Experimental method for simulating well killing effect of rescue well under different communication points

Abstract

The invention relates to an experimental method for simulating the well killing effect of a rescue well under different communication points. Comprising the following steps that (1) a communication point adjusting device is installed on the upper portion of a visual shaft, the bottom of the visual shaft is connected with a gas injection system through a pipeline, the outer end of the communication point adjusting device is connected with a liquid injection system through a pipeline, and the top of the visual shaft is connected with a gas-liquid separator and an outlet flow measuring instrument through pipelines; (5) experimental measurement: recording the injection angle of the injection pipe at the communication point after the liquid phase injection flow is stable, and (6) replacing the injection pipe at the communication point so as to realize the adjustment of the injection angle of the kill fluid, and repeating the steps (2)-(5). The well killing simulation device has the advantages that well killing process simulation of the rescue well at different communication points can be achieved, the multiphase flow law in the well killing cylinder is revealed, and therefore the well killing effect of the rescue well under different working conditions is researched, and well killing parameters of the rescue well are optimized.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of oil drilling engineering, in particular to an experimental method for simulating the well killing effect of a relief well under different communication points. BACKGROUND

[0002] Blowout control is one of the most serious safety accidents in deepwater offshore oil drilling operations. When blowout control occurs in the main well, well killing in the relief well becomes an effective means to completely solve the blowout accident. The well killing in the relief well mainly injects well killing fluid into the lost control main well through the drill pipe or annulus from the communication position to reestablish the pressure balance in the well, and ultimately achieve well killing rescue.

[0003] A relief well well killing simulation experiment device and method was applied for by the team of the present unit in 2018, with Chinese patent number CN201810004155.0 and patent name. It includes an experimental wellbore, a gas injection system, a liquid injection system, a gas-liquid separation system, a back pressure control system and a liquid discharge system. The gas injection system and the liquid injection system inject gas and liquid into the experimental wellbore, respectively. The experimental wellbore simulates the gas-liquid two-phase flow condition in the accident well. The mixed fluid flows out of the experimental wellbore and is separated into gas and liquid by the gas-liquid separation system. The back pressure control system controls the size of the wellhead back pressure. After the experiment is completed, the liquid discharge system discharges the liquid. The gas injection system automatically adjusts the gas injection speed according to the change of the experimental wellbore bottom hole pressure, truly reflects the process of continuously reducing gas well production in the well killing process, and thus realizes the coupling simulation of the wellbore and the formation. The present application provides a set of relief well well killing simulation device and method, which can simulate the change of the accident well bottom hole pressure under different well killing parameters, and provide model parameters and experimental data for the design and research of the relief well well killing construction parameters. The deficiency of the present application is that it is designed for a fixed communication point of the relief well well killing, and cannot meet the design of the relief well well killing parameters under multiple different communication points.

[0004] In addition, the existing relief well well killing parameter design under different communication points relies on numerical simulation and limited field experience. Although numerical simulation can make preliminary prediction, its reliability seriously depends on the accuracy of the wellbore model, and the actual situation is complex and changeable, which may cause large deviation between the simulation results and the actual situation. In addition, the existing commercial software lacks accurate characterization ability for the mixed flow characteristics of the well killing fluid in the wellbore and the dynamic change law of the wellbore pressure after the relief well and the main well are connected at different communication points. This will lead to difficulties in accurately quantifying the relief well well killing effect under different communication positions, communication angles, well killing fluid discharge and physical properties when facing complex working conditions of the relief well well killing, and further cannot select the well killing parameters with the best well killing effect in the actual relief well well killing operation, resulting in well killing failure or too long well killing time, increasing the well killing risk and cost, and causing serious consequences. SUMMARY

[0005] The present application aims at the above-mentioned defects existing in the prior art, and provides an experimental method for simulating well killing effect of a rescue well under different communication points, which can realize well killing process simulation of the rescue well under different communication points, study flow pattern development characteristics of the upper part of the communication point, the communication point and the bottom of the wellbore, reveal multiphase flow law of the well killing fluid-intruded fluid in the well killing tube, and thus study well killing effect of the rescue well under different working conditions, and further optimize well killing parameters of the rescue well.

[0006] The experimental method for simulating well killing effect of a rescue well under different communication points provided by the present application has the technical scheme comprising the following processes: (1) constructing an experimental device for simulating well killing effect of a rescue well under different communication points, installing a communication point adjusting device (2) at the upper part of a visualized wellbore (1), connecting a gas injection system to the bottom of the visualized wellbore (1) through a pipeline, connecting a liquid injection system to the outer end of the communication point adjusting device (2) through a pipeline, and connecting a gas-liquid separator (8) and an outlet flow measuring instrument (9) to the top of the visualized wellbore (1) through a pipeline; (2) pipeline cleaning: repeatedly cleaning the pipeline for 2-3 times in the mode of gas injection-water injection, so as to ensure that the experimental fluid injected in the experimental process is not polluted; (3) gas injection: first, adjust a back pressure valve (13) to make the pressure of the gas in a gas storage tank (15) when the gas is injected into the visualized wellbore (1) less than 0.4 MPa, and then adjust the opening degree of an air inlet control valve (14) through a control panel (11) to ensure that the gas flow in the injection process is stable; (4) liquid injection: set the output frequency of a frequency conversion controller (6) to make a gear pump (4) at a stable rotating speed, and then realize the fixation of the liquid phase injection displacement, and when the gas velocity in the visualized wellbore (1) is stable, start the gear pump (4), and then stably inject the well killing fluid into the visualized wellbore (1) through the injection pipe with different angles; (5) experimental measurement: after the liquid phase injection flow reaches stability, record the injection angle of the injection pipe of the communication point, and record the flow pattern of the well killing fluid at the communication point, and at the same time, record the liquid outflow mass per unit time at the outlet of the gas-liquid separator (8); (6) replace the injection pipe of the communication point to realize the adjustment of the injection angle of the well killing fluid, repeat steps (2)-(5), and complete the well killing effect experiment of the rescue well under different communication points under the condition of the same gas velocity and the same liquid velocity; After one set of experimental measurement is completed, adjust the gas velocity and the liquid velocity, repeat the experimental steps (2)-(6), and until the well killing effect experiment of the rescue well under different communication points under the condition of different gas velocities and different liquid velocities is completed.

[0007] Preferably, the upper part of the visualization wellbore (1) is provided with a communication point adjusting device (2), the bottom of the visualization wellbore (1) is connected with a gas injection system through a pipeline, the outer end of the communication point adjusting device (2) is connected with a liquid injection system through a pipeline, and the top of the visualization wellbore (1) is connected with a gas-liquid separator (8) and an outlet flow meter (9) through a pipeline; The gas injection system comprises a gas flow meter (10), a pressure sensor (12), a back pressure valve (13), an air inlet control valve (14), a gas storage tank (15) and an air compressor (16), the upper part of the gas storage tank (15) is connected with the air compressor (16), and the lower part is sequentially connected with the air inlet control valve (14), the back pressure valve (13), the pressure sensor (12) and the gas flow meter (10) through a pipeline; The liquid injection system comprises a liquid flow meter (3), a gear pump (4), a water storage tank (5), a frequency conversion controller (6) and a data acquisition system (7), the liquid flow meter (3), the gear pump (4) and the water storage tank (5) are sequentially connected through a pipeline at the outer end of the communication point adjusting device (2), the liquid flow meter (3) is connected with the data acquisition system (7) through a signal line, the gear pump (4) is connected with the frequency conversion controller (6) through a signal line, and the frequency conversion controller (6) is connected with the data acquisition system (7) through a signal line.

[0008] Preferably, the outer side of the visualization wellbore (1) is provided with a high-speed camera (17) at the upper part of the communication point, a high-speed camera (18) at the communication point and a high-speed camera (19) at the bottom of the wellbore.

[0009] Preferably, the gas flow meter (10), the pressure sensor (12) and the air inlet control valve (14) are connected with a control console (11) through signal lines respectively.

[0010] Preferably, the communication point adjusting device (2) is provided with a plurality of injection pipes with different angles, and the liquid injection system is connected through the injection pipes with different angles.

[0011] Preferably, the injection angles of the injection pipes are 90°, 60°, 45° and 30° with the axis direction respectively.

[0012] Compared with the prior art, the application has the following beneficial effects: 1. The application can simulate the killing effect of a rescue well under different communication points, thereby providing certain support for optimizing the killing parameter design of the rescue well, the application can simulate the relationship between different blowout gas velocities, different killing fluid velocities and different injection angles of the killing fluid and the killing effect of the rescue well, thereby the most suitable communication point between the rescue well and the main wellbore can be designed according to the specific conditions in the actual killing parameter design of the rescue well, and the killing effect of the rescue well can be optimized; 2. Compared with the traditional empirical method and numerical simulation method, the application can solve the problem of connection point position selection in the relief well pressure well parameter design through a simple experimental simulation method, the required experimental equipment is simple, easy to assemble, and the errors of the traditional empirical method and numerical simulation method are reduced, the time and cost in the relief well pressure well parameter design are saved, and the risk of blowout accident aggravation is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 is a connection schematic diagram of embodiment 1 of the application; Figure 2 is a connection schematic diagram of embodiment 2 of the application; In the above figure: visualized wellbore (1), connection point adjusting device (2), liquid flowmeter (3), gear pump (4), water storage tank (5), frequency converter controller (6), data acquisition system (7), gas-liquid separator (8), outlet flow measuring instrument (9), gas injection system including gas flowmeter (10), control console (11), pressure sensor (12), back pressure valve (13), air inlet control valve (14), gas storage tank (15), air compressor (16), high-speed camera at the upper part of the connection point (17), high-speed camera at the connection point (18), high-speed camera at the bottom of the wellbore (19), camera acquisition system (20). DETAILED DESCRIPTION

[0014] The preferred embodiments of the application are described below in conjunction with the accompanying drawings, and it should be understood that the preferred embodiments described herein are only used to illustrate and explain the application, and are not used to limit the application.

[0015] Embodiment 1, refer to Figure 1 The application refers to an experimental method for simulating the effect of relief well pressure well under different connection points, and the technical scheme comprises the following processes: (1) Constructing an experimental device for simulating the effect of relief well pressure well under different connection points, installing a connection point adjusting device (2) at the upper part of the visualized wellbore (1), connecting a gas injection system through a pipeline at the bottom of the visualized wellbore (1), connecting a liquid injection system through a pipeline at the outer end of the connection point adjusting device (2), and connecting a gas-liquid separator (8) and an outlet flow measuring instrument (9) through a pipeline at the top of the visualized wellbore (1); (2) Pipeline cleaning: repeatedly clean the pipeline 2-3 times in the mode of gas injection-cleaning water, to ensure that the experimental fluid injected in the experimental process is not contaminated; (3) Gas injection: first, adjust the back pressure valve (13) to make the pressure of the gas in the gas storage tank (15) when injected into the visualized wellbore (1) less than 0.4 MPa, and adjust the opening degree of the air inlet control valve (14) through the control console (11) to ensure the stability of the gas flow in the injection process; (Four) liquid injection: by setting the output frequency of the frequency converter controller (6), the gear pump (4) is at a stable speed, and then the liquid injection displacement is fixed, when the gas velocity in the visualization wellbore (1) is stable, the gear pump (4) is started, and the well killing fluid is injected into the visualization wellbore (1) through the injection pipe at different angles; (Five) experimental measurement: after the liquid injection flow reaches stability, the injection angle of the injection pipe at the connection point is recorded, and the flow pattern of the well killing fluid at the connection point is recorded, and the liquid outflow mass per unit time at the outlet of the gas-liquid separator (8) is recorded; (Six) replace the injection pipe at the connection point to adjust the injection angle of the well killing fluid, repeat steps (two) to (five), and complete the well killing effect experiment of the rescue well under different connection points under the same gas velocity and the same liquid velocity conditions; After completing a set of experimental measurements, adjust the gas velocity and liquid velocity conditions, and repeat the experimental steps (two) to (six), until the well killing effect experiment of the rescue well under different connection points under different gas velocity and different liquid velocity conditions is completed.

[0016] The upper part of the visualization wellbore (1) mentioned in the application is provided with a connection point adjusting device (2), the bottom of the visualization wellbore (1) is connected with a gas injection system through a pipeline, the outer end of the connection point adjusting device (2) is connected with a liquid injection system through a pipeline, and the top of the visualization wellbore (1) is connected with a gas-liquid separator (8) and an outlet flow measuring instrument (9) through a pipeline; The gas injection system comprises a gas flow meter (10), a pressure sensor (12), a back pressure valve (13), an air inlet control valve (14), a gas storage tank (15) and an air compressor (16), the upper part of the gas storage tank (15) is connected with the air compressor (16), and the lower part is sequentially connected with the air inlet control valve (14), the back pressure valve (13), the pressure sensor (12) and the gas flow meter (10) through pipelines; The liquid injection system comprises a liquid flow meter (3), a gear pump (4), a water storage tank (5), a frequency conversion controller (6) and a data acquisition system (7), the outer end of the connection point adjusting device (2) is sequentially connected with the liquid flow meter (3), the gear pump (4) and the water storage tank (5) through pipelines, the liquid flow meter (3) is connected with the data acquisition system (7) through a signal line, the gear pump (4) is connected with the frequency conversion controller (6) through a signal line, and the frequency conversion controller (6) is connected with the data acquisition system (7) through a signal line.

[0017] The outer side of the visualization wellbore (1) is respectively provided with a connection point upper high-speed camera (17), a connection point high-speed camera (18) and a wellbore bottom high-speed camera (19).

[0018] The gas flow meter (10), the pressure sensor (12) and the air inlet control valve (14) are connected to the control console (11) through signal lines respectively.

[0019] The connecting point adjusting device (2) is provided with injection pipes with different angles, and the injection pipes are connected with the liquid injection system.

[0020] The injection angles of the injection pipes are 90°, 60°, 45° and 30° with the axial direction respectively.

[0021] In example 2, the experimental method for simulating the well killing effect of the relief well at different connecting points is different from that in example 1. Refer to Figure 2 The connecting point adjusting device (2) can be provided with two layers according to needs, so that more angles are met, and more data can be obtained.

[0022] The experimental method of the embodiment includes the following specific processes. ①Check the air tightness of the air inlet pipeline and valve, and check the leak of the visual wellbore (1) and the liquid phase pipeline, check the performance of the pressure sensor (12), the liquid flow meter (3) and the gas flow meter (10), and ensure that the whole experimental device can be normally used; before the experiment, the fluid pipeline is cleaned by using the method of "gas injection-water flushing" alternately, and the process is repeated for 2-3 cycles, so as to completely remove the potential pollutants on the inner wall of the pipeline, so as to ensure the purity of the injected experimental fluid and avoid the pollution of the experimental fluid; ②Establish the simulation environment of fluid injection in the visual wellbore (1) after the blowout of the deepwater drilling well is out of control: before the formal start of the gas injection operation, the back pressure valve (13) needs to be accurately adjusted first, and the core purpose is to establish a controllable back pressure, so that the wellhead injection pressure is always stable below the preset safety threshold (i.e. less than 0.4 MPa) when the gas in the gas storage tank (15) is injected into the visual wellbore (1), which is the pressure safety control link; on the basis of stable pressure parameters, the operator needs to finely adjust the opening of the air inlet control valve (14) through the control console (11), and adjust the valve in a small and gradual way by monitoring the data of the gas flow meter (10) in real time, so that the gas flow quickly reaches and stabilizes at the target value, so as to ensure that the gas flow rate in the whole injection process is stable and controllable, which is the flow stability control link. ③When the simulation condition of the blowout is established, the rescue well is connected to the main well and the well killing is simulated: the connecting point between the rescue well and the main well is selected, a 90° injection pipe is selected first, that is, the injection pipe is perpendicular to the visualized well (1), the connecting pipe is connected, and the injection of the well killing fluid is then performed; before the gear pump (4) is started to inject the liquid phase, the first task is to set the operation parameters of the driving motor, the output frequency of the frequency conversion controller (6) is accurately set, the speed of the motor is directly controlled, so that the gear pump (4) connected thereto obtains a constant and accurate speed, after the setting is completed, a key prerequisite is met: the gas phase flow rate in the visualized well (1) has reached and remained stable through the previous operation; at this time, the gear pump (4) can be started. After the gear pump (4) is started, it will continuously and stably inject the preset displacement of the well killing fluid into the well at a constant speed, so as to realize accurate control of the downhole working condition; ④Experimental result measurement: when the liquid phase injection flow rate is confirmed to reach and remain stable, the key phenomenon and data recording work can be started. This step mainly includes two parallel tasks: morphological observation recording: at the observation section or the visualized connecting point, the flow morphology of the well killing fluid under the action of gas phase entrainment is observed and recorded in detail. The upper high-speed camera (17) at the connecting point, the high-speed camera (18) at the connecting point and the high-speed camera (19) at the bottom of the well are used to assist recording, and the flow state characteristics are accurately described on the recording table; Liquid phase production measurement: at the outlet of the gas-liquid separator (8) at the end of the flow process, the liquid flow meter (3) or the weighing device is used to accurately record the separated liquid mass flow rate per unit time; ⑤The connecting point between the rescue well and the main well can be changed, the optional angles are 90°, 60°, 45°, 30°, steps ②-④ are repeated, and the simulation experiment of the well killing effect of the rescue well under different connecting points is completed; more angle simulation experiments can also be realized by adding a second layer of connecting point adjusting device (2).

[0023] The above is only part of the preferred embodiments of the present application, any person skilled in the art can modify the above described technical solutions or modify them into equivalent technical solutions. Therefore, the corresponding simple modification or equivalent transformation according to the technical solutions of the present application is within the scope of protection claimed by the present application.

Claims

1. An experimental method for simulating the well control effect of rescue wells under different connectivity points, characterized in that: Includes the following processes: (a) Construct an experimental device to simulate the well control effect of rescue wells under different connection points. Install a connection point adjustment device (2) on the upper part of the visualization wellbore (1). Connect a gas injection system through a pipeline at the bottom of the visualization wellbore (1). Connect a liquid injection system through a pipeline at the outer end of the connection point adjustment device (2). Connect a gas-liquid separator (8) and an outlet flow meter (9) through a pipeline at the top of the visualization wellbore (1). (ii) Pipeline cleaning: Clean the pipeline repeatedly with air injection and clean water 2-3 times to ensure that the experimental fluid injected during the experiment is not contaminated; (III) Gas injection: First, adjust the back pressure valve (13) so that the pressure of the gas in the gas storage tank (15) when it is injected into the visualized wellbore (1) is less than 0.4MPa. Adjust the opening of the gas inlet control valve (14) through the control console (11) to ensure that the gas flow rate is stable during the injection process. (iv) Liquid injection: By setting the output frequency of the frequency converter (6), the gear pump (4) is kept at a stable speed, thereby achieving a fixed liquid injection displacement. When the gas velocity in the visualized wellbore (1) is stable, the gear pump (4) is turned on, and the kill fluid is injected stably into the visualized wellbore (1) through injection pipes at different angles. (v) Experimental measurement: After the liquid phase injection flow rate reaches a stable state, record the injection angle of the injection pipe at the connection point and the flow pattern of the kill fluid at the connection point. At the same time, record the liquid outflow mass per unit time at the outlet of the gas-liquid separator (8). (vi) Replace the injection pipe at the connection point to adjust the injection angle of the kill fluid. Repeat steps (ii) to (v) to complete the well kill effect experiment of the rescue well at different connection points under the same gas velocity and the same fluid velocity. After completing a set of experimental measurements, adjust the gas velocity and liquid velocity conditions, and repeat experimental steps (II) to (VI) until the well control effect experiment of rescue wells at different connection points under different gas velocity and liquid velocity conditions is completed.

2. The experimental method for simulating the well control effect of rescue wells under different connectivity points as described in claim 1, characterized in that: The upper part of the visualization well shaft (1) is equipped with a connection point adjustment device (2), the bottom of the visualization well shaft (1) is connected to a gas injection system through a pipeline, the outer end of the connection point adjustment device (2) is connected to a liquid injection system through a pipeline, and the top of the visualization well shaft (1) is connected to a gas-liquid separator (8) and an outlet flow meter (9) through a pipeline. The gas injection system includes a gas flow meter (10), a pressure sensor (12), a back pressure valve (13), an intake control valve (14), a gas storage tank (15), and an air compressor (16). The upper part of the gas storage tank (15) is connected to the air compressor (16), and the lower part is connected to the intake control valve (14), the back pressure valve (13), the pressure sensor (12), and the gas flow meter (10) in sequence through pipelines. The liquid injection system includes a liquid flow meter (3), a gear pump (4), a water storage tank (5), a frequency converter (6), and a data acquisition system (7). The liquid flow meter (3), the gear pump (4), and the water storage tank (5) are connected in sequence through pipelines at the outer end of the connection point regulating device (2). The liquid flow meter (3) is connected to the data acquisition system (7) through a signal line. The gear pump (4) is connected to the frequency converter (6) through a signal line. The frequency converter (6) is connected to the data acquisition system (7) through a signal line.

3. The experimental method for simulating the well control effect of rescue wells under different connectivity points as described in claim 1, characterized in that: A high-speed camera (17) at the top of the connection point, a high-speed camera (18) at the connection point, and a high-speed camera (19) at the bottom of the well are respectively installed on the outside of the visualization well shaft (1).

4. The experimental method for simulating the well control effect of rescue wells under different connectivity points as described in claim 1, characterized in that: The gas flow meter (10), pressure sensor (12) and intake control valve (14) are connected to the control console (11) via signal lines.

5. The experimental method for simulating the well control effect of rescue wells under different connectivity points according to claim 1, characterized in that: The connection point adjustment device (2) is equipped with multiple injection pipes at different angles, which are connected to the liquid injection system.

6. The experimental method for simulating the well control effect of rescue wells under different connectivity points according to claim 1, characterized in that: The injection angles of the injection tubes are 90°, 60°, 45° and 30° with respect to the axial direction.

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