Old well shaft reconstruction cement sheath simulation device and simulation method

Abstract

The invention provides an old well shaft reconstruction cement sheath simulation device and simulation method, and relates to the technical field of cement sheath integrity detection. The old well shaft reconstruction cement sheath simulation method comprises the following steps: constructing a shaft stratum model; obtaining a pre-reconstruction strength parameter of the old well shaft model before shaft reconstruction; the inner side of the sleeve is filled with an expansion liner tube; secondary perforation is formed, so that an old well shaft model after shaft reconstruction is formed; and obtaining a reconstructed strength parameter of the old well shaft model after shaft reconstruction. According to the old well shaft reconstruction cement sheath simulation method provided by the embodiment of the invention, the strength parameters of the shaft model before and after reconstruction can be tested so as to evaluate the influence of shaft reconstruction on the integrity of the cement sheath.

Description

Technical Field

[0001] This application relates to the technical field of cement sheath integrity detection, and particularly to a simulation device and method for the reconstructed cement sheath of an old wellbore Background Art

[0002] With the long-term development of oil and gas fields, the integrity of old wellbores may deteriorate due to various reasons, such as wellbore deformation, casing corrosion, and cement sheath seal failure, which pose a serious threat to the safe production and productivity improvement of oil and gas wells. In order to restore and improve the integrity of old wellbores, it is necessary to reconstruct old wellbores, such as expanding tube wellbore reconstruction.

[0003] The expanding tube wellbore reconstruction technology involves lowering an expandable liner into the wellbore and expanding it to its maximum diameter. The expanded liner can be tightly attached to the inner wall of the original casing to seal the original perforations; then, through secondary perforation operations, new perforations are formed in the expanded liner, casing, and cement sheath to increase the seepage channels for oil and gas. This process can reconstruct the sealing performance and pressure-bearing capacity of the wellbore, improve the oil and gas recovery efficiency, and extend the service life of old wells. However, the dynamic impact load generated by secondary perforation operations will cause certain damage to the cement sheath. In order to ensure the reliability of old wellbore reconstruction, it is necessary to evaluate the impact of wellbore reconstruction on the integrity of the cement sheath.

[0004] The existing technology has simulated the damage of the cement sheath under the action of perforation dynamic impact load through live perforation shooting tests and combined with a jet flow morphology simulation model. However, the above research mainly focuses on new wells and lacks the test of the cementing strength of the cementing interface after the reconstruction of old wellbores, which is not conducive to evaluating the impact of wellbore reconstruction on the integrity of the cement sheath. Summary of the Invention

[0005] The embodiments of this application provide a simulation device and method for the reconstructed cement sheath of an old wellbore, which can test the strength parameters before and after the reconstruction of the old wellbore to evaluate the impact of wellbore reconstruction on the integrity of the cement sheath.

[0006] In a first aspect, this application provides a simulation method for the reconstructed cement sheath of an old wellbore, including:

[0007] Constructing a wellbore formation model; the wellbore formation model includes a formation model and an old wellbore model before wellbore reconstruction, which are stacked in sequence from the outside to the inside;

[0008] The old wellbore model before wellbore reconstruction includes a cement sheath and a casing. The outer surface of the cement sheath contacts the formation model, the inner surface of the cement sheath contacts the casing, and the wellbore formation model is also provided with initial perforations that penetrate the cement sheath and the casing;

[0009] Obtain the pre - reconstruction strength parameters of the old wellbore model before the reconstruction of the wellbore, where the pre - reconstruction strength parameters include the pre - reconstruction cementing strength and the pre - reconstruction anti - channeling strength;

[0010] Fill an expandable liner inside the casing;

[0011] Form secondary perforations to form the old wellbore model after the reconstruction of the wellbore; the secondary perforations penetrate through the cement sheath, the casing, and the expandable liner;

[0012] Obtain the post - reconstruction strength parameters of the old wellbore model after the reconstruction of the wellbore, where the post - reconstruction strength parameters include the post - reconstruction cementing strength and the post - reconstruction anti - channeling strength.

[0013] As an optional implementation manner, obtaining the pre - reconstruction cementing strength includes:

[0014] Obtain the first cementing strength between the cement sheath and the casing;

[0015] Obtain the second cementing strength between the cement sheath and the formation model;

[0016] Obtaining the post - reconstruction cementing strength includes:

[0017] Obtain the third cementing strength between the cement sheath and the casing;

[0018] Obtain the fourth cementing strength between the cement sheath and the formation model.

[0019] As an optional implementation manner, obtaining the first cementing strength between the cement sheath and the casing includes:

[0020] Inject detection water into the space between the cement sheath and the casing from the top of the wellbore model at the injection pressure;

[0021] Obtain the current pressure between the bottom of the cement sheath and the casing;

[0022] Gradually increase the injection pressure;

[0023] If the pressure difference between the injection pressure and the current pressure starts to be equal to 0, obtain the first cementing strength according to the injection pressure;

[0024] Obtaining the third cementing strength between the cement sheath and the casing includes:

[0025] Inject detection water into the space between the cement sheath and the casing from the top of the wellbore model at the injection pressure;

[0026] Obtain the current pressure between the bottom of the cement sheath and the casing;

[0027] Gradually increase the water injection pressure;

[0028] If the pressure difference between the water injection pressure and the current pressure starts to be equal to 0, obtain the third cementing strength according to the water injection pressure.

[0029] As an alternative implementation, obtaining the second cementing strength between the cement sheath and the formation model includes:

[0030] Inject inspection water into the space between the cement sheath and the formation model from the top of the wellbore model at the water injection pressure;

[0031] Obtain the current pressure between the bottom end of the cement sheath and the formation model;

[0032] Gradually increase the water injection pressure;

[0033] If the pressure difference between the water injection pressure and the current pressure starts to be equal to 0, obtain the second cementing strength according to the water injection pressure;

[0034] Obtaining the fourth cementing strength between the cement sheath and the formation model includes:

[0035] Inject inspection water into the space between the cement sheath and the formation model from the top of the wellbore model at the water injection pressure;

[0036] Obtain the current pressure between the bottom end of the cement sheath and the formation model;

[0037] Gradually increase the water injection pressure;

[0038] If the pressure difference between the water injection pressure and the current pressure starts to be equal to 0, obtain the fourth cementing strength according to the water injection pressure.

[0039] As an alternative implementation, obtaining the anti-channeling strength before reconstruction includes:

[0040] Inject inspection water into the inner side of the casing from the top of the wellbore model at the water injection pressure;

[0041] Obtain the current pressure between the cement sheath and the casing, and obtain the current pressure between the cement sheath and the formation model;

[0042] Gradually increase the water injection pressure;

[0043] If the pressure difference between the water injection pressure and at least one of the current pressures starts to be equal to 0, obtain the anti-channeling strength before reconstruction according to the water injection pressure.

[0044] As an alternative implementation, obtaining the anti-channeling strength after reconstruction includes:

[0045] Inject detection water into the inside of the expansion liner from the top end of the wellbore model at an injection pressure;

[0046] Obtain the current pressure between the cement sheath and the casing, and obtain the current pressure between the cement sheath and the formation model;

[0047] Gradually increase the injection pressure;

[0048] If the pressure difference between the injection pressure and at least one of the current pressures starts to be equal to 0, obtain the reconstructed anti-channeling strength based on the injection pressure.

[0049] As an alternative implementation, a fluorescent tracer is provided in the detection water; the method further includes:

[0050] When the pressure difference between the injection pressure and the current pressure is equal to 0, obtain the flow path of the detection water between the top end and the bottom end of the wellbore model according to the fluorescent tracer.

[0051] As an alternative implementation, when forming the secondary perforations, the secondary perforations are not communicated with the initial perforations.

[0052] In a second aspect, the present application provides a simulation device for reconstructing a cement sheath in an old wellbore, including a main body, a first end cover and a second end cover;

[0053] The first end cover is arranged at the first end of the main body, the second end cover is arranged at the second end of the main body, the first end cover and the second end cover are arranged opposite to each other, and at least a wellbore formation model is constructed between the first end cover and the second end cover.

[0054] As an alternative implementation, the first end cover is provided with a water inlet, and the water inlet is at least used to inject detection water into the top end of the wellbore formation model;

[0055] The second end cover is provided with a drain port, and the drain port is at least used to drain the detection water from the bottom end of the wellbore.

[0056] The simulation device and method for the reconstructed cement sheath of an old wellbore provided by the embodiments of the present application. Among them, the simulation method for the reconstructed cement sheath of an old wellbore can respectively obtain the corresponding strength parameters of the old wellbore model before and after reconstruction by constructing the old wellbore model before wellbore reconstruction and the old wellbore model after wellbore reconstruction. It can not only measure the cementing strength of the cementing surface of the old well with an expansion liner under the condition of secondary perforation, but also measure the anti-channeling strength of the cement sheath at the perforation holes, which is convenient for quantifying the influence of wellbore reconstruction on the structure of the old wellbore, so as to systematically evaluate the influence of old wellbore reconstruction on the integrity of the cement sheath, especially the cementing strength of the cementing surface. This method helps to provide important theoretical basis and technical support for optimizing wellbore reconstruction technology, improving the service life and safety of old wells. The simulation device for the reconstructed cement sheath of an old wellbore can simulate the on-site working conditions to lower the expansion liner and carry out secondary perforation operations, thereby simulating the influence of the old wellbore reconstruction process on the integrity of the cement sheath, and making up for the deficiency that the existing testing devices for the integrity of the cement sheath do not consider the wellbore reconstruction process. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] The accompanying drawings herein are incorporated into the specification and form a part of the specification, showing embodiments consistent with the present application, and are used together with the specification to explain the principles of the present application.

[0058] Figure 1 It is a schematic structural diagram of the formation model and the old wellbore model before wellbore reconstruction in the simulation device for the reconstructed cement sheath of an old wellbore provided by the embodiments of the present application;

[0059] Figure 2 It is a schematic structural diagram of the formation model and the old wellbore model after wellbore reconstruction in the simulation device for the reconstructed cement sheath of an old wellbore provided by the embodiments of the present application;

[0060] Figure 3 It is a usage state diagram of the simulation device for the reconstructed cement sheath of an old wellbore provided by the embodiments of the present application;

[0061] Figure 4 It is a schematic structural diagram of the perforating gun in the simulation device for the reconstructed cement sheath of an old wellbore provided by the embodiments of the present application;

[0062] Figure 5 It is a schematic flow diagram of the simulation method for the reconstructed cement sheath of an old wellbore provided by the embodiments of the present application.

[0063] Description of the reference numerals:

[0064] 100 - Wellbore formation model; 101 - Initial perforation; 102 - Secondary perforation; 103 - First interface; 104 - Second interface; 105 - Casing pressure chamber; 110 - Formation model; 120 - Cement sheath; 130 - Casing; 140 - Expansion liner;

[0065] 201 - Confining pressure chamber; 210 - Main body; 220 - First end cap; 221 - Casing fluid inlet; 222 - Confining pressure chamber fluid inlet; 223 - First interface fluid inlet; 224 - Second interface fluid inlet; 230 - Second end cap; 231 - Casing fluid outlet; 232 - Confining pressure chamber fluid outlet; 233 - First interface fluid outlet; 234 - Second interface fluid outlet;

[0066] 301 - Casing flow pipeline; 302 - Casing inlet pressure gauge; 303 - Casing inlet control valve; 304 - Second hydraulic pump; 305 - Heater; 306 - Casing liquid storage tank; 307 - Casing outlet pressure gauge; 308 - Casing outlet control valve; 309 - Casing temperature sensor;

[0067] 401 - Confining pressure chamber inlet pipeline; 402 - Confining pressure chamber inlet pressure gauge; 403 - Confining pressure chamber inlet control valve; 404 - First hydraulic pump; 405 - Confining pressure chamber liquid storage tank; 406 - Confining pressure chamber outlet pipeline; 407 - Confining pressure chamber outlet pressure gauge; 408 - Confining pressure chamber outlet control valve; 409 - Confining pressure chamber waste liquid tank;

[0068] 501 - First interface inlet pipeline; 502 - First interface inlet pressure gauge; 503 - First interface inlet control valve; 504 - First interface outlet pipeline; 505 - First interface outlet pressure gauge; 506 - First interface outlet control valve; 507 - Second interface inlet pipeline; 508 - Second interface inlet pressure gauge; 509 - Second interface inlet control valve; 510 - Second interface outlet pipeline; 511 - Second interface outlet pressure gauge; 512 - Second interface outlet control valve; 513 - Third hydraulic pump; 514 - Interface liquid storage tank; 515 - Interface waste liquid tank;

[0069] 600 - Perforating gun; 610 - Gun head; 620 - Gun body; 630 - Gun tail; 640 - Perforating charge; 650 - Detonating cord; 660 - Initiator.

[0070] Through the above - mentioned drawings, specific embodiments of the present application have been shown, and there will be more detailed descriptions hereinafter. These drawings and textual descriptions are not intended to limit the scope of the concept of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. Detailed implementation manners

[0071] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the following will clearly and completely describe the technical solutions in the embodiments of this application with reference to the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are some, but not all, of the embodiments of this application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this application without creative efforts shall fall within the scope of protection of the embodiments of this application.

[0072] In the embodiments of this application, the orientation or positional relationships indicated by terms such as "upper", "lower", "inner", "middle", "outer", "front", and "back" are based on the orientation or positional relationships shown in the accompanying drawings. These terms are mainly used to better describe the embodiments of this application and their embodiments, and are not used to limit that the indicated devices, elements, or components must have a specific orientation, or be constructed and operated in a specific orientation. Also, in addition to being able to represent orientation or positional relationships, some of the above terms may also be used to represent other meanings. For example, the term "upper" may also be used to represent a certain attachment relationship or connection relationship in some cases. For those of ordinary skill in the art, the specific meanings of these terms in the embodiments of this application can be understood according to specific circumstances.

[0073] In addition, the terms "arrangement", "connection", and "fixation" should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or there can be internal communication between two devices, elements, or components. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of this disclosure can be understood according to specific circumstances.

[0074] In the description of the embodiments of this application, the terms "first", "second", "third", "fourth", etc. (if any) in the specification, claims, and the above accompanying drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of this application described here, for example, can be implemented in an order other than those illustrated or described here.

[0075] In the embodiments of this application, words such as "exemplarily" or "for example" are used to represent examples, illustrations, or explanations. Any embodiment or design solution described as "exemplarily" or "for example" in the embodiments of this application should not be construed as being more preferred or having more advantages than other embodiments or design solutions. Rather, using words such as "exemplarily" or "for example" is intended to present relevant concepts in a specific manner.

[0076] As can be seen from the background art, with the passage of time in oil and gas field development, the integrity of the wellbores of old wells may deteriorate due to various reasons, such as wellbore deformation, casing corrosion, and cement sheath seal failure. These deterioration phenomena increase the risk of wellbore barrier failure, leading to oil and gas leakage, which seriously affects the safe production and productivity improvement of oil and gas wells. Therefore, reconstructing the wellbores of old wells to restore or improve their integrity has gradually become an important means to increase production and reduce costs in oil and gas fields.

[0077] Reconstruction techniques such as expandable tubular wellbore reconstruction can effectively block the original perforations and rebuild the sealing and pressure-bearing capacity of the wellbore by lowering an expandable liner into the wellbore and expanding it to tightly adhere to the inner wall of the original casing. This technique can not only extend the service life of old wells but also improve the overall development efficiency of oil and gas fields.

[0078] After the original perforations are blocked, new perforations need to be formed in the expandable liner, casing, and cement sheath through secondary perforation operations to increase the seepage channels of oil and gas, thereby improving the oil and gas recovery efficiency. Secondary perforation operation is an important step in the reconstruction of old wellbores, which can establish new oil and gas channels and effectively extend the service life of old wells.

[0079] However, the dynamic impact load generated during the secondary perforation operation can damage the cement sheath. This damage may lead to crack propagation and strength degradation of the cement sheath, which in turn affects the safety and production of oil and gas wells. To ensure the reliability of old wellbore reconstruction, it is necessary to evaluate the impact of wellbore reconstruction on the integrity of the cement sheath.

[0080] The existing technology simulates the damage of the cement sheath under the action of perforation dynamic impact load through live firing perforation target tests and combined with jet flow morphology simulation models. However, the objects of the above research are mainly new wells, lacking the test of the cementing bond strength of the cementing interface after the reconstruction of old wellbores, which is not conducive to evaluating the impact of wellbore reconstruction on the integrity of the cement sheath.

[0081] In view of this, an embodiment of the present application provides a simulation device and method for reconstructing a cement sheath in an old wellbore. The simulation method for reconstructing the cement sheath in the old wellbore includes: constructing a wellbore formation model; the wellbore formation model includes a formation model and an old wellbore model before wellbore reconstruction, which are stacked in sequence from outside to inside; the old wellbore model before wellbore reconstruction includes a cement sheath and a casing, the outer surface of the cement sheath contacts the formation model, the inner surface of the cement sheath contacts the casing, and the wellbore model is also provided with initial perforations that penetrate the cement sheath and the casing; obtaining the pre-reconstruction strength parameters of the old wellbore model before wellbore reconstruction, the pre-reconstruction strength parameters including the pre-reconstruction cementing strength and the pre-reconstruction anti-channeling strength; filling an expandable liner inside the casing; forming secondary perforations to form the old wellbore model after wellbore reconstruction; the secondary perforations penetrate the cement sheath, the casing, and the expandable liner; obtaining the post-reconstruction strength parameters of the old wellbore model after wellbore reconstruction, the post-reconstruction strength parameters including the post-reconstruction cementing strength and the post-reconstruction anti-channeling strength.

[0082] The simulation method for reconstructing the cement sheath in the old wellbore provided by the embodiment of the present application can quantify the influence of wellbore reconstruction on the structure of the old wellbore by constructing the old wellbore model before wellbore reconstruction and the old wellbore model after wellbore reconstruction, and respectively obtaining the corresponding strength parameters of the old wellbore models before and after reconstruction, so as to systematically evaluate the influence of the old wellbore reconstruction process on the integrity of the cement sheath, especially the cementing strength of the cementing interface. This method helps to provide important theoretical basis and technical support for optimizing the wellbore reconstruction technology and improving the service life and safety of old wells.

[0083] The technical solutions of the present application will be described in detail below in conjunction with the accompanying drawings and specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments.

[0084] Combined Figures 1 to 3 As shown, on the one hand, an embodiment of the present application provides a simulation device for reconstructing a cement sheath in an old wellbore, including a reaction kettle, the reaction kettle includes a main body 210, a first end cover 220, and a second end cover 230; the first end cover 220 is arranged at the first end of the main body 210, the second end cover 230 is arranged at the second end of the main body 210, the first end cover 220 and the second end cover 230 are arranged opposite to each other, and at least the wellbore formation model 100 is constructed between the first end cover 220 and the second end cover 230.

[0085] Among them, the main body 210, the first end cover 220, and the second end cover 230 can enclose a closed cavity for accommodating the wellbore formation model 100. The wellbore formation model 100 can be centrally arranged in this closed cavity. There is a gap between the outer peripheral side of the wellbore formation model 100 and the inner wall of the main body 210. This gap forms a confining pressure cavity 201. By controlling the pressure in the confining pressure cavity 201, the actual working environment of the old wellbore can be simulated inside the reaction kettle.

[0086] Exemplarily, the main body 210 and the first end cap 220, and the main body 210 and the second end cap 230 can be fixedly connected by bolts to ensure the effectiveness and disassembly convenience of the connection.

[0087] In some embodiments, the first end cap 220 is provided with a water inlet for injecting detection water at least into the top of the wellbore formation model 100; the second end cap 230 is provided with a drain outlet for discharging the detection water from the bottom of the wellbore formation at least.

[0088] Through the water inlet, fluid pressure can be applied to the wellbore formation model 100 to simulate the fluid environment in the wellbore for pressure testing. The setting of the drain outlet allows the detection water to be discharged after passing through the wellbore formation model 100 to ensure the continuity of fluid circulation and pressure testing.

[0089] It should be noted that, as shown in Figure 1 the wellbore formation model 100 includes a formation model 110 and an old wellbore model before wellbore reconstruction, which are stacked in sequence from outside to inside; the old wellbore model before wellbore reconstruction includes a cement sheath 120 and a casing 130. The outer surface of the cement sheath 120 contacts the formation model 110, and the inner surface of the cement sheath 120 contacts the casing 130. The wellbore model is also provided with initial perforations 101 that penetrate through the cement sheath 120 and the casing 130.

[0090] Among them, in the old wellbore model before wellbore reconstruction, there is an annulus pressure chamber 105 inside the casing 130; a first interface 103 is formed between the outer surface of the cement sheath 120 and the formation model 110, and a second interface 104 is formed between the inner surface of the cement sheath 120 and the outer surface of the casing 130.

[0091] As shown in Figure 2 when wellbore reconstruction is carried out, an expandable liner 140 can be filled inside the casing 130 to make the expandable liner 140 expand and tightly adhere to the inner wall of the original casing 130; and secondary perforation 102 operations are carried out inside the expandable liner 140 to form an old wellbore model after wellbore reconstruction. Among them, the secondary perforations 102 formed by the secondary perforation 102 operations penetrate through the cement sheath 120, the casing 130, and the expandable liner 140.

[0092] In the old wellbore model after wellbore reconstruction, the cavity inside the expandable liner 140 is the annulus pressure chamber 105, a first interface 103 is formed between the outer surface of the cement sheath 120 and the formation model 110, and a second interface 104 is formed between the inner surface of the cement sheath 120 and the outer surface of the casing 130.

[0093] In some embodiments, the water inlet includes a casing flow inlet 221, an annulus pressure chamber flow inlet 222, a first interface flow inlet 223, and a second interface flow inlet 224. The drain outlet includes a casing flow outlet 231, an annulus pressure chamber flow outlet 232, a first interface flow outlet 233, and a second interface flow outlet 234.

[0094] Among them, the casing flow inlet 221 can communicate with the top end of the casing pressure chamber 105, and the casing flow outlet 231 can communicate with the bottom end of the casing pressure chamber 105.

[0095] The annulus pressure chamber flow inlet 222 can communicate with the top end of the annulus pressure chamber 201, and the annulus pressure chamber flow outlet 232 can communicate with the bottom end of the annulus pressure chamber 201.

[0096] The first interface flow inlet 223 can communicate with the top end of the first interface 103, and the first interface flow outlet 233 can communicate with the bottom end of the first interface 103.

[0097] The second interface flow inlet 224 can communicate with the top end of the second interface 104, and the second interface flow outlet 234 can communicate with the bottom end of the second interface 104.

[0098] It should be noted that when the wellbore formation model 100 is located inside the reaction kettle, the end of the wellbore formation model 100 facing the first end cap 220 is the top end of the wellbore formation model 100; the end of the wellbore formation model 110 facing the second end cap 230 is the bottom end of the wellbore formation model 100.

[0099] Specifically, the simulation device for reconstructing the cement sheath of the old wellbore provided by the embodiments of the present application provides a closed and controllable experimental environment through the combination of the main body 210 and the end caps, for simulating the actual working conditions of the old wellbore. Combining the settings of the water inlet and the drain outlet ensures the feasibility and continuity of the fluid pressure test, enabling researchers to evaluate the effectiveness and reliability of the wellbore reconstruction technology under laboratory conditions.

[0100] In some embodiments, the simulation device for reconstructing the cement sheath of the old wellbore further includes a casing temperature and pressure control component, which is used to control the pressure and temperature inside the casing 130.

[0101] The casing temperature and pressure control component includes a casing flow pipeline 301 and a casing temperature sensor 309. The first end of the casing flow pipeline 301 communicates with the casing flow inlet 221, and the second end of the casing flow pipeline 301 communicates with the casing flow outlet 231; the casing temperature sensor 309 is installed inside the casing pressure chamber 105 to detect the temperature inside the casing pressure chamber 105.

[0102] On the casing flow pipeline 301, a casing inflow pressure gauge 302, a casing inflow control valve 303, a second hydraulic pump 304, a heater 305, a casing liquid storage tank 306, a casing outflow control valve 308, and a casing outflow pressure gauge 307 are sequentially connected from the first end to the second end.

[0103] Among them, the casing inflow pressure gauge 302 and the casing inflow control valve 303 are arranged close to the casing inlet 221, and the casing outflow control valve 308 and the casing outflow pressure gauge 307 are arranged close to the casing outlet 231.

[0104] The casing flow pipeline 301 is used for transporting liquid; the casing liquid storage tank 306 is used for storing liquid.

[0105] The second hydraulic pump 304 is used for pressurizing the liquid injected into the casing pressure chamber 105.

[0106] Both the casing inflow pressure gauge 302 and the casing outflow pressure gauge 307 are used for monitoring pressure.

[0107] Both the casing inflow control valve 303 and the casing outflow control valve 308 are used for regulating the liquid flow.

[0108] The heater 305 is used for heating the liquid;

[0109] Among them, the liquid includes detection water and ordinary water.

[0110] In some embodiments, the simulation device for reconstructing the cement sheath of the old wellbore also includes a confining pressure control assembly, which is used for controlling the pressure in the confining pressure chamber 201.

[0111] The confining pressure control assembly includes a confining pressure chamber inflow pipeline 401 and a confining pressure chamber outflow pipeline 406.

[0112] The first end of the confining pressure chamber inflow pipeline 401 communicates with the confining pressure chamber inlet 222, and the second end of the confining pressure chamber inflow pipeline 401 is connected with a confining pressure chamber liquid storage tank 405. On the confining pressure chamber inflow pipeline 401, a confining pressure chamber inflow pressure gauge 402, a confining pressure chamber inflow control valve 403, and a first hydraulic pump 404 are also sequentially connected from the first end to the second end.

[0113] The first end of the confining pressure chamber outflow pipeline 406 communicates with the confining pressure chamber outlet 232, and the second end of the confining pressure chamber outflow pipeline 406 is connected with a confining pressure chamber waste liquid tank 409. On the confining pressure chamber outflow pipeline 406, a confining pressure chamber outflow pressure gauge 407 and a confining pressure chamber outflow control valve 408 are also sequentially connected from the first end to the second end.

[0114] Among them, the confining pressure chamber inflow pipeline 401 and the confining pressure chamber outflow pipeline 406 are used for transporting liquid.

[0115] The confining pressure chamber liquid storage tank 405 is used to store liquid, and the confining pressure chamber waste liquid tank 409 is used to store the liquid flowing out through the confining pressure chamber outlet 232.

[0116] The first hydraulic pump 404 is used to pressurize the liquid injected into the confining pressure chamber 201.

[0117] Both the confining pressure chamber inlet pressure gauge 402 and the confining pressure chamber outlet pressure gauge 407 are used to monitor the pressure.

[0118] Both the confining pressure chamber inlet control valve 403 and the confining pressure chamber outlet control valve 408 are used to regulate the liquid flow;

[0119] Among them, the liquid includes detection water and ordinary water.

[0120] In some embodiments, the simulation device for reconstructing the cement sheath of the old wellbore also includes an interface strength test component, and the interface strength test component is used to measure the bonding strength of the first interface 103 and the second interface 104.

[0121] The interface strength test component includes a first interface inlet pipe 501, a second interface inlet pipe 507, a first interface outlet pipe 504, and a second interface outlet pipe 510.

[0122] The first end of the first interface inlet pipe 501 is communicated with the first interface inlet 223, the first end of the second interface inlet pipe 507 is communicated with the second interface inlet 224, the second ends of both the first interface inlet pipe 501 and the second interface inlet pipe 507 are communicated with the interface liquid storage tank 514, and a third hydraulic pump 513 is connected between the second ends of the first interface inlet pipe 501 and the second interface inlet pipe 507 and the interface liquid storage tank 514.

[0123] The first interface inlet pipe 501 is also connected with a first interface inlet pressure gauge 502 and a first interface inlet control valve 503; the second interface inlet pipe 507 is also connected with a second interface inlet pressure gauge 508 and a second interface inlet control valve 509.

[0124] The first end of the first interface outlet pipe 504 is communicated with the first interface outlet 233, the first end of the second interface outlet pipe 510 is communicated with the second interface outlet 234, and the second ends of both the first interface outlet pipe 504 and the second interface outlet pipe 510 are communicated with the interface waste liquid tank 515.

[0125] The first interface outlet pipe 504 is also connected with a first interface outlet pressure gauge 505 and a first interface outlet control valve 506; the second interface outlet pipe 510 is connected with a second interface outlet pressure gauge 511 and a second interface outlet control valve 512.

[0126] Among them, the first interface inflow pipeline 501, the second interface inflow pipeline 507, the first interface outflow pipeline 504, and the second interface outflow pipeline 510 are used to transport liquids.

[0127] The interface liquid storage tank 514 is connected and used to store liquids, and the interface waste liquid tank 515 is used to store the liquids flowing out through the first interface outflow port 233 and the second interface outflow port 234.

[0128] The third hydraulic pump 513 is used to pressurize the liquids injected into the first interface 103 or the second interface 104.

[0129] The first interface inflow pressure gauge 502, the first interface outflow pressure gauge 505, the second interface inflow pressure gauge 508, and the second interface outflow pressure gauge are all used to monitor the pressure.

[0130] The first interface inflow control valve 503, the first interface outflow control valve 506, the second interface inflow control valve 509, and the second interface outflow control valve 512 are all used to regulate the liquid flow;

[0131] Among them, the liquids include detection water and ordinary water.

[0132] In some embodiments, the casing temperature and pressure control component, the confining pressure control component, and the interface strength test component can be respectively communicatively connected to a computer, so as to control the pipe temperature and pressure control component, the confining pressure control component, and the interface strength test component through the computer, improving the convenience and controllability of the test.

[0133] Figure 4 It is a schematic structural diagram of a perforating gun in the simulation device for reconstructing the cement sheath of an old wellbore provided by the embodiment of the present application. In some embodiments, the perforating gun 600 can be used for the secondary perforation 102 operation.

[0134] Combined Figure 4 As shown, the perforating gun 600 includes a gun head 610, a gun body 620, a gun tail 630, perforating charges 640, detonating cords 650, and detonators 660. The height of the gun tail 630 can be adjusted to adapt to the height of the wellbore formation model 100; the number, type, and charge amount of the perforating charges can be changed to adapt to the required secondary perforation 102 parameters.

[0135] Figure 5 It is a schematic flow diagram of the simulation method for reconstructing the cement sheath of an old wellbore provided by the embodiment of the present application. On the other hand, the embodiment of the present application provides a simulation method for reconstructing the cement sheath 120 of an old wellbore, using the simulation device for reconstructing the cement sheath of an old wellbore provided in any of the above embodiments, specifically including the following steps:

[0136] S101. Construct the wellbore formation model 100. The wellbore formation model 100 includes a formation model 110 and an old wellbore model before wellbore reconstruction, which are stacked in sequence from the outside to the inside.

[0137] The old wellbore model before wellbore reconstruction includes a cement sheath 120 and a casing 130. The outer surface of the cement sheath 120 contacts the formation model 110, and the inner surface of the cement sheath 120 contacts the casing 130. The wellbore formation model 100 is also provided with initial perforations 101, and the initial perforations 101 penetrate through the cement sheath 120 and the casing 130.

[0138] S102. Obtain the strength parameters before reconstruction of the old wellbore model before wellbore reconstruction. The strength parameters before reconstruction include the cementing strength before reconstruction and the anti-channeling strength before reconstruction.

[0139] S103. Fill an expandable liner 140 inside the casing 130.

[0140] S104. Form secondary perforations 102 to form the old wellbore model after wellbore reconstruction. The secondary perforations 102 penetrate through the cement sheath 120, the casing 130, and the expandable liner 140.

[0141] S105. Obtain the strength parameters after reconstruction of the old wellbore model after wellbore reconstruction. The strength parameters after reconstruction include the cementing strength after reconstruction and the anti-channeling strength after reconstruction.

[0142] Among them, the steps of constructing the wellbore formation model 100 are specifically as follows:

[0143] S1011. Prepare a formation model 110 with a wellbore.

[0144] S1012. Apply a mud cake on the outer wall of the casing 130 and the inner wall of the formation model 110 to simulate the old wellbore. Place the formation model 110 in the center of the main body 210 of the reactor, and then place the casing 130 in the center of the wellbore of the formation model 110. There is an annular cavity between the outer wall of the casing 130 and the inner wall of the wellbore.

[0145] S1013. Prepare the cement slurry used in the experiment.

[0146] S1014. Inject the cement slurry into the annular cavity between the casing 130 and the formation model 110 to form a cement sheath 120. Seal the main body 210 with a first end cap 220 and a second end cap 230, and install a casing temperature and pressure control component, a confining pressure control component, and an interface strength test component in sequence.

[0147] Among them, the cementing surface between the cement sheath 120 and the casing 130 is the first interface 103, and the cementing surface between the cement sheath 120 and the formation model 110 is the second interface 104.

[0148] S1015. Pressurize the casing pressure chamber 105, the confining pressure chamber 201, and the annular cavity between the formation model 110 and the casing 130 respectively;

[0149] S1016. After the pressure test, cure the cement sheath 120 according to the actual downhole temperature and pressure conditions of the old well;

[0150] S1017. Release the pressure;

[0151] S1018. Open the first end cap 220, assemble the perforating gun 600 according to the perforating parameters corresponding to the initial perforation 101 and center it in the casing pressure chamber 105, and perform perforating operations to form the initial perforation 101.

[0152] It should be noted that after performing step S102, repeat step S101 to construct a new wellbore formation model 100, and based on the new wellbore formation model 100, perform step S103, step S104, and step S105. That is, construct a new wellbore formation model 100, reconstruct the old wellbore model before wellbore reconstruction in the new wellbore formation model 100 to obtain the old wellbore model after wellbore reconstruction, and detect the strength parameters after reconstruction of the old wellbore model after wellbore reconstruction.

[0153] Among them, after filling the expansion liner 140 inside the casing 130, open the casing inflow control valve 303, inject high-pressure detection water from the casing liquid storage tank 306 into the casing pressure chamber 105 through the second hydraulic pump 304, and then hold the pressure to make the expansion liner 140 expand to tightly adhere to the inner wall of the casing 130. The filling of the expansion liner 140 can enhance the sealing performance and pressure-bearing capacity of the wellbore and simulate the state of the wellbore after reconstruction.

[0154] Among them, forming the secondary perforation 102 is the key to evaluating the influence of the secondary perforation 102 on the integrity of the cement sheath 120. By forming the secondary perforation 102, the actual working state of the old wellbore after reconstruction can be simulated. Specifically, the perforating gun 600 can be used to perform perforating operations at positions different from the initial perforation 101 to form the secondary perforation 102.

[0155] Specifically, by constructing the old wellbore model before wellbore reconstruction and the old wellbore model after wellbore reconstruction and obtaining the corresponding strength parameters, the influence of the secondary perforation 102 on the wellbore structure after wellbore reconstruction can be quantified, so as to systematically evaluate the influence of the secondary perforation 102 operation on the integrity of the cement sheath 120 during the old wellbore reconstruction process. This method helps to provide important theoretical basis and technical support for optimizing the wellbore reconstruction technology, improving the service life and safety of old wells.

[0156] In some embodiments, obtaining the bonding strength before reconstruction includes:

[0157] Through the casing temperature and pressure control component and the confining pressure control component, combined with the actual working environment of the old wellbore, simulate the pressure and temperature required for the experiment;

[0158] Obtain the first bonding strength between the cement sheath 120 and the casing 130;

[0159] Obtain the second bonding strength between the cement sheath 120 and the formation model 110.

[0160] It can be understood that the first bonding strength reflects the bonding quality and mechanical properties between the cement sheath 120 and the casing 130. Good bonding strength helps to prevent fluid channeling and structural failure, and is an important indicator for evaluating the initial integrity of the wellbore.

[0161] The second bonding strength reflects the bonding quality between the cement sheath 120 and the formation. The second bonding strength is an important factor to ensure the wellbore stability and prevent the intrusion of external formation fluids.

[0162] In some embodiments, obtaining the reconstructed bonding strength includes:

[0163] Construct the wellbore formation model 100, and through the casing temperature and pressure control component and the confining pressure control component, combined with the actual working environment of the old wellbore, simulate the pressure and temperature required for the experiment;

[0164] Obtain the third bonding strength between the cement sheath 120 and the casing 130;

[0165] Obtain the fourth bonding strength between the cement sheath 120 and the formation model 110.

[0166] It can be understood that the third bonding strength reflects the bonding quality of the reconstructed cement sheath 120 and the casing 130, which helps to judge the impact of the reconstruction process on the wellbore integrity, especially after the secondary perforation 102.

[0167] The fourth bonding strength reflects the bonding quality of the reconstructed cement sheath 120 and the formation, which helps to judge the stability and sealing performance of the reconstructed wellbore in the formation.

[0168] Specifically, by obtaining the initial and reconstructed bonding strengths respectively, the change in the bonding quality between the cement sheath 120 and the casing 130 and the formation during the wellbore reconstruction process can be comprehensively evaluated. This evaluation helps to identify the impact of the secondary perforation 102 and the reconstruction process on the wellbore integrity, guide the optimization of the reconstruction technology, and improve the safety and service life of the wellbore.

[0169] In some embodiments, obtaining the first bonding strength between the cement sheath 120 and the casing 130 includes:

[0170] Inject the detection water into the space between the cement sheath 120 and the casing 130 from the top of the wellbore model at the injection pressure;

[0171] Obtain the current pressure between the bottom end of the cement sheath 120 and the casing 130;

[0172] Gradually increase the water injection pressure;

[0173] If the pressure difference between the water injection pressure and the current pressure starts to be equal to 0, obtain the first bond strength based on the water injection pressure.

[0174] Among them, the pressure value displayed by the first interface inflow pressure gauge 502 is the pressure value of the water injection pressure, and the pressure value displayed by the first interface outflow pressure gauge 505 is the pressure value of the current pressure. During the process of gradually increasing the water injection pressure, it can be increased by 0.1 MPa each time and then left standing for 5 to 10 minutes, and the readings of the first interface inflow pressure gauge 502 and the first interface outflow pressure gauge 505 are monitored in real time. When the readings of the first interface inflow pressure gauge 502 and the first interface outflow pressure gauge 505 are the same, that is, the difference in the pressure difference between the water injection pressure and the current pressure is 0, it means that the bond between the cement sheath 120 and the casing 130 has failed.

[0175] Before the readings of the first interface inflow pressure gauge 502 and the first interface outflow pressure gauge 505 are the same, the difference between the first interface inflow pressure gauge 502 and the first interface outflow pressure gauge 505 can reflect the first bond strength of the first interface 103.

[0176] In some embodiments, obtaining the third bond strength between the cement sheath 120 and the casing 130 includes:

[0177] Inject detection water into the space between the cement sheath 120 and the casing 130 from the top of the wellbore model at the water injection pressure;

[0178] Obtain the current pressure between the bottom end of the cement sheath 120 and the casing 130;

[0179] Gradually increase the water injection pressure;

[0180] If the pressure difference between the water injection pressure and the current pressure starts to be equal to 0, obtain the third bond strength based on the water injection pressure.

[0181] Among them, the pressure value displayed by the first interface inflow pressure gauge 502 is the pressure value of the water injection pressure, and the pressure value displayed by the first interface outflow pressure gauge 505 is the pressure value of the current pressure. During the process of gradually increasing the water injection pressure, it can be increased by 0.1 MPa each time and then left standing for 5 to 10 minutes, and the readings of the first interface inflow pressure gauge 502 and the first interface outflow pressure gauge 505 are monitored in real time. When the readings of the first interface inflow pressure gauge 502 and the first interface outflow pressure gauge 505 are the same, that is, the difference in the pressure difference between the water injection pressure and the current pressure is 0, it means that the bond between the reconstructed cement sheath 120 and the casing 130 has failed.

[0182] Before the readings of the first interface inflow pressure gauge 502 and the first interface outflow pressure gauge 505 are consistent, the difference between the first interface inflow pressure gauge 502 and the first interface outflow pressure gauge 505 can reflect the third cementing strength of the first interface 103 after the reconstruction of the old wellbore.

[0183] Through the above steps, the cementing strength between the initial and reconstructed cement sheath 120 and the casing 130 can be effectively measured. This process not only helps to evaluate the effectiveness of wellbore reconstruction, but also provides data support for optimizing the reconstruction technology, thereby improving the safety and service life of the wellbore.

[0184] In some embodiments, obtaining the second cementing strength between the cement sheath 120 and the formation model 110 includes:

[0185] Injecting detection water between the cement sheath 120 and the formation model 110 from the top of the wellbore model with a water injection pressure;

[0186] Obtaining the current pressure between the bottom end of the cement sheath 120 and the formation model 110;

[0187] Gradually increasing the water injection pressure;

[0188] If the pressure difference between the water injection pressure and the current pressure starts to be equal to 0, the second cementing strength is obtained according to the water injection pressure.

[0189] Among them, the pressure value displayed by the second interface inflow pressure gauge 508 is the pressure value of the water injection pressure, and the pressure value displayed by the second interface outflow pressure gauge 511 is the pressure value of the current pressure. During the process of gradually increasing the water injection pressure, it can be increased by 0.1 MPa each time and then left still for 5 to 10 minutes, and the readings of the second interface inflow pressure gauge 508 and the second interface outflow pressure gauge 511 are monitored in real time. When the readings of the second interface inflow pressure gauge 508 and the second interface outflow pressure gauge 511 are consistent, that is, the difference between the water injection pressure and the current pressure is 0, it means that the bonding between the cement sheath 120 and the formation model 110 has failed.

[0190] Before the readings of the second interface inflow pressure gauge 508 and the second interface outflow pressure gauge 511 are consistent, the difference between the second interface inflow pressure gauge 508 and the second interface outflow pressure gauge 511 can reflect the second cementing strength of the second interface 104.

[0191] In some embodiments, obtaining the fourth cementing strength between the cement sheath 120 and the formation model 110 includes:

[0192] Injecting detection water between the cement sheath 120 and the formation model 110 from the top of the wellbore model with a water injection pressure;

[0193] Obtain the current pressure between the bottom end of the cement sheath 120 and the formation model 110;

[0194] Gradually increase the water injection pressure;

[0195] If the pressure difference between the water injection pressure and the current pressure starts to be equal to 0, obtain the fourth cementing strength based on the water injection pressure.

[0196] Among them, the pressure value displayed by the pressure gauge 508 for the inflow at the second interface is the pressure value of the water injection pressure, and the pressure value displayed by the pressure gauge 511 for the outflow at the second interface is the pressure value of the current pressure. During the process of gradually increasing the water injection pressure, it can be increased by 0.1 MPa each time and then left static for 5 to 10 minutes, and the readings of the pressure gauge 508 for the inflow at the second interface and the pressure gauge 511 for the outflow at the second interface are monitored in real time. When the readings of the pressure gauge 508 for the inflow at the second interface and the pressure gauge 511 for the outflow at the second interface are the same, that is, the difference in the pressure difference between the water injection pressure and the current pressure is 0, it means that the bond between the reconstructed cement sheath 120 and the formation model 110 has failed.

[0197] Before the readings of the pressure gauge 508 for the inflow at the second interface and the pressure gauge 511 for the outflow at the second interface are the same, the difference between the pressure gauge 508 for the inflow at the second interface and the pressure gauge 511 for the outflow at the second interface can reflect the fourth cementing strength of the second interface 104 after the reconstruction of the old wellbore.

[0198] Through the above steps, the cementing strength between the initial and reconstructed cement sheath 120 and the formation model 110 can be effectively measured. This process not only helps to evaluate the effectiveness of wellbore reconstruction, but also provides data support for optimizing the reconstruction technology, thereby improving the safety and service life of the wellbore.

[0199] In some embodiments, obtaining the anti-channeling strength before reconstruction includes:

[0200] Inject the detection water into the inner side of the casing 130 from the top end of the wellbore model at the water injection pressure;

[0201] Obtain the current pressure between the cement sheath 120 and the casing 130, and obtain the current pressure between the cement sheath 120 and the formation model 110;

[0202] Gradually increase the water injection pressure;

[0203] If the pressure difference between the water injection pressure and at least one current pressure starts to be equal to 0, obtain the anti-channeling strength before reconstruction based on the water injection pressure.

[0204] Among them, the pressure value displayed by the pressure gauge 302 for the inflow of the casing is the pressure value of the water injection pressure, and the pressure values displayed by the pressure gauge 502 for the inflow at the first interface, the pressure gauge 505 for the outflow at the first interface, the pressure gauge 508 for the inflow at the second interface, and the pressure gauge 511 for the outflow at the second interface can all be used as the pressure values of the current pressure.

[0205] Exemplarily, during the process of gradually increasing the water injection pressure, it can be increased by 0.1 MPa each time.

[0206] Monitor the readings of the casing inflow pressure gauge 302, the first interface inflow pressure gauge 502, the first interface outflow pressure gauge 505, the second interface inflow pressure gauge 508, and the second interface outflow pressure gauge 511 in real time.

[0207] When the reading of the casing inflow pressure gauge 302 is consistent with any one of the readings of the first interface inflow pressure gauge 502, the first interface outflow pressure gauge 505, the second interface inflow pressure gauge 508, and the second interface outflow pressure gauge 511, that is, when the difference between the water injection pressure and the current pressure is 0, it means that the cement sheath 120 has leaked. Then, the value of the casing inflow pressure gauge 302 before the readings are consistent can reflect the anti-leakage strength of the cement sheath 120 before reconstruction.

[0208] In some embodiments, obtaining the anti-leakage strength after reconstruction includes:

[0209] Inject detection water into the inner side of the expandable liner 140 from the top of the wellbore model at the water injection pressure.

[0210] Obtain the current pressure between the cement sheath 120 and the casing 130, and obtain the current pressure between the cement sheath 120 and the formation model 110.

[0211] Gradually increase the water injection pressure.

[0212] If the pressure difference between the water injection pressure and at least one current pressure starts to be equal to 0, obtain the anti-leakage strength after reconstruction according to the water injection pressure.

[0213] Among them, the pressure value displayed by the casing inflow pressure gauge 302 is the pressure value of the water injection pressure, and the pressure values displayed by the first interface inflow pressure gauge 502, the first interface outflow pressure gauge 505, the second interface inflow pressure gauge 508, and the second interface outflow pressure gauge 511 can all be used as the pressure values of the current pressure.

[0214] Exemplarily, during the process of gradually increasing the water injection pressure, it can be increased by 0.1 MPa each time.

[0215] Monitor the readings of the casing inflow pressure gauge 302, the first interface inflow pressure gauge 502, the first interface outflow pressure gauge 505, the second interface inflow pressure gauge 508, and the second interface outflow pressure gauge 511 in real time.

[0216] When the reading of the casing inflow pressure gauge 302 is the same as that of any one of the first interface inflow pressure gauge 502, the first interface outflow pressure gauge 505, the second interface inflow pressure gauge 508, and the second interface outflow pressure gauge 511, that is, the difference between the water injection pressure and the current pressure difference is 0, it means that the reconstructed cement sheath 120 has leaked. Then, the value of the casing inflow pressure gauge 302 before the readings are the same can reflect the anti-channeling strength of the cement sheath 120 after the reconstruction of the old wellbore.

[0217] In some embodiments, a fluorescent tracer is provided in the detection water; the method further includes: when the pressure difference between the water injection pressure and the current pressure is equal to 0, obtaining the flow path of the detection water between the top and bottom of the wellbore model according to the fluorescent tracer.

[0218] It can be understood that through the flow path of the fluorescent tracer, the flow situation of the detection water in the wellbore model can be intuitively observed to identify possible leakage paths or poorly sealed areas in the wellbore model.

[0219] Specifically, for the old wellbore before reconstruction, after obtaining the first cementing strength between the cement sheath 120 and the casing 130 and the second cementing strength between the cement sheath 120 and the formation model 110, the cement sheath 120 can be removed and a fluorescent tracer can be used to observe the failure position and range of the cement sheath 120 before reconstruction.

[0220] For the old wellbore after reconstruction, after obtaining the third cementing strength between the cement sheath 120 and the casing 130 and the fourth cementing strength between the cement sheath 120 and the formation model 110, the cement sheath 120 can be removed and a fluorescent tracer can be used to observe the failure position and range of the cement sheath 120 after reconstruction.

[0221] By comparing and combining the changes in the cementing strength and the failure position and range before and after the reconstruction of the old wellbore, the influence degree of the wellbore reconstruction process on the deterioration of the integrity of the old well cement sheath can be studied.

[0222] In some embodiments, for the old wellbore before reconstruction, after obtaining the anti-channeling strength before reconstruction, the cement sheath 120 can be removed and a fluorescent tracer can be used to observe the channeling path on the surface of the cement sheath 120 before reconstruction and the first cementing surface where channeling first occurs.

[0223] For the old wellbore after reconstruction, after obtaining the anti-channeling strength after reconstruction, the cement sheath 120 can be removed and a fluorescent tracer can be used to observe the channeling path on the surface of the cement sheath 120 after reconstruction and the first cementing surface where channeling first occurs.

[0224] Among them, the cementing surface includes the first interface 103 and the second interface 104.

[0225] Furthermore, by comparing and combining the changes in the anti-channeling strength and the failure conditions of the old wellbore before and after reconstruction, the influence degree of the wellbore reconstruction process on the deterioration of the integrity of the old well cement sheath can be studied.

[0226] In some embodiments, when forming the secondary perforation 102, the secondary perforation 102 is not communicated with the initial perforation 101.

[0227] It can be understood that the position of the secondary perforation 102 does not overlap with the initial perforation 101, which can avoid the interference of the secondary perforation 102 on the initial perforation 101 and ensure the independence and effectiveness of the secondary perforation 102.

[0228] In summary, the simulation device for the cement sheath of the old wellbore reconstruction provided by the embodiments of the present application can simulate the influence of the old wellbore reconstruction process on the integrity of the cement sheath 120 by simulating the on-site working conditions and lowering the expandable liner 140 and carrying out the secondary perforation 102 operation, making up for the deficiency that the existing test devices for the integrity of the cement sheath 120 do not consider the wellbore reconstruction process, and contributing to providing important theoretical basis and technical support for optimizing the wellbore reconstruction technology, improving the service life and safety of old wells.

[0229] The simulation method for the cement sheath of the old wellbore reconstruction provided by the embodiments of the present application can not only measure the bonding strength of the old wellbore before and after reconstruction at the first interface 103 and the second interface 104, but also measure the anti-channeling strength of the cement sheath 120 at the perforation position before and after reconstruction, and can quantify the influence of the wellbore reconstruction on the wellbore structure. In addition, this method also uses a fluorescent tracer to mark the cement sheath 120, and can directly observe the channeling path and range of the cement sheath 120 interface, which is convenient for better quantifying and evaluating the integrity of the cement sheath 120.

[0230] Finally, it should be noted that those skilled in the art will easily think of other implementation schemes of the embodiments of the present application after considering the specification and practicing the application disclosed herein. The embodiments of the present application are intended to cover any variations, uses or adaptive changes of the embodiments of the present application, and these variations, uses or adaptive changes follow the general principles of the embodiments of the present application and include the common general knowledge or conventional technical means in the technical field not disclosed in the embodiments of the present application. The specification and the embodiments are only regarded as exemplary, and the true scope and spirit of the embodiments of the present application are pointed out by the following claims.

[0231] It should be understood that the embodiments of the present application are not limited to the exact structures already described and shown in the drawings, and various modifications and changes can be made without departing from its scope. The scope of the embodiments of the present application is only limited by the appended claims.

Claims

1. A simulation method for reconstructing cement sheath in an old wellbore, characterized in that: include: Constructing a wellbore formation model (100); the wellbore formation model (100) comprises formation models (110) stacked in sequence from outside to inside and an old wellbore model before wellbore reconstruction; The old wellbore model before wellbore reconstruction comprises a cement ring (120) and a casing (130), the outer surface of the cement ring (120) contacts the formation model (110), and the inner surface of the cement ring (120) contacts the casing (130), and the wellbore formation model (100) is further provided with an initial perforation (101), and the initial perforation (101) penetrates the cement ring (120) and the casing (130); Obtaining pre-reconstruction strength parameters of the old wellbore model before the wellbore reconstruction, wherein the pre-reconstruction strength parameters include pre-reconstruction cementation strength and pre-reconstruction anti-channeling strength; Filling an expansion liner (140) inside the casing (130); Secondary perforations (102) are formed to form a wellbore model of the old well after wellbore reconstruction; the secondary perforations (102) penetrate the cement ring (120), the casing (130) and the expandable liner (140); The reconstructed strength parameters of the old wellbore model after the wellbore reconstruction are obtained, wherein the reconstructed strength parameters include the reconstructed bonding strength and the reconstructed anti-channeling strength.

2. The simulation method for reconstructing cement sheath in old wellbore according to claim 1 is characterized in that: Obtaining the bonding strength before reconstruction includes: Obtaining a first bonding strength between the cement ring (120) and the casing (130); Obtaining a second bonding strength between the cement ring (120) and the formation model (110); Obtaining the post-reconstruction bonding strength includes: Obtaining a third bonding strength between the cement ring (120) and the casing (130); A fourth bonding strength between the cement ring (120) and the formation model (110) is obtained.

3. The simulation method for reconstructing cement sheath in old wellbore according to claim 2 is characterized in that: Obtaining a first bonding strength between the cement ring (120) and the casing (130), comprising: Injecting test water from the top of the wellbore model into the space between the cement ring (120) and the casing (130) at water injection pressure; Obtaining the current pressure between the bottom end of the cement ring (120) and the casing (130); gradually increasing the water injection pressure; If the pressure difference between the water injection pressure and the current pressure is initially equal to 0, the first bonding strength is obtained according to the water injection pressure; Obtaining a third bonding strength between the cement ring (120) and the casing (130), comprising: Injecting test water from the top of the wellbore model into the space between the cement ring (120) and the casing (130) at water injection pressure; Obtaining the current pressure between the bottom end of the cement ring (120) and the casing (130); gradually increasing the water injection pressure; If the pressure difference between the water injection pressure and the current pressure is initially equal to 0, the third bonding strength is obtained according to the water injection pressure.

4. The simulation method for reconstructing cement sheath in old wellbore according to claim 2 is characterized in that: Obtaining a second bonding strength between the cement sheath (120) and the formation model (110), comprising: Injecting test water from the top of the wellbore model into the space between the cement sheath (120) and the formation model (110) at water injection pressure; Acquiring the current pressure between the bottom end of the cement ring (120) and the formation model (110); gradually increasing the water injection pressure; If the pressure difference between the water injection pressure and the current pressure is initially equal to 0, the second bonding strength is obtained according to the water injection pressure; Obtaining a fourth bonding strength between the cement sheath (120) and the formation model (110), comprising: Injecting test water from the top of the wellbore model into the space between the cement sheath (120) and the formation model (110) at water injection pressure; Acquiring the current pressure between the bottom end of the cement ring (120) and the formation model (110); gradually increasing the water injection pressure; If the pressure difference between the water injection pressure and the current pressure is initially equal to 0, the fourth bonding strength is obtained according to the water injection pressure.

5. The simulation method for reconstructing cement sheath in old wellbore according to claim 1 is characterized in that: Obtaining the anti-channeling strength before reconstruction includes: Injecting test water into the inner side of the casing (130) from the top of the wellbore model at water injection pressure; Acquiring the current pressure between the cement ring (120) and the casing (130), and acquiring the current pressure between the cement ring (120) and the formation model (110); gradually increasing the water injection pressure; If the pressure difference between the water injection pressure and at least one of the current pressures is initially equal to 0, the anti-channeling strength before reconstruction is obtained according to the water injection pressure.

6. The simulation method for reconstructing cement sheath in old wellbore according to claim 1 is characterized in that: Obtaining the post-reconstruction anti-channeling strength includes: Injecting test water into the inside of the expandable liner (140) from the top of the wellbore model at water injection pressure; Acquiring the current pressure between the cement ring (120) and the casing (130), and acquiring the current pressure between the cement ring (120) and the formation model (110); gradually increasing the water injection pressure; If the pressure difference between the water injection pressure and at least one of the current pressures is initially equal to 0, the post-reconstruction anti-channeling strength is obtained according to the water injection pressure.

7. The simulation method for reconstructing cement sheath of an old wellbore according to any one of claims 3 to 6, characterized in that: A fluorescent tracer is provided in the test water; the method further comprises: When the pressure difference between the injection pressure and the current pressure is equal to 0, the flow path of the test water between the top and bottom of the wellbore model is obtained according to the fluorescent tracer.

8. The simulation method for reconstructing cement sheath in old wellbore according to claim 1 is characterized in that: When the secondary perforations (102) are formed, the secondary perforations (102) are not connected to the initial perforations (101).

9. A simulation device for reconstructing cement sheath in old wellbore, characterized in that: It comprises a main body (210), a first end cover (220) and a second end cover (230); The first end cover (220) is arranged at the first end of the main body (210), and the second end cover (230) is arranged at the second end of the main body (210). The first end cover (220) and the second end cover (230) are arranged opposite to each other, and the first end cover (220) and the second end cover (230) are at least used to construct a wellbore formation model (100).

10. The simulation device for reconstructing cement sheath in old wellbore according to claim 9, characterized in that: The first end cover (220) is provided with a water inlet, and the water inlet is at least used to inject test water into the top of the wellbore formation model (100); The second end cover (230) is provided with a drainage port, and the drainage port is at least used to discharge the detection water from the bottom end of the wellbore formation.

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