Well completion method without injection-production string for salt cavern energy storage well

Abstract

The invention relates to a salt cavern energy storage well non-injection-production string well completion method, which is used for performing multi-time well completion operation, and comprises the following steps of: when the last time of well completion operation is performed, arranging an initial cement sheath well wall along the well wall in a well shaft; after drilling of the last time is completed, a plurality of well cementation casing pipes are put into the shaft and along the initial cement sheath well wall in sequence to reach the preset depth in the shaft; cement paste is injected into an annular space, located between the well cementation casing pipe and the initial cement sheath well wall, in the shaft, and well cementation operation is conducted; and after the well cementation operation is completed, all the well cementation sleeves are pulled out one by one, so that the initial cement sheath well wall forms a formed cement sheath well wall with a smooth and firm wall surface. The technical problems that the sleeve is corroded in the salt cavern building process, so that the strength of the sleeve is reduced, and the stability of the salt cavern becomes poor are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of underground storage, especially to a salt cavern energy storage well without injection and production pipe string completion method. BACKGROUND

[0002] The salt cavern gas storage is formed by injecting fresh water into the underground thick salt layer or salt dome to dissolve the salt layer, and then discharging the saturated or nearly saturated brine. Due to the characteristics of salt rock, such as dense structure, low porosity, low permeability, large plastic deformation capacity and damage self-healing, the salt rock can be used as the best medium for storing oil, natural gas and related products.

[0003] Under the background of carbon sequestration and rapid development of hydrogen energy, the storage and utilization of CO2 and H2 have put forward huge demands for large-scale underground storage space. China has rich salt rock resources, and the annual output of rock salt is close to 50 million tons. According to the current output, the newly added old cavity is 20 million m 3 Using underground salt caverns can effectively solve the problem of energy storage such as CO2 and H2. However, in the process of building a salt cavern, the conventional completion method must use a casing to establish a flow channel between the ground and the salt cavern. The material of the casing (steel) is easily corroded by brine, CO2 and H2, which will damage its strength and is not conducive to the long-term stable operation of the salt cavern storage.

[0004] In view of the problem that the casing is corroded in the process of building a salt cavern, which reduces the strength of the casing and deteriorates the stability of the salt cavern, there is no effective solution at present.

[0005] Therefore, the present application is proposed by the present inventor with years of experience and practice in the relevant industry to overcome the defects of the prior art. SUMMARY

[0006] The purpose of the present application is to provide a salt cavern energy storage well without injection and production pipe string completion method. In the completion process, the last opening uses a cement ring for completion, which avoids direct contact between the casing and the storage fluid during the construction and operation of the salt cavern, and also avoids the casing damage caused by corrosion and hydrogen embrittlement when using the casing, effectively avoiding the damage to the integrity of the wellbore.

[0007] The purpose of the present application can be achieved by the following scheme:

[0008] The present application provides a salt cavern energy storage well without injection and production pipe string completion method for multi-opening completion operation, which comprises the following steps:

[0009] When performing the last opening completion operation, an initial cement ring well wall is arranged along the well wall in the wellbore;

[0010] after the last drilling, sequentially lowering a plurality of cementing casings into the wellbore along the initial cement sheath wall to a preset depth in the wellbore;

[0011] injecting cement slurry into the annulus between the cementing casings and the initial cement sheath wall in the wellbore to perform cementing operation;

[0012] after the cementing operation is completed, sequentially pulling out all the cementing casings to form a smooth and solid shaped cement sheath wall.

[0013] In a preferred embodiment of the present application, before the plurality of cementing casings are sequentially lowered into the wellbore along the initial cement sheath wall to a preset depth in the wellbore, a lubricating layer is provided on the outer wall of each cementing casing to reduce frictional resistance.

[0014] In a preferred embodiment of the present application, the lubricating layer is formed by spraying a lubricating release agent formed by mixing a concrete release agent and a lubricant on the outer wall of the cementing casing.

[0015] In a preferred embodiment of the present application, before the plurality of cementing casings are sequentially lowered into the wellbore along the initial cement sheath wall to a preset depth in the wellbore, a centralizer with a lifting self-unlocking function is provided on the cementing casing to center the cementing casing in the wellbore.

[0016] In a preferred embodiment of the present application, at least one of the three sequentially connected cementing casings is provided with the centralizer.

[0017] In a preferred embodiment of the present application, the centralizer comprises at least two annular casing clamping members and a plurality of spring sheets, the plurality of spring sheets are arranged in a circumferential direction of the casing clamping members, and the two ends of the spring sheets are connected to the two casing clamping members, respectively.

[0018] The inner wall of the casing clamping member is provided with a plurality of tooth plates in the circumferential direction, the tooth plates are provided with a plurality of teeth arranged in an array on the plate surface facing the axis direction of the centralizer, the casing clamping member is sleeved on the outside of the cementing casing, and the end of the tooth is abutted against the outer wall of the cementing casing.

[0019] In a preferred embodiment of the present application, the cementing casing is in a centralizing state, the two casing clamping members are moved towards each other to press the spring sheets to bend away from the axis direction of the centralizer, and at least the middle outer wall of the spring sheet is abutted against the inner wall of the wellbore.

[0020] In a preferred embodiment of the present application, the sleeve holder is provided with a buckle structure that automatically releases the locking of the casing shoe by the tooth plate when the casing shoe is lifted up;

[0021] The buckle structure comprises a receiving groove on the inner wall of the sleeve holder and an extension plate on the top of the tooth plate, the bottom of the receiving groove is open, and a reverse hook-shaped retreat stop step is formed at the opening, the extension plate has a retreat stop boss, the lower part of the retreat stop step has a first guide surface that is inclined from bottom to top away from the axis of the centralizer, and the upper part of the retreat stop boss has a second guide surface that is inclined from bottom to top away from the axis of the centralizer;

[0022] When the well completion operation is performed, the retreat stop boss is below the retreat stop step, the end of the protruding tooth abuts against the outer wall of the casing shoe, and the buckle structure is in a locked state;

[0023] When the casing shoe is lifted up, the tooth plate moves upward with the casing shoe, the first guide surface and the second guide surface fit and guide the retreat stop boss to enter the receiving groove from the bottom opening of the receiving groove, the end of the protruding tooth is separated from the outer wall of the casing shoe, and the buckle structure is in an unlocked state.

[0024] In a preferred embodiment of the present application, when the buckle structure is in the unlocked state, the bottom of the retreat stop boss abuts against the top of the retreat stop step.

[0025] In a preferred embodiment of the present application, the buckle structure further comprises a limiting groove on the inner wall of the sleeve holder and a limiting boss on the plate surface of the tooth plate that is opposite to the axis of the centralizer;

[0026] When the well completion operation is performed, the limiting boss is below the limiting groove, and the limiting boss abuts against the inner wall of the sleeve holder below the limiting groove to make the end of the protruding tooth abut against the outer wall of the casing shoe;

[0027] When the casing shoe is lifted up, the limiting boss moves upward with the tooth plate and enters the limiting groove, and the top of the limiting boss abuts against the inner wall of the top of the limiting groove.

[0028] In a preferred embodiment of the present application, the number of the limiting bosses is two, and the two limiting bosses are respectively on the top and bottom of the plate surface of the tooth plate that is opposite to the axis of the centralizer, and the limiting groove is two corresponding to the limiting bosses.

[0029] In a preferred embodiment of the present application, the number of the buckle structures is multiple, and the multiple buckle structures are arranged along the circumference of the casing clamp.

[0030] In a preferred embodiment of the present application, a sealing ring is arranged on the inner wall of the casing clamp along the circumference thereof, and the sealing ring is tightly fitted with the outer wall of the cementing casing.

[0031] In a preferred embodiment of the present application, the well completion operation is two-trip completion, and the one-trip completion operation is performed before the last-trip completion operation.

[0032] In the one-trip completion operation, drilling is performed downwardly to below the soil surface layer, and the surface casing is lowered.

[0033] In a preferred embodiment of the present application, after the cementing operation is completed, the surface casing is retained in the wellbore, and the surface casing is located outside the formed cement sheath.

[0034] In a preferred embodiment of the present application, the well completion operation is three-trip completion, and the one-trip completion operation and the two-trip completion operation are sequentially performed before the last-trip completion operation.

[0035] In the one-trip completion operation, drilling is performed downwardly to below the soil surface layer, and the surface casing is lowered.

[0036] In the two-trip completion operation, drilling is performed downwardly to below the soil water-bearing and gas-bearing layer, and the technical casing is lowered.

[0037] In a preferred embodiment of the present application, after the cementing operation is completed, the surface casing and the technical casing are retained in the wellbore, and the surface casing is located outside the technical casing, and the technical casing is located outside the formed cement sheath.

[0038] In a preferred embodiment of the present application, the thickness of the formed cement sheath is 1.5 inches to 2.0 inches.

[0039] In a preferred embodiment of the present application, the cement slurry injected into the annulus between the wellbore, the cementing casing and the initial cement sheath is anticorrosive cement slurry.

[0040] According to the above description, the salt cavern energy storage well completion method without injection and production string has the following characteristics and advantages:

[0041] When the last opening well completion operation is carried out, a cement sheath is arranged on the well wall of the wellbore to form an initial cement sheath well wall, and after the last opening well drilling is completed, a plurality of cementing casings are sequentially lowered into the wellbore to a preset depth in the wellbore; then, cement slurry is injected into the annulus between the cementing casing and the initial cement sheath well wall to carry out cementing operation; after all the cementing casings are pulled out one by one, the cement slurry is supplemented to the annulus and a shaped cement sheath well wall with smooth wall surface and strong strength is formed on the basis of the initial cement sheath well wall, so as to achieve the purpose of cementing.

[0042] During the entire completion process of the last opening, cement sheath is used for completion operation, and after the cementing casing is finally pulled out, the shaped cement sheath well wall serves as the wellbore wall, so that the fluid flowing through the wellbore directly contacts the shaped cement sheath well wall during the construction and operation of the salt cavern, thereby avoiding direct contact with the cementing casing and avoiding casing damage caused by corrosion, hydrogen embrittlement and other factors during use of the cementing casing, so as to effectively avoid damage to the integrity of the wellbore and ensure the strength of the wellbore and the long-term and stable operation of the salt cavern. BRIEF DESCRIPTION OF DRAWINGS

[0043] The following drawings are only intended to illustrate and explain the present application and do not limit the scope of the present application.

[0044] Among them:

[0045] Figure 1 : It is the flow chart of the salt cavern energy storage well without injection and production string completion method of the present application.

[0046] Figure 2 : It is the wellbore structure schematic diagram of the second opening well completion operation in the salt cavern energy storage well without injection and production string completion method of the present application.

[0047] Figure 3 : It is the wellbore structure schematic diagram of the third opening well completion operation in the salt cavern energy storage well without injection and production string completion method of the present application.

[0048] Figure 4 : It is the setting position schematic diagram of the centralizer in the salt cavern energy storage well without injection and production string completion method of the present application.

[0049] Figure 5 : It is the structure schematic diagram of the centralizer in the salt cavern energy storage well without injection and production string completion method of the present application.

[0050] Figure 6 : It is the top view of the centralizer in the salt cavern energy storage well without injection and production string completion method of the present application.

[0051] Figure 7 : It is Figure 5 : It is the local enlarged view of position A.

[0052] Figure 8: The buckle structure in the centralizer of the application is in the locked state.

[0053] Figure 9 : The buckle structure in the centralizer of the application is in the unlocked state.

[0054] The reference signs in the application are as follows:

[0055] 1, shaped cement annular wall; 2, cementing casing;

[0056] 3, centralizer; 301, casing clamping part;

[0057] 3011, accommodating groove; 30111, retreat stop step;

[0058] 3012, limiting groove; 302, spring piece;

[0059] 303, toothed plate; 3031, protruding tooth;

[0060] 3032, outer extension plate; 30321, retreat stop boss;

[0061] 3033, limiting boss; 304, buckle structure;

[0062] 305, sealing ring; 4, surface casing;

[0063] 5, technical casing; 6, soil surface layer;

[0064] 7, soil water and gas bearing layer. DETAILED DESCRIPTION

[0065] In order to have a clearer understanding of the technical features, objects and effects of the application, the specific embodiments of the application will be described with reference to the drawings.

[0066] As shown in Figure 1 , the application provides a salt cavern energy storage well without injection and production pipe column completion method, which is used for multi-opening completion operation, and the method comprises the following steps:

[0067] Step S1: when performing the last opening completion operation, an initial cement annular wall is arranged along the well wall in the wellbore;

[0068] Step S2: after the last opening drilling, a plurality of cementing casings 2 are sequentially lowered into the wellbore to a preset depth along the initial cement annular wall;

[0069] Step S3: cement slurry is injected into the annulus between the cementing casing 2 and the initial cement annular wall in the wellbore, and cementing operation is performed;

[0070] Step S4: After the cementing operation is completed, all the cementing casings 2 are pulled out one by one, so that the initial cement sheath well wall forms the smooth and solid shaped cement sheath well wall 1.

[0071] In the present application, the cement sheath is arranged on the well wall of the wellbore to form the initial cement sheath well wall when the last drilling round completion operation is performed, and then a plurality of cementing casings 2 are sequentially lowered into the wellbore to a preset depth in the wellbore after the last drilling round is completed. Then, the cementing operation is performed by injecting cement slurry into the annulus between the cementing casing 2 and the initial cement sheath well wall. After all the cementing casings 2 are pulled out one by one, the cement slurry is supplemented to the annulus and forms the smooth and solid shaped cement sheath well wall 1 on the basis of the initial cement sheath well wall, thereby achieving the purpose of cementing. During the entire completion operation of the last drilling round, the cement sheath is used for the completion operation, and after the cementing casings 2 are finally pulled out, the shaped cement sheath well wall 1 serves as the wellbore wall. During the construction and operation of the salt cavern, the fluid flowing through the wellbore directly contacts the shaped cement sheath well wall 1, thereby avoiding direct contact with the cementing casing. At the same time, the casing damage caused by corrosion, hydrogen embrittlement and other factors that are prone to occur when the cementing casing is used is avoided, the integrity of the wellbore is effectively protected, and the strength of the wellbore and the long-term and stable operation of the salt cavern are ensured.

[0072] In an optional embodiment of the present application, before the last drilling round completion operation is performed (i.e., before step S1 is performed), the completion operations of other drilling rounds can be performed according to the wellbore structure in a conventional manner (using the existing cementing process and cement slurry system), and the cementing cement slurry needs to be returned to the ground. Only when the last drilling round completion operation is performed, the shaped cement sheath well wall 1 is established to play a role in preventing corrosion of the well wall.

[0073] In an optional embodiment of the present application, before the plurality of cementing casings 2 are sequentially lowered into the wellbore to a preset depth along the initial cement sheath well wall (i.e., after the last drilling round is completed and before the cementing casing 2 is lowered), a lubricating layer is arranged on the outer wall of each cementing casing 2 that needs to be lowered. The lubricating layer is used to reduce the frictional resistance between the cementing casing 2 and the cement sheath, thereby facilitating the easy pulling out of the cementing casing 2.

[0074] Further, the lubricating layer can be formed by spraying a lubricating release agent on the outer wall of the cementing casing 2. The lubricating release agent is formed by mixing a concrete release agent and a lubricant. The concrete release agent and the lubricant are only mixed, and no chemical reaction occurs between them, so as to increase the lubricating function. After the shaped cement sheath well wall 1 is solidified, the cementing casing 2 can be smoothly pulled out. On the premise that the cementing casing 2 and the shaped cement sheath well wall 1 are not cemented, the frictional resistance between the outer wall of the cementing casing 2 and the shaped cement sheath well wall 1 during the pulling out of the cementing casing 2 is further reduced.

[0075] In an alternative embodiment of the present application, before sequentially running the plurality of cementing casings 2 into the wellbore and along the initial cement sheath well wall to a predetermined depth in the wellbore (i.e. before step S2), a centralizer 3 with a lifting self-unlocking function is arranged on the cementing casing 2, as shown in Figure 4 The centralizer 3 is used to ensure that the cementing casing 2 is located at the central position of the wellbore (i.e. the cementing casing 2 is coaxial with the wellbore) after the cementing casing 2 is run into the wellbore, thereby achieving a more uniform thickness of the formed cement sheath at each position in the circumferential direction. After the formed cement sheath well wall 1 solidifies, during the process of lifting the cementing casing 2, the centralizer 3 and the cementing casing 2 are automatically unlocked under the action of the lifting tension on the cementing casing 2, so that the cementing casing 2 can be smoothly lifted out, and the centralizer 3 remains in the formed cement sheath well wall 1.

[0076] Further, at least one of the three sequentially connected cementing casings 2 is provided with a centralizer 3 to ensure that the plurality of cementing casings 2 sequentially run into the wellbore are located at the central position in the wellbore.

[0077] In this embodiment, as shown in Figures 5 to 9 The centralizer 3 includes at least two annular casing clamping members 301 and a plurality of long strip-shaped spring pieces 302, the plurality of spring pieces 302 are spaced and uniformly arranged along the circumferential direction of the casing clamping members 301, and one end of each spring piece 302 is connected to one casing clamping member 301, and the other end of each spring piece 302 is connected to the other casing clamping member 301; a plurality of toothed plates 303 are uniformly arranged on the inner wall of the casing clamping member 301 along the circumferential direction thereof, the toothed plates 303 have a plurality of arrayed protruding teeth 3031 on the plate surface facing the axis direction of the centralizer 3, the shape and size of the casing clamping member 301 are adapted to the cementing casing 2, so that the casing clamping member 301 can be sleeved on the outside of the cementing casing 2, and the end of the protruding teeth 3031 on the toothed plate 303 can abut against the outer wall of the cementing casing 2, and the cementing casing 2 is in a centralizing state, by applying pressure into the wellbore, the two casing clamping members 301 are moved towards each other to press the spring pieces 302 to bend away from the axis direction of the centralizer 3, so that at least the middle part of the spring pieces 302 abut against the inner wall of the wellbore, thereby clamping and centralizing the cementing casing 2 at the central position in the wellbore. In another alternative embodiment, the existing spring centralizer can also be directly used to manufacture the centralizer 3, and the toothed plates 303 are arranged at both ends of the spring centralizer for improvement, which can meet the construction requirements.

[0078] Specifically, as shown in Figures 5 to 9As shown, the sleeve clamping piece 301 is provided with a buckle structure 304 for automatically releasing the locking of the tooth plate 303 to the cementing casing 2 when the cementing casing 2 is lifted up. The buckle structure 304 comprises a containing groove 3011 on the inner wall of the sleeve clamping piece 301 and an extension plate 3032 on the top of the tooth plate 303. The bottom of the containing groove 3011 is open, and a reverse hook-shaped retreat-stop step 30111 is formed at the opening. The extension plate 3032 has a retreat-stop boss 30321. The lower part of the retreat-stop step 30111 has a first guide surface inclined from bottom to top away from the axis of the centralizer 3, and the upper part of the retreat-stop boss 30321 has a second guide surface inclined from bottom to top away from the axis of the centralizer 3. Figure 7 As shown, when the well completion operation is performed, the retreat-stop boss 30321 is below the retreat-stop step 30111, the end of the protruding tooth 3031 abuts against the outer wall of the cementing casing 2, and the buckle structure 304 is in the locked state. Figure 8 As shown, when the cementing casing 2 is lifted up, the tooth plate 303 moves up with the cementing casing 2, the first guide surface and the second guide surface are in contact and guide the retreat-stop boss 30321 to enter the containing groove 3011 from the bottom opening of the containing groove 3011, the end of the protruding tooth 3031 is separated from the outer wall of the cementing casing 2, and the buckle structure 304 is in the unlocked state.

[0079] Further, as shown, Figure 9 As shown, when the buckle structure 304 is in the unlocked state, the bottom of the retreat-stop boss 30321 abuts against the top of the retreat-stop step 30111, so that the tooth plate 303 remains stationary when the cementing casing 2 is lifted up, and the tooth plate 303 neither continues to move up with the cementing casing 2 nor retreats.

[0080] Further, as shown, Figures 7 to 9 As shown, the buckle structure 304 further comprises a limiting groove 3012 on the inner wall of the sleeve clamping piece 301 and a limiting boss 3033 on the plate surface of the tooth plate 303 facing away from the axis of the centralizer 3. Figure 7 As shown, when the well completion operation is performed, the limiting boss 3033 is below the limiting groove 3012, and the limiting boss 3033 abuts against the inner wall of the sleeve clamping piece 301 below the limiting groove 3012, so that the end of the protruding tooth 3031 abuts against the outer wall of the cementing casing 2. Figure 8 As shown, when the cementing casing 2 is lifted up, the limiting boss 3033 moves up with the tooth plate 303 and enters the limiting groove 3012, the top of the limiting boss 3033 abuts against the top inner wall of the limiting groove 3012, so as to position the tooth plate 303 when the cementing casing 2 is lifted up.

[0081] Further, as shown, Figures 7 to 9As shown, the number of limiting bosses 3033 is two, one limiting boss 3033 is located on the top of the plate surface of the tooth plate 303 away from the axis direction of the centralizer 3, and the other limiting boss 3033 is located on the bottom of the plate surface of the tooth plate 303 away from the axis direction of the centralizer 3, and the limiting groove 3012 is corresponding to the two limiting bosses 3033, thereby ensuring the stable positioning effect of the tooth plate 303 as a whole.

[0082] Further, the number of buckle structures 304 is multiple, and the multiple buckle structures 304 are arranged along the circumference of the sleeve clamping piece 301 and are uniformly arranged.

[0083] Further, as shown, Figures 7 to 9 As shown, the inner wall of the sleeve clamping piece 301 is provided with a sealing ring 305 along the circumference thereof, the sealing ring 305 is tightly combined with the outer wall of the cementing sleeve 2, so that the cement slurry cannot enter the matching connection position between the tooth plate 303 and the sleeve clamping piece 301 during the cement slurry injection process, thereby ensuring that the mud slurry does not affect the self-unlocking function of the centralizer 3. The sealing ring 305 can be made of soft rubber material, but is not limited to this. The sealing ring 305 has a relatively thin thickness, so that the sealing ring 305 will be cut off and damaged during the lifting of the cementing sleeve 2, but it does not affect the normal lifting of the cementing sleeve 2.

[0084] In an optional embodiment of the present application, the cement slurry injected into the annulus between the wellbore and the initial cement sheath well wall (i.e., in step S3) can be a corrosion-resistant cement slurry. The corrosion-resistant cement slurry refers to a cement slurry system that can maintain the strength of the cement sheath under the long-term corrosion of CO2 and / or H2 after the cement slurry is solidified. After the cementing sleeve 2 is lifted, the inner wall of the entire wellbore becomes the contact surface of the formed cement sheath well wall 1 and the environment gas, and the amount of gas permeated into the formed cement sheath well wall 1 will be much higher than that in the conventional casing cementing scheme. Therefore, a corrosion-resistant cement slurry is needed to ensure that the formed cement sheath well wall 1 will not be corroded in the long-term use state. The corrosion-resistant cement slurry can use the existing corrosion-resistant cement slurry, of course, a corresponding corrosion inhibitor can also be added according to the environment gas to achieve the corresponding corrosion prevention effect. The type and dosage of the added corrosion inhibitor can be adjusted according to the actual environment gas, which is not limited here.

[0085] In the present application, the size of the wellbore (or wellbore) and the size of the cementing sleeve 2 can be designed according to the well structure and the strength of the cement sheath. Since the inner side of the formed cement sheath well wall 1 is not supported by the cementing sleeve 2 after the last drilling completion, the thickness of the formed cement sheath well wall 1 should be appropriately increased according to the strength of the formed cement sheath well wall 1. When the hole diameter of the last drilling and the cementing sleeve 2 are preset, the thickness of the formed cement sheath well wall 1 should be ensured to be 1.5 inches to 2.0 inches.

[0086] In an alternative embodiment of the present application, as shown in Figure 2 When the well completion operation is two-run completion (i.e. the well structure is designed as two-run), the one-run completion operation is performed before the last-run completion operation. To ensure the stability of the well wall in the soft soil layer section of the soil surface 6 and the stable installation of the wellhead device, a large-size drill bit is used to drill down below the soil surface 6 and the surface casing 4 is lowered during the one-run completion operation. After the cementing operation is completed, the surface casing 4 remains in the wellbore without being pulled out, and the surface casing 4 is located at the outer periphery of the formed cement sheath well wall 1. The cement slurry injected during the two-run cementing operation needs to be returned to the ground to protect the surface casing 4 from contacting the ambient gas. After the cement slurry solidifies, the cementing casing 2 is pulled out and the formed cement sheath well wall 1 without injection-production string is formed.

[0087] In another alternative embodiment of the present application, as shown in Figure 3 When the well completion operation is three-run completion (i.e. the well structure is designed as three-run), the one-run completion operation and the two-run completion operation are sequentially performed before the last-run completion operation. During the one-run completion operation, a large-size drill bit is used to drill down below the soil surface 6 and the surface casing 4 is lowered. During the two-run completion operation, the technical casing 5 is lowered by drilling down below the soil layer 7 containing water and gas. After the cementing operation is completed, the surface casing 4 and the technical casing 5 remain in the wellbore without being pulled out, and the surface casing 4 is located at the outer periphery of the technical casing 5, and the technical casing 5 is located at the outer periphery of the formed cement sheath well wall 1. On the basis of leaving sufficient space for the formation of the cement sheath well wall 1, the cement sheath of the three-run completion is ensured not to be eroded by water and gas in the formation. The cement slurry during the three-run cementing operation needs to be returned to the ground to protect the technical casing 5 from contacting the gas.

[0088] The following is a specific embodiment provided by the present application:

[0089] The depth of the salt rock layer is 1000m, the depth of the three-opening well is designed to be 1050m, wherein the high-pressure water-bearing layer is at 700m-750m, so the three-opening well structure can be used; the 17.5-inch drill bit is used in the first opening to drill to the formation depth of 70m, the surface casing pipe 4 with a diameter of 16 inches is lowered to cement the well, and the cement slurry needs to be returned to the ground; the 15-inch drill bit is used in the second opening to drill to the formation depth of 800m, the technical casing pipe 5 with a diameter of 13.5 inches is lowered to cement the well and isolate the high-pressure water-bearing layer, and the cement slurry needs to be returned to the ground; the 12.25-inch drill bit is used in the third opening to drill to the formation depth of 1050m, the cementing casing pipe 2 with a diameter of 8.625 inches is used in the third opening to build the initial cement ring well wall (thickened cement ring), the lubricating release agent is uniformly sprayed on the outer wall of each cementing casing pipe 2 before the cementing casing pipe 2 is lowered, and one of every three connected cementing casing pipes 2 is provided with a centralizer 3 with the function of lifting the cementing casing pipe 2 to be unlocked. After the cementing casing pipe 2 is lowered to the preset depth in the wellbore, the prefabricated anticorrosive cement slurry is injected into the annulus in the well, and then the cement slurry is allowed to solidify; after the anticorrosive cement slurry is solidified, the cementing casing pipe 2 is lifted out, the cementing casing pipe 2 is not cemented with the cement slurry under the action of the lubricating release agent, and the lifting force makes the centralizer 3 complete the unlocking. After the cementing casing pipe 2 is completely lifted out, the centralizer 3 remains in the cement ring, and the initial cement ring well wall forms the formed cement ring well wall 1 with smooth and strong wall surface.

[0090] The salt cavern energy storage well completion method without injection and production pipe column has the characteristics and advantages that:

[0091] The salt cavern energy storage well completion method without injection and production pipe column can effectively solve the problem of corrosion of the casing pipe by brine during the construction of the salt cavern storage, and can solve the problem of corrosion of the casing pipe by environmental gas under high pressure after the construction of the storage, thereby preventing casing damage, providing a new completion method for the construction of the salt cavern, and providing important technical support for the long-term stable operation of the salt cavern.

[0092] The above merely illustrates the specific embodiments of the present application, and is not used to limit the scope of the present application. Any equivalent changes and modifications made by any person skilled in the art without departing from the concept and principle of the present application shall fall within the scope of protection of the present application.

Claims

1. A method for completing salt cavern energy storage wells without injection and production tubing, used for multiple well completion operations, characterized in that, The method comprises the following steps: arranging an initial cement sheath along the well wall in the wellbore when performing the last drilling operation; sequentially lowering a plurality of cementing casings into the wellbore to a preset depth along the initial cement sheath after the last drilling operation; injecting cement slurry into the annulus between the cementing casings and the initial cement sheath to perform cementing operation; after the cementing operation is completed, lifting the cementing casings one by one to form a smooth and strong shaped cement sheath along the initial cement sheath.

2. The salt cavern energy storage well no-flow string completion method of claim 1, wherein, Before the step of sequentially lowering a plurality of cementing casings into the wellbore to a preset depth, a lubricating layer is arranged on the outer wall of each cementing casing to reduce frictional resistance.

3. The salt cavern energy storage well no-flow string completion method of claim 2, wherein, The lubricating layer is formed by spraying a lubricating release agent formed by mixing a concrete release agent and a lubricant on the outer wall of the cementing casing.

4. The salt cavern energy storage well no-flow string completion method of claim 1, wherein, Before the step of sequentially lowering a plurality of cementing casings into the wellbore to a preset depth, a centralizer with a lifting self-unlocking function is arranged on the cementing casing to center the cementing casing in the wellbore.

5. The salt cavern energy storage well no-flow string completion method of claim 4, wherein, At least one of the three sequentially connected cementing casings is provided with the centralizer.

6. The salt cavern energy storage well no-flow string completion method of claims 4 or 5, wherein, The centralizer comprises at least two annular casing clamping members and a plurality of spring sheets, the spring sheets are arranged in a circumferential direction of the casing clamping members, and the two ends of the spring sheets are connected to the two casing clamping members, respectively. The inner wall of the casing clamping member is provided with a plurality of tooth plates in the circumferential direction, the tooth plates are provided with a plurality of teeth arranged in an array on the plate surface facing the axis direction of the centralizer, the casing clamping member is arranged outside the cementing casing, and the end of the tooth is in abutment with the outer wall of the cementing casing.

7. The salt cavern energy storage well no-flow string completion method of claim 6, wherein, When the cementing casing is in the centralizing state, the two casing clamping members move towards each other to press the spring sheets to bend away from the axis direction of the centralizer, and at least the middle outer wall of the spring sheet is in abutment with the inner wall of the wellbore.

8. The salt cavern energy storage well no-flow string completion method of claim 6, wherein, The casing clamping member is provided with a buckle structure that automatically releases the locking of the tooth plate to the cementing casing when the cementing casing is lifted. The buckle structure comprises a receiving groove on the inner wall of the casing clamping member and an extension plate on the top of the tooth plate, the bottom of the receiving groove is open, and a reverse hook-shaped stop step is formed at the opening, the extension plate is provided with a reverse stop boss, the lower part of the stop step is provided with a first guide surface inclined away from the axis direction of the centralizer from bottom to top, and the upper part of the reverse stop boss is provided with a second guide surface inclined away from the axis direction of the centralizer from bottom to top. When the cementing operation is performed, the reverse stop boss is below the stop step, the end of the tooth is in abutment with the outer wall of the cementing casing, and the buckle structure is in a locked state. When the cementing casing is lifted out of the wellbore, the tooth plate moves upward with the cementing casing, the first guide surface and the second guide surface are in close contact, the stop boss is guided to enter the accommodation groove from the bottom opening of the accommodation groove, the end of the tooth is separated from the outer wall of the cementing casing, and the buckle structure is in the unlocked state.

9. The salt cavern energy storage well no-flow string completion method of claim 8, wherein, When the buckle structure is in the unlocked state, the bottom of the stop boss is in abutment with the top of the stop step.

10. The salt cavern energy storage well no-flow string completion method of claim 8, wherein, The buckle structure further comprises a limiting groove on the inner wall of the casing clamp and a limiting boss on the plate surface of the tooth plate opposite to the axis direction of the centralizer; When the well completion operation is completed, the limiting boss is below the limiting groove, and the limiting boss is in abutment with the inner wall of the casing clamp below the limiting groove, so that the end of the tooth is in abutment with the outer wall of the cementing casing; When the cementing casing is lifted out of the wellbore, the limiting boss moves upward with the tooth plate and enters the limiting groove, and the top of the limiting boss is in abutment with the inner wall of the top of the limiting groove.

11. The salt cavern energy storage well no-flow string completion method of claim 10, wherein, The number of the limiting boss is two, and the two limiting bosses are respectively located at the top and bottom of the plate surface of the tooth plate opposite to the axis direction of the centralizer, and the limiting groove is two corresponding to the limiting boss.

12. The salt cavern energy storage well no-flow string completion method of claim 8, wherein, The number of the buckle structure is multiple, and the multiple buckle structures are arranged along the circumference of the casing clamp.

13. The salt cavern energy storage well no-flow string completion method of claim 6, wherein, A sealing ring is arranged on the inner wall of the casing clamp along the circumference thereof, and the sealing ring is in close contact with the outer wall of the cementing casing.

14. The salt cavern energy storage well no-flow string completion method of claim 1, wherein, The well completion operation is two-opening completion, and before the last opening completion operation is performed, a one-opening completion operation is performed. During the one-opening completion operation, drilling is performed downwardly below the soil surface layer, and a surface casing is lowered.

15. The salt cavern energy storage well no-flow string completion method of claim 14, wherein, After the cementing operation is completed, the surface casing is retained in the wellbore, and the surface casing is located at the outer periphery of the formed cement ring well wall.

16. The salt cavern energy storage well no-flow string completion method of claim 1, wherein, The well completion operation is three-opening completion, and before the last opening completion operation is performed, a one-opening completion operation and a two-opening completion operation are sequentially performed. During the one-opening completion operation, drilling is performed downwardly below the soil surface layer, and a surface casing is lowered. During the two-opening completion operation, drilling is performed downwardly below the soil water and gas layer, and a technical casing is lowered.

17. The salt cavern energy storage well no-flow string completion method of claim 16, wherein, After the cementing operation is completed, the surface casing and the technical casing are retained in the wellbore, and the surface casing is located at the outer periphery of the technical casing, and the technical casing is located at the outer periphery of the formed cement ring well wall.

18. The salt cavern energy storage well no-flow string completion method of claim 1, wherein, The thickness of the formed cement ring well wall is 1.5 inches to 2.0 inches.

19. The salt cavern energy storage well no-flow string completion method of claim 1, wherein, The cement slurry is injected into the annulus between the wellbore and the initial cement ring well wall, and the cement slurry is anticorrosive cement slurry.

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