A shallow gas formation-wellbore coupling blowout visualization simulation device and method

Abstract

The application discloses a kind of shallow gas formation-wellbore coupling blowout visualization simulation device and method, including visual wellbore component, simulation formation box, liquid phase supply unit, gas phase supply unit, separation tank, data monitoring unit;Simulation formation box is provided with simulation formation sand in it, simulation formation box is connected with gas supply unit;Visual wellbore component includes simulation wellbore transparent tube, simulation wellbore transparent tube is provided with mutually isolated injection cavity and reflux cavity, injection cavity bottom end is inserted into simulation formation sand, reflux cavity bottom end is connected on simulation formation box, injection cavity top end is connected with liquid supply unit, gas supply unit, reflux cavity top is connected with separation tank.The application forms formation-wellbore coupling flow cavity with reflux cavity and simulation formation box internal space, can simulate shallow gas into wellbore from formation during the process of fluid exchange, pressure transmission and formation sand production phenomenon, realizes the visualization observation of gas, liquid, solid three-phase flow process.

Description

Technical Field

[0001] This invention relates to the field of shallow gas well control and multiphase flow simulation technology in marine drilling, and particularly to a shallow gas formation-wellbore coupled venting visualization simulation device and method. Background Technology

[0002] Shallow gas is a typical geological hazard source in offshore drilling, characterized by its shallow burial depth, pressure sensitivity, high-pressure eruption, and difficulty in prediction. During offshore drilling operations, when encountering formations containing shallow gas, the gas may enter the wellbore within a short period, triggering complex accidents such as well kicks, blowouts, formation sand production, wellbore instability, and wellbore collapse. These incidents severely impact the safety of offshore drilling operations and may cause environmental pollution and economic losses. Therefore, conducting simulation experiments on the coupled venting process of shallow gas formations and wellbore is of great significance for understanding the pressure transmission, multiphase flow, formation sand production, and erosion evolution after shallow gas intrudes into the wellbore.

[0003] Most existing shallow gas or gas intrusion simulation devices focus on observing the two-phase flow of gas and liquid within the wellbore or the shallow gas escape process. They struggle to simultaneously achieve coupled connectivity between the formation and the wellbore, multi-condition switching, and visualization of the gas, liquid, and solid three-phase flow processes. While some devices can simulate gas intrusion into the wellbore, they lack a coupled formation space to fill with simulated formation sand, making it difficult to reflect the migration, erosion, and sand production processes of shallow gas in loose, weakly cemented formations. Although some devices have pressure or flow monitoring capabilities, they cannot simultaneously acquire wellbore pressure, formation pressure, gas-liquid flow rate, and multiphase flow image information, making it difficult to fully reveal the fluid exchange and pressure response mechanisms during the shallow gas formation-wellbore coupled venting process.

[0004] Furthermore, in actual offshore drilling processes, shallow gas release may simultaneously involve complex conditions such as normal drilling fluid circulation, pump shutdown and circulation interruption, formation sand production, and multiphase coupled gas-liquid-solid flow. Existing experimental devices typically operate under single conditions and cannot achieve switching between drilling fluid circulation release and pump shutdown and circulation interruption release on the same experimental platform, nor can they systematically compare factors such as different formation particle sizes, compaction degrees, gas supply pressures, and fluid supply flow rates. Therefore, it is necessary to propose a shallow gas release simulation device and method that can achieve formation-wellbore coupling, visual observation of gas-liquid-solid three-phase flow, simultaneous acquisition of multiple parameters, and simulation switching of multiple operating conditions. Summary of the Invention

[0005] The purpose of this invention is to provide a shallow gas formation-wellbore coupled visualization simulation device and method, which solves the problems mentioned in the background art of existing shallow gas venting simulation devices, such as insufficient formation-wellbore coupling, limited visualization and observation capabilities, insufficient multi-condition simulation capabilities, and incomplete parameter acquisition.

[0006] The present invention adopts the following technical solution:

[0007] The present invention provides a shallow gas formation-wellbore coupled blowout visualization simulation device, comprising a visualization wellbore assembly, a simulated formation box, a liquid phase supply unit, a gas phase supply unit, a separation tank, and a data monitoring unit;

[0008] The simulated formation box is equipped with simulated formation sand, and the simulated formation box is connected to the gas supply unit;

[0009] The visualization wellbore assembly includes a simulated wellbore transparent tube, which contains an injection chamber and a return chamber that are isolated from each other. The bottom port of the injection chamber is inserted into the simulated formation sand, the bottom port of the return chamber is connected to the simulated formation box, the top port of the injection chamber is connected to the liquid supply unit and the gas supply unit, and the top of the return chamber is connected to the separation tank.

[0010] The data monitoring unit includes a pressure sensor and an image acquisition unit. The pressure sensor and the image acquisition unit are electrically connected to the data processing system. The pressure sensor is arranged on the transparent tube of the simulated wellbore and the simulated formation box. The lens of the image acquisition unit faces the transparent tube and the simulated formation box.

[0011] Preferably, the simulated wellbore transparent tube is a cylindrical structure with a closed top and an open bottom. A simulated drill rod is provided at the axis of the simulated wellbore transparent tube. The injection chamber is located inside the simulated drill rod. The top end of the simulated drill rod passes through the top end of the simulated wellbore transparent tube and is connected to the liquid supply unit and the gas supply unit.

[0012] The annular cylindrical cavity formed by the simulated drill pipe and the inner wall of the simulated wellbore transparent tube is the reflux cavity.

[0013] The bottom end of the simulated drill pipe is inserted into the simulated formation sand;

[0014] The top of the simulated well shaft transparent tube is provided with a discharge port, which is connected to the reflux chamber and the discharge port is connected to the separation tank through a pipeline.

[0015] Preferably, the simulated formation box includes a sand box shell for holding the simulated formation sand, the top of the sand box shell is sealed with a transparent cover plate, the transparent cover plate is provided with an installation hole in the middle, and the bottom end of the simulated wellbore transparent pipe is sealed and inserted into the installation hole.

[0016] The side wall of the sand box shell is provided with an air inlet, which is connected to the gas supply unit.

[0017] The simulated formation box also includes a top plate reinforcing rib, which is pressed onto the transparent cover plate and is fixedly connected to the bottom plate of the sand box shell by a bolt assembly.

[0018] Preferably, the pressure sensor includes a formation pressure sensor, which is disposed on the sand box housing.

[0019] Preferably, the gas phase supply unit includes an air compressor, the output end of which is connected to an air storage tank, and the outlet end of the air storage tank is provided with a first gas phase branch pipe and a second gas phase branch pipe. The end of the first gas phase branch pipe is connected to the injection chamber, and the end of the second gas phase branch pipe is connected to the air inlet.

[0020] A first gas phase control valve is provided on the first gas phase branch pipe, a second gas phase control valve is provided on the second gas phase branch pipe, and a third gas phase control valve is provided between the air compressor and the air storage tank.

[0021] Preferably, the data monitoring unit further includes a first gas flow meter and a second gas flow meter. The first gas flow meter is installed on the first gas phase branch pipe, and the second gas flow meter is installed on the second gas phase branch pipe. The first gas flow meter and the second gas flow meter are electrically connected to the data processing system.

[0022] Preferably, the pressure sensor further includes a first wellbore pressure sensor, a second wellbore pressure sensor, and a third wellbore pressure sensor, which are respectively disposed at the upper, middle, and lower positions of the simulated wellbore transparent tube.

[0023] Preferably, the liquid supply unit includes a storage tank, which is connected to the injection chamber via a liquid phase pipe;

[0024] The liquid phase pipe is equipped with a liquid transfer pump and a liquid phase control valve;

[0025] The data monitoring unit also includes a liquid flow meter, which is installed on the liquid phase tube and is electrically connected to the data processing system.

[0026] Preferably, the separation tank has a cylindrical structure, and a filter plate is fixedly installed on the upper part of the inner wall of the separation tank.

[0027] This invention also discloses a visualization simulation method for shallow gas formation-wellbore coupled venting, comprising the following steps:

[0028] Step 1: Calibrate the data monitoring unit;

[0029] Step 2: Turn on the air compressor, the third gas phase control valve, and the second gas phase control valve to inject gas into the simulated formation sand through the air inlet on the simulated formation box to establish the simulated formation base pressure;

[0030] After the pressure inside the simulated formation box stabilizes, the blowout simulation phase begins.

[0031] Step 3: Turn on the liquid transfer pump and liquid phase control valve to inject the simulated drilling fluid into the simulated formation sand through the injection chamber. The simulated drilling fluid then flows from the simulated formation sand into the return chamber, and finally flows from the top of the return chamber into the separation tank, thus simulating the normal drilling fluid circulation conditions.

[0032] Step 4: Open the first gas phase control valve to allow gas to flow into the separation tank through the injection chamber, the simulated formation sand, and the return chamber, in order to simulate the venting process of shallow gas after entering the wellbore;

[0033] The gas, liquid, and solid mixture that flows into the separation tank through the reflux chamber can be reused and added to the storage tank after filtration and separation.

[0034] During this process, the gas entering from the injection chamber, the simulated drilling fluid, the gas entering from the air inlet, and the sand in the simulated formation sand interact together in the simulated formation box and the return chamber to form a multiphase coupled flow of gas, liquid, and solid.

[0035] Step 5: The pressure sensor transmits the pressure data collected from the simulated formation box and the simulated wellbore transparent pipe to the data processing system for analysis and processing;

[0036] The image acquisition unit transmits the acquired image data of the gas-liquid-solid multiphase flow pattern, sand transport, and formation erosion morphology in the simulated formation box and the simulated wellbore transparent pipe to the data processing system for analysis and processing.

[0037] Step Six: Simulate the pump stoppage and circulation interruption venting condition. Turn off the liquid phase supply unit and keep the gas phase supply unit open, so that gas continuously enters the simulated formation box and the simulated wellbore transparent tube to simulate the shallow gas formation-wellbore coupled venting process under the condition of no drilling fluid circulation. At the same time, the data monitoring unit continuously collects and monitors data. By comparing and analyzing the pressure response, multiphase flow pattern and formation erosion morphology under the drilling fluid circulation condition and the pump stoppage and circulation interruption condition, the influence of the drilling fluid circulation state on the shallow gas venting process can be analyzed.

[0038] Step 7: After the experiment is completed, shut down all the liquid phase supply units and the gas phase supply units, and depressurize the simulated formation box and the simulated wellbore transparent pipe.

[0039] The separation tank was emptied, and the simulated formation box was dismantled and cleaned.

[0040] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0041] (i) This invention uses a simulated wellbore transparent tube and a transparent simulated formation box structure, and is equipped with an image acquisition unit to observe the gas-liquid-solid multiphase flow pattern, sand particle transport trajectory and formation erosion morphology. It improves the problem that traditional devices are difficult to observe the formation-wellbore coupled blowout process intuitively, and realizes the visualization observation of the gas, liquid and solid three-phase flow process.

[0042] (ii) By sealing and connecting the visualized wellbore assembly with the simulated formation box assembly, the present invention forms a formation-wellbore coupled flow cavity with the return cavity of the wellbore annular flow channel structure and the internal space of the simulated formation box, which can simulate the fluid exchange, pressure transmission and formation sand production phenomenon during the process of shallow gas entering the wellbore from the formation.

[0043] (III) This invention uses multiple pressure sensors, formation pressure sensors, liquid flow meters and gas flow meters on a simulated wellbore transparent pipe to simultaneously collect experimental parameters, thereby obtaining the correspondence between wellbore pressure, formation pressure, gas-liquid flow rate and image information, providing experimental data for shallow gas well control risk assessment and multiphase flow law research.

[0044] (iv) The present invention is equipped with a liquid phase circulation branch and a dual gas phase supply branch, which can not only input simulated drilling fluid into the simulated well transparent tube, but also input gas into the simulated drill pipe and simulated formation sand respectively, thereby realizing the simulation of drilling fluid circulation and release, pump stoppage and circulation interruption release, and shallow gas release simulation under different gas supply conditions. Attached Figure Description

[0045] The present invention will be further described below with reference to the accompanying drawings.

[0046] Figure 1 This is a schematic diagram of the shallow gas formation-wellbore coupled blowout visualization simulation device of the present invention. Figure 1 ;

[0047] Figure 2 This is a schematic diagram of the shallow gas formation-wellbore coupled blowout visualization simulation device of the present invention. Figure 2 ;

[0048] Figure 3 This is a schematic diagram of the simulated formation box structure in the shallow gas formation-wellbore coupled blowout visualization simulation device of the present invention. Figure 1 ;

[0049] Figure 4 This is a schematic diagram of the simulated formation box structure in the shallow gas formation-wellbore coupled blowout visualization simulation device of the present invention. Figure 2 ;

[0050] Figure 5 This is a schematic diagram of the separation tank structure in the shallow gas formation-wellbore coupled blowout visualization simulation device of the present invention;

[0051] Explanation of reference numerals in the attached drawings: 1. Visualized wellbore assembly; 1-1. Simulated wellbore transparent pipe; 1-1-1. Discharge port; 1-2. Injection chamber; 1-3. Return chamber; 1-4. Simulated drill pipe; 2. Simulated formation box; 2-1. Sand box shell; 2-1-1. Air inlet; 2-2. Transparent cover plate; 2-2-1. Mounting hole; 2-3. Top plate reinforcing rib; 3. Liquid phase supply unit; 3-1. Liquid storage tank; 3-2. Liquid phase pipe; 3-3. Liquid transfer pump; 3-4. Liquid phase control valve; 4. Gas phase supply unit; 4-1. Air compressor; 4-2. Gas storage tank; 4-3. First gas phase branch pipe; 4-4, Second gas phase branch pipe; 4-5, First gas phase control valve; 4-6, Second gas phase control valve; 4-7, Third gas phase control valve; 5, Separator; 5-1, Filter plate; 6, Data monitoring unit; 6-1, Pressure sensor; 6-1-1, First wellbore pressure sensor; 6-1-2, Second wellbore pressure sensor; 6-1-3, Third wellbore pressure sensor; 6-1-4, Formation pressure sensor; 6-2, Image acquisition unit; 6-3, Data processing system; 6-4, Liquid flow meter; 6-5, First gas flow meter; 6-6, Second gas flow meter; 7, Simulated formation sand. Detailed Implementation

[0052] To make the technical problems, technical solutions, and beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0053] like Figures 1 to 5 As shown in the figure, this embodiment discloses a shallow gas formation-wellbore coupled blowout visualization simulation device and method, including a visualization wellbore component 1, a simulated formation box 2, a liquid phase supply unit 3, a gas phase supply unit 4, a separation tank 5, and a data monitoring unit 6.

[0054] The simulated formation chamber 2 contains simulated formation sand 7, which can be replaced with sand samples of different particle sizes and compaction degrees according to experimental needs to simulate different shallow loose formation conditions. The simulated formation chamber 2 is connected to the gas supply unit 4.

[0055] The visualized wellbore assembly 1 includes a simulated wellbore transparent tube 1-1, which is a cylindrical structure closed at the top and open at the bottom. A simulated drill pipe 1-4 is located at the axis of the simulated wellbore transparent tube 1-1. An injection chamber 1-2 is provided inside the simulated drill pipe 1-4, which runs vertically through it. The annular cylindrical cavity formed by the outer wall of the simulated drill pipe 1-4 and the inner wall of the simulated wellbore transparent tube 1-1 is a return chamber 1-3.

[0056] The bottom port of injection chamber 1-2 is inserted into the simulated formation sand 7, and the bottom port of return chamber 1-3 is connected to the simulated formation box 2, so that return chamber 1-3 is connected to the interior of simulated formation box 2. The top port of injection chamber 1-2 is connected to liquid supply unit 3 and gas supply unit 4. The top of the simulated wellbore transparent pipe 1-1 is provided with discharge port 1-1-1, which is connected to return chamber 1-3. Discharge port 1-1-1 is connected to separation tank 5 through a pipeline, thereby connecting return chamber 1-3 and separation tank 5.

[0057] The top seal of the simulated drill pipe 1-4 passes through the top of the simulated wellbore transparent tube 1-1 and is connected to the liquid supply unit 3 and the gas supply unit 4 so that the liquid supply unit 3 and the gas supply unit 4 can supply liquid and gas into the injection chamber 1-2.

[0058] The data monitoring unit 6 includes a pressure sensor 6-1 and an image acquisition unit 6-2. The pressure sensor 6-1 and the image acquisition unit 6-2 are electrically connected to the data processing system 6-3. The pressure sensor 6-1 is arranged on the transparent tube 1-1 of the simulated wellbore and the simulated formation box 2. The image acquisition unit 6-2 is a high-definition high-speed camera, with the camera lens facing the transparent tube 1-1 and the simulated formation box 2.

[0059] The simulated formation box 2 includes a sand box shell 2-1 for holding simulated formation sand 7. A transparent cover plate 2-2 is sealed to the top of the sand box shell 2-1, and a sealing gasket is provided between the transparent cover plate 2-2 and the sand box shell 2-1 to enhance the seal. An installation hole 2-2-1 is provided in the middle of the transparent cover plate 2-2, and the bottom end of the simulated wellbore transparent pipe 1-1 is sealed and inserted into the installation hole 2-2-1, thereby connecting the return chamber 1-3 to the interior of the simulated formation box 2. The bottom end of the simulated drill pipe 1-4 (i.e., the injection chamber 1-2) is directly inserted into the simulated formation sand 7.

[0060] The side wall of the sand box shell 2-1 is provided with an air inlet 2-1-1, which is connected to the gas supply unit 4.

[0061] In this embodiment, the simulated formation box 2 also includes a top plate reinforcing rib 2-3, which presses on the transparent cover plate 2-2. The top plate reinforcing rib 2-3 is fixedly connected to the bottom plate of the sand box shell 2-1 by a bolt assembly.

[0062] The pressure sensor 6-1 includes a formation pressure sensor 6-1-4, which is installed on the sand box shell 2-1 to monitor the pressure changes inside the simulated formation box 2 during the experiment.

[0063] In this embodiment, the gas phase supply unit 4 includes an air compressor 4-1. The output end of the air compressor 4-1 is connected to the air storage tank 4-2. The air outlet end of the air storage tank 4-2 is provided with a first gas phase branch pipe 4-3 and a second gas phase branch pipe 4-4. The end of the first gas phase branch pipe 4-3 is connected to the injection chamber 1-2, and the end of the second gas phase branch pipe 4-4 is connected to the air inlet 2-1-1.

[0064] A first gas phase control valve 4-5 is installed on the first gas phase branch pipe 4-3, a second gas phase control valve 4-6 is installed on the second gas phase branch pipe 4-4, and a third gas phase control valve 4-7 is installed between the air compressor 4-1 and the air storage tank 4-2.

[0065] The data monitoring unit 6 also includes a first gas flow meter 6-5 and a second gas flow meter 6-6. The first gas flow meter 6-5 is installed on the first gas phase branch pipe 4-3, and the second gas flow meter 6-6 is installed on the second gas phase branch pipe 4-4. The first gas flow meter 6-5 and the second gas flow meter 6-6 are electrically connected to the data processing system 6-3 through pipelines (not shown in the figure).

[0066] The pressure sensor 6-1 also includes a first wellbore pressure sensor 6-1-1, a second wellbore pressure sensor 6-1-2, and a third wellbore pressure sensor 6-1-3. The first wellbore pressure sensor 6-1-1, the second wellbore pressure sensor 6-1-2, and the third wellbore pressure sensor 6-1-3 are respectively set at the upper, middle, and lower positions of the simulated wellbore transparent tube 1-1, and are used to monitor the pressure changes in different positions of the return cavity 1-3 during the monitoring experiment.

[0067] In this embodiment, the liquid phase supply unit 3 includes a storage tank 3-1 containing simulated drilling fluid. The storage tank 3-1 is connected to the injection chamber 1-2 via a liquid phase pipe 3-2. A liquid transfer pump 3-3 and a liquid phase control valve 3-4 are installed on the liquid phase pipe 3-2. Opening the liquid phase control valve 3-4 and the liquid transfer pump 3-3 allows the simulated drilling fluid to be injected into the injection chamber 1-2 through the liquid phase pipe 3-2. The fluid then flows through the bottom of the injection chamber 1-2 into simulated formation sand 7, and then flows upwards back into the return chamber 1-3, carrying sand with it into the separation tank 5.

[0068] The data monitoring unit 6 also includes a liquid flow meter 6-4, which is installed on the liquid phase pipe 3-2 and is electrically connected to the data processing system 6-3 through a pipeline.

[0069] In this embodiment, the separation tank 5 has a cylindrical structure. A filter plate 5-1 is fixedly installed on the upper part of the inner wall of the separation tank 5. The filter plate 5-1 can filter the simulated drilling fluid to the bottom. The filtered simulated drilling fluid can be added back into the storage tank 3-1 for recycling. The bottom of the separation tank 5 is also provided with a discharge port with a valve.

[0070] This embodiment also discloses a visualization simulation method for shallow gas formation-wellbore coupled venting, including the following steps:

[0071] Before conducting the experiment, simulated formation sand 7 with appropriate particle size and compaction degree was selected according to the experimental requirements and loaded into the simulated formation box 2. The simulated formation box 2 was then installed, ensuring that the simulated wellbore transparent pipe 1-1 was sealed and installed on the mounting hole 2-2-1 of the simulated formation box 2, and the second gas phase branch pipe 4-4 was sealed and installed on the gas inlet 2-1-1, without leakage. At this time, the return chamber 1-3 and the internal space of the simulated formation box 2 form a formation-wellbore coupled flow chamber. After assembly, the liquid supply unit 3, gas supply unit 4, and separation tank 5 were assembled, and the connection and sealing status of each pipeline were checked.

[0072] Step 1: Calibrate the data monitoring unit 6, and calibrate the pressure sensor 6-1, image acquisition unit 6-2, data processing system 6-3, liquid flow meter 6-4, first gas flow meter 6-5, and second gas flow meter 6-6.

[0073] Step 2: Turn on the air compressor 4-1, the third gas phase control valve 4-7, and the second gas phase control valve 4-6 to inject gas into the simulated formation sand 7 through the air inlet 2-1-1 on the simulated formation box 2 to establish the simulated formation base pressure.

[0074] After the internal pressure of the simulated formation box 2 stabilizes, the blowout simulation stage begins.

[0075] Step 3: Turn on the liquid transfer pump 3-3 and the liquid phase control valve 3-4 to inject the simulated drilling fluid into the simulated formation sand 7 through the injection chamber 1-2. The simulated drilling fluid then flows from the simulated formation sand 7 into the return chamber 1-3, and finally flows from the top of the return chamber 1-3 into the separation tank 5, thus simulating the normal drilling fluid circulation conditions.

[0076] Step 4: Open the first gas phase control valve 4-5, allowing gas to flow into the separator 5 through the injection chamber 1-2, simulated formation sand 7, and return chamber 1-3, simulating the blowout process after shallow gas enters the wellbore. During this process, the gas entering from the injection chamber 1-2, the simulated drilling fluid, the gas entering from the gas inlet 2-1-1, and the sand in the simulated formation sand 7 interact together in the simulated formation box 2 and the return chamber 1-3, forming a multiphase coupled flow of gas, liquid, and solid.

[0077] The gas, liquid, and solid mixture that flows into the separator 5 through the reflux chamber 1-3 can be reused after filtration and separation, and replenished into the storage tank 3-1.

[0078] Step 5: During the above experiment, the pressure sensor 6-1 will transmit the pressure data collected from the simulated formation box 2 and the simulated wellbore transparent tube 1-1 to the data processing system 6-3 for analysis and processing.

[0079] Image acquisition unit 6-2 transmits the acquired images of gas-liquid-solid multiphase flow patterns, sand transport, and formation erosion morphology in the simulated formation box 2 and the simulated wellbore transparent tube 1-1 to the data processing system 6-3 for analysis and processing.

[0080] The flow data collected by the liquid flow meter 6-4, the first gas flow meter 6-5, and the second gas flow meter 6-6 are all transmitted to the data processing system 6-3 for analysis and processing.

[0081] Step Six: Simulate the pump stoppage and circulation interruption blowout condition. Close the liquid phase supply unit 3 passage while keeping the gas phase supply unit 4 passage open, allowing gas to continuously enter the simulated formation box 2 and the simulated wellbore transparent pipe 1-1 to simulate the shallow gas formation-wellbore coupling blowout process under conditions without drilling fluid circulation. Specifically, for conventional drilling processes, when the pump stops and circulation is interrupted for blowout, the first gas phase control valve 4-5 on the first gas phase branch pipe 4-3 connected to the upper end of the injection chamber 1-2 does not need to be opened; only the second gas phase branch pipe 4-4 connected to the formation simulation unit needs to be opened and kept unobstructed. During gas drilling or underbalanced drilling processes, when the pump stops and circulation is interrupted for blowout, both the first gas phase branch pipe 4-3 and the second gas phase branch pipe 4-4 need to be kept open and unobstructed.

[0082] Meanwhile, the data monitoring unit 6 continuously collects and monitors data. By comparing and analyzing the pressure response, multiphase flow pattern, and formation erosion morphology under drilling fluid circulation conditions and pump stoppage and circulation interruption conditions, the influence of drilling fluid circulation status on the shallow gas release process can be analyzed.

[0083] Step 7: After the experiment is completed, shut down all liquid phase supply units 3 and gas phase supply units 4, and depressurize the simulated formation box 2 and the simulated wellbore transparent tube 1-1.

[0084] Empty the separation tank 5 and dismantle and clean the simulated formation box 2.

[0085] When conducting comparative experiments under different formation conditions and fluid supply conditions, the simulated formation sand 7 with appropriate particle size and compaction degree can be replaced, and the flow parameters of the liquid flow meter 6-4, the first gas flow meter 6-5, and the second gas flow meter 6-6 can be adjusted accordingly to obtain wellbore pressure, formation pressure, flow rate changes, multiphase flow patterns, sand particle migration, and formation erosion morphology under different experimental conditions. By comparing the acquired data and image data under different experimental conditions, it is possible to analyze the pressure transmission law, fluid exchange characteristics, and formation sand production mechanism during the shallow gas formation-wellbore coupled blowout process.

[0086] The shallow gas formation-wellbore coupled blowout visualization simulation device and method disclosed in this embodiment can be used for shallow gas well control risk assessment in offshore drilling, sand production simulation in shallow loose formations, research on gas-liquid-solid multiphase flow laws, and well control process optimization experiments. By adjusting the particle size and compaction degree of the simulated formation sand 7, the liquid supply parameters of the liquid phase supply unit 3, and the gas supply parameters of the gas phase supply unit 4, the formation-wellbore coupled blowout process under different shallow gas formation conditions and different drilling conditions can be simulated.

[0087] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A shallow gas formation-wellbore coupled blowout visualization simulation device, characterized in that: It includes a visualization wellbore assembly (1), a simulated formation box (2), a liquid phase supply unit (3), a gas phase supply unit (4), a separation tank (5), and a data monitoring unit (6); The simulated formation box (2) is equipped with simulated formation sand (7), and the simulated formation box (2) is connected to the gas supply unit (4); The visualization wellbore assembly (1) includes a simulated wellbore transparent tube (1-1), which is provided with an injection chamber (1-2) and a return chamber (1-3) that are isolated from each other. The bottom port of the injection chamber (1-2) is inserted into the simulated formation sand (7), the bottom port of the return chamber (1-3) is connected to the simulated formation box (2), the top port of the injection chamber (1-2) is connected to the liquid supply unit (3) and the gas supply unit (4), and the top of the return chamber (1-3) is connected to the separation tank (5). The data monitoring unit (6) includes a pressure sensor (6-1) and an image acquisition unit (6-2). The pressure sensor (6-1) and the image acquisition unit (6-2) are electrically connected to the data processing system (6-3). The pressure sensor (6-1) is arranged on the simulated wellbore transparent tube (1-1) and the simulated formation box (2). The lens of the image acquisition unit (6-2) faces the transparent tube (1-1) and the simulated formation box (2).

2. The shallow gas formation-wellbore coupled blowout visualization simulation device according to claim 1, characterized in that: The simulated wellbore transparent tube (1-1) is a cylindrical structure with a closed top and an open bottom. A simulated drill rod (1-4) is provided at the axis of the simulated wellbore transparent tube (1-1). The injection chamber (1-2) is located inside the simulated drill rod (1-4). The top end of the simulated drill rod (1-4) passes through the top end of the simulated wellbore transparent tube (1-1) and is connected to the liquid supply unit (3) and the gas supply unit (4). The annular cylindrical cavity formed by the simulated drill pipe (1-4) and the inner wall of the simulated wellbore transparent tube (1-1) is the reflux cavity (1-3). The bottom end of the simulated drill rod (1-4) is inserted into the simulated formation sand (7); The top of the simulated well transparent tube (1-1) is provided with a discharge port (1-1-1), which is connected to the reflux chamber (1-3) and the discharge port (1-1-1) is connected to the separation tank (5) through a pipeline.

3. The shallow gas formation-wellbore coupled blowout visualization simulation device according to claim 1, characterized in that: The simulated formation box (2) includes a sand box shell (2-1) for holding the simulated formation sand (7). The top of the sand box shell (2-1) is sealed with a transparent cover plate (2-2). The middle part of the transparent cover plate (2-2) is provided with an installation hole (2-2-1). The bottom end of the simulated well transparent pipe (1-1) is sealed and inserted into the installation hole (2-2-1). The side wall of the sand box shell (2-1) is provided with an air inlet (2-1-1), which is connected to the gas supply unit (4). The simulated stratum box (2) also includes a top plate reinforcing rib (2-3), which presses on the transparent cover plate (2-2). The top plate reinforcing rib (2-3) is fixedly connected to the bottom plate of the sand box shell (2-1) by a bolt assembly.

4. The shallow gas formation-wellbore coupled blowout visualization simulation device according to claim 3, characterized in that: The pressure sensor (6-1) includes a formation pressure sensor (6-1-4), which is mounted on the sand box housing (2-1).

5. The shallow gas formation-wellbore coupled blowout visualization simulation device according to claim 3, characterized in that: The gas phase supply unit (4) includes an air compressor (4-1), the output end of which is connected to an air storage tank (4-2). The air storage tank (4-2) is provided with a first gas phase branch pipe (4-3) and a second gas phase branch pipe (4-4) at its outlet end. The end of the first gas phase branch pipe (4-3) is connected to the injection chamber (1-2), and the end of the second gas phase branch pipe (4-4) is connected to the air inlet (2-1-1). A first gas phase control valve (4-5) is provided on the first gas phase branch (4-3), a second gas phase control valve (4-6) is provided on the second gas phase branch (4-4), and a third gas phase control valve (4-7) is provided between the air compressor (4-1) and the air storage tank (4-2).

6. The shallow gas formation-wellbore coupled blowout visualization simulation device according to claim 5, characterized in that: The data monitoring unit (6) further includes a first gas flow meter (6-5) and a second gas flow meter (6-6). The first gas flow meter (6-5) is installed on the first gas phase branch pipe (4-3), and the second gas flow meter (6-6) is installed on the second gas phase branch pipe (4-4). The first gas flow meter (6-5) and the second gas flow meter (6-6) are electrically connected to the data processing system (6-3).

7. The shallow gas formation-wellbore coupled blowout visualization simulation device according to claim 1, characterized in that: The pressure sensor (6-1) also includes a first wellbore pressure sensor (6-1-1), a second wellbore pressure sensor (6-1-2), and a third wellbore pressure sensor (6-1-3), which are respectively located at the upper, middle, and lower positions of the simulated wellbore transparent tube (1-1).

8. The shallow gas formation-wellbore coupled blowout visualization simulation device according to claim 1, characterized in that: The liquid supply unit (3) includes a storage tank (3-1), which is connected to the injection chamber (1-2) via a liquid phase pipe (3-2). The liquid phase pipe (3-2) is equipped with a liquid transfer pump (3-3) and a liquid phase control valve (3-4). The data monitoring unit (6) also includes a liquid flow meter (6-4), which is installed on the liquid phase tube (3-2) and is electrically connected to the data processing system (6-3).

9. The shallow gas formation-wellbore coupled blowout visualization simulation device according to claim 1, characterized in that: The separation tank (5) has a cylindrical structure, and a filter plate (5-1) is fixedly installed on the upper part of the inner wall of the separation tank (5).

10. A visualization simulation method for shallow gas formation-wellbore coupled venting, characterized in that: Includes the following steps: Step 1: Calibrate the data monitoring unit (6); Step 2: Turn on the air compressor (4-1), the third gas phase control valve (4-7), and the second gas phase control valve (4-6) to fill the simulated formation sand (7) with gas through the air inlet (2-1-1) on the simulated formation box (2) to establish the simulated formation base pressure; After the internal pressure of the simulated formation box (2) stabilizes, the blowout simulation stage begins; Step 3: Turn on the liquid transfer pump (3-3) and the liquid phase control valve (3-4) to inject the simulated drilling fluid into the simulated formation sand (7) through the injection chamber (1-2). The simulated drilling fluid then flows from the simulated formation sand (7) into the return chamber (1-3) and finally flows from the top of the return chamber (1-3) into the separation tank (5) to simulate the normal drilling fluid circulation conditions. Step 4: Open the first gas phase control valve (4-5) to allow the gas to flow into the separation tank (5) through the injection chamber (1-2), the simulated formation sand (7), and the return chamber (1-3) to simulate the venting process of shallow gas after entering the wellbore; The gas, liquid and solid mixture flowing into the separation tank (5) through the reflux chamber (1-3) can be reused after being filtered and separated, and replenished into the storage tank (3-1). During this process, the gas entering from the injection chamber (1-2), the simulated drilling fluid, the gas entering from the air inlet (2-1-1), and the sand in the simulated formation sand (7) interact together in the simulated formation box (2) and the return chamber (1-3) to form a gas, liquid, and solid multiphase coupled flow. Step 5: The pressure sensor (6-1) transmits the pressure data collected from the simulated formation box (2) and the simulated wellbore transparent pipe (1-1) to the data processing system (6-3) for analysis and processing; The image acquisition unit (6-2) transmits the acquired image data of gas-liquid-solid multiphase flow patterns, sand transport, and formation erosion morphology in the simulated formation box (2) and the simulated wellbore transparent pipe (1-1) to the data processing system (6-3) for analysis and processing. Step 6: Simulate the pump stoppage and circulation interruption venting condition, shut down the liquid phase supply unit (3), keep the gas phase supply unit (4) open, so that the gas continuously enters the simulated formation box (2) and the simulated wellbore transparent tube (1-1) to simulate the shallow gas formation-wellbore coupling venting process under the condition of no drilling fluid circulation. At the same time, the data monitoring unit (6) continuously collects and monitors data. By comparing and analyzing the pressure response, multiphase flow pattern and formation erosion morphology under the drilling fluid circulation condition and the pump stoppage and circulation interruption condition, the influence of the drilling fluid circulation state on the shallow gas venting process can be analyzed. Step 7: After the experiment is completed, shut down all the liquid phase supply units (3) and the gas phase supply units (4), and depressurize the simulated formation box (2) and the simulated wellbore transparent pipe (1-1); Empty the separation tank (5) and dismantle and clean the simulated formation box (2).

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