A device and method for simulating the formation breathing effect

Abstract

This application provides a formation breathing effect simulation device and method, relating to the field of laboratory experimental technology for drilling and completion in the oil and gas industry. It includes a simulated formation system, a fluid supply system, and a true triaxial testing machine; the testing machine is equipped with a heating component; the simulated formation system is located within the testing machine and includes upper and lower simulated formations, which contact to form simulated formation fractures, and both form a simulated wellbore with injection channels; the wellbore penetrates the upper formation but not the lower formation; a displacement sensor is installed in the lower simulated formation; the fluid supply system includes first, second, and third branches; the first branch includes a first drilling fluid container, a hydraulic pump, and a first valve; the second branch includes a second valve and a second drilling fluid container; the first and second branches are connected by a connecting channel, and the third branch includes a pressure gauge and a third valve. This solution addresses the technical problem of failing to clarify the generation mechanism and stage characteristics of the formation breathing effect under actual stress and temperature conditions due to neglecting formation temperature.

Description

Technical Field

[0001] This application relates to the field of laboratory experimental technology for drilling and completion in the oil and gas industry, and in particular to a formation breathing effect simulation device and method. Background Technology

[0002] Global offshore oil and gas resources are abundant and of profound strategic energy significance. Offshore oil and gas reserves account for approximately one-third of the world's total. More than half of these resources are located on shallow continental shelves, making them the forefront and future main battleground of the global oil industry. Offshore oil and gas exploration and development is a continuation of onshore exploration and development, evolving from shallow to deep seas and from simple to complex methods. Offshore oil and gas exploration is becoming increasingly common, with offshore drilling operations spanning all sea areas globally, and the water depth for offshore oil and gas development has advanced by leaps and bounds.

[0003] However, offshore drilling conditions are relatively harsh, and the actual drilling and development process faces extremely severe technical challenges, one of which is the formation breathing effect. The "formation breathing effect" refers to the phenomenon where a small, continuous amount of fluid leaks from the wellbore during drilling fluid circulation, and then flows back into the wellbore when the circulation stops. In complex formations, when well kicks and the breathing effect coexist, misjudgments are highly likely, increasing the difficulty of well control. Improper handling can lead to additional time and costs, or even wellbore failure.

[0004] In existing technologies, the influence of different pressures on formation breathing effect is mainly studied by adjusting the formation pressure value, but the formation temperature environment is not considered, so it is impossible to clarify the generation mechanism and stage characteristics of formation breathing effect under real stress and formation temperature conditions. Summary of the Invention

[0005] This application provides a formation breathing effect simulation device and method to solve the technical problem that the prior art does not consider the formation temperature environment during the experiment, which makes it impossible to clarify the generation mechanism and stage characteristics of the formation breathing effect under real ground stress and formation temperature conditions.

[0006] In a first aspect, embodiments of this application provide a formation breathing effect simulation device, including a formation simulation system, a liquid supply system, and a true triaxial testing machine;

[0007] The true triaxial testing machine is equipped with a heating component, and the simulated formation system is installed inside the true triaxial testing machine;

[0008] The simulated formation system includes: an upper simulated formation and a lower simulated formation; the contact surface between the upper simulated formation and the lower simulated formation forms a simulated formation fracture; the upper simulated formation and the lower simulated formation are jointly provided with a simulated wellbore, and the simulated wellbore is provided with injection channels; wherein, the simulated wellbore penetrates the upper simulated formation but does not penetrate the lower simulated formation;

[0009] Multiple displacement sensors are installed outside the lower simulated stratum.

[0010] The liquid supply system includes: a first branch, a second branch, and a third branch;

[0011] The first branch is sequentially equipped with a first drilling fluid container, a hydraulic pump, and a first valve; the second branch is sequentially equipped with a second valve and a second drilling fluid container.

[0012] The first branch and the second branch are simultaneously connected to the injection channel via the third branch, and a pressure gauge and a third valve are provided on the third branch.

[0013] In one possible implementation, a plurality of grooves are provided on the exterior of the lower simulated stratum, and the displacement sensor is installed in each of the grooves.

[0014] In one possible implementation, if the plurality of grooves are arranged in a circular array around the simulated wellbore, then the plurality of displacement sensors are used together to detect the average opening of the simulated formation fractures.

[0015] In one possible implementation, the plurality of grooves are distributed at equal intervals along a preset path, and the plurality of displacement sensors are used together to detect the gradual change in the opening of the simulated formation fracture.

[0016] In one possible implementation, a first electronic scale is also provided on the first branch, and a second electronic scale is also provided on the second branch;

[0017] The first drilling fluid container is placed on the first electronic scale, and the second drilling fluid container is placed on the second electronic scale.

[0018] In one possible implementation, it further includes: a wireless signal receiver;

[0019] The displacement sensor is a wireless sensor;

[0020] The wireless signal receiver is used to acquire the opening of the simulated formation fracture from the displacement sensor via wireless signal.

[0021] In one possible implementation, the first valve and the second valve are both one-way valves, and the third valve is a back pressure valve.

[0022] When calculating the leakage, the drilling fluid in the first drilling fluid container flows sequentially through the first valve and the third valve to the simulated wellbore;

[0023] When calculating the backflow rate, the drilling fluid in the simulated wellbore flows sequentially through the third valve and the second valve to the second drilling fluid container.

[0024] In one possible implementation, it further includes: a pressure-resistant sealed box;

[0025] The simulated formation system is installed inside the pressure-resistant sealing box, which is installed inside the true triaxial testing machine.

[0026] Secondly, embodiments of this application provide a method for simulating formation breathing effects. The method is used in the formation breathing effect simulation device provided in the first aspect of this application. The device includes: a simulated formation system, a fluid supply system, and a true triaxial testing machine. The fluid supply system includes a first valve, a second valve, a third valve, a hydraulic pump, a first drilling fluid container, and a second drilling fluid container. The true triaxial testing machine is equipped with a heating component. The method then includes:

[0027] The simulated formation system is immersed in drilling fluid until the immersion time reaches a preset time, resulting in a saturated simulated formation system.

[0028] The saturated simulated formation system is installed inside the true triaxial testing machine;

[0029] Open the first valve and the third valve, close the second valve, zero the weight of the second drilling fluid container, apply confining pressure through the true triaxial testing machine, and turn on the heating assembly;

[0030] When the saturated simulated formation system reaches the first preset pressure and preset temperature, the first weight of the first drilling fluid container is recorded, the hydraulic pump is turned on, and the drilling fluid in the first drilling fluid container is pumped to the saturated simulated formation system through the hydraulic pump until the saturated simulated formation system experiences a formation breathing effect. Then, the first valve, the third valve, and the hydraulic pump are closed, and the second weight of the first drilling fluid container is recorded.

[0031] Open the second valve and gradually open the third valve. When the pressure of the saturated simulated formation system gradually decreases to the second preset pressure, close the second valve and the third valve, and record the third weight of the second drilling fluid container.

[0032] The leakage and backflow of the drilling fluid are obtained based on the first weight, the second weight, and the third weight.

[0033] Open the second valve and the third valve to depressurize the saturated simulated formation system.

[0034] In one possible implementation, the fluid supply system further includes a first electronic scale and a second electronic scale, with the first drilling fluid container placed on the first electronic scale and the second drilling fluid container placed on the second electronic scale;

[0035] The step of obtaining the leakage and flowback of the drilling fluid based on the first weight, the second weight, and the third weight includes:

[0036] The first weight and the second weight are obtained from the first electronic scale;

[0037] The leakage amount is obtained based on the first weight and the second weight; wherein, the leakage amount is the difference between the first weight and the second weight;

[0038] The third weight is obtained based on the second electronic scale;

[0039] The backflow amount is obtained based on the third weight; wherein the backflow amount is equal to the third weight.

[0040] This application provides a formation breathing effect simulation device and method, comprising: a simulated formation system, a fluid supply system, and a true triaxial testing machine; the true triaxial testing machine is equipped with a heating component, and the simulated formation system is installed inside the true triaxial testing machine; the simulated formation system includes: an upper simulated formation and a lower simulated formation; a contact surface between the upper and lower simulated formations forms simulated formation fractures; a simulated wellbore is jointly provided for the upper and lower simulated formations, and a fluid injection channel is provided on the simulated wellbore; multiple displacement sensors are provided outside the lower simulated formation; the fluid supply system includes: a first branch, a second branch, and a third branch; a first drilling fluid container, a hydraulic pump, and a first valve are sequentially provided on the first branch; a second valve and a second drilling fluid container are sequentially provided on the second branch; the first and second branches are simultaneously connected to the fluid injection channel through the third branch, and a pressure gauge and a third valve are provided on the third branch. Through the above structural design, the following technical effects are achieved: By combining a true triaxial testing machine and heating components, the formation breathing effect under real downhole stress and temperature conditions can be studied, thus providing guidance for the study of the formation breathing effect formation mechanism and the identification and judgment of the breathing effect; The simulated formation system includes an upper simulated formation and a lower simulated formation. The advantage of this setting is that the formation lithology can be adjusted according to the research objectives. For example, when studying the breathing effect of sandstone formations, both the upper and lower simulated formations are made of sandstone; if the study is to study sandstone and mudstone cross-contamination formations, the lithology of the upper or lower simulated formation can be replaced with mudstone; The diameter of the borehole can be adjusted to simulate the formation breathing effect under different wellbore sizes, and the potential influence of wellbore size on the breathing effect can be analyzed; In addition, the borehole inclination angle can also be adjusted according to experimental needs to simulate the formation breathing effect during deviated well drilling, and the potential influence of wellbore inclination angle on the formation breathing effect can be analyzed. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0043] Figure 1 This is a schematic diagram of the structure of the formation breathing effect simulation device provided in the embodiments of this application;

[0044] Figure 2 This is a schematic diagram of the structure of the true triaxial testing machine provided in the embodiments of this application;

[0045] Figure 3 Installation diagram of the displacement sensor provided in the embodiments of this application Figure 1 ;

[0046] Figure 4 Installation diagram of the displacement sensor provided in the embodiments of this application Figure 2 ;

[0047] Figure 5 This is a schematic diagram of the structure of the pressure-resistant sealing box provided in the embodiments of this application;

[0048] Figure 6 A schematic diagram illustrating the relationship between drilling fluid loss and experimental time provided in an embodiment of this application;

[0049] Figure 7 This is a schematic diagram illustrating the relationship between drilling fluid flowback volume and experimental time, provided in an embodiment of this application.

[0050] Figure 8 This is a schematic diagram illustrating the relationship between simulated wellbore pressure, simulated formation fracture aperture, and experimental time, provided in an embodiment of this application.

[0051] Figure label:

[0052] 100 - Simulated formation system; 110 - Upper simulated formation; 120 - Lower simulated formation; 130 - Simulated formation fracture; 140 - Simulated wellbore; 150 - Injection channel; 160 - Displacement sensor; 200 - Fluid supply system; 210 - First branch; 211 - First drilling fluid container; 212 - Hydraulic pump; 213 - First valve; 214 - First electronic scale; 220 - Second branch; 221 - Second valve; 222 - Second drilling fluid container; 223 - Second electronic scale; 230 - Third branch; 231 - Pressure gauge; 232 - Third valve; 300 - True triaxial testing machine; 310 - Heating assembly; 400 - Pressure-resistant sealing box. Detailed Implementation

[0053] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of the embodiments of this invention.

[0054] In the embodiments of this application, the terms "first" and "second" are used to distinguish identical or similar items with substantially the same function and effect. Those skilled in the art will understand that the terms "first" and "second" do not limit the quantity or execution order, and that "first" and "second" do not necessarily imply difference. It should be noted that in the embodiments of this application, words such as "exemplary" or "for example" are used to indicate examples, illustrations, or explanations. Any embodiment or design scheme described as "exemplary" or "for example" in the embodiments of this application should not be construed as being better or more advantageous than other embodiments or design schemes. Specifically, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner. In the embodiments of this application, "at least one" refers to one or more, and "more than one" refers to two or more.

[0055] It should be noted that the phrase "at...time" in the embodiments of this application can refer to the instant at which a certain situation occurs, or to a period of time after the occurrence of a certain situation; the embodiments of this application do not specifically limit this. Furthermore, the water and sand discharge device provided in the embodiments of this application is merely an example; the water and sand discharge device package may also include more or fewer components.

[0056] First, the terms used in the embodiments of this application will be explained accordingly:

[0057] Formation breathing effect: During drilling fluid circulation, drilling fluid enters the underground through the drill bit and flows to the formation near the wellbore. These formations often have a certain porosity and permeability, allowing drilling fluid to enter the underground fluid system. When drilling fluid enters the pores of the formation, it is similar to the process of "inhaling air," and the drilling fluid is "absorbed" into the underground, which is called fluid loss. When the drilling fluid stops circulating, the pressure inside the wellbore will suddenly drop, while the pore pressure underground may still be relatively high. At this time, the underground fluid will flow back into the wellbore from the formation due to the pressure difference, similar to the process of "exhaling air." This reverse flow process is called fluid backflow.

[0058] Well kick: During drilling, a well kick occurs when the formation pressure exceeds the pressure inside the wellbore, causing the drilling fluid to be pushed into the wellbore by the formation fluid. Well kicks are typically caused by the following reasons: when the formation pore pressure is too high, exceeding the pressure inside the wellbore, underground fluids may suddenly enter the wellbore; a well kick may also occur when the drilling fluid density is insufficient to resist the formation pressure. The danger of a well kick lies in the fact that the sudden influx of fluid into the wellbore can cause a sharp increase in pressure, thereby threatening well control safety and potentially causing blowouts, equipment damage, or even wellbore failure.

[0059] In order to clearly understand the technical solutions of the embodiments of this application, the solutions of the prior art will be described in detail first.

[0060] In existing technologies, the influence of different pressures on formation breathing effects is mainly studied by adjusting the magnitude of formation pressure.

[0061] However, existing technologies do not take into account the formation temperature environment, and therefore cannot clarify the generation mechanism and stage characteristics of formation breathing effect under real geostress and formation temperature conditions.

[0062] Therefore, how to design a formation breathing effect simulation device that can take into account real ground stress and formation temperature conditions is a problem that urgently needs to be solved in the embodiments of this application.

[0063] Therefore, in view of the above-mentioned technical problems existing in the prior art, the embodiments of this application provide a formation breathing effect simulation device and method, which can be used in the field of drilling and completion laboratory experimental technology in the oil and gas industry. It aims to consider the actual ground stress and formation temperature conditions in order to clarify the generation mechanism and stage characteristics of the formation breathing effect under the actual ground stress and formation temperature conditions.

[0064] The following describes the application scenarios of a formation breathing effect simulation device and method provided in the embodiments of this application. These application scenarios are merely examples, intended to help those skilled in the art understand the technical content of the embodiments of this application, but do not imply that the embodiments of this application cannot be used in other devices, systems, environments, or scenarios.

[0065] 1) Oil and gas field development and formation analysis: Accurate analysis of the pressure, temperature, and dynamic response of underground formations before drilling and well completion has a significant impact on oil and gas extraction. This device can be used to simulate formation behavior under actual stress and temperature conditions, providing a more reliable data foundation for oil and gas field development.

[0066] 2) Oil and gas well design: During drilling, the underground formation is affected by factors such as drilling fluid and pressure, which may cause a breathing effect, affecting wellbore stability and wellbore design. This device can simulate formation response under different stress and temperature conditions, helping to improve wellbore stability prediction, wellbore structure design, and drilling fluid selection.

[0067] 3) Oil and gas reservoir engineering: This device helps to study how the formation changes in temperature, pressure, etc., during long-term production, and thus affects the permeability and gas / oil production characteristics of the reservoir.

[0068] The embodiments of this application are described below with reference to the accompanying drawings.

[0069] Figure 1 This is a schematic diagram of the structure of the formation breathing effect simulation device provided in the embodiments of this application, as shown below. Figure 1 As shown in the figure, this application provides a formation breathing effect simulation device.

[0070] It includes a simulated formation system 100, a liquid supply system 200, and a true triaxial testing machine 300.

[0071] Figure 2 This is a schematic diagram of the structure of the true triaxial testing machine provided in the embodiments of this application, as shown below. Figure 2 As shown, the true triaxial testing machine 300 provides the geostress conditions required for the experiment and can apply pressure to the simulated formation system 100 from three directions.

[0072] The true triaxial testing machine 300 is equipped with a heating component 310, and the simulated formation system 100 is installed inside the true triaxial testing machine 300.

[0073] In this embodiment, the heating component 310 installed on the true triaxial testing machine 300 is used to provide and maintain the formation temperature environment required for the experiment; the simulated formation system 100 is located inside the true triaxial testing machine 300, and can be provided with realistic in-situ stress conditions by the true triaxial testing machine 300. By combining the true triaxial testing machine and the heating component, the formation breathing effect under real downhole stress and temperature conditions can be studied, thereby providing guidance for the study of the formation breathing effect formation mechanism and the study of breathing effect identification and judgment.

[0074] The simulated formation system 100 includes: an upper simulated formation 110 and a lower simulated formation 120; the contact surface between the upper simulated formation 110 and the lower simulated formation 120 forms a simulated formation fracture 130; the upper simulated formation 110 and the lower simulated formation 120 are jointly provided with a simulated wellbore 140, and the simulated wellbore 140 is provided with a fluid injection channel 150.

[0075] In this embodiment, the simulated wellbore 140 penetrates the upper simulated formation 110 but does not penetrate the lower simulated formation 120.

[0076] Specifically, the simulated stratigraphic system 100 includes an upper simulated stratigraphic system 110 and a lower simulated stratigraphic system 120. The advantage of this setting is that the lithology of the stratigraphic system can be adjusted according to the research objectives. For example, if the study is on the breathing effect of sandstone strata, both the upper and lower simulated stratigraphic systems will be made of sandstone. If the study is on sandstone and mudstone cross-stratigraphic systems, the lithology of either the upper or lower simulated stratigraphic system can be changed to mudstone.

[0077] The contact surface between the upper simulated stratum 110 and the lower simulated stratum 120 is used as a simulated stratum fracture 130 for experimental research.

[0078] A borehole is drilled in the middle of the simulated formation system 100 to simulate the wellbore 140. Specifically, a pre-fabricated through-hole is constructed within the upper simulated formation 110 to simulate the upper half of the wellbore 140; a pre-fabricated non-through-hole is constructed within the lower simulated formation 120 to simulate the lower half of the wellbore 140. Optionally, the diameter of the boreholes can be adjusted to simulate the formation breathing effect under different wellbore sizes, analyzing the potential impact of wellbore size on the breathing effect. Furthermore, the borehole inclination angle can also be adjusted according to experimental requirements to simulate the formation breathing effect during deviated well drilling, analyzing the potential impact of wellbore inclination angle on the formation breathing effect.

[0079] Multiple displacement sensors 160 are installed on the outside of the lower simulated stratum 120.

[0080] In this embodiment, multiple displacement sensors 160 are provided on the outside of the lower simulated formation 120 to monitor the change in the opening of the simulated formation fracture 130 during the test. Optionally, the displacement sensors 160 are fixed and sealed with epoxy resin.

[0081] The liquid supply system 200 includes: a first branch 210, a second branch 220 and a third branch 230.

[0082] The first branch 210 is equipped with a first drilling fluid container 211, a hydraulic pump 212 and a first valve 213 in sequence; the second branch 220 is equipped with a second valve 221 and a second drilling fluid container 222 in sequence.

[0083] In this embodiment, from left to right, the first branch 210 is provided with a first drilling fluid container 211, a hydraulic pump 212 and a first valve 213 in sequence, and the second branch 220 is provided with a second valve 221 and a second drilling fluid container 222 in sequence.

[0084] The first branch 210 and the second branch 220 are simultaneously connected to the injection channel 150 via the third branch 230. The third branch 230 is equipped with a pressure gauge 231 and a third valve 232.

[0085] In this embodiment, the first branch 210 is connected to the injection channel 150 via the third branch 230, and the second branch 220 is also connected to the injection channel 150 via the third branch 230. A pressure gauge 231 and a third valve 232 are installed on the third branch 230. The pressure gauge 231 is used to monitor the pressure of the simulated wellbore 140 in real time and transmits the signal to the microcomputer for recording via a signal transmission line.

[0086] This application provides a formation breathing effect simulation device, comprising: a simulated formation system, a fluid supply system, and a true triaxial testing machine; the true triaxial testing machine is equipped with a heating component, and the simulated formation system is installed inside the true triaxial testing machine; the simulated formation system includes: an upper simulated formation and a lower simulated formation; a contact surface between the upper and lower simulated formations forms simulated formation fractures; a simulated wellbore is jointly provided for the upper and lower simulated formations, and a fluid injection channel is provided on the simulated wellbore; multiple displacement sensors are provided on the exterior of the lower simulated formation; the fluid supply system includes: a first branch, a second branch, and a third branch; a first drilling fluid container, a hydraulic pump, and a first valve are sequentially provided on the first branch; a second valve and a second drilling fluid container are sequentially provided on the second branch; the first and second branches are simultaneously connected to the fluid injection channel through the third branch, and a pressure gauge and a third valve are provided on the third branch. Through the above structural design, the following technical effects are achieved: By combining a true triaxial testing machine and heating components, the formation breathing effect under real downhole stress and temperature conditions can be studied, thus providing guidance for the study of the formation breathing effect formation mechanism and the identification and judgment of the breathing effect; The simulated formation system includes an upper simulated formation and a lower simulated formation. The advantage of this setting is that the formation lithology can be adjusted according to the research objectives. For example, when studying the breathing effect of sandstone formations, both the upper and lower simulated formations are made of sandstone; if the study is to study sandstone and mudstone cross-contamination formations, the lithology of the upper or lower simulated formation can be replaced with mudstone; The diameter of the borehole can be adjusted to simulate the formation breathing effect under different wellbore sizes, and the potential influence of wellbore size on the breathing effect can be analyzed; In addition, the borehole inclination angle can also be adjusted according to experimental needs to simulate the formation breathing effect during deviated well drilling, and the potential influence of wellbore inclination angle on the formation breathing effect can be analyzed.

[0087] In one possible design, based on the above embodiment, the lower simulated stratum 120 is provided with multiple grooves on its exterior, and each groove is equipped with a displacement sensor 160.

[0088] In this embodiment, the lower simulated stratum 120 has multiple grooves on its exterior. The advantage of using the grooves to install the displacement sensor 160 is that the grooves act as physical constraints, which can effectively prevent the displacement sensor from being displaced due to external forces or vibrations, thereby improving the accuracy and reliability of the measurement. At the same time, the grooves can provide a certain degree of physical protection for the displacement sensor, preventing it from being subjected to external impacts or other mechanical damage during use.

[0089] Based on the above embodiments, this application provides a formation breathing effect simulation device. Figure 3 Installation diagram of the displacement sensor provided in the embodiments of this application Figure 1 ,like Figure 3As shown in the figure, the small rectangles represent grooves, and multiple grooves in the device are distributed in a circular array around the simulated wellbore 140.

[0090] In this embodiment, the installation position of the displacement sensor 160 is kept at the same distance from the simulated wellbore 140. The advantage of this setting is that multiple displacement sensors 160 are used together to detect the average opening of the simulated formation fracture 130.

[0091] Figure 4 Installation diagram of the displacement sensor provided in the embodiments of this application Figure 2 In one possible design, based on the above embodiments, such as... Figure 4 As shown in the figure, the small rectangles represent grooves, and multiple grooves are distributed at equal intervals along a preset path.

[0092] In this embodiment, the displacement sensors 160 are evenly distributed along a straight line. The advantage of this arrangement is that multiple displacement sensors 160 are used together to detect the gradual change in the opening of the simulated formation fracture 130.

[0093] Based on the above embodiments, this application provides a formation breathing effect simulation device, wherein a first electronic scale 214 is also provided on the first branch 210 of the device, and a second electronic scale 223 is also provided on the second branch 220.

[0094] The first drilling fluid container 211 is placed on the first electronic scale 214, and the second drilling fluid container 222 is placed on the second electronic scale 223.

[0095] In this embodiment, the first drilling fluid container 211 is placed on the first electronic scale 214, and the second drilling fluid container 222 is placed on the second electronic scale 223. The advantage of this arrangement is that the consumption, addition, and trend of the liquid in the first and second drilling fluid containers can be monitored in real time, ensuring that the ideal drilling fluid performance is maintained throughout the drilling process.

[0096] Based on the above embodiments, this application provides a formation breathing effect simulation device, which further includes: a wireless signal receiver;

[0097] Displacement sensor 160 is a wireless sensor.

[0098] In this embodiment, the wireless signal receiver is used to acquire the opening of the simulated formation fracture 130 from the displacement sensor 160 via wireless signal. The advantages of using a wireless sensor are: wireless displacement sensors do not require cable connections, greatly simplifying installation and wiring; simultaneously, the sensor placement is no longer limited by physical wiring, meaning that displacement sensors can be easily added, moved, or redeployed to adapt to dynamically changing monitoring needs; wireless displacement sensors enable remote data acquisition and monitoring, as the sensor transmits data via a wireless signal receiver, allowing operators to view monitoring results in real time at a remote location, reducing the complexity of on-site operations and the probability of personnel being exposed to harsh environments.

[0099] Based on the above embodiments, this application provides a formation breathing effect simulation device, wherein the first valve 213 and the second valve 221 in the device are both one-way valves, and the third valve 232 is a back pressure valve.

[0100] In this embodiment, the check valve only allows fluid to flow in one direction, and the back pressure valve is used to maintain a certain pressure in the system. The advantages of using a check valve and a back pressure valve are: the check valve can prevent the liquid from flowing in the opposite direction, thereby damaging the equipment; the back pressure valve can ensure that the system maintains the necessary minimum pressure during operation. If the pressure in the system is too low, the back pressure valve will automatically close to prevent the system from malfunctioning due to insufficient pressure.

[0101] Specifically, when calculating the leakage, the drilling fluid in the first drilling fluid container 211 flows sequentially through the first valve 213 and the third valve 232 to the simulated wellbore 140; when calculating the backflow, the drilling fluid in the simulated wellbore 140 flows sequentially through the third valve 232 and the second valve 221 to the second drilling fluid container 222.

[0102] In one possible design, based on the above embodiments, it further includes: a pressure-resistant sealing box 400.

[0103] The simulated formation system 100 is installed inside the pressure-resistant sealing box 400, which is installed inside the true triaxial testing machine 300.

[0104] Figure 5 This is a schematic diagram of the structure of the pressure-resistant sealing box provided in the embodiments of this application, as shown below. Figure 5 As shown, the pressure-resistant sealed box 400 includes a sealing box cover and a sealing box body. Installing the simulated formation system inside the pressure-resistant sealed box ensures the system's airtightness during the experiment, thereby guaranteeing the accuracy of the experimental results.

[0105] This embodiment provides a method for simulating formation breathing effect. The method is used in the formation breathing effect simulation device provided in the above embodiment. The device includes: a simulated formation system, a fluid supply system, and a true triaxial testing machine. The fluid supply system includes a first valve, a second valve, a third valve, a hydraulic pump, a first drilling fluid container, and a second drilling fluid container. The true triaxial testing machine is equipped with a heating component. The method then includes:

[0106] S101. Immerse the simulated formation system in drilling fluid until the immersion time reaches the preset time to obtain a saturated simulated formation system.

[0107] Specifically, before conducting S101, the rock type of the simulated formation system, the diameter of the simulated wellbore, and the dip angle are selected according to the experimental requirements.

[0108] The simulated formation system is immersed in drilling fluid until the preset immersion time is reached (in this embodiment, the preset time is no less than 48 hours) to saturate the simulated formation system. This prevents a large amount of fluid from the simulated wellbore from intruding into the formation pores during the test, which could affect the test results. Optionally, this step can be adjusted according to experimental requirements to achieve the experimental effect of analyzing the influence of drilling fluid properties on formation breathing effect.

[0109] S102. Install the saturated simulated formation system inside the true triaxial testing machine.

[0110] Specifically, the saturated simulated formation system is removed, a displacement sensor is installed, and the sensor is sealed and fixed with epoxy resin. Then, the saturated simulated formation system is placed in a sealed box, and finally the simulated formation system, the liquid supply system, and the true triaxial testing machine are assembled.

[0111] S103. Open the first and third valves, close the second valve, zero the weight of the second drilling fluid container, apply confining pressure through the true triaxial testing machine, and turn on the heating assembly.

[0112] Specifically, before proceeding to S103, drilling fluid is added to the first drilling fluid container, but not to the second. The properties of the drilling fluid in this step should be consistent with those in S101. After adding the drilling fluid, the airtightness of the experimental setup needs to be tested, which includes the following steps:

[0113] S1031. Open the first valve and the third valve, close the second valve, set the confining pressure in three directions using the true triaxial testing machine, turn on the hydraulic pump, and when the pressure gauge reading reaches the set confining pressure, turn off and open the first valve, the third valve, and the hydraulic pump, and observe whether the pressure gauge reading is stable.

[0114] Specifically, in this embodiment, the confining pressure in all three directions is set to 2 MPa. The confining pressure set using a true triaxial testing machine can be determined according to the actual situation, and no specific restrictions are imposed here.

[0115] S1032. If the pressure gauge reading remains stable and does not decrease, proceed to S103.

[0116] Specifically, a stable pressure gauge reading indicates that the device is airtight.

[0117] S1033. If the pressure gauge reading drops significantly, close the first valve and open the second and third valves to release pressure. After releasing pressure, inspect the device and repair any leaks. Repeat S1031-S1033 until the pressure gauge reading stabilizes and does not drop further.

[0118] Specifically, a significant drop in pressure gauge reading indicates a leak in the device, requiring leak repair and repeated airtightness testing until the device passes the airtightness test.

[0119] After the airtightness test of the device is completed, a downhole thermo-mechanical condition simulation is performed, namely S103.

[0120] S104. When the saturated simulated formation system reaches the first preset pressure and preset temperature, record the first weight of the first drilling fluid container, turn on the hydraulic pump, and pump the drilling fluid in the first drilling fluid container to the saturated simulated formation system through the hydraulic pump until the saturated simulated formation system experiences formation breathing effect, then close the first valve, the third valve and the hydraulic pump, and record the second weight of the first drilling fluid container.

[0121] Optionally, this step can adjust the values ​​of the first preset pressure and preset temperature to simulate different downhole thermo-mechanical conditions.

[0122] Specifically, when the simulated formation system reaches the first preset pressure and preset temperature after saturation, the displacement sensor reading is reset to zero and the first weight of the first drilling fluid container is recorded.

[0123] Turn on the hydraulic pump to inject drilling fluid to simulate the bottom hole pressure during the drilling fluid circulation process. Continuously increase the drilling fluid pressure and observe the changes in the displacement sensor value. When the displacement sensor value is non-zero and continues to rise, it indicates that the simulated formation fracture has opened, the drilling fluid has invaded the formation, and the formation breathing effect has occurred.

[0124] After closing the first valve, the third valve, and the hydraulic pump, and maintaining a stable internal pressure, record the second weight of the first drilling fluid container.

[0125] In S104, the weight of the first drilling fluid container should be continuously recorded to reflect changes in drilling fluid leakage. The electronic pressure gauge and displacement sensor should be kept open to continuously record leakage, simulated wellbore pressure, and simulated formation fracture opening data for subsequent experimental result comparison and analysis.

[0126] In this embodiment, there are no specific restrictions on the method of recording the first weight and the second weight of the first drilling fluid container.

[0127] S105. Open the second valve and gradually open the third valve. When the pressure of the simulated formation system after saturation gradually decreases to the second preset pressure, close the second and third valves and record the third weight of the second drilling fluid container.

[0128] In S105, the weight of the second drilling fluid container should be continuously recorded to reflect changes in the drilling fluid flowback rate. The electronic pressure gauge and displacement sensor should be kept constantly open to continuously record the flowback rate, simulated wellbore pressure, and simulated formation fracture aperture data for subsequent experimental result comparison and analysis.

[0129] S106. Based on the first weight, the second weight, and the third weight, obtain the leakage and flowback of the drilling fluid.

[0130] In this embodiment, the amount of drilling fluid loss can be obtained by measuring the first and second weights of the first drilling fluid container; and the amount of drilling fluid backflow can be obtained by measuring the third weight of the second drilling fluid container.

[0131] S107. Open the second and third valves to depressurize the saturated simulated formation system.

[0132] Specifically, after the test is completed, the second and third valves are opened to release the pressure. After the pressure is released, the saturated simulated formation system is removed and cleaned to prepare for the next set of experiments.

[0133] Based on the above embodiments, this embodiment provides a method for simulating formation breathing effects. The fluid supply system further includes a first electronic scale and a second electronic scale, with a first drilling fluid container placed on the first electronic scale and a second drilling fluid container placed on the second electronic scale, comprising:

[0134] The first and second weights are obtained from the first electronic scale;

[0135] The leakage amount is obtained based on the first weight and the second weight; where the leakage amount is the difference between the first weight and the second weight.

[0136] The third weight is obtained from the second electronic scale;

[0137] The amount of backflow is obtained from the third weight; where the amount of backflow is equal to the third weight.

[0138] The formation breathing effect simulation method provided in this embodiment can achieve the formation breathing effect simulation method provided in the above embodiment, and its effect is the same as that of the formation breathing effect simulation method provided in the above embodiment, so it will not be described again here.

[0139] The following analysis is based on a specific set of experimental data:

[0140] After the experiment was completed, the results were analyzed. The drilling fluid leakage, flowback, simulated wellbore pressure, and simulated formation fracture aperture recorded in the experiment were exported and analyzed. By aligning the time axes of simulated wellbore pressure and simulated formation fracture aperture, the relationship between simulated wellbore pressure and simulated formation fracture aperture can be analyzed. By changing parameters such as formation lithology, simulated wellbore diameter and inclination angle, simulated wellbore pressure, drilling fluid rheology, geostress, and formation temperature in the experiment, the influence of simulated wellbore-formation parameters on the formation breathing effect characteristics can be analyzed.

[0141] During the experiment, the confining pressure of the formation was set to σ3 = 2 MPa, and the heating components were set to a constant temperature.

[0142] Figure 6 This is a schematic diagram illustrating the relationship between drilling fluid loss and experimental time provided in an embodiment of this application, as shown below. Figure 6 As shown in the figure, the horizontal axis represents the experimental time in minutes, and the vertical axis represents the leakage in grams.

[0143] Figure 7 This is a schematic diagram illustrating the relationship between drilling fluid flowback volume and experimental time provided in an embodiment of this application, as shown below. Figure 7 As shown in the figure, the horizontal axis represents the experimental time in minutes, and the vertical axis represents the amount of backflushing in grams.

[0144] Figure 8 This is a schematic diagram illustrating the relationship between simulated wellbore pressure, simulated formation fracture aperture, and experimental time, as provided in the embodiments of this application. Figure 8 As shown in the figure, the horizontal axis represents the experimental time in minutes; the vertical axis represents the simulated wellbore pressure and the simulated formation fracture aperture. The simulated wellbore pressure is in megapascals, and the simulated formation fracture aperture is in millimeters. The solid line represents the simulated wellbore pressure, and the dashed line represents the simulated formation fracture aperture.

[0145] comprehensive Figure 6 , Figure 7 and Figure 8 The experimental results will now be analyzed.

[0146] Depend on Figure 8 It can be seen that during the 0-1 minute phase, the simulated wellbore pressure continuously increases, while the simulated formation fracture aperture remains at 0. Figure 6The drilling fluid loss reflects the weight of the drilling fluid injected into the simulated wellbore. During the 1-6 minute stage, the simulated wellbore pressure exceeds σ3 and continues to increase, while the simulated formation fracture aperture gradually increases, indicating a breathing effect. The increased drilling fluid loss indicates that some drilling fluid has flowed into the opened fractures. During the 6-12.5 minute stage, corresponding to the pressure stabilization stage in S104, the simulated wellbore pressure and simulated formation fracture aperture remain constant. After 12.5 minutes, corresponding to S105, the third valve is gradually opened, the simulated wellbore pressure decreases, and the simulated formation fracture aperture decreases accordingly. The drilling fluid continues to flow back to the second drilling fluid container, and the second electronic scale records the amount of drilling fluid flowed back. Figure 7 Drilling fluid backflow after 12.5 minutes.

[0147] After the test, the difference between the final leakage and the final backflow is calculated, which is the actual leakage of drilling fluid.

[0148] So far, the technical solutions of the embodiments of this application have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is readily understood by those skilled in the art that the protection scope of the embodiments of this application is obviously not limited to these specific embodiments. The above embodiments are only used to illustrate the technical solutions of the embodiments of this application, and not to limit them. Although the embodiments of this application have been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the various embodiments of this application.

Claims

1. A formation breathing effect simulation apparatus, characterized by, It includes a simulated formation system (100), a liquid supply system (200), and a true triaxial testing machine (300); The true triaxial testing machine (300) is equipped with a heating component (310), and the simulated formation system (100) is installed inside the true triaxial testing machine (300); The simulated formation system (100) includes an upper simulated formation (110) and a lower simulated formation (120); the contact surface between the upper simulated formation (110) and the lower simulated formation (120) forms a simulated formation fracture (130); the upper simulated formation (110) and the lower simulated formation (120) are jointly provided with a simulated wellbore (140), and the simulated wellbore (140) is provided with a fluid injection channel (150); wherein, the simulated wellbore (140) penetrates the upper simulated formation (110) but does not penetrate the lower simulated formation (120). Multiple displacement sensors (160) are installed outside the lower simulated stratum (120). The liquid supply system (200) includes: a first branch (210), a second branch (220) and a third branch (230); The first branch (210) is provided with a first drilling fluid container (211), a hydraulic pump (212) and a first valve (213) in sequence; the second branch (220) is provided with a second valve (221) and a second drilling fluid container (222) in sequence. The first branch (210) and the second branch (220) are connected to the injection channel (150) through the third branch (230), and the third branch (230) is equipped with a pressure gauge (231) and a third valve (232).

2. The apparatus of claim 1, wherein, The lower simulated stratum (120) has multiple grooves on its exterior, and each groove is equipped with a displacement sensor (160).

3. The apparatus of claim 2, wherein, The plurality of grooves are arranged in a circular array around the simulated wellbore (140), and the plurality of displacement sensors (160) are used together to detect the average opening of the simulated formation fracture (130).

4. The apparatus of claim 2, wherein, The multiple grooves are distributed at equal intervals along a preset path, and the multiple displacement sensors (160) are used together to detect the gradual change in the opening of the simulated formation fracture (130).

5. The apparatus of claim 2, wherein, The first branch (210) is also equipped with a first electronic scale (214), and the second branch (220) is also equipped with a second electronic scale (223). The first drilling fluid container (211) is placed on the first electronic scale (214), and the second drilling fluid container (222) is placed on the second electronic scale (223).

6. The apparatus of claim 5, wherein, Also includes: Wireless signal receiver; The displacement sensor (160) is a wireless sensor; The wireless signal receiver is used to acquire the opening of the simulated formation fracture (130) from the displacement sensor (160) via wireless signal.

7. The apparatus of claim 1, wherein, The first valve (213) and the second valve (221) are both one-way valves, and the third valve (232) is a back pressure valve; When calculating the leakage, the drilling fluid in the first drilling fluid container (211) flows sequentially through the first valve (213) and the third valve (232) to the simulated wellbore (140). When calculating the backflow rate, the drilling fluid in the simulated wellbore (140) flows sequentially through the third valve (232) and the second valve (221) to the second drilling fluid container (222).

8. The apparatus of claim 1, wherein, Also includes: Pressure-resistant sealed box (400); The simulated formation system (100) is installed inside the pressure-resistant sealing box (400), which is installed inside the true triaxial testing machine (300).

9. A method of modeling the breathing effect of a formation, the method comprising: The method is used in the formation breathing effect simulation device as described in any one of claims 1 to 8, the device comprising: a formation simulation system, a fluid supply system, and a true triaxial testing machine; wherein, the fluid supply system comprises a first valve, a second valve, a third valve, a hydraulic pump, a first drilling fluid container, and a second drilling fluid container, and the true triaxial testing machine is equipped with a heating component, then the method comprises: The simulated formation system is immersed in drilling fluid until the immersion time reaches a preset time, resulting in a saturated simulated formation system. The saturated simulated formation system is installed inside the true triaxial testing machine; Open the first valve and the third valve, close the second valve, zero the weight of the second drilling fluid container, apply confining pressure through the true triaxial testing machine, and turn on the heating assembly; When the saturated simulated formation system reaches the first preset pressure and preset temperature, the first weight of the first drilling fluid container is recorded, the hydraulic pump is turned on, and the drilling fluid in the first drilling fluid container is pumped to the saturated simulated formation system through the hydraulic pump until the saturated simulated formation system experiences a formation breathing effect. Then, the first valve, the third valve, and the hydraulic pump are closed, and the second weight of the first drilling fluid container is recorded. Open the second valve and gradually open the third valve. When the pressure of the saturated simulated formation system gradually decreases to the second preset pressure, close the second valve and the third valve, and record the third weight of the second drilling fluid container. The leakage and backflow of the drilling fluid are obtained based on the first weight, the second weight, and the third weight. Open the second valve and the third valve to depressurize the saturated simulated formation system.

10. The method according to claim 9, wherein, The fluid supply system also includes a first electronic scale and a second electronic scale, with the first drilling fluid container placed on the first electronic scale and the second drilling fluid container placed on the second electronic scale; The step of obtaining the leakage and flowback of the drilling fluid based on the first weight, the second weight, and the third weight includes: The first weight and the second weight are obtained from the first electronic scale; The leakage amount is obtained based on the first weight and the second weight; wherein, the leakage amount is the difference between the first weight and the second weight; The third weight is obtained based on the second electronic scale; The flowback volume is determined from the third weight; wherein the flowback volume is equal to the third weight.

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