Device and method for measuring shearing and cementing strength of high-temperature and high-pressure well cementation interface

Abstract

The invention discloses a high-temperature and high-pressure well cementation interface shear cementing strength measuring device and method, and belongs to the field of oil and gas well cementation. The device comprises a kettle body, an oil storage tank, a hydraulic pump, an electric control system, a display, a supporting frame and a base, wherein the kettle body comprises a top cover, an upper kettle, a lower kettle, a bottom cover, a simulation sleeve, a simulation stratum, a positioning steel cylinder, a piston cylinder body, an inner piston, an outer piston and a floating bearing plate. The method comprises the following steps: pouring cement paste into an annular space between a simulation casing and a simulation stratum; curing the cement paste at constant temperature and constant pressure; slowly increasing the pressure of the inner cavity of the piston, and enabling the inner piston to move downwards until the simulation sleeve is separated from the cement sheath; the pressure of the inner cavity of the piston is continuously increased, and the outer piston moves downwards under the pushing action of the inner piston until the cement sheath is separated from the simulated stratum. The test process is controllable, the test result conforms to the underground environment, and an important technical means is provided for optimizing the cement slurry performance and well cementation process parameters and further improving the well cementation quality of an oil and gas well.

Description

Technical Field

[0001] The invention belongs to the field of oil and gas well cementing, and specifically relates to a device and a method for curing an interface shear bonding strength test piece in a high temperature and high pressure environment and measuring the shear bonding strength of one or two interfaces of cementing. Background Art

[0002] Cementing is a key link between oil and gas well drilling and subsequent completion, testing, and oil / gas production. The quality of cementing not only affects whether subsequent operations of a well can be carried out smoothly, but also affects the progress, safety and benefits of oil and gas field exploration and development.

[0003] The main purpose of cementing is, firstly, to fix, support and protect the casing through the cement sheath, to prevent the casing from axial slippage, radial expansion / contraction, corrosion by formation water and other secondary accidents during the subsequent production process, to ensure the life of the oil and gas wells and meet the needs of long-term development of oil and gas fields; secondly, to achieve interlayer isolation of the formation outside the casing and prevent annular flow through good bonding between the cement sheath and the formation and casing. In the subsequent drilling, fracturing and other production processes, due to changes in temperature and pressure in the casing, the interface bonding between the cement sheath and the formation and casing is easily destroyed, resulting in interlayer isolation failure, formation fluid from the wellbore to the wellhead annulus, and abnormal pressure in the wellhead annulus. Therefore, it is particularly important to test, evaluate and control the interface bonding quality between the cement sheath and the formation and casing.

[0004] There are three commonly used evaluation indicators for cementing interface bonding quality: 1) Interface shear bonding strength, that is, the ability of the interface between the casing and the cement sheath (referred to as the first interface) or the interface between the cement sheath and the formation (referred to as the second interface) to resist slippage when subjected to axial shear force; 2) Interface hydraulic bonding strength, that is, the ability of the interface to resist water penetration and channeling after the cement stone is bonded to the casing and the formation; 3) Interface bonding strength, that is, when the formation confining pressure and the casing internal pressure change, the first and second cementing interfaces are subjected to vertical tension and compression, and the interface can resist the casing from separating from the cement stone or the cement stone from the formation.

[0005] The most commonly used measurement is the shear bond strength. Cement slurry is poured into the steel cylinder mold, and the cement slurry is bonded to the steel cylinder after solidification and hardening. Then, a compressive strength tester is used to press down the cement stone cylinder from the steel cylinder to test the force required to break the interface bond between the cement stone cylinder and the steel cylinder. The force is then divided by the area of ​​the interface to obtain the shear bond strength of the interface in the simulated well. If a simulated rock core is placed in the cement slurry, the pressure that loosens the rock core from the cement stone is measured in the same way to calculate the shear bond strength of the two interfaces in the well.

[0006] "An in-situ testing device and method for cement stone bonding strength under simulated high temperature and high pressure underground working conditions" (CN110470596A), "An experimental device and method for testing cement bonding strength of cementing" (CN115931543A), by testing the bonding strength of the first interface of cement sheath under high temperature and high pressure, avoid the risk of structural or strength changes when the cured samples are transferred to indoor room at normal temperature and pressure; "A sample preparation device for cementing interface bonding strength testing" (CN214251753U), by pressurizing the annulus to form virtual mud similar to the actual underground working conditions on the core surface, to test the shear bonding strength of the second interface of cement sheath under normal pressure or pressure holding and setting state. However, the above devices cannot measure the shear bonding strength of the first interface and the second interface at the same time, and cannot explore the influence of changes in casing internal pressure and formation pressure on the interface bonding strength.

[0007] Some scholars also measured the shear bond strength of the first and second interfaces at the same time, and simulated the formation and flushing of drilling mud cake under high temperature and high pressure (Xu Bihua et al. New method for testing the bond strength of oil well cement ring under high temperature and high pressure [J]. Natural Gas Industry, 2016, Vol. 36 (11): 65-69), but the essence is still to maintain under high temperature and high pressure and test the shear bond strength at normal temperature and pressure, which cannot accurately reflect the shear bond strength of the first and second interfaces. The "cement bond strength test device" (CN105422080A) cannot simulate the changes in formation pressure and casing internal pressure, and cannot reflect the interface shear bond strength under actual working conditions.

[0008] It can be seen that the conventional method can only measure the shear bond strength of the first or second cementing interface separately. At the same time, there are also problems such as curing cement stone under high temperature and high pressure and testing the shear bond strength at normal temperature and pressure, and the huge temperature and pressure difference affects the measurement results. Moreover, it is impossible to test the shear bond strength on the first and second cementing interfaces when the formation pressure and casing internal pressure change as needed. Summary of the invention

[0009] The purpose of the present invention is to provide a device for measuring the shear bond strength of the cementing interface at a high temperature and high pressure. The device has a reliable principle and is easy to operate. By curing the test piece in a high temperature and high pressure environment and measuring the shear bond strength of the first and second interfaces of the cementing, the maintenance and testing are integrated, thereby exploring the influence of changes in formation pressure and casing internal pressure on the shear bond strength of the first and second interfaces of the cementing. The device has broad market application prospects.

[0010] Another object of the present invention is to provide a method for measuring the shear bond strength of the high-temperature and high-pressure cementing interface using the above-mentioned device. The test process is controllable and the test results are more in line with the downhole environment. It provides an important technical means for studying the influencing factors of the shear bond strength of the cementing interface, optimizing cement slurry performance and cementing process parameters, and further improving the cementing quality of oil and gas wells.

[0011] In order to achieve the above technical objectives, the present invention adopts the following technical solutions.

[0012] A high-temperature and high-pressure cementing interface shear bond strength measuring device is mainly composed of a top cover, an upper kettle, a lower kettle, a bottom cover, a simulated formation, a simulated casing, a positioning steel cylinder, a floating support plate, a piston cylinder, an inner piston, an outer piston, a pressure regulator, a hydraulic pump, a liquid inlet pressure pipeline with a valve, a gas pipeline, an overflow pipeline with a condensate tank and a back pressure valve, a heating and insulation sleeve, a support frame, an electric control system, a display and a base.

[0013] The top cover is connected to the upper kettle by bolts, and the top cover is provided with two through holes, which are respectively connected to the liquid inlet pressure pipeline and the gas pipeline with valves.

[0014] The upper kettle is a hollow thick-walled cylindrical kettle body with smooth inner wall; a plurality of through holes are arranged on the side, respectively connected with the liquid inlet pressure pipeline, gas pipeline and overflow pipeline; the bottom is a circular flange, which is connected to the lower kettle by bolts.

[0015] The lower kettle is a hollow, thick-walled cylindrical kettle body with a smooth inner wall. It has a corresponding circular flange on the top and is connected to the upper kettle by bolts. There are three sizes of inner diameters in the lower kettle: the upper part has the largest inner diameter, and the step formed is provided with a positioning block to support the positioning steel cylinder; the middle part has the second largest inner diameter, and the floating support plate can slide up and down on its inner wall; the lower part has the smallest inner diameter, and the step formed is used to support the floating support plate; the side is connected to the liquid inlet pressure pipeline and the gas pipeline / overflow pipeline with a valve.

[0016] The bottom cover is connected to the lower kettle through bolts, and a seal is achieved between the two through a sealing ring.

[0017] The simulated stratum is a real stratum cylinder cut from outcropping rocks in the well or a simulated stratum cylinder made of concrete-like materials, which is fixed in a positioning steel cylinder by resin or cement. The upper and lower end surfaces of the simulated stratum are properly polished and smooth, and its lower end surface cooperates with an annular sealing sheet to form a seal.

[0018] The simulation sleeve is a thick-walled metal cylinder with an exhaust hole and a corresponding sealing plug on the upper end face. Liquid is introduced into the inner cavity of the simulation sleeve to exhaust the air. After the exhaust is completed, the sealing plug is tightened to form the inner cavity of the simulation sleeve. Two notches are symmetrically arranged on the lower end face, corresponding to the screws in the positioning groove in the center of the floating support plate, so as to realize the circumferential fixation of the simulation sleeve.

[0019] The positioning steel cylinder is a hollow thick-walled metal cylinder with a convex edge at the lower end. The convex edge sits on the positioning block set at the largest inner diameter part of the lower kettle to achieve positioning of itself and the simulated formation. Circumferential sealing rings are provided on the side surfaces of the convex edge and the side surfaces of the main body, which are respectively sealed with the upper inner wall of the lower kettle and the lower inner wall of the upper kettle.

[0020] The simulated casing, simulated formation and positioning steel cylinder constitute a test piece.

[0021] The floating support plate is provided with a circumferential sealing ring groove and a sealing ring on the side, which cooperate with the inner wall of the lower kettle to achieve sealing, and form the lower chamber of the lower kettle with the bottom cover. There is a boss on the upper part of the floating support plate, and its outer diameter is larger than the inner diameter of the positioning steel cylinder. A groove for fixing the simulation casing is provided on its upper end surface, and positioning grooves for annular sealing gaskets are provided at the positions corresponding to the positioning steel cylinder and the simulation formation. By filling the sealing ring and the annular sealing gasket, under the upward action of the pressure in the lower chamber of the lower kettle, they cooperate with the lower end surfaces of the simulation casing, the positioning steel cylinder and the simulation formation to form a seal and form the upper chamber of the lower kettle. Through the corresponding liquid inlet pressure-injection pipeline and the gas pipeline / test overflow pipeline, the upper chamber of the lower kettle is pressurized, exhausted and overflow tested; a gas channel is provided in the boss, and the pressure of the upper chamber of the lower kettle is transmitted to the simulation casing through the channel.

[0022] The piston cylinder is a thick-walled metal cylinder fixed on the top cover. It cooperates with the inner piston with a sealing ring to form a piston cavity. The piston cavity is exhausted and pressurized through the liquid inlet and pressure-pressurizing pipeline and gas pipeline of the top cover, thereby pushing the inner piston and the outer piston downward to simulate the shear bonding strength of the first and second interfaces of cementing.

[0023] The inner piston is a two-stage solid metal cylinder with a larger upper part and a smaller lower part. A circumferential sealing ring is provided on the outer side of the upper cylinder, which cooperates with the inner wall of the piston cylinder to form a seal and straighten the coaxiality; the diameter of the lower cylinder is 2-3mm smaller than the outer diameter of the simulated casing to ensure that the inner piston will not touch the cement ring when pressing down the simulated casing.

[0024] The outer piston is a thick-walled metal cylinder that is larger at the top and smaller at the bottom. The inner diameter of the upper cylinder matches the outer diameter of the piston cylinder, and the two are sealed and coaxially aligned through a sealing ring; the outer diameter of the lower cylinder is 1.5-2mm smaller than the outer diameter of the cement ring, and the inner diameter is 1.5-2mm larger than the inner diameter of the cement ring; after the inner piston presses down the simulated casing, destroys the simulated cementing interface, and continues to move downward for a certain distance, the outer piston moves downward under the push of the inner piston, thereby pressing down the cement ring to test the shear bonding strength of the simulated cementing interface.

[0025] The pressure regulator can control the pressure of each chamber automatically or manually.

[0026] The liquid inlet pressure pipelines are used to pressure the liquid inlet to each chamber, and are all high-pressure pipelines to increase the pressure level of the device.

[0027] The overflow pipeline with the condensation tank and the back pressure valve is used to discharge the corresponding volume of liquid when the piston cylinder is pressurized, the inner / outer piston moves downward, the simulated casing / cement ring moves downward, and the volume of the upper kettle outer cavity and the lower kettle upper cavity increases, so as to maintain the stability of the pressure of the upper kettle outer cavity and the lower kettle upper cavity to prevent their changes from affecting the accuracy of the test results.

[0028] The condensation tank, after being connected to a tap water source, is used to cool the high-temperature and high-pressure fluid discharged from the kettle body to prevent the high-temperature fluid from damaging the downstream back-pressure valve.

[0029] The back pressure valve is used to adjust the back pressure of the overflow liquid from the kettle during the test, ensuring the pressure stability of the upper kettle outer cavity and the lower kettle upper cavity, and avoiding the influence of pressure fluctuation on the test results.

[0030] The hydraulic pump is a high-pressure pump, which is connected to the liquid inlet pressure pipeline to pressurize and relieve the pressure of each chamber.

[0031] The electric control system sets, controls and displays the temperature and pressure of the outer cavity of the upper kettle, the inner cavity of the piston, the upper cavity of the lower kettle and the lower cavity of the lower kettle.

[0032] The kettle body is supported by a supporting frame fixed to a base, and the outer wall is covered with a heating and heat-insulating jacket.

[0033] The support frame is constructed of square steel, aluminum profiles and other similar materials, and is fixed on the base of the device to fix and support the kettle body and corresponding pipelines to prevent them from becoming unstable or shifting during installation and testing.

[0034] The base is made of steel plates or similar materials and is used to install the support frame. The bottom is provided with movable and positionable universal wheels to facilitate the movement and positioning of the device.

[0035] The method for measuring the shear bond strength of the high-temperature and high-pressure cementing interface using the above device comprises the following steps in sequence:

[0036] (1) Pressurize the lower chamber of the lower kettle to form an effective seal between the boss of the pressure transmission support plate and the lower end surface of the specimen, remove the top cover of the upper kettle, and slowly pour the prepared cement slurry into the annular space between the simulated casing and the simulated formation;

[0037] (2) Let the liquid enter the inner cavity of the simulated casing and exhaust the air, then tighten the plug of the exhaust hole of the simulated casing and connect the upper kettle with the top cover;

[0038] (3) Liquid is introduced into and exhausted from the outer cavity of the upper kettle and the inner cavity of the piston, the pressure of the outer cavity of the upper kettle, i.e., the confining pressure of the formation, is set, pressure is applied to the upper cavity of the lower kettle and the inner cavity of the simulated casing, i.e., the inner pressure of the casing, the kettle body is heated and the temperature is increased. When the temperature reaches the set target, the cement slurry is cured at a constant temperature and pressure;

[0039] (4) After the cement slurry is cured to the set age, the pressure in the lower chamber of the lower kettle is reduced to a level lower than the pressure in the upper chamber of the lower kettle. The floating support plate is separated from the lower end surface of the specimen and moves downward until it is seated on the last step in the lower kettle. The valve of the liquid inlet pressure test pipeline in the lower chamber of the lower kettle is closed.

[0040] (5) Open the overflow pipeline valves of the upper kettle outer chamber and the lower kettle upper chamber, slowly increase the pressure in the piston cavity, and the inner piston moves downward to press the simulated casing until the simulated casing is separated from the cement ring; continue to increase the pressure in the piston cavity, and the outer piston moves downward under the pushing action of the inner piston to press the cement ring until the cement ring is separated from the simulated formation;

[0041] (6) Calculate the shear bond strength of the first and second interfaces of the simulated cementing:

[0042] Cementing-interface shear bond strength

[0043] Shear bond strength of cementing interface

[0044] Where P 1 is the cementing-interface shear bond strength, kPa;

[0045] P 2 is the shear bond strength of the cementing interface, kPa;

[0046] P D is the pressure of the upper chamber of the lower kettle, kPa;

[0047] F 1 The maximum force to simulate the moment when the casing is separated from the cement sheath, kN;

[0048] F 2 is the maximum force at the moment when the cement sheath separates from the simulated stratum, kN;

[0049] A 1 is the contact area between the simulated casing and cement sheath, m 2 ;

[0050] A 2 is the contact area between cement sheath and simulated formation, m 2 .

[0051] Furthermore, by changing the pressure of the upper kettle outer chamber and the pressure of the lower kettle upper chamber, the shear bonding strength of the first and second cementing interfaces under different formation confining pressures and casing internal pressures was tested.

[0052] Compared with the prior art, the present invention has the following beneficial effects:

[0053] 1) Curing and testing the shear bonding strength of the first and second interfaces of the simulated cementing under high temperature and high pressure avoids the problem of curing under high temperature and high pressure in the conventional method but having to cool down and reduce pressure before testing the shear bonding strength of the interface under normal pressure;

[0054] 2) The pressure inside the simulated casing was adjusted by a hydraulic pump to test the shear bond strength when there were different radial pressure differences inside and outside the simulated casing, so as to study the effect of pressure changes inside the simulated casing on the interface shear bond strength;

[0055] 3) By replacing the simulated casing with different outer diameters and the matching floating support plates, the shear bond strength corresponding to cement sheaths with different thicknesses was obtained, thereby studying the effect of cement sheath thickness on the interface shear bond strength;

[0056] 4) It can significantly reduce the complexity of experimental operations and greatly reduce the development cost and experimental cost of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 This is a cross-sectional view of the high-temperature and high-pressure cementing interface shear bond strength measurement device.

[0058] Figure 2 A schematic diagram of the overall structure of the device.

[0059] In the figure: 1—gas pipeline; 2—top cover; 3—sealing ring; 4—gas pipeline; 5—valve; 6—valve; 7—condensate tank; 8—back pressure valve; 9—overflow pipeline; 10—upper kettle; 11—upper kettle outer cavity; 12—piston cylinder; 13—piston inner cavity; 14—inner piston; 15—outer piston; 16—simulated casing inner cavity; 17—connecting bolt; 18—lower kettle; 19—support frame; 20—pressure gauge; 21—valve; 22—pressure regulator; 23—liquid inlet pressure pipeline; 24—plug; 25—simulated casing; 26—simulated formation; 27—positioning steel cylinder; 28—liquid inlet pressure pipeline; 29—lower kettle upper cavity; 30—floating support plate; 31—lower kettle lower cavity; 32—bottom cover; 33—oil storage tank; 34—hydraulic pump; 35—electric control system; 36—display; 37—base. DETAILED DESCRIPTION

[0060] The present invention is further described below with reference to the accompanying drawings and embodiments, so that those skilled in the art can understand the present invention. However, it should be clear that the embodiments described are part of the embodiments of the present application, not all of the embodiments. For those skilled in the art, all other embodiments obtained without creative work are protected.

[0061] A high-temperature and high-pressure cementing interface shear bond strength measuring device comprises a kettle body, an oil storage tank 33, a hydraulic pump 34, an electronic control system 35, a display 36, a support frame 19 and a base 37. The kettle body is supported by the support frame 19 fixed to the base 37. The kettle body is connected to the oil storage tank 33, the hydraulic pump 34, the electronic control system 35 and the display 36 in sequence. A heating and heat preservation sleeve is arranged on the outer wall of the kettle body to connect to the temperature control system. The kettle body comprises a top cover 2, an upper kettle 10, a lower kettle 18, a bottom cover 32, a simulated casing 25, a simulated formation 26, a positioning steel cylinder 27, a piston cylinder 12, an inner piston 14, an outer piston 15 and a floating support plate 30.

[0062] The top cover 2 is connected to the upper kettle 10 by bolts, the bottom cover 32 is connected to the lower kettle 18 by bolts, the upper kettle and the lower kettle are flange-connected by connecting bolts 17, and a test piece is placed in the upper kettle. The test piece is composed of a simulated casing 25, a simulated formation 26 and a positioning steel cylinder 27 from the inside to the outside. An annular space is formed between the simulated casing and the simulated formation. The simulated formation is fixed in the positioning steel cylinder by resin or cement, and a seal is achieved between the positioning steel cylinder and the inner wall of the upper kettle; the piston cylinder 12 is placed above the test piece, and the test piece is placed in the upper kettle. The floating support plate 30 is located below the parts; the lower kettle has three sizes of inner diameters: the upper inner diameter is the largest, and the step formed is provided with a positioning block to support the positioning steel cylinder 27; the middle inner diameter is the second largest, and the floating support plate 30 can slide up and down on its inner wall; the lower inner diameter is the smallest, and the step formed is used to support the floating support plate; the piston cylinder 12 is a thick-walled metal cylinder fixed to the top cover, and the piston cylinder forms a piston cavity 13 through the inner piston 14, and the piston cavity is connected to the liquid inlet pressure pipeline through the two through holes of the top cover. 23 and gas pipeline 1, the piston cylinder body forms an upper kettle outer chamber 11 through the outer piston 15, and the upper kettle outer chamber is provided with a liquid inlet pressure pipeline 28, a gas pipeline 4 and an overflow pipeline 9; the inner piston is a double-stage cylinder with a larger upper portion and a smaller lower portion, the upper cylinder cooperates with the inner wall of the piston cylinder to form a seal, and the diameter of the lower cylinder is smaller than the outer diameter of the simulation casing; the outer piston is a thick-walled cylinder with a larger upper portion and a smaller lower portion, the upper cylinder cooperates with the outer wall of the piston cylinder to achieve a seal, the outer diameter of the lower cylinder is smaller than the outer diameter of the cement ring, and the inner diameter is larger than the outer diameter of the water ring The inner diameter of the mud ring; the floating support plate 30 is sealed by cooperating with the inner wall of the lower kettle through the circumferential sealing ring on the side, and forms a lower kettle lower cavity 31 with the bottom cover 32. There is a boss on the top of the floating support plate, and the outer diameter of the boss is larger than the inner diameter of the positioning steel cylinder. When the boss fits with the lower end surface of the specimen, an upper cavity 29 of the lower kettle is formed. The upper cavity 29 of the lower kettle and the lower cavity 31 of the lower kettle are both provided with a liquid inlet pressure pipeline and an overflow pipeline, and a gas channel is provided in the boss, through which the pressure of the upper cavity of the lower kettle is transmitted to the inner cavity 16 of the simulation casing.

[0063] Furthermore, a groove for fixing the simulated casing is provided in the center of the boss of the floating support plate, and a positioning groove for an annular sealing gasket is provided corresponding to the position of the positioning steel cylinder and the simulated formation. By filling the sealing ring and the annular sealing gasket, a seal is formed with the lower end surface of the specimen under the upward action of the pressure in the lower chamber of the lower kettle.

[0064] Furthermore, the upper end surface of the simulation sleeve is provided with an exhaust hole and a corresponding sealing plug 24, through which the exhaust hole is used to exhaust the liquid in the simulation sleeve, and the sealing plug is tightened to form the inner cavity 16 of the simulation sleeve, and the lower end surface is circumferentially fixed by the groove in the center of the floating support plate boss.

[0065] Furthermore, the lower end of the positioning steel cylinder has a convex edge, and a positioning block is arranged at a position on the inner wall of the lower kettle corresponding to the convex edge to further fix the positioning steel cylinder.

[0066] Furthermore, the inner cavity of the piston is exhausted and pressurized through the liquid inlet and pressure-pressurizing pipelines and gas pipelines at the top cover, and the inner piston and the outer piston are pushed downward to test the shear bonding strength of the first and second cementing interfaces respectively.

[0067] Furthermore, the inner piston has a circumferential sealing ring on the outer side of the upper cylinder, which cooperates with the inner wall of the piston cylinder to form a seal and straighten the coaxiality. The diameter of the lower cylinder is 2-3mm smaller than the outer diameter of the simulated casing, ensuring that the inner piston will not touch the cement ring when pressing down the simulated casing, thereby testing the shear bonding strength of the cementing interface.

[0068] Furthermore, the inner diameter of the upper cylinder of the outer piston matches the outer diameter of the piston cylinder, and the two are sealed and coaxially aligned through a sealing ring. The outer diameter of the lower cylinder is 1.5-2mm smaller than the outer diameter of the cement ring, and the inner diameter is 1.5-2mm larger than the inner diameter of the cement ring. After the inner piston presses down the simulated casing and destroys the first cementing interface, it continues to move downward for a certain distance. Under the push of the inner piston, the outer piston moves downward and presses the cement ring to test the shear bonding strength of the second cementing interface.

[0069] Furthermore, a pressure gauge 20, a valve 21 and a pressure regulator 22 are provided on the liquid inlet pressure-pressurizing pipeline 23, and the pressure regulator controls the pressure of each chamber.

[0070] Furthermore, the oil overflow pipeline 9 is provided with a valve 6, a condensation tank 7 and a back pressure valve 8. The valve is used to isolate or connect the condensation tank and the back pressure valve at the rear end. The overflowed hot oil is discharged after being cooled in the condensation tank to prevent high-temperature liquid from entering and damaging the back pressure valve.

[0071] The method for measuring the shear bond strength of the high-temperature and high-pressure cementing interface using the above device comprises the following steps in sequence:

[0072] Prepare and fix the simulated stratum 26: Take a thick glass plate, apply a layer of butter on the surface, place the positioning steel cylinder on it, put the prepared simulated stratum ring into the steel cylinder, and pour cement slurry into the annulus between the simulated stratum and the inner wall of the steel cylinder, and wait for it to solidify and harden.

[0073] Install the positioning steel cylinder 27 and the simulated casing 25: place the floating support plate 30 on the last step of the lower kettle 18; start the hydraulic pump to fill and exhaust the lower chamber of the lower kettle, pressurize the lower chamber of the lower kettle, push the floating support plate upward, place the positioning steel cylinder 27 with simulated strata on the floating support plate, and place the simulated casing 25 with a sealing ring in the central groove of the floating support plate.

[0074] Pour cement slurry and connect the upper kettle 10 and the lower kettle 18: prepare cement slurry as required, slowly pour it into the annulus between the simulated casing and the simulated formation to achieve the connection and sealing of the upper kettle and the lower kettle, and tighten the bolts 17.

[0075] Apply initial pressure to the lower chamber 31 of the lower kettle: start the corresponding pressure regulator to ensure that the pressure transmission support plate 30 can always support the cement slurry and the simulated casing.

[0076] Liquid inlet and exhaust: Liquid is inlet and exhaust is conducted to the upper chamber 29 of the lower kettle through the exhaust hole of the simulated sleeve. After exhaust is completed, the plug of the exhaust hole is tightened to seal the inner chamber 16 of the simulated sleeve. After installing the top cover, liquid is inlet and exhaust is conducted to the inner chamber 13 of the piston and the outer chamber 11 of the upper kettle.

[0077] Apply initial pressure to the outer cavity 11 of the upper kettle, the inner cavity 13 of the piston, the upper cavity 29 of the lower kettle and the inner cavity 16 of the simulated casing: turn on the hydraulic pump to apply pressure to each cavity. The pressure in the outer cavity of the upper kettle is slightly higher than the pressure in the upper cavity of the lower kettle and the inner cavity of the simulated casing to prevent the simulated casing from moving upward.

[0078] Cement slurry waiting for setting: Heat the kettle body, and when the temperature reaches the set target, maintain the cement slurry at constant temperature and pressure until the set age.

[0079] Measure the initial bonding strength of the simulated cementing interface: reduce the pressure of the upper kettle outer chamber to the pressure of the lower kettle upper chamber; reduce the pressure of the lower chamber of the lower kettle to a level 0.5 MPa lower than the pressure of the upper chamber of the lower kettle, separate the floating support plate from the lower end surface of the specimen, move downward until it is seated on the step in the lower kettle, close the valve of the liquid inlet pressure pipeline of the lower chamber of the lower kettle, and open the valve of the overflow pipeline; slowly increase the pressure in the piston cavity until the simulated casing moves downward and the pressure in the piston cavity drops, thereby obtaining the pressure difference that drives the simulated casing to move, and calculate the initial shear bonding strength of the cementing interface when there is no pressure difference inside and outside the simulated casing.

[0080] When measuring the change in the casing pressure, simulate the bonding strength of the cementing interface: slowly and synchronously increase or decrease the pressure of the upper kettle outer cavity and the lower kettle upper cavity to the set target pressure to ensure that the upper and lower pressure differences of the casing are basically balanced, and then gradually open the back pressure valve until it drips, and complete the setting of the back pressure valve target pressure; gradually increase the pressure in the piston cavity until the simulated casing is pushed down again and the pressure in the piston cavity drops suddenly. At this time, the pressure difference between the piston cavity and the upper kettle outer cavity is the upper and lower pressure difference required to overcome the interface shear bonding strength caused by the radial pressure difference of the simulated casing. Based on this, the shear bonding strength caused by the radial pressure difference can be calculated; repeat this step to obtain more interface shear bonding strengths under the radial pressure difference of the simulated casing until the inner piston contacts the outer piston, the outer piston starts to press down the cement ring, and the pressure rises sharply.

[0081] Measure the initial bonding strength of the simulated cementing interface: After the outer piston contacts the cement ring, continue to increase the pressure in the piston cavity, and push the inner and outer pistons downward at the same time, and press down the simulated casing and cement ring synchronously. Test to obtain the upper and lower pressure differences required to destroy the simulated two interfaces, and calculate the corresponding shear bonding strength of the two interfaces. Gradually reduce the target pressure of the upper kettle outer cavity, the lower kettle upper cavity, and the corresponding overflow pipeline back pressure valve, starting from the initial maintenance pressure of the cement ring, first measure the shear bonding strength of the two interfaces under zero radial pressure difference, and then gradually increase the target pressure of the upper kettle outer cavity, the lower kettle upper cavity, and the corresponding overflow pipeline back pressure valve, and measure the shear bonding strength of the two interfaces under different radial pressure differences.

Claims

1. A high-temperature and high-pressure cementing interface shear bond strength measuring device, comprising a kettle, an oil storage tank (33), a hydraulic pump (34), an electronic control system (35), a display (36), a support frame (19) and a base (37), wherein the kettle is supported by a support frame fixed to the base, the kettle is connected to the oil storage tank, the hydraulic pump, the electronic control system and the display in sequence, and a heating and heat preservation sleeve is arranged on the outer wall of the kettle body to connect to the temperature control system, characterized in that: The kettle body comprises a top cover (2), an upper kettle (10), a lower kettle (18), a bottom cover (32), a simulated casing (25), a simulated formation (26), a positioning steel cylinder (27), a piston cylinder (12), an inner piston (14), an outer piston (15) and a floating support plate (30). The top cover (2) is connected to the upper kettle (10) by bolts, the bottom cover (32) is connected to the lower kettle (18) by bolts, the upper kettle and the lower kettle are connected by flanges, and a test piece is placed in the upper kettle. The test piece is, from inside to outside, the simulated casing (25), the simulated formation (26) and the positioning steel cylinder (27). ), an annular space is formed between the simulated casing and the simulated formation, the simulated formation is fixed in the positioning steel cylinder by resin or cement, and the positioning steel cylinder is sealed with the inner wall of the upper kettle; the piston cylinder (12) is above the test piece, and the floating support plate (30) is below the test piece; there are three sizes of inner diameters in the lower kettle: the upper inner diameter is the largest, and the step formed is provided with a positioning block to support the positioning steel cylinder (27); the middle inner diameter is the second largest, and the floating support plate (30) can slide up and down on its inner wall; the lower inner diameter is the smallest, and the step formed is used to support the floating support plate; the piston cylinder (12) is a thick-walled fixed to the top cover A metal cylinder, wherein an inner piston (14) is formed inside the piston cylinder to form a piston inner cavity (13), the piston inner cavity is connected to a liquid inlet pressure pipeline and a gas pipeline respectively through two through holes of a top cover, and an outer piston (15) is formed outside the piston cylinder to form an upper kettle outer cavity (11), and a liquid inlet pressure pipeline, a gas pipeline and an overflow pipeline are arranged in the upper kettle outer cavity; the inner piston is a double-stage cylinder with a larger upper portion and a smaller lower portion, the upper cylinder cooperates with the inner wall of the piston cylinder to form a seal, and the diameter of the lower cylinder is smaller than the outer diameter of the simulation sleeve; the outer piston is a thick-walled cylinder with a larger upper portion and a smaller lower portion, the upper cylinder cooperates with the outer wall of the piston cylinder to achieve a seal, and the lower cylinder The outer diameter of the cylinder is smaller than the outer diameter of the cement ring, and the inner diameter is larger than the inner diameter of the cement ring; the floating support plate (30) is sealed by cooperating with the inner wall of the lower kettle through the circumferential sealing ring on the side, and forms a lower kettle lower cavity (31) with the bottom cover (32); a boss is provided on the top of the floating support plate, and the outer diameter of the boss is larger than the inner diameter of the positioning steel cylinder. When the boss is in contact with the lower end surface of the test piece, an upper cavity (29) of the lower kettle is formed. The upper cavity (29) of the lower kettle and the lower cavity (31) of the lower kettle are both provided with a liquid inlet pressure pipeline and an overflow pipeline, and a gas channel is provided in the boss, through which the pressure of the upper cavity of the lower kettle is transmitted to the inner cavity (16) of the simulation casing.

2. A high temperature and high pressure cementing interface shear bond strength measuring device as claimed in claim 1, characterized in that: A groove for fixing the simulated casing is provided in the center of the boss of the floating support plate, and a positioning groove for an annular sealing gasket is provided corresponding to the position of the positioning steel cylinder and the simulated formation. By filling the sealing ring and the annular sealing gasket, a seal is formed with the lower end surface of the specimen under the upward action of the pressure in the lower chamber of the lower kettle.

3. A high temperature and high pressure cementing interface shear bond strength measuring device as claimed in claim 1, characterized in that: The upper end surface of the simulation sleeve is provided with an exhaust hole and a corresponding sealing plug. The exhaust hole is used to exhaust the liquid in the simulation sleeve. The sealing plug is tightened to form the inner cavity of the simulation sleeve. The lower end surface is circumferentially fixed by the groove in the center of the floating support plate boss.

4. A high temperature and high pressure cementing interface shear bond strength measuring device as claimed in claim 1, characterized in that: The lower end of the positioning steel cylinder has a convex edge, and a positioning block is arranged at a position corresponding to the convex edge on the inner wall of the lower kettle to further fix the positioning steel cylinder.

5. The high temperature and high pressure cementing interface shear bond strength measuring device according to claim 1, characterized in that: The inner piston has a circumferential sealing ring on the outer side of the upper cylinder, which cooperates with the inner wall of the piston cylinder to form a seal and straighten the coaxiality. The diameter of the lower cylinder is 2-3mm smaller than the outer diameter of the simulation sleeve.

6. A high temperature and high pressure cementing interface shear bond strength measuring device as claimed in claim 1, characterized in that: The inner diameter of the upper cylinder of the outer piston matches the outer diameter of the piston cylinder, and the sealing and coaxial alignment are achieved through a sealing ring. The outer diameter of the lower cylinder is 1.5-2mm smaller than the outer diameter of the cement ring, and the inner diameter is 1.5-2mm larger than the inner diameter of the cement ring.

7. A high temperature and high pressure cementing interface shear bond strength measuring device as claimed in claim 1, characterized in that: The liquid inlet pressure-pressurizing pipeline is provided with a pressure gauge, a valve and a pressure regulator.

8. The high temperature and high pressure cementing interface shear bond strength measuring device according to claim 1, characterized in that: The oil overflow pipeline is provided with a valve, a condensate tank and a back pressure valve.

9. A method for measuring the shear bond strength of a high-temperature and high-pressure cementing interface using the device of claim 1, 2, 3, 4, 5, 6, 7 or 8, comprising the following steps in sequence: (1) Pressurize the lower chamber of the lower kettle to form an effective seal between the boss of the pressure transmission support plate and the lower end surface of the specimen, remove the top cover of the upper kettle, and slowly pour the prepared cement slurry into the annular space between the simulated casing and the simulated formation; (2) Let the liquid enter the inner cavity of the simulated casing and exhaust the air, then tighten the plug of the exhaust hole of the simulated casing and connect the upper kettle with the top cover; (3) Liquid is introduced into and exhausted from the outer cavity of the upper kettle and the inner cavity of the piston, the pressure of the outer cavity of the upper kettle, i.e., the confining pressure of the formation, is set, pressure is applied to the upper cavity of the lower kettle and the inner cavity of the simulated casing, i.e., the inner pressure of the casing, the kettle body is heated and the temperature is increased. When the temperature reaches the set target, the cement slurry is cured at a constant temperature and pressure; (4) After the cement slurry is cured to the set age, the pressure in the lower chamber of the lower kettle is reduced to a level lower than the pressure in the upper chamber of the lower kettle. The floating support plate is separated from the lower end surface of the specimen and moves downward until it is seated on the last step in the lower kettle. The valve of the liquid inlet pressure test pipeline in the lower chamber of the lower kettle is closed. (5) Open the overflow pipeline valves of the upper kettle outer chamber and the lower kettle upper chamber, slowly increase the pressure in the piston inner chamber, and move the inner piston downward to press down the simulated casing until the simulated casing is separated from the cement ring; The pressure in the piston cavity is continuously increased, and the outer piston moves downward under the pushing action of the inner piston to press down the cement ring until the cement ring is separated from the simulated formation; (6) Calculate the shear bond strength of the first and second interfaces of the simulated cementing.

10. The method according to claim 9, characterized in that In the step (6), the shear bonding strength of the first and second interfaces of the simulated cementing is calculated as follows: Cementing-interface shear bond strength Shear bond strength of cementing interface Where P1 is the cementing-interface shear bond strength, kPa; P2 is the shear bond strength of the cementing interface, kPa; P D is the pressure of the upper chamber of the lower kettle, kPa; F1 is the maximum force at the moment when the casing is separated from the cement sheath, kN; F2 is the maximum force at the moment when the cement sheath separates from the simulated formation, kN; A1 is the contact area between the simulated casing and cement sheath, m 2 ; A2 is the contact area between cement sheath and simulated formation, m 2 .

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