A system and method for predicting ground collapse laws, and a device for predicting ground collapse laws

Abstract

This specification proposes a formation collapse law prediction system and its prediction method and device. The method includes: taking the signal reception time when the first sound wave receiving end receives the sound wave signal as the first time; taking the signal reception time when the second sound wave receiving end receives the sound wave signal as the second time; calculating the longitudinal wave velocity according to the first time and the second time; calculating the transverse wave velocity according to the longitudinal wave velocity; determining the rock mechanical characteristic parameters of the target simulated formation according to the longitudinal wave velocity and the transverse wave velocity; determining the formation collapse pressure of the target simulated formation according to the rock mechanical characteristic parameters of the target simulated formation; taking the formation collapse pressure of the target simulated formation as the formation collapse pressure of the target formation. Based on the above-mentioned formation collapse law prediction system and its prediction method, it is possible to simulate the downhole environment, and determine the collapse pressure of the target formation according to the simulated downhole environment, thereby improving the safety of drilling operations.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas drilling engineering, and in particular to a system for predicting formation collapse laws and a prediction method and device thereof. Background Art

[0002] During the drilling operation, the formations around the wellbore will be subjected to both the liquid column pressure and the ground stress of the drilling fluid. When the liquid column pressure of the drilling fluid is insufficient, the formation will be sheared, causing the wellbore wall to collapse, which will affect the safety of the drilling operation. At the same time, as the drilling fluid penetrates into the formation, it will change the pore pressure inside the formation, and then change the ground stress, which also increases the possibility of wellbore wall collapse. Under the immersion of the drilling fluid, the mechanical properties of the rock will change, and the originally stable formation may become unstable. How to accurately obtain the collapse pressure of the formation and then predict the collapse cycle of the formation based on the collapse pressure of the formation is very important to ensure drilling safety.

[0003] In the prior art, a downhole environment simulation device is usually used to simulate the stress of the formation. This downhole environment simulation device needs to include multiple acoustic instruments and multiple pressure sensors to measure acoustic data and mechanical data in different directions, and then calculate the formation collapse pressure based on the acoustic data and mechanical data in different directions. This device has a high deployment cost and is not conducive to popularization and application.

[0004] Currently, no effective solution has been proposed for the above technical problems. Summary of the invention

[0005] This specification proposes a system for predicting formation collapse rules and a prediction method and device thereof, which can solve the technical problem that the formation collapse pressure cannot be accurately obtained in the prior art.

[0006] The purpose of the embodiments of this specification is to provide a system for predicting formation collapse laws, the system at least comprising a downhole environment simulation unit, a liquid pressure loading unit, a ground stress loading unit, and an acoustic wave measurement unit; wherein the downhole environment simulation unit at least comprises a simulated formation; the simulated formation includes a simulated wellbore inside; the ground stress loading unit at least comprises a high-pressure servo pump, a ground stress high-pressure pipeline, a ground stress control valve, and a pressurized end cover; the high-pressure servo pump applies ground stress to the simulated formation through the ground stress high-pressure pipeline and the pressurized end cover to obtain a pressurized simulated formation; the pressurized end cover is located outside the simulated formation; the ground stress control valve is used to control ground stress; the liquid pressure loading unit at least comprises a high-pressure pump, a fluid injection high-pressure pipeline, and a fluid injection control valve; the high-pressure pump is used to inject high-pressure fluid into the pressurized simulated formation through the fluid injection high-pressure pipeline and inject high-pressure fluid into the pressurized simulated formation inside the pressurized simulated formation A simulated wellbore is injected with drilling fluid to obtain a target simulated formation; wherein the target simulated formation includes a simulated wellbore into which drilling fluid is injected; the fluid injection control valve is used to control the drilling fluid pressure injected into the high-pressure pipeline; the acoustic wave measurement unit at least includes an acoustic wave transmitting end, a first acoustic wave receiving end, a second acoustic wave receiving end, and a server; the acoustic wave transmitting end, the first acoustic wave receiving end, and the second acoustic wave receiving end are vertically arranged inside the simulated wellbore into which drilling fluid is injected; the acoustic wave transmitting end is used to transmit an acoustic wave signal to the target simulated formation; the first acoustic wave receiving end and the second acoustic wave receiving end are used to receive the acoustic wave signal and transmit the signal receiving time to the server; the server is used to determine the longitudinal wave velocity according to the signal receiving time, determine the transverse wave velocity according to the longitudinal wave velocity, determine the rock mechanical characteristic parameters according to the longitudinal wave velocity and the transverse wave velocity, and determine the formation collapse pressure of the target formation according to the rock mechanical characteristic parameters.

[0007] Furthermore, in another embodiment of the method, the downhole environment simulation unit also includes a sealing rubber sleeve; the sealing rubber sleeve is located between the simulated formation and the pressurized end cover; and the sealing rubber sleeve is used to seal the simulated formation.

[0008] Furthermore, in another embodiment of the method, the liquid pressure loading unit also includes an injection port; the high-pressure pump, the fluid injection control valve, and the injection port are connected via the fluid injection high-pressure pipeline.

[0009] Furthermore, in another embodiment of the method, the geostress loading unit also includes a loading cylinder sleeve; the high-pressure servo pump, the geostress control valve, and the loading cylinder sleeve are connected via a geostress high-pressure pipeline; and the loading cylinder sleeve is connected to the pressurizing end cover.

[0010] Furthermore, in another embodiment of the method, the sound wave measuring unit also includes a signal transmission line; the sound wave transmitting end, the first sound wave receiving end, the second sound wave receiving end, and the server are connected via the signal transmission line.

[0011] On the other hand, the purpose of the embodiment of this specification is to provide a method for predicting formation collapse law, which is applied to the above-mentioned formation collapse law prediction system, and the method includes:

[0012] The signal receiving time when the first sound wave receiving end receives the sound wave signal is taken as the first time;

[0013] The signal receiving time when the second sound wave receiving end receives the sound wave signal is taken as the second time;

[0014] Calculate the longitudinal wave velocity according to the first time and the second time;

[0015] Calculate the shear wave velocity based on the longitudinal wave velocity;

[0016] Determine the rock mechanical property parameters of the target simulated formation according to the longitudinal wave velocity and the shear wave velocity;

[0017] Determine the formation collapse pressure of the target simulated formation according to the rock mechanical characteristic parameters of the target simulated formation;

[0018] The formation collapse pressure of the target simulation formation is taken as the formation collapse pressure of the target formation.

[0019] Furthermore, in another embodiment of the method, the rock mechanical property parameters include: dynamic elastic modulus, dynamic Poisson's ratio, and internal friction angle.

[0020] Furthermore, in another embodiment of the method, after the formation collapse pressure of the target simulated formation is used as the formation collapse pressure of the target formation, the method further includes:

[0021] Determining a collapse period of a target formation according to a formation collapse pressure of the target formation;

[0022] Take corresponding wellbore protection measures according to the collapse cycle of the target formation.

[0023] On the other hand, the purpose of the embodiment of this specification is to provide a device for predicting formation collapse law, the device comprising:

[0024] A first measuring module, configured to use a signal receiving time when the first sound wave receiving end receives the sound wave signal as a first time;

[0025] A second measuring module, used for taking the signal receiving time when the first sound wave receiving end receives the sound wave signal as the second time;

[0026] A first calculation module, used for calculating the longitudinal wave velocity according to the first time and the second time;

[0027] A second calculation module is used to calculate the shear wave velocity according to the longitudinal wave velocity;

[0028] The third calculation module is used to determine the rock mechanical characteristic parameters of the target simulated formation according to the longitudinal wave velocity and the shear wave velocity;

[0029] A fourth calculation module is used to determine the formation collapse pressure of the target simulated formation according to the rock mechanical characteristic parameters of the target simulated formation;

[0030] The fifth calculation module is used to use the formation collapse pressure of the target simulated formation as the formation collapse pressure of the target formation.

[0031] On the other hand, the embodiments of the present specification further provide a computer-readable storage medium having computer instructions stored thereon, and the computer-readable storage medium implements the above-mentioned method for predicting formation collapse laws when executing the instructions.

[0032] An embodiment of the present specification provides a method for predicting formation collapse rules, which takes the signal receiving time when the first sound wave receiving end receives the sound wave signal as the first time; takes the signal receiving time when the second sound wave receiving end receives the sound wave signal as the second time; calculates the longitudinal wave velocity according to the first time and the second time; calculates the transverse wave velocity according to the longitudinal wave velocity; determines the rock mechanical characteristic parameters of the target simulated formation according to the longitudinal wave velocity and the transverse wave velocity; determines the formation collapse pressure of the target simulated formation according to the rock mechanical characteristic parameters of the target simulated formation; and takes the formation collapse pressure of the target simulated formation as the formation collapse pressure of the target formation.

[0033] Furthermore, after the formation collapse pressure of the target simulated formation is used as the formation collapse pressure of the target formation, the collapse period of the target formation can be determined according to the formation collapse pressure of the target formation; and corresponding wellbore protection measures can be taken according to the collapse period of the target formation. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of this specification, the drawings required for use in the embodiments will be briefly introduced below. The drawings described below are only some embodiments recorded in this specification. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0035] Figure 1 It is a flow chart of an embodiment of a method for predicting formation collapse law provided in this specification;

[0036] Figure 2 It is a structural schematic diagram of an embodiment of a system for predicting formation collapse law provided in this specification;

[0037] Figure 3 It is a schematic diagram of the module structure of an embodiment of a device for predicting stratum collapse law provided in this specification;

[0038] Figure 4 This is a schematic diagram of the structural composition of a server provided in this manual. DETAILED DESCRIPTION

[0039] In order to enable those skilled in the art to better understand the technical solutions in this specification, the technical solutions in the embodiments of this specification will be clearly and completely described below in conjunction with the drawings in the embodiments of this specification. Obviously, the described embodiments are only part of the embodiments of this specification, not all of the embodiments. Based on the embodiments in this specification, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of this specification.

[0040] Considering that during the drilling operation, the formation around the wellbore will be subjected to both the liquid column pressure of the drilling fluid and the ground stress, the liquid column pressure provides support for the well wall. When the liquid column pressure of the drilling fluid is insufficient, the formation will be sheared, causing the wellbore wall to collapse, which in turn affects the safety of the drilling operation. At the same time, as the drilling fluid penetrates into the formation, it will change the pore pressure inside the formation, thereby changing the effective stress, and the mechanical parameters of the formation will also change, which also increases the possibility of well wall collapse. Accurately obtaining the collapse law of the formation is very important for ensuring drilling safety.

[0041] It is further considered that in the prior art, a downhole environment simulation device is usually used to simulate the stress condition of the formation. This downhole environment simulation device needs to include multiple acoustic instruments and multiple pressure sensors to measure acoustic data and mechanical data in different directions, and then calculate the formation collapse pressure based on the acoustic data and mechanical data in different directions. The installation cost of this device is high, which is not conducive to promotion and application.

[0042] In view of the above-mentioned problems existing in the existing methods and the specific reasons for the above-mentioned problems, the present application introduces a formation collapse law prediction system based on longitudinal wave velocity and a prediction method thereof to ensure the safety of oil and gas drilling projects.

[0043] Based on the above ideas, this specification proposes a formation collapse law prediction system, which at least includes a downhole environment simulation unit, a liquid pressure loading unit, a ground stress loading unit, and an acoustic wave measurement unit; wherein the downhole environment simulation unit at least includes a simulated formation; the simulated formation includes a simulated wellbore; the ground stress loading unit at least includes a high-pressure servo pump, a ground stress high-pressure pipeline, a ground stress control valve, and a pressurized end cover; the high-pressure servo pump applies ground stress to the simulated formation through the ground stress high-pressure pipeline and the pressurized end cover to obtain a pressurized simulated formation; the pressurized end cover is located outside the simulated formation; the ground stress control valve is used to control ground stress; the liquid pressure loading unit at least includes a high-pressure pump, a fluid injection high-pressure pipeline, and a fluid injection control valve; the high-pressure pump is used to inject high-pressure fluid into the pressurized simulated formation through the fluid injection high-pressure pipeline and inject high-pressure fluid into the pressurized simulated formation. A simulated wellbore is injected with drilling fluid to obtain a target simulated formation; wherein the target simulated formation includes a simulated wellbore into which drilling fluid is injected; the fluid injection control valve is used to control the drilling fluid pressure injected into the high-pressure pipeline; the acoustic wave measurement unit at least includes an acoustic wave transmitting end, a first acoustic wave receiving end, a second acoustic wave receiving end, and a server; the acoustic wave transmitting end, the first acoustic wave receiving end, and the second acoustic wave receiving end are vertically arranged inside the simulated wellbore into which drilling fluid is injected; the acoustic wave transmitting end is used to transmit an acoustic wave signal to the target simulated formation; the first acoustic wave receiving end and the second acoustic wave receiving end are used to receive the acoustic wave signal and transmit the signal receiving time to the server; the server is used to determine the longitudinal wave velocity according to the signal receiving time, determine the transverse wave velocity according to the longitudinal wave velocity, determine the rock mechanical characteristic parameters according to the longitudinal wave velocity and the transverse wave velocity, and determine the formation collapse pressure of the target formation according to the rock mechanical characteristic parameters.

[0044] In some embodiments, the purpose of injecting high-pressure fluid into the pressurized simulated formation is to increase the formation pore pressure; the purpose of injecting drilling fluid into the simulated wellbore inside the pressurized simulated formation is to increase the fluid column pressure in the well.

[0045] In some embodiments, the geostress includes: overburden pressure applied in the up-down vertical direction, and horizontal geostress applied in the left-right horizontal direction.

[0046] In some embodiments, the downhole environment simulation unit further includes a sealing rubber sleeve; the sealing rubber sleeve is located between the simulated formation and the pressurized end cover; the sealing rubber sleeve is used to seal the simulated formation.

[0047] In some embodiments, the simulated formation can be obtained by cutting and processing an artificial formation or natural rock, and a hole with a certain diameter is drilled in the middle of the simulated formation to obtain a simulated wellbore. A sealing rubber sleeve is wrapped around the outside of the simulated formation, and the sealing rubber sleeve is used to seal the simulated formation to ensure that the subsequent applied formation fluid pressure does not leak; the formation fluid pressure specifically includes: formation pore pressure and fluid column pressure in the well.

[0048] In some embodiments, the liquid pressure loading unit further includes an injection port; the high-pressure pump, the fluid injection control valve, and the injection port are connected via the fluid injection high-pressure pipeline.

[0049] In some embodiments, the injection port includes: a first injection port, a second injection port, and a third injection port; the first injection port and the second injection port are used to inject high-pressure fluid into the simulated formation to apply formation pore pressure to the simulated formation; the third injection port is used to inject drilling fluid into the simulated wellbore to apply in-well liquid column pressure to the simulated formation; the injection port is embedded after drilling threaded holes on the pressurized end cover and the sealing rubber sleeve.

[0050] In some embodiments, the fluid injection high-pressure pipeline includes a first pipeline, a second pipeline, and a third pipeline; the fluid injection control valve includes a first control valve, a second control valve, and a third control valve.

[0051] In some embodiments, the high-pressure pump, the first control valve, and the first injection port are connected through a first pipeline; the first control valve can control the flow rate of the high-pressure fluid in the first pipeline.

[0052] In some embodiments, the high-pressure pump, the second control valve, and the second injection port are connected via a second pipeline; the second control valve can control the flow rate of the high-pressure fluid in the second pipeline.

[0053] In some embodiments, the high-pressure pump, the third control valve, and the third injection port are connected through a third pipeline; the third control valve can control the drilling fluid flow in the third pipeline, and then control the in-well liquid column pressure (drilling fluid pressure) generated by the drilling fluid.

[0054] In some embodiments, the liquid pressure loading unit further includes a first pressure gauge, and the first pressure gauge is used to display the pressure value applied by the high-pressure pump.

[0055] In some embodiments, the geostress loading unit further includes a loading cylinder sleeve; the high-pressure servo pump, the geostress control valve, and the loading cylinder sleeve are connected via a geostress high-pressure pipeline; and the loading cylinder sleeve is connected to the pressurizing end cover.

[0056] In some embodiments, the loading cylinder sleeve includes: a first overburden pressure loading cylinder sleeve, a second overburden pressure loading cylinder sleeve, a first horizontal ground stress loading cylinder sleeve, and a second horizontal ground stress loading cylinder sleeve.

[0057] In some embodiments, the geostress control valve includes a fourth control valve, a fifth control valve, a sixth control valve, and a seventh control valve.

[0058] In some embodiments, the ground stress high-pressure pipeline includes a fourth pipeline, a fifth pipeline, a sixth pipeline, and a seventh pipeline.

[0059] In some embodiments, the pressurized end cap includes a first overburden pressurized end cap, a second overburden pressurized end cap, a first horizontal geostress pressurized end cap, and a second horizontal geostress pressurized end cap.

[0060] In some embodiments, the geostress loading unit may further include a second pressure gauge, and the second pressure gauge is used to display the pressure value applied by the high-pressure servo pump.

[0061] In some embodiments, the high-pressure servo pump, the fourth control valve, and the first horizontal stress-loaded cylinder sleeve are connected through a fourth pipeline; the first horizontal stress-loaded cylinder sleeve and the first horizontal stress-pressurized end cover are connected.

[0062] In some embodiments, the high-pressure servo pump, the fifth control valve, and the second horizontal stress-loaded cylinder sleeve are connected through a fifth pipeline; the second horizontal stress-loaded cylinder sleeve is connected to the second horizontal stress-pressurized end cover.

[0063] In some embodiments, the high-pressure servo pump, the sixth control valve, and the first overburden pressure loading cylinder sleeve are connected via a sixth pipeline; the first overburden pressure loading cylinder sleeve is connected to the first overburden pressurization end cover.

[0064] In some embodiments, the high-pressure servo pump, the seventh control valve, and the second overburden pressure loading cylinder sleeve are connected through a seventh pipeline; the second overburden pressure loading cylinder sleeve is connected to the second overburden pressurization end cover.

[0065] In some embodiments, the sound wave measuring unit further includes a signal transmission line; the sound wave transmitting end, the first sound wave receiving end, the second sound wave receiving end, and the server are connected via the signal transmission line.

[0066] In some embodiments, in order to prevent the drilling fluid from damaging the signal transmission line, a protective shell may be installed outside the signal transmission line, and the contact portion between the protective shell and the pressurized end cover needs to be sealed.

[0067] In some embodiments, the server may be a terminal device with data processing capabilities, such as a desktop computer, a tablet computer, a laptop computer, a smart phone, etc., which is not limited in this description; the server may also display the signal reception time in real time.

[0068] See also Figure 2As shown, the embodiment of this specification also proposes a specific system for predicting the law of formation collapse. Among them, 10 represents a simulated formation, 11 represents a simulated wellbore, 200 represents a high-pressure pump, 201 represents a first pressure gauge, 202 represents a first control valve, 203 represents a first injection port, 204 represents a third control valve, 205 represents a third injection port, 206 represents a second control valve, 207 represents a second injection port, 208 represents a first pipeline, 209 represents a second pipeline, 210 represents a third pipeline, 300 represents a high-pressure servo pump, 301 represents a second pressure gauge, 302 represents a first horizontal ground stress pressurization end cap, 303 represents a second horizontal ground stress pressurization end cap, 304 represents a second overburden pressurization end cap, 305 represents a first overburden pressurization end cap, 306 represents a sealing rubber sleeve, 307 represents a fourth pipeline, and 308 represents a first horizontal ground stress pressurization end cap. 8 represents the fifth pipeline, 309 represents the sixth pipeline, 310 represents the seventh pipeline, 311 represents the fourth control valve, 312 represents the fifth control valve, 313 represents the seventh control valve, 314 represents the sixth control valve, 315 represents the first overburden pressure-loaded cylinder sleeve, 316 represents the second overburden pressure-loaded cylinder sleeve, 317 represents the first horizontal ground stress-loaded cylinder sleeve, 318 represents the second horizontal ground stress-loaded cylinder sleeve, 4 represents the protective shell, 40 represents the sound wave transmitting end, 41 represents the first sound wave receiving end, 42 represents the second sound wave receiving end, 43 represents the signal transmission line, 44 represents the server, 200 may also include a high-pressure pump controller 2, 300 may also include a high-pressure servo pump controller 3, 1 represents the wellbore wall of the simulated wellbore.

[0069] In some embodiments, the above-mentioned formation collapse pressure law prediction can be used in the following way:

[0070] Step 1, control the seventh control valve 313 and the sixth control valve 314 to open, control the high-pressure servo pump 300 to open for pressurization, apply overburden pressure to the first overburden pressure loading cylinder sleeve 315 and the second overburden pressure loading cylinder sleeve 316 through the sixth pipeline 309 and the seventh pipeline 310, and the first overburden pressure loading cylinder sleeve 315 and the second overburden pressure loading cylinder sleeve 316 apply the overburden pressure to the simulated formation 10 by squeezing the first overburden pressure loading end cover 305 and the second overburden pressure loading end cover 304; when the applied overburden pressure reaches 20% of the first pressure preset value, control the seventh control valve 313 and the sixth control valve 314 to close, control the fourth control valve 311 and the fifth control valve 312 to open, and the high-pressure servo pump 300 applies the overburden pressure to the first horizontal stress through the fourth pipeline 307 and the fifth pipeline 308. The loading cylinder sleeve 317 and the second horizontal geostress loading cylinder sleeve 318 apply horizontal geostress. The first horizontal geostress loading cylinder sleeve 317 and the second horizontal geostress loading cylinder sleeve 318 apply horizontal geostress to the simulated formation 10 by squeezing the first horizontal geostress pressurization end cover 302 and the second horizontal geostress pressurization end cover 303. When the applied horizontal geostress reaches 20% of the first pressure preset value, the fourth control valve 311 and the fifth control valve 312 are controlled to be closed, and the seventh control valve 313 and the sixth control valve 314 are controlled to be opened. The above operation is repeated to apply geostress to the simulated formation from the up and down directions and the left and right directions in turn until the applied geostress is equal to the first pressure preset value, and the high-pressure servo pump 300 is closed to obtain a pressurized simulated formation. The first pressure preset value is specifically the overburden pressure of the target formation, which can be obtained based on density logging data.

[0071] Step 2, control the first control valve 202, the third control valve 204, and the second control valve 206 to open, and control the high-pressure pump 200 to open; further, the high-pressure pump 200 injects high-pressure fluid into the pressurized simulated formation through the first pipeline 208 and the first injection port 203, the high-pressure pump 200 injects high-pressure fluid into the pressurized simulated formation through the second pipeline 209 and the second injection port 207, and the high-pressure pump 200 injects drilling fluid into the simulated wellbore 11 in the pressurized simulated formation through the third pipeline 210 and the third injection port 205; when the liquid column pressure in the well is equal to the second pressure preset value, turn off the high-pressure pump 300 to stop the injection, and obtain the target simulated formation; the second pressure preset value is specifically the liquid column pressure in the well of the target formation, which can be calculated based on the drilling fluid density and the drilling fluid column height; wherein, the purpose of injecting high-pressure fluid into the pressurized simulated formation is to generate formation pore pressure; the purpose of injecting drilling fluid into the simulated wellbore in the pressurized simulated formation is to generate liquid column pressure in the well;

[0072] Step 3, control the sound wave transmitting end 40 to open, and transmit the sound wave signal to the target simulated formation. The first sound wave receiving end 41 and the second sound wave receiving end 42 receive the sound wave signal emitted by the sound wave transmitting end 40 and record the signal receiving time. The signal receiving time is transmitted to the server 44 through the signal transmission line 43. The server 44 first receives the signal receiving time, and then determines the longitudinal wave velocity according to the signal receiving time, determines the transverse wave velocity according to the longitudinal wave velocity, determines the rock mechanical characteristic parameters according to the longitudinal wave velocity and the transverse wave velocity, and determines the formation collapse pressure of the target formation according to the rock mechanical characteristic parameters.

[0073] Through the above embodiments, the ground stress, formation pore pressure, and liquid column pressure in the downhole environment can be simulated based on the formation collapse law prediction system to obtain the target simulated formation; the formation collapse pressure of the target simulated formation is further calculated, and the formation collapse pressure of the target simulated formation is used as the formation collapse pressure of the target formation, and the target formation is the real formation.

[0074] This specification also proposes a method for predicting the law of formation collapse, which is applied to the above-mentioned system for predicting the law of formation collapse, see Figure 1 As shown, the method includes:

[0075] S101: The signal receiving time when the first sound wave receiving end receives the sound wave signal is taken as the first time.

[0076] In some embodiments, the first time is recorded as t1.

[0077] S102: The signal receiving time when the second sound wave receiving end receives the sound wave signal is taken as the second time.

[0078] In some embodiments, the first time is recorded as t2.

[0079] S103: Calculate the longitudinal wave velocity according to the first time and the second time.

[0080] In some embodiments, the longitudinal wave velocity may be calculated specifically according to the following formula:

[0081]

[0082] Among them, v p represents the longitudinal wave velocity, and L represents the distance between the first sound wave receiving end and the second sound wave receiving end.

[0083] S104: Calculate the shear wave velocity according to the longitudinal wave velocity.

[0084] S105: Determine rock mechanical characteristic parameters of the target simulated formation according to the longitudinal wave velocity and the shear wave velocity.

[0085] In some embodiments, the above-mentioned rock mechanical property parameters may include: dynamic elastic modulus, dynamic Poisson's ratio, and internal friction angle.

[0086] In some embodiments, determining the rock mechanical characteristic parameters of the target simulated formation according to the longitudinal wave velocity and the shear wave velocity may include:

[0087] The dynamic elastic modulus is calculated according to the following formula:

[0088]

[0089] Among them, E d is the dynamic elastic modulus, ρ is the drilling fluid density, v p is the longitudinal wave velocity, v s is the shear wave velocity.

[0090] The dynamic Poisson's ratio is calculated as follows:

[0091]

[0092] Among them, μ d is the dynamic Poisson's ratio.

[0093] Calculate the internal friction angle according to the following formula:

[0094]

[0095] in, is the internal friction angle.

[0096] S106: Determine the formation collapse pressure of the target simulation formation according to the rock mechanical characteristic parameters of the target simulation formation.

[0097] In some embodiments, the formation collapse pressure of the target simulated formation is determined according to the rock mechanical property parameters of the target simulated formation. In specific implementation, it may include: calculating the equivalent drilling fluid density according to the rock mechanical property parameters of the target simulated formation, and then determining the formation collapse pressure of the target simulated formation according to the equivalent drilling fluid density.

[0098] Specifically, the equivalent drilling fluid density can be calculated according to the following formula:

[0099]

[0100] Among them, ρ m is the equivalent drilling fluid density; η is the rock nonlinear correction coefficient, which can be 0.9-0.95 for shale; σ H is the maximum horizontal ground stress, which can be loaded according to actual conditions; σ his the minimum horizontal ground stress, which can be loaded according to the actual situation; C is the first intermediate parameter; K is the second intermediate parameter; α is the effective stress coefficient, dimensionless, generally 0.5-0.8; P p is the formation pore pressure, which can be determined according to the P-wave velocity; H is the simulated wellbore depth.

[0101] In some embodiments, C and K can be calculated by the following formula:

[0102]

[0103] Among them, V cl Indicates the mud content and can be obtained through logging data.

[0104]

[0105] In some embodiments, when the density of the drilling fluid is greater than or equal to the equivalent drilling fluid density, the fluid column pressure in the well can provide sufficient support for the well wall; therefore, the formation collapse pressure of the target simulated formation can be obtained through the equivalent drilling fluid density.

[0106] S107: Taking the formation collapse pressure of the target simulation formation as the formation collapse pressure of the target formation.

[0107] In some embodiments, after the formation collapse pressure of the target simulated formation is used as the formation collapse pressure of the target formation, the method further includes:

[0108] S1: determining the collapse period of the target formation according to the formation collapse pressure of the target formation;

[0109] S2: Take corresponding wellbore protection measures according to the collapse cycle of the target formation.

[0110] In some embodiments, the above-mentioned well wall protection measures may specifically include increasing the density of the drilling fluid, etc.

[0111] Based on the above-mentioned method for predicting the law of formation collapse, this specification also proposes an embodiment of a device for predicting the law of formation collapse, see Figure 3 As shown, the device for predicting stratum collapse law specifically includes the following modules: a first measurement module 3001, a second measurement module 3002, a first calculation module 3003, a second calculation module 3004, a third calculation module 3005, a fourth calculation module 3006, and a fifth calculation module 3007.

[0112] The first measuring module 3001 is used to take the signal receiving time when the first sound wave receiving end receives the sound wave signal as the first time;

[0113] The second measuring module 3002 is used to use the signal receiving time when the first sound wave receiving end receives the sound wave signal as the second time;

[0114] A first calculation module 3003, used to calculate the longitudinal wave velocity according to the first time and the second time;

[0115] The second calculation module 3004 is used to calculate the shear wave velocity according to the longitudinal wave velocity;

[0116] The third calculation module 3005 is used to determine the rock mechanical characteristic parameters of the target simulated formation according to the longitudinal wave velocity and the shear wave velocity;

[0117] A fourth calculation module 3006 is used to determine the formation collapse pressure of the target simulated formation according to the rock mechanical characteristic parameters of the target simulated formation;

[0118] The fifth calculation module 3007 is used to use the formation collapse pressure of the target simulation formation as the formation collapse pressure of the target formation.

[0119] In some embodiments, the first calculation module 3003 may be used to calculate the longitudinal wave velocity according to the following formula:

[0120]

[0121] In some embodiments, the third calculation module 3005 may be used to calculate the dynamic elastic modulus according to the following formula:

[0122]

[0123] Among them, E d is the dynamic elastic modulus, ρ is the drilling fluid density, v p is the longitudinal wave velocity, v s is the shear wave velocity.

[0124] In some embodiments, the third calculation module 3005 may be further used to calculate the dynamic Poisson's ratio according to the following formula:

[0125]

[0126] Among them, μ d is the dynamic Poisson's ratio.

[0127] In some embodiments, the third calculation module 3005 can also be used to calculate the internal friction angle according to the following formula:

[0128]

[0129] in, is the internal friction angle.

[0130] In some embodiments, the fourth calculation module 3006 can be specifically used to calculate the equivalent drilling fluid density according to the rock mechanical characteristic parameters of the target simulated formation, and then determine the formation collapse pressure of the target simulated formation according to the equivalent drilling fluid density.

[0131] It should be noted that the units, devices or modules described in the above embodiments can be implemented by computer chips or entities, or by products with certain functions. For the convenience of description, the above devices are described separately by functions divided into various modules. Of course, when implementing this specification, the functions of each module can be implemented in the same or more software and / or hardware, or the modules that implement the same function can be implemented by a combination of multiple sub-modules or sub-units. The device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0132] The embodiments of the present specification also provide a computer storage medium for a method for predicting formation collapse laws, wherein the computer storage medium stores computer program instructions, which, when executed, achieve the following: taking the signal receiving time when the first sound wave receiving end receives the sound wave signal as the first time; taking the signal receiving time when the second sound wave receiving end receives the sound wave signal as the second time; calculating the longitudinal wave velocity according to the first time and the second time; calculating the transverse wave velocity according to the longitudinal wave velocity; determining the rock mechanical characteristic parameters of the target simulated formation according to the longitudinal wave velocity and the transverse wave velocity; determining the formation collapse pressure of the target simulated formation according to the rock mechanical characteristic parameters of the target simulated formation; and taking the formation collapse pressure of the target simulated formation as the formation collapse pressure of the target formation.

[0133] In this embodiment, the storage medium includes, but is not limited to, a random access memory (RAM), a read-only memory (ROM), a cache, a hard disk (HDD), or a memory card. The memory may be used to store computer program instructions. The network communication unit may be an interface for network connection communication set in accordance with the standard specified by the communication protocol.

[0134] In this embodiment, the functions and effects specifically implemented by the program instructions stored in the computer storage medium can be explained in comparison with other implementations and will not be described in detail here.

[0135] The present specification also provides a server, including a processor and a memory for storing processor executable instructions. When the processor is implemented, it can perform the following steps according to the instructions: taking the signal reception time when the first sound wave receiving end receives the sound wave signal as the first time; taking the signal reception time when the second sound wave receiving end receives the sound wave signal as the second time; calculating the longitudinal wave velocity according to the first time and the second time; calculating the transverse wave velocity according to the longitudinal wave velocity; determining the rock mechanical characteristic parameters of the target simulated formation according to the longitudinal wave velocity and the transverse wave velocity; determining the formation collapse pressure of the target simulated formation according to the rock mechanical characteristic parameters of the target simulated formation; taking the formation collapse pressure of the target simulated formation as the formation collapse pressure of the target formation.

[0136] In order to complete the above instructions more accurately, refer to Figure 4 As shown, the embodiment of this specification also provides another specific server, wherein the server includes a network communication port 401, a processor 402 and a memory 403, and the above structures are connected through internal cables so that each structure can perform specific data interaction.

[0137] The network communication port 401 may be specifically used to obtain the signal receiving time when the first sound wave receiving end receives the sound wave signal and the signal receiving time when the second sound wave receiving end receives the sound wave signal.

[0138] The processor 402 can be specifically used to use the signal receiving time when the first sound wave receiving end receives the sound wave signal as the first time; use the signal receiving time when the second sound wave receiving end receives the sound wave signal as the second time; calculate the longitudinal wave velocity according to the first time and the second time; calculate the transverse wave velocity according to the longitudinal wave velocity; determine the rock mechanical characteristic parameters of the target simulated formation according to the longitudinal wave velocity and the transverse wave velocity; determine the formation collapse pressure of the target simulated formation according to the rock mechanical characteristic parameters of the target simulated formation; and use the formation collapse pressure of the target simulated formation as the formation collapse pressure of the target formation.

[0139] The memory 403 may be specifically used to store corresponding instruction programs.

[0140] In this embodiment, the network communication port 401 can be a virtual port that is bound to different communication protocols so that different data can be sent or received. For example, the network communication port can be a port responsible for web data communication, a port responsible for FTP data communication, or a port responsible for email data communication. In addition, the network communication port can also be a physical communication interface or communication chip. For example, it can be a wireless mobile network communication chip, such as GSM, CDMA, etc.; it can also be a Wifi chip; it can also be a Bluetooth chip.

[0141] In this embodiment, the processor 402 may be implemented in any appropriate manner. For example, the processor may take the form of a microprocessor or processor and a computer-readable medium storing a computer-readable program code (such as software or firmware) executable by the (micro)processor, a logic gate, a switch, an application specific integrated circuit (ASIC), a programmable logic controller, and an embedded microcontroller, etc. This specification does not limit this.

[0142] In this embodiment, the memory 403 may include multiple levels. In a digital system, anything that can store binary data can be a memory; in an integrated circuit, a circuit with a storage function that has no physical form is also called a memory, such as RAM, FIFO, etc.; in a system, a storage device with a physical form is also called a memory, such as a memory stick, TF card, etc.

[0143] Although the present specification provides method operation steps as described in the embodiments or flow charts, more or less operation steps may be included based on conventional or non-creative means. The order of steps listed in the embodiments is only one way of executing the order of many steps, and does not represent a unique execution order. When the device or client product in practice is executed, it can be executed in sequence or in parallel according to the method shown in the embodiments or the drawings (for example, a parallel processor or a multi-threaded processing environment, or even a distributed data processing environment). The term "include", "include" or any other variant thereof is intended to cover non-exclusive inclusion, so that the process, method, product or device including a series of elements includes not only those elements, but also includes other elements that are not explicitly listed, or also includes elements inherent to such a process, method, product or device. In the absence of more restrictions, it is not excluded that there are other identical or equivalent elements in the process, method, product or device including the elements. The first, second, etc. words are used to represent the name, and do not represent any particular order.

[0144] Those skilled in the art also know that, in addition to implementing the controller in a purely computer-readable program code, the controller can be made to implement the same function in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers by logically programming the method steps. Therefore, such a controller can be considered as a hardware component, and the devices for implementing various functions included therein can also be considered as structures within the hardware component. Or even, the devices for implementing various functions can be considered as both software modules for implementing the method and structures within the hardware component.

[0145] This specification may be described in the general context of computer-executable instructions executed by a computer, such as program modules. Generally, program modules include routines, programs, objects, components, data structures, classes, etc. that perform specific tasks or implement specific abstract data types. This specification may also be practiced in distributed computing environments where tasks are performed by remote processing devices connected through a communication network. In a distributed computing environment, program modules may be located in local and remote computer storage media including storage devices.

[0146] Through the description of the above embodiments, it can be known that those skilled in the art can clearly understand that the present specification can be implemented by means of software plus a necessary general hardware platform. Based on such an understanding, the technical solution of the present specification can essentially be embodied in the form of a software product, which can be stored in a storage medium such as ROM / RAM, a disk, an optical disk, etc., and includes a number of instructions for enabling a computer device (which can be a personal computer, a mobile terminal, a server, or a network device, etc.) to execute the methods described in each embodiment of the present specification or some parts of the embodiments.

[0147] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. This specification can be used in many general or special computer system environments or configurations. For example: personal computers, server computers, handheld devices or portable devices, tablet devices, multi-processor systems, microprocessor-based systems, set-top boxes, programmable electronic devices, network PCs, minicomputers, mainframe computers, distributed computing environments including any of the above systems or devices, etc.

[0148] Although the present specification is described through embodiments, those skilled in the art will appreciate that there are many modifications and changes to the present specification without departing from the spirit of the present specification, and it is intended that the appended claims include these modifications and changes without departing from the spirit of the present specification.

Claims

1. A system for predicting stratum collapse law, characterized in that: The system at least includes a downhole environment simulation unit, a liquid pressure loading unit, a ground stress loading unit, and an acoustic wave measurement unit; Wherein, the downhole environment simulation unit at least includes a simulated formation; the simulated formation includes a simulated wellbore; The geostress loading unit at least comprises a high-pressure servo pump, a geostress high-pressure pipeline, a geostress control valve, and a pressurizing end cover; the high-pressure servo pump applies geostress to the simulated formation through the geostress high-pressure pipeline and the pressurizing end cover to obtain a pressurized simulated formation; the pressurizing end cover is located outside the simulated formation; the geostress control valve is used to control geostress; The liquid pressure loading unit at least includes a high-pressure pump, a fluid injection high-pressure pipeline, and a fluid injection control valve; the high-pressure pump is used to inject high-pressure fluid into the pressurized simulated formation through the fluid injection high-pressure pipeline and to inject drilling fluid into the simulated wellbore inside the pressurized simulated formation to obtain a target simulated formation; wherein the target simulated formation includes a simulated wellbore into which the drilling fluid is injected; the fluid injection control valve is used to control the drilling fluid pressure in the fluid injection high-pressure pipeline; The acoustic wave measurement unit at least includes an acoustic wave transmitting end, a first acoustic wave receiving end, a second acoustic wave receiving end, and a server; the acoustic wave transmitting end, the first acoustic wave receiving end, and the second acoustic wave receiving end are vertically arranged inside a simulated wellbore injected with drilling fluid; the acoustic wave transmitting end is used to transmit an acoustic wave signal to a target simulated formation; the first acoustic wave receiving end and the second acoustic wave receiving end are used to receive the acoustic wave signal and transmit the signal receiving time to the server; the server is used to determine the longitudinal wave velocity according to the signal receiving time, determine the shear wave velocity according to the longitudinal wave velocity, determine the rock mechanical characteristic parameters according to the longitudinal wave velocity and the shear wave velocity, and determine the formation collapse pressure of the target formation according to the rock mechanical characteristic parameters, including: Determine the equivalent drilling fluid density according to the rock mechanical property parameters of the target simulated formation, including dynamic elastic modulus, dynamic Poisson's ratio and internal friction angle; The formation collapse pressure of the target simulated formation is determined according to the equivalent drilling fluid density.

2. The system according to claim 1, characterized in that The downhole environment simulation unit also includes a sealing rubber sleeve; the sealing rubber sleeve is located between the simulated formation and the pressurized end cover; the sealing rubber sleeve is used to seal the simulated formation.

3. The system according to claim 1, characterized in that The liquid pressure loading unit also includes an injection port; the high-pressure pump, the fluid injection control valve, and the injection port are connected via the fluid injection high-pressure pipeline.

4. The system according to claim 1, characterized in that The in-situ stress loading unit further comprises a loading cylinder sleeve; the high-pressure servo pump, the in-situ stress control valve and the loading cylinder sleeve are connected via an in-situ stress high-pressure pipeline; the loading cylinder sleeve is connected to the pressurizing end cover.

5. The system according to claim 1, characterized in that The sound wave measuring unit also includes a signal transmission line; the sound wave transmitting end, the first sound wave receiving end, the second sound wave receiving end, and the server are connected via the signal transmission line.

6. A method for predicting stratum collapse law, characterized in that: The method is applied to the formation collapse law prediction system according to any one of claims 1 to 5, and the method comprises: The signal receiving time when the first sound wave receiving end receives the sound wave signal is taken as the first time; The signal receiving time when the second sound wave receiving end receives the sound wave signal is taken as the second time; Calculate the longitudinal wave velocity according to the first time and the second time; Calculate the shear wave velocity based on the longitudinal wave velocity; Determine the rock mechanical property parameters of the target simulated formation according to the longitudinal wave velocity and the shear wave velocity; Determine the formation collapse pressure of the target simulated formation according to the rock mechanical characteristic parameters of the target simulated formation; The formation collapse pressure of the target simulation formation is taken as the formation collapse pressure of the target formation.

7. The method according to claim 6, characterized in that The rock mechanical characteristic parameters include: dynamic elastic modulus, dynamic Poisson's ratio, and internal friction angle.

8. The method according to claim 6, characterized in that After the formation collapse pressure of the target simulated formation is used as the formation collapse pressure of the target formation, the method further includes: Determining a collapse period of a target formation according to a formation collapse pressure of the target formation; Take corresponding wellbore protection measures according to the collapse cycle of the target formation.

9. A device for predicting stratum collapse law, characterized in that: The device is applied to the stratum collapse law prediction system according to any one of claims 1 to 5, and the device comprises: A first measuring module, configured to use a signal receiving time when the first sound wave receiving end receives the sound wave signal as a first time; A second measuring module, used for taking the signal receiving time when the second sound wave receiving end receives the sound wave signal as the second time; A first calculation module, used for calculating the longitudinal wave velocity according to the first time and the second time; A second calculation module is used to calculate the shear wave velocity according to the longitudinal wave velocity; The third calculation module is used to determine the rock mechanical characteristic parameters of the target simulated formation according to the longitudinal wave velocity and the shear wave velocity; A fourth calculation module is used to determine the formation collapse pressure of the target simulated formation according to the rock mechanical characteristic parameters of the target simulated formation; The fifth calculation module is used to use the formation collapse pressure of the target simulated formation as the formation collapse pressure of the target formation.

10. A computer-readable storage medium, characterized in that: Computer instructions are stored thereon, and when the instructions are executed by a processor, the steps of the method according to any one of claims 6 to 8 are implemented.

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