WO2021159836A1

WO2021159836A1 - Natural gas hydrate cavity completion evaluation and testing apparatus and method

Info

Publication number: WO2021159836A1
Application number: PCT/CN2020/135065
Authority: WO
Inventors: 卢静生; 梁德青; 李栋梁; 何勇; 史伶俐
Original assignee: 中国科学院广州能源研究所
Priority date: 2020-03-27
Filing date: 2020-12-10
Publication date: 2021-08-19
Also published as: CN111472729B; CN111472729A

Abstract

A natural gas hydrate cavity completion evaluation and testing apparatus, comprising a reaction kettle system, a cavity completion system, a confining pressure control system, an entrance pressure control system, an exit pressure control system, a gas-liquid-solid separation system, a temperature control system, and a data collection and processing system. The reaction kettle system is used to simulate in situ generation of a natural gas hydrate, cavity completion, and exploitation. The temperature control system provides a constant temperature environment for the apparatus. The cavity completion system, the confining pressure control system, the entrance pressure control system, the exit pressure control system, and the gas-liquid-solid separation system are used to control pressure and flow states during experimentation. The data collection and processing system is used to collect and process parameters during experimentation. A natural gas hydrate cavity completion evaluation and testing method, implemented using the testing apparatus.

Description

Natural gas hydrate cave completion evaluation test device and method

Technical field

The invention relates to the technical field of natural gas hydrate development, in particular to a natural gas hydrate cave completion evaluation test device and method.

Background technique

Natural gas hydrates are widely distributed in deep-sea sediments or frozen land on land. The reserves are very huge, which is twice the total carbon content of conventional fuels in the world. It is a potential future energy source.

However, hydrate reservoirs have complex structures, low permeability, complex mineral composition, and complex temperature and pressure. Therefore, there may be problems such as low productivity and sand production during the development of hydrate reservoirs. The gas production of the reservoir after cave completion is After perforation is completed, hydraulic fracturing is 3-20 times that of hydraulic fracturing, and the cost is lower than that of large-scale hydraulic fracturing. Therefore, the use of cave completion technology to collapse the target reservoir to expand the borehole to form caves can not only improve the conductivity of diagenesis or high-strength hydrate reservoirs, but also provide a larger cave space for sand control and precipitation. Wait.

However, for hydrate development, cave completion is a brand-new technology. Therefore, the mechanism of cave completion in diagenetic or high-strength hydrate reservoirs is still unclear, and the implementation effect has not been effectively evaluated. At the same time, due to the large capital investment, long operation time, and many uncertain factors in conducting field test of hydrate cave completion, and it is difficult to evaluate and interpret the stimulation mechanism after the completion of on-site cave, therefore, the current research on hydrate cave completion There is very little research on the mechanism of increasing production and the effect of sand control.

Summary of the invention

In view of the shortcomings of the prior art, one of the objectives of the present invention is to provide a natural gas hydrate cave completion evaluation test device, which can be used to simulate and evaluate the cave completion process and obtain the stimulation mechanism of cave completion in hydrate reservoirs.

In order to achieve the above objectives, the technical solution adopted by the present invention is:

A gas hydrate cave completion evaluation test device, including:

The reactor system includes a reactor, a confining pressure piston and a wellbore; the confining piston includes a piston body extending into the reactor and a connecting part. The lower end of the connecting part is fixedly connected to the piston body, and the upper end extends out of the reactor; The inner cavity of the reactor is divided into a core chamber and a confining pressure chamber; the wellbore is vertically arranged in the core chamber, the upper end is connected with the cave completion system, and the lower end is connected with the gas-liquid-solid separation system; multiple sets of monitoring probes are installed in the reactor core chamber and the wellbore ；

The cave completion system includes a fluid chamber 1, a booster pump and a buffer tank. The fluid chamber is divided into two paths after the booster pump and the buffer tank. One is connected to the upper end of the wellbore, and the other is connected to the inlet of the core chamber;

The inlet pressure control system includes a gas source, a gas buffer tank and a gas booster pump. The gas source is connected to the inlet of the core chamber after the gas booster pump and the gas buffer tank;

The outlet pressure control system includes a gas flow meter and a vacuum pump. The vacuum pump is connected to the core chamber outlet via the gas flow meter;

The gas-liquid-solid separation system includes an electric valve, a gas-liquid-solid separation tank, a gas flow meter and a liquid production recovery device. The outlet of the liquid-solid separation tank is connected;

The data acquisition and processing system is electrically connected with the sensing elements of the reactor system, cave completion system, inlet pressure control system, outlet pressure control system, and gas-liquid-solid separation system to collect and process the sensing signals of each sensing element.

As an improvement of the present invention, the cave completion system further includes an ignition controller and a downhole igniter. The downhole igniter is arranged in the wellbore and is electrically connected to the ignition controller outside the reactor.

Another object of the present invention is to provide a gas hydrate cave completion evaluation test method, which is implemented based on the above test device, and includes the following steps:

Step 1: Fill the core sample into the core chamber of the reactor, seal and vacuum with a vacuum pump, and at the same time compact and maintain the sample by the confining piston, respectively inject gas or/and liquid into the core chamber, and test the fluid flow through the monitoring probe The physical property parameter F1 of the core;

Step 2: Take out the core, dry it, and fill in the core chamber again after quantifying the amount of water. After sealing, use a vacuum pump to evacuate. At the same time, the sample is compacted and held by the confining pressure piston, and the gas booster pump and gas buffer tank are used to feed the core chamber. Inject high-pressure natural gas, and control the temperature of the reactor through the matching temperature-controlled water jacket to generate natural gas hydrate;

Step 3: After the hydrate formation is completed, pass gas or/and liquid into the core chamber, and test the physical property parameter F2 of the fluid flowing through the hydrate core through the monitoring probe;

Step 4: Carry out cave completion operations, including downhole ignition and explosion, downhole high-pressure fluid fracturing, liquid nitrogen fracturing cave-making methods to implement completion operations, or take out the hydrate core in a low-temperature environment and implement hole drilling;

Step 5: Inject gas or/and liquid into the core chamber, and test the physical property parameter F3 of the hydrate core after the fluid flows through the cave after the completion of the well through the monitoring probe;

Step 6: Turn on the electric valve, the fluid in the core chamber flows out through the wellbore, the gas-liquid-solid output is obtained through the metering system of the gas-liquid-solid separation tank, and the physical parameter F4 of the mining process is collected in real time through the monitoring probe;

Step 7: Analyze the above-mentioned physical parameters F1-F4, and obtain the test results of the core and hydrate core cave before, after, during and after the cave, so as to realize the evaluation of the cave completion effect.

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

1. The present invention can realize in-situ synthesis of hydrate reservoirs under confining pressure conditions, and monitor the synthesis process, changes in temperature, pressure, and reservoir structure before and after cave completion and before and after mining.

2. The present invention can evaluate the completion of hydrate caves, explore its stimulation mechanism, and provide support and verification for the design of hydrate cave completions.

Description of the drawings

The drawings of the specification forming a part of the application are used to provide a further understanding of the application, and the exemplary embodiments and descriptions of the application are used to explain the application, and do not constitute an improper limitation of the application.

Figure 1 is a structural block diagram of the testing device of the present invention;

Figure 2 is a bottom view of the reactor system of the present invention;

Fig. 3 is a working flow chart of the present invention. The hydrate cave completion simulation system is the disclosed gas hydrate cave completion evaluation test device.

Description of Reference Signs: 1-fluid chamber 1 (deionized water, fracturing fluid, water jet liquid, liquid nitrogen, etc.); 2-booster pump; 3-buffer tank; 4-ignition controller; 5-piston; 6 -Reactor; 7-Downhole igniter; 8-wellbore; 9-electric valve; 10-visualization gas-liquid-solid separation tank; 11-camera; 12-temperature-controlled water jacket; 13-temperature water bath; 14-production liquid recovery Device; 15-gas source (natural gas, nitrogen, mixed gas, etc.); 16-gas buffer tank; 17-gas booster pump; 18-flow meter; 19-gas flowmeter; 20-resistance, temperature, pressure and sound wave probe 21-core chamber; 22-vacuum pump; 23-fluid chamber two (confining pressure liquid); 24-advection pump; V1～V11-valve; P1～P6-pressure gauge; PX-pressure sensor; TX-temperature sensor group; S-strain sensor.

Detailed ways

In order to make the above-mentioned objects, features and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

As shown in Figure 1 and Figure 2, a natural gas hydrate cave completion evaluation test device, including a reactor system, cave completion system, confining pressure control system, inlet pressure control system, outlet pressure control system, gas-liquid-solid separation System, temperature control system, data acquisition and processing system, as well as pipelines, valves and control systems connecting various components.

The reactor system is used to simulate the in-situ generation of natural gas hydrate, cave completion and exploitation, including the reactor 6, the confining piston 5 and the wellbore 8. The reactor 6 has a cylindrical shape and is placed horizontally. The middle of the top protrudes upwards to form a round table where the confining piston 5 is arranged. The top and two sides of the round table are provided with detachable top and side covers through O-rings and bolts. Seal it. The confining piston 5 includes a piston body extending into the reactor 6 and a connecting part. The lower end of the connecting part is fixedly connected to the piston body, and the upper end extends out of the reactor 6; the piston body divides the inner cavity of the reactor into a core chamber 21 and a surrounding part. Pressure cavity. The wellbore 8 is vertically arranged in the core chamber 21, the upper end is connected to the cave completion system via the confining pressure piston 5, and the lower end is connected to the gas-liquid-solid separation system. There are multiple sets of resistance, temperature, pressure and sonic probes 20 inside the core chamber 21 and the wellbore 8. The specific layout is designed according to the needs of the experiment, and the external resistance meter, sonic meter, pressure sensor PX and temperature sensor TX are connected through data lines. The electrical connection is used to obtain the stratified resistance, temperature, pressure and sound waves in the core chamber 21, and the segment resistance, temperature, pressure and sound waves of the wellbore 8 are obtained.

The temperature control system includes a temperature control water jacket 12 and a temperature water bath 13. The temperature control water jacket 12 is wrapped on the outside of the reactor 6 and is connected to the temperature water bath 13 to control the formation of natural gas hydrate and caves in the core chamber 21 The temperature of the well completion and mining process.

The cave completion system, the confining pressure control system, the inlet pressure control system, the outlet pressure control system and the gas-liquid-solid separation system constitute the stress-strain control system of the device, which is used to control the pressure and gas-liquid-solid flow state of the core chamber 21 throughout the experiment. Realize hydrate core generation, cave completion and mining.

Cave completion system, including fluid chamber 1, booster pump 2, valve V1, buffer tank 3, valve V2, valve V3, valve V5, valve V6, pressure gauge P1, pressure gauge P3, ignition controller 4 and downhole ignition器7. The fluid chamber 1 is divided into two paths through the booster pump 2, the valve V1, and the buffer tank. The entrance of the ventricle 21 is connected, and the downhole igniter 7 is arranged in the wellbore 8 and is electrically connected to the ignition controller 4 outside the reactor 6. In addition, the fluid chamber 1 is directly connected to the inlet of the core chamber 21 via the booster pump 2, the valve V6, and the pressure gauge P3. It should be noted that the fluid chamber-1 can be a combined chamber, and each chamber stores different liquids, such as deionized water, fracturing fluid, water jet, liquid nitrogen, etc., and the type of liquid is controlled by a valve. In this way, the cave completion system can first inject fracturing fluid, water jet fluid, and liquid nitrogen into the wellbore 8 for high-pressure fluid fracturing and liquid nitrogen fracturing, and secondly, it can inject fluid into the core chamber 21 ( For fluid testing of cores, hydrate cores, cave completions, etc.), thirdly, deionized water can be directly injected into the core chamber 21 to synthesize natural gas hydrate, and fourthly, the ignition controller 4 can control the downhole igniter 7 to ignite and make the downhole The gas burns or explodes to create cavities.

Confining pressure control system, including fluid chamber two 23, advection pump 24 and strain sensor S. The second fluid chamber 23 injects the confining pressure liquid into the confining pressure chamber through the advection pump 24 to control the movement of the confining piston 5 and the pressure of the confining pressure chamber (the confining pressure of the core chamber 21), and the strain sensor S is used to monitor the pressure of the confining pressure chamber.

Imported pressure control system, including gas source 15, valve V8, gas booster pump 17, gas buffer tank 16, pressure gauge P2, valve V7 and pressure gauge P3. The gas source 15 is connected to the inlet of the core chamber 21 via a valve V8, a gas booster pump 17, a gas buffer tank 16, a pressure gauge P2, a valve V7, and a pressure gauge P3. It should be noted that the gas source 15 may be a combined chamber, and each chamber stores different gases, such as natural gas, nitrogen, mixed gas, etc., and the gas outlet type is controlled by a valve. In this way, the imported pressure control system can first inject natural gas into the core chamber 21 to synthesize natural gas hydrate, and secondly inject gas into the core chamber 21 for fluid testing (core, hydrate core, cave completion, etc.). After burning or exploding to create a cave, inject nitrogen and other non-combustible gases to extinguish the fire.

The outlet pressure control system includes pressure gauge P4, valve V4, flow meter 18, valve V11 and vacuum pump 22. The outlet of the core chamber 21 is divided into two paths through the pressure gauge P4, the valve V4, and the flow meter 18. One path is connected to the vacuum pump 22 through the valve V11, and the other path is connected to the visual gas-liquid-solid separation tank 10 of the gas-liquid-solid separation system.

The gas-liquid-solid separation system includes a pressure gauge P6, an electric valve 6, a visual gas-liquid-solid separation tank 10, a camera system 11, a pressure gauge P5, a valve V9, a gas flow meter 19, a valve V10, and a liquid production recovery device 14. The lower end of the wellbore 8 is connected to the inlet of the visualization gas-liquid-solid separation tank 10 through the pressure gauge P6 and the electric valve 6; the gas outlet of the visualization gas-liquid-solid separation tank 10 is connected to the gas flowmeter 19 through the pressure gauge P5 and valve V9; the visualization gas-liquid-solid The liquid-solid fluid produced by the separation tank 10 flows into the subsequent liquid production recovery device 14 through the valve V10 to obtain specific liquid and solid output. The camera system 11 is arranged beside the visualized gas-liquid-solid separation tank 10 to record the gas-liquid-solid production situation of the visualized gas-liquid-solid separation tank 10 in an image manner. In addition to recording the gas output, the gas flow meter 19 is also used to adjust the gas production rate and the gas pressure.

Data acquisition and processing system, including data acquisition instrument, data processing workstation and display equipment. The data acquisition instrument is electrically connected to the sensing elements of the above systems, and is used to collect the resistance, temperature, pressure and sound waves in the hydrate core and wellbore, to collect the pressure values of the pressure gauges P1 to P6, and to collect visualized gas and liquid The output of the gas, liquid, and solid three phases separated by the solid separation tank 10 and other sensing elements for control and measurement are used to obtain experimental parameters. According to the collected experimental parameters, the data processing workstation uses software to analyze the resistance, temperature, pressure and sound waves of the wellbore and hydrate core, and derives the temperature, pressure, and hydrate content of the core, hydrate core, cave after completion, and during the mining process. , Reservoir morphology (caves, fractures, etc.), fluid flow, etc., to realize the evaluation test of cave completion, and optimize the cave completion by optimizing the cave completion technology and parameters.

As shown in Figure 3, in conjunction with the working process of the test device, the following further describes the gas hydrate cave completion evaluation test method, which mainly includes the following steps:

(1) Core test: Add a core to the core chamber 21, close the top and side covers of the core chamber 21, and seal with O-rings and bolts, and close all valves. Open the valves V11 and V4 and use the vacuum pump 22 to vacuum, then close the vacuum pump 22 and the valve V4, open the advection pump 24 to inject the confining pressure liquid of the fluid chamber two 23 into the confining pressure chamber of the reactor 6 and maintain the confining pressure. The fluid test is then carried out, including gas test and liquid test. The gas test is to open valves V8, V7 and V4, and pressurize the gas from the gas source 15 through the gas booster pump 17, and then flow through the gas buffer tank 16 into the core chamber 21; The liquid test is to turn on the liquid in the booster pump 2 and pressurize the fluid chamber 1, and enter the core chamber 21 through the valve V1, the mixing chamber 3, and the valve V5. The above tests keep the flow constant and flow out from the flow meter 18, and monitor the pressure gauge P2 in real time. /P3/P4 and the value changes of each probe, get the physical property parameter F1.

(2) Sample synthesis: After drying the core after the core test, add a constant amount of water. Then the water-containing core is added to the core chamber 21, the top and side covers of the core chamber 21 are closed, and sealed with O-rings and bolts, and all valves are closed. Open the valves V11 and V4 and use the vacuum pump 22 to vacuum, then close the vacuum pump 22 and the valve V4; open the gas source 15 to inject natural gas into the core chamber 21 through the gas booster pump 17, valves V8 and V7, and gas buffer tank 16. The valve V8 is closed, the temperature water bath 13 is started, the cold medium flows into the temperature control water jacket 12 through the pipeline for temperature control, and the hydrate core is generated.

It should be noted that when the dry core is added to the core chamber 21, while the natural gas is injected through the gas source 15, deionized water needs to be injected through the fluid chamber 1-1.

Then proceed to hydrate core gas or liquid test, the test method is the same as step (1), the physical property parameter F2 is obtained, and then all valves are closed.

(3) Cave completion operation: Open the valve V1 and turn on the booster pump 2 to boost the liquid in the fluid chamber 1, and perform the booster mixing operation in the mixing chamber 3. When the preset conditions are reached, the V2 and V3 valves are opened, and the working fluid is injected into the core chamber 21 through the wellbore 8, and cavitation operations are performed through fracturing fluid, water jet fluid, and liquid nitrogen. Or use combustion, blasting operations, etc.: the ignition controller 4 controls the downhole igniter 7 to ignite, so that the downhole gas burns or explodes to create caverns, and then injects incombustible gas such as nitrogen through the gas booster pump 17, valves V7 and V8 to extinguish the fire.

Then proceed to hydrate core gas or liquid test, the test method is the same as step (1), the physical property parameter F3 is obtained, and then all valves are closed.

(4) Exploitation operation: Open valves V9, V10 and electric valve 9 at the same time, and fluid flows from the hydrate core through the wellbore 8 into the visual gas-liquid-solid separation tank 10; the camera system 11 is used to record the visual gas-liquid-solid separation tank 10 gas-liquid-solid production If the situation occurs, the gas flow meter 19 is used to adjust the gas production rate and gas pressure. Collect the produced liquid-solid fluid through the valve V10 and the liquid production recovery device 14, use the gas flow meter 19 to collect the gas production rate and cumulative gas production, and collect the resistance, temperature, and pressure in real time through the arranged resistance, temperature, pressure and sonic probe 20 And sonic data.

Then proceed to hydrate core gas or liquid test, the test method is the same as step (1), the physical property parameter F4 is obtained, and then all valves are closed.

(5) Analysis and calculation: According to the collected data, use software to analyze the pressure, sound wave, temperature, resistance, and production data in the wellbore and hydrate core, and deduce the temperature, pressure, and reservoir caves of the reservoir cave completion and wellbore Fractures, hydrate content, productivity, etc., to realize the testing and evaluation of hydrate cave completion. By optimizing the size, direction, layout method and other parameters of the cavity-making operation, the productivity can be increased.

In summary, the present invention can test hydrate cave completion conditions. Although it is mainly used for hydrate cave completion evaluation design and testing, it can also be applied to conventional oil, gas and water cave completion evaluation design and testing.

The above-mentioned embodiments are only to illustrate the technical concept and characteristics of the present invention, and their purpose is to enable those of ordinary skill in the art to understand the content of the present invention and implement them accordingly, and should not limit the protection scope of the present invention. All equivalent changes or modifications made according to the essence of the content of the present invention should be covered by the protection scope of the present invention.

Claims

A gas hydrate cave completion evaluation test device, which is characterized in that it comprises:

The reactor system includes a reactor, a confining pressure piston and a wellbore; the confining piston includes a piston body extending into the reactor and a connecting part. The lower end of the connecting part is fixedly connected to the piston body, and the upper end extends out of the reactor; The inner cavity of the reactor is divided into a core chamber and a confining pressure chamber; the wellbore is vertically arranged in the core chamber, the upper end is connected with the cave completion system, and the lower end is connected with the gas-liquid-solid separation system; multiple sets of monitoring probes are installed in the reactor core chamber and the wellbore ；

The cave completion system includes a fluid chamber 1, a booster pump and a buffer tank. The fluid chamber is divided into two paths after the booster pump and the buffer tank. One is connected to the upper end of the wellbore, and the other is connected to the inlet of the core chamber;

The inlet pressure control system includes a gas source, a gas buffer tank and a gas booster pump. The gas source is connected to the inlet of the core chamber after the gas booster pump and the gas buffer tank;

The outlet pressure control system includes a gas flow meter and a vacuum pump. The vacuum pump is connected to the core chamber outlet via the gas flow meter;

The gas-liquid-solid separation system includes an electric valve, a gas-liquid-solid separation tank, a gas flow meter and a liquid production recovery device. The outlet of the liquid-solid separation tank is connected;

The data acquisition and processing system is electrically connected with the sensing elements of the reactor system, cave completion system, inlet pressure control system, outlet pressure control system, and gas-liquid-solid separation system to collect and process the sensing signals of each sensing element.
The gas hydrate cave completion evaluation test device according to claim 1, characterized in that: the cave completion system further comprises an ignition controller and a downhole igniter, the downhole igniter is arranged in the wellbore and is connected with The ignition controller outside the reactor is electrically connected.
A gas hydrate cave completion evaluation test method, implemented based on the test device of claim 1 or 2, characterized in that it comprises the following steps:

Step 1: Fill the core sample into the core chamber of the reactor, seal and vacuum with a vacuum pump, and at the same time compact and maintain the sample by the confining piston, respectively inject gas or/and liquid into the core chamber, and test the fluid flow through the monitoring probe The physical property parameter F1 of the core;

Step 2: Take out the core, dry it, and fill in the core chamber again after quantifying the amount of water. After sealing, use a vacuum pump to evacuate. At the same time, the sample is compacted and held by the confining pressure piston, and the gas booster pump and gas buffer tank are used to feed the core chamber. Inject high-pressure natural gas, and control the temperature of the reactor through the matching temperature-controlled water jacket to generate natural gas hydrate;

Step 3: After the hydrate formation is completed, pass gas or/and liquid into the core chamber, and test the physical property parameter F2 of the fluid flowing through the hydrate core through the monitoring probe;

Step 4: Carry out cave completion operations, including downhole ignition and explosion, downhole high-pressure fluid fracturing, and liquid nitrogen fracturing cave-making methods to implement well completion operations, or take out hydrate cores in a low-temperature environment and implement hole-making caverns;

Step 5: Inject gas or/and liquid into the core chamber, and test the physical property parameter F3 of the hydrate core after the fluid flows through the cave after the completion of the well through the monitoring probe;

Step 6: Turn on the electric valve, the fluid in the core chamber flows out through the wellbore, the gas-liquid-solid output is obtained through the metering system of the gas-liquid-solid separation tank, and the physical parameter F4 of the mining process is collected in real time through the monitoring probe;

Step 7: Analyze the above-mentioned physical parameters F1-F4, and obtain the test results of the core and hydrate core cave before, after, during and after the cave, so as to realize the evaluation of the cave completion effect.