Chemtronics CTSR-5, Chemtronics CTSR-1 is a commercially available paint for protection against water, chemicals, and UV light produced by Chemtronics, USA. DuPont TM Silicone-Surface Safe Lubricant Aerosol is a silicone surface safe lubricant aerosol produced by DuPont. 3M Spray Silicone Lubricant - Low VOC is a low volatile organic compound (VOC) silicone lubricant spray produced by 3M.

[0044] In one embodiment of the present application, the silicone coating liquid is selected from one or more of Chemtronics CTSR-12, Chemtronics CTSR-5, Chemtronics CTSR-1, preferably Chemtronics CTSR-12.

[0045] In one embodiment of the present application, the thickness of the silicone coating layer is 1-200 μm, for example, the thickness of the silicone coating layer can be 1 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, 100 μm, 105 μm, 110 μm, 115 μm, 120 μm, 130 μm, 130 μm, 135 μm, 140 μm, 145 μm, 150 μm, 160 μm, 165 μm, 170 μm, 175 μm, 180 μm, 190 μm, 195 μm, 200 μm, and any number between these values, preferably 30-70 μm.

[0046] In the present application, the thickness of the silicone coating can be obtained by cutting the polyurethane component with the coating, and measuring the coating thickness with an optical microscope.

[0047] If the thickness of the silicone coating is too large, it will result in a slow dissolving speed of the bridge plug body and the rubber rubber after the fracturing is completed, which is not conducive to the self-dissolution of the dissolvable bridge plug. If the thickness of the silicone coating is too small, the effect of delaying the diffusion of the fracturing fluid is weak, and the delayed dissolution effect is not good. It is found through research that when the thickness of the silicone coating is within the above-mentioned preferred range, the pressure bearing and dissolution effect of the dissolvable bridge plug are better.

[0048] In an embodiment of the present application, the surface of the bridge plug body is provided with the silicone coating.

[0049] The silicone coating can not only be provided on the surface of the bridge plug body and the rubber rubber, but also can be provided on other equipment or equipment components, such as bridge plugs, packers, isolation valves, oil pipes, joint pipes, sucker rods, submersible pumps, submersible pump motor protection packages, packer elements, blowout preventers, blowout preventer elements, O-rings, T-rings, centralizers, hangers, swivel bridge plugs, swivel bridge plug catchers, check valves, general valves, one-way valves, differential valves, circulating valves, balance valves, safety valves, fluid flow control valves, sliding seals, connectors, disconnecting device tools, downhole filters, motor heads, recovery and fishing tools, bottom hole assemblies, sealing assemblies, buckle assemblies, anchor assemblies, shear-type anchor assemblies, stop positioners, sensor protectors, gaskets, pump shaft seals, pipe seals, valve seals, seals and insulators used in electrical elements, seals used in optical fiber connections, fluid pressure sealing elements, and combinations thereof.

[0050] The second aspect of the present application provides a preparation method of a dissolvable bridge plug, which comprises: first spraying a silicone coating liquid on a rubber rubber for curing to obtain a rubber rubber provided with a silicone coating; and then sleeving the rubber rubber provided with the silicone coating on a bridge plug body to obtain a dissolvable bridge plug.

[0051] In an embodiment of the present application, the rubber rubber is subjected to cleaning treatment before the silicone coating is sprayed. The cleaning treatment mode includes but is not limited to cleaning the surface of the rubber rubber with isopropyl alcohol and / or ethanol to remove dust and oil stains.

[0052] In an embodiment of the present application, the silicone coating liquid is selected from Chemtronics CTSR-12, Chemtronics CTSR-5, Chemtronics CTSR-1, DuPont TMone or more of Silicone-Surface Safe Lubricant Aerosol, 3M Spray Silicone Lubricant-Low VOC, Clarion M Silicone Spray.

[0053] In an embodiment of the present application, the silicone coating liquid is selected from one or more of Chemtronics CTSR-12, Chemtronics CTSR-5, Chemtronics CTSR-1, further preferably Chemtronics CTSR-12.

[0054] It is found through research that when the silicone coating layer is prepared by using Chemtronics CTSR-12, the pressure-bearing capacity and dissolving effect of the soluble bridge plug are both better.

[0055] In an embodiment of the present application, the operation condition of spraying includes that the spraying temperature is room temperature, the environmental humidity is 40-60%, and the spraying distance is 10-100 cm. By controlling the operation condition of spraying, the quality of the silicone coating layer can be further improved, and the alleviating effect of the silicone coating layer on the rubber rubber cylinder dissolution is enhanced.

[0056] The room temperature in the present application has the known meaning, and the present application does not make special limitation thereto. The temperature of the room temperature can be 25-35℃.

[0057] In an embodiment of the present application, the environmental humidity can be 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, and any number among these values, preferably 45-55%.

[0058] In an embodiment of the present application, the spraying distance can be 10 cm, 15 cm, 20 cm, 25 cm, 30 cm, 35 cm, 40 cm, 45 cm, 50 cm, 55 cm, 60 cm, 65 cm, 70 cm, 75 cm, 80 cm, 85 cm, 90 cm, 95 cm, 100 cm, and any number among these values, preferably 20-40 cm.

[0059] In an embodiment of the present application, the spraying is performed for N times, wherein 1≤N≤15, and N is an integer. It has been found that, for the same thickness of the silicone coating, compared with one-time spraying, multi-time spraying can avoid the occurrence of pores or bubbles in the silicone coating, and can further improve the delayed dissolution effect of the silicone coating on the rubber sleeve.

[0060] In an embodiment of the present application, N can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or the like; preferably, 1≤N≤6, and N is an integer; further preferably, 2≤N≤4, and N is an integer.

[0061] In an embodiment of the present application, the operation interval between adjacent spraying operations is 10-30 min.

[0062] It has been found that, after each spraying operation of the silicone coating solution is completed, the silicone coating solution can be left to stand for a period of time, so as to ensure that the silicone coating solution that has been sprayed can first form a relatively firm film layer, so as to prevent the film layer formed by the silicone coating solution in the previous spraying operation from being wrinkled in the next spraying operation. In addition, the next spraying operation can cover or fill the gaps in the film layer caused by solvent volatilization in the previous spraying operation, thereby helping to improve the compactness of the silicone coating.

[0063] In an embodiment of the present application, the operation interval between adjacent spraying operations can be 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, 16 min, 17 min, 18 min, 19 min, 20 min, 21 min, 22 min, 23 min, 24 min, 25 min, 26 min, 27 min, 28 min, 29 min, 30 min, and any number between these values, preferably 15-25 min.

[0064] In an embodiment of the present application, the curing operation conditions include that the curing temperature is room temperature to 100℃, and the curing time is 10 min-48 h.

[0065] In an embodiment of the present application, the curing temperature can be room temperature, 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃, 100℃, and any number between these values, preferably room temperature to 50℃, further preferably room temperature.

[0066] In an embodiment of the present application, the curing time can be 10 min, 30 min, 1 h, 3 h, 5 h, 7 h, 9 h, 11 h, 13 h, 15 h, 18 h, 20 h, 22 h, 24 h, 26 h, 28 h, 30 h, 35 h, 38 h, 40 h, 44 h, 48 h, preferably 20-28 h.

[0067] In an embodiment of the present application, the thickness of the silicone coating layer is 1-200 μm, for example, the thickness of the silicone coating layer can be 1 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, 100 μm, 105 μm, 110 μm, 115 μm, 120 μm, 130 μm, 130 μm, 135 μm, 140 μm, 145 μm, 150 μm, 160 μm, 165 μm, 170 μm, 175 μm, 180 μm, 190 μm, 195 μm, 200 μm, and any number between these values, preferably 30-70 μm.

[0068] The thickness of the silicone coating layer obtained by each spraying can be determined by the person skilled in the art as needed or according to the target thickness and the number of spraying, and in some embodiments, the thickness of the silicone coating layer obtained by each spraying is 10-20 μm, for example, can be 10 μm, 12 μm, 14 μm, 16 μm, 18 μm, 20 μm, and any number between these values.

[0069] In an embodiment of the present application, the method comprises the following steps:

[0070] 1) spraying the silicone coating liquid on the rubber rubber sleeve to cure, obtaining a rubber rubber sleeve provided with a silicone coating layer;

[0071] 2) spraying the silicone coating liquid on the surface of the bridge plug body to cure, obtaining a bridge plug body provided with a silicone coating layer;

[0072] 3) sleeving the rubber rubber sleeve provided with a silicone coating layer on the bridge plug body provided with a silicone coating layer, obtaining a soluble bridge plug.

[0073] In the present application, the preparation method of the bridge plug body provided with a silicone coating layer is the same as the preparation method of the rubber rubber sleeve provided with a silicone coating layer, and the present application will not be repeated here. The rubber rubber sleeve and the bridge plug body are both provided with a layer of silicone coating layer, which can better improve the pressure bearing performance and dissolution effect of the soluble bridge plug.

[0074] The present application will be described in detail below by way of examples. The bridge plug body was purchased from Kunfu, product model No. 10021180-AA. The rubber sleeve was purchased from Esco Plastics, product model No. DR-043. The rubber base material was of the same material as the rubber sleeve.

[0075] Example 1

[0076] The surface of the rubber sleeve was cleaned with isopropyl alcohol to remove dust and oil residue; Chemtronics -CTSR-12 was sprayed onto the surface of the rubber base material in two times under the conditions of room temperature, humidity of 50%, and spraying distance of 30 cm, and then cured at room temperature for 24 h to obtain a rubber sleeve provided with a silicone coating; wherein the spraying operation conditions were the same each time, the operation time interval between adjacent two spraying operations was 20 min (i.e. after spraying each layer, the next layer was sprayed after standing for 20 min), and the thickness of the silicone coating was 33 μm; the rubber sleeve provided with the silicone coating was sleeved on the bridge plug body to obtain a soluble bridge plug.

[0077] Example 2

[0078] The surface of the rubber base material was cleaned with isopropyl alcohol to remove dust and oil residue; Chemtronics -CTSR-12 was sprayed onto the surface of the rubber base material in three times under the conditions of room temperature, humidity of 45%, and spraying distance of 35 cm, and then cured at room temperature for 24 h to obtain a rubber sleeve provided with a silicone coating; wherein the spraying operation conditions were the same each time, the operation time interval between adjacent two spraying operations was 25 min (i.e. after spraying each layer, the next layer was sprayed after standing for 25 min), and the thickness of the silicone coating was 48 μm; the rubber sleeve provided with the silicone coating was sleeved on the bridge plug body to obtain a soluble bridge plug.

[0079] Example 3

[0080] The surface of the rubber base material was cleaned with isopropyl alcohol to remove dust and oil residue; Chemtronics -CTSR-12 was sprayed onto the surface of the rubber base material in four times under the conditions of room temperature, humidity of 55%, and spraying distance of 20 cm, and then cured at room temperature for 24 h to obtain a rubber sleeve provided with a silicone coating; wherein the spraying operation conditions were the same each time, the operation time interval between adjacent two spraying operations was 15 min (i.e. after spraying each layer, the next layer was sprayed after standing for 15 min), and the thickness of the silicone coating was 60 μm; the rubber sleeve provided with the silicone coating was sleeved on the bridge plug body to obtain a soluble bridge plug.

[0081] Example 4

[0082] The surface of the rubber base material was cleaned with isopropyl alcohol to remove dust and oil residue; Chemtronics -CTSR-12 was sprayed on the surface of the rubber base material under the conditions of room temperature, humidity of 40%, spraying distance of 10 cm, and 6 times of spraying, and then cured at 40 °C for 12 h to obtain a rubber rubber sleeve provided with a silicone coating; wherein the spraying operation conditions of each time were the same, the operation time interval between adjacent two times of spraying was 30 min (that is, after spraying each layer, the next layer was sprayed after standing for 30 min), and the thickness of the silicone coating was 90 μm; the above rubber rubber sleeve provided with a silicone coating was sleeved on the bridge plug body to obtain a soluble bridge plug.

[0083] Example 5

[0084] The surface of the rubber base material was cleaned with isopropyl alcohol to remove dust and oil residue; Chemtronics -CTSR-12 was sprayed on the surface of the rubber base material under the conditions of room temperature, humidity of 60%, spraying distance of 50 cm, and 8 times of spraying, and then cured at 50 °C for 3 h to obtain a rubber rubber sleeve provided with a silicone coating; wherein the spraying operation conditions of each time were the same, the operation time interval between adjacent two times of spraying was 10 min (that is, after spraying each layer, the next layer was sprayed after standing for 10 min), and the thickness of the silicone coating was 120 μm; the above rubber rubber sleeve provided with a silicone coating was sleeved on the bridge plug body to obtain a soluble bridge plug.

[0085] Example 6

[0086] The same as example 3, except that the thickness of the silicone coating was 80 μm; the surface of the rubber base material was cleaned with isopropyl alcohol to remove dust and oil residue; Chemtronics -CTSR-12 was sprayed on the surface of the rubber base material under the conditions of room temperature, humidity of 55%, spraying distance of 20 cm, and 4 times of spraying, and then cured at room temperature for 24 h to obtain a rubber rubber sleeve provided with a silicone coating; wherein the spraying operation conditions of each time were the same, the operation time interval between adjacent two times of spraying was 15 min (that is, after spraying each layer, the next layer was sprayed after standing for 15 min), and the thickness of the silicone coating was 80 μm; the above rubber rubber sleeve provided with a silicone coating was sleeved on the bridge plug body to obtain a soluble bridge plug.

[0087] Microstructure characterization of rubber element

[0088] Referring to examples 1-6, Chemtronics - CTSR-12, rubber elements A-G provided with a silicone coating in turn were obtained. The rubber elements A-G were characterized by optical microscopy, wherein the test results of the rubber elements A-G were similar. It can be known from the optical microscopy characterization results that the silicone coating in the rubber elements A-G is dense and uniform, and there is no bubble in the silicone coating, and the adhesion and consistency of the silicone coating with the rubber substrate surface are very good.

[0089] For example, the rubber element C (i.e., the rubber element provided with a silicone coating on the rubber substrate according to the reference example 3) was characterized by optical microscopy to characterize the microstructure of the cross section of the rubber element C. The optical microscopy characterization results of the cross section of the rubber element C are shown in FIG. 1. It can be known from FIG. 1 that the silicone coating on the rubber element C is dense and uniform, and there is no bubble in the silicone coating, and the adhesion and consistency of the silicone coating with the rubber substrate surface are very good, and the thickness of the silicone coating part marked in FIG. 1 is 33 μm.

[0090] Pressure-bearing capacity test of the dissolvable bridge plug

[0091] The pressure-bearing capacity of the dissolvable bridge plugs prepared in the examples 1-6 was tested, and the test results are shown in Table 1. For example, the dissolvable bridge plug prepared in the example 1 was tested according to the following method:

[0092] (1) The dissolvable bridge plug was soaked in water at 60℃ for 2h, and then was set in a sleeve filled with clean water at room temperature; (2) the dissolvable bridge plug was subjected to pressure at 140℃ for 12h in clean water with a pressure difference of 38MPa, and the change of the pressure drop with time was recorded; (3) then the pressure difference was increased to 60MPa, and the dissolvable bridge plug was subjected to pressure for 12h, and then the pressure difference was increased to 70MPa, and the dissolvable bridge plug was subjected to pressure for 30min, and the change of the pressure drop with time was recorded; wherein the total pressure drop of the dissolvable bridge plug in step (2) was less than 5MPa, and the total pressure drop of the dissolvable bridge plug in step (3) was less than 15MPa, indicating that the dissolvable bridge plug can stably bear pressure, and can effectively delay the dissolution speed of the rubber rubber cylinder during the fracturing operation, and can effectively bear pressure.

[0093] Table 1

[0094] It can be known from Table 1 that the total pressure drop of the dissolvable bridge plug prepared in the examples 1-6 of the present application in step (2) is less than 5MPa, and the total pressure drop of the dissolvable bridge plug in step (3) is less than 15MPa, indicating that the dissolvable bridge plug can stably bear pressure, and can effectively bear pressure during the fracturing operation.

[0095] Dissolution test of the dissolvable bridge plug

[0096] (1) The solubility of the soluble bridge plugs prepared in Examples 1-6 was tested, and the test results are shown in Table 2. Taking the soluble bridge plug prepared in Example 1 as an example, the specific test method is as follows:

[0097] The soluble bridge plug after completing the pressure test was first soaked in a 95℃, 1.05wt% KCl aqueous solution for 5 days, and then soaked in a 95℃, 2.1wt% KCl aqueous solution for 10 days. After the solubility test was completed, the maximum size of the dissolved fragments was measured, and the weight of the dissolved fragments was measured.

[0098] Wherein, after the solubility test, the maximum size of the dissolved fragments is less than or equal to 2cm, and the total weight loss of the soluble bridge plug is greater than or equal to 95%, indicating that the soluble bridge plug can be quickly dissolved after the fracturing operation.

[0099] Figure 2 is a graph showing the changes of the soluble bridge plug prepared in Example 3 during the dissolution process. As shown in Figure 2, the soluble bridge plug was dissolved into large fragments on the ninth day, the fragments were further reduced on the twelfth day, and the fragments were completely broken into fine residues after the fifteenth day.

[0100] Table 2

[0101] As shown in Table 2, the soluble bridge plugs prepared in Examples 1-6 of the present application have a maximum size of the dissolved fragments of less than 2cm after the solubility test, and the total weight loss of the soluble bridge plug is more than 95%, indicating that the soluble bridge plug can be quickly dissolved after the fracturing operation.

[0102] In combination with Table 1 and Table 2, the pressure performance and solubility performance of the soluble bridge plug prepared in Example 3 are the best. By comparing Example 3 and Comparative Example 1, it can be seen that within the scope defined in the present application, by adjusting the thickness of the silicone coating, the pressure effect and solubility effect of the soluble bridge plug can be further improved.

[0103] (2) The rubber base material without a silicone coating and the soluble bridge plugs prepared in Examples 1-6 were respectively soaked in 150℃, 0.3% KCl to test their solubility, and the effect of the silicone coating on the solubility of the delayed rubber base material was observed. The dissolution time of different soluble bridge plugs was prolonged.

[0104] Figure 3 shows the dissolution results of the rubber base material without a silicone coating (upper picture) and the soluble bridge plug prepared in Example 1 (lower picture). As shown in Figure 3, the rubber base material without a silicone coating began to dissolve at 8h, while the soluble bridge plug dissolved after 24h, which indicates that the silicone coating can delay the dissolution of the soluble rubber for at least 16 hours.

[0105] The thickness of the silicone coating needs to be designed to balance the performance of delaying the dissolution of soluble rubber with reducing coating time and cost. Thicker coatings improve barrier properties but require more coating time and cost.

[0106] (3) Apply Chemtronics coating to the rubber substrate as described in Example 1. -CTSR-12 was used to prepare rubber element H, with different rubber substrates, the product model of which was DR-127. The DR-127 rubber substrate without silicone coating and the prepared rubber element H were first immersed in 140℃, 0.3% KCl solution for 24 hours, and then immersed in 95℃, 0.3% KCl solution for 10 days. Their dissolution capacity was tested to observe the effect of the silicone coating on delaying the dissolution of the rubber substrate. The dissolution time of different rubber elements was prolonged.

[0107] Figure 4 shows the dissolution results of the DR-127 rubber substrate without silicone coating (top image) and the prepared rubber element H (bottom image). As can be seen from Figure 4, the DR-127 rubber substrate without silicone coating fractured after aging at 140℃ for 24 hours and broke apart after aging at 95℃ for 1 day. Rubber element H did not fracture after aging at 140℃ for 24 hours, fractured after aging at 95℃ for 1 day, and broke apart after aging at 95℃ for 3 days. The results indicate that, compared to the DR-127 rubber substrate without silicone coating, the silicone coating delayed the dissolution of rubber element H by 2 days.

[0108] The data above shows that the present invention uses an organosilicon coating on the outer surface of the rubber sleeve to prepare a soluble bridge plug that can delay dissolution during fracturing operations and dissolve rapidly after fracturing operations.

[0109] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A soluble bridge plug comprising a bridge plug body and a rubber bung sleeved on the bridge plug body, characterized in that, The outer surface of the rubber rubber cylinder is provided with a silicone coating.

2. The soluble bridge plug of claim 1, wherein, The surface of the bridge plug body is provided with the silicone coating.

3. The soluble bridge plug of claim 1 or 2, wherein, The silicone coating is formed by curing a silicone coating liquid.

4. The soluble bridge plug of claim 3, wherein, the silicone coating fluid is selected from the group consisting of Chemtronics CTSR-12, Chemtronics CTSR-5, Chemtronics CTSR-1, DuPont TM one or more of Silicone-Surface Safe Lubricant Aerosol, 3M Spray Silicone Lubricant - Low VOC, Clarion M Silicone Spray.

5. The dissolvable bridge plug of any one of claims 1-4, wherein, The thickness of the silicone coating is 1-200 microns.

6. The soluble bridge plug of claim 5, wherein, The thickness of the silicone coating is 30-70 microns.

7. A method of preparing a soluble bridge plug, characterized by, The method comprises: first, spraying a silicone coating liquid on the rubber rubber cylinder for curing to obtain a rubber rubber cylinder provided with a silicone coating; then, sleeving the rubber rubber cylinder provided with the silicone coating on the bridge plug body to obtain a soluble bridge plug.

8. The production method according to claim 7, wherein Before spraying the silicone coating liquid, the rubber rubber cylinder is subjected to cleaning treatment.

9. The production method according to claim 7, wherein the silicone coating fluid is selected from the group consisting of Chemtronics CTSR-12, Chemtronics CTSR-5, Chemtronics CTSR-1, DuPont TM one or more of Silicone-Surface Safe Lubricant Aerosol, 3M Spray Silicone Lubricant - Low VOC, Clarion M Silicone Spray.

10. The production process according to any one of claims 7 to 9, wherein, The spraying operation condition comprises: spraying temperature is room temperature, ambient humidity is 40-60%, spraying distance is 10-100 cm.

11. The production process according to any one of claims 7 to 10, wherein, The spraying frequency is N, 1≤N≤15, and N is an integer.

12. The method of making according to claim 11, wherein, The operation interval between adjacent spraying operations is 10-30 min.

13. The production process according to any one of claims 7 to 12, wherein, The curing operation condition comprises: curing temperature is room temperature to 100 DEG C, and curing time is 10 min-48 h.

14. The production process according to any one of claims 7 to 13, wherein, The thickness of the silicone coating is 1-200 microns.

15. The production process according to any one of claims 7 to 14, wherein, The method comprises the following steps: (1) spraying a silicone coating liquid on the rubber rubber cylinder for curing to obtain a rubber rubber cylinder provided with a silicone coating; (2) spraying a silicone coating liquid on the surface of the bridge plug body for curing to obtain a bridge plug body provided with a silicone coating; (3) sleeving the rubber rubber cylinder provided with the silicone coating on the bridge plug body provided with the silicone coating to obtain a soluble bridge plug.

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