CN105909224A - Natural gas hydrate dual-horizontal-well electrical heating auxiliary depressurization exploitation experimental device and working method - Google Patents

Abstract

The invention discloses an experimental device and a working method for exploiting natural gas hydrate by electric heating and depressurization in double-horizontal wells, including a gas injection system, an electric power system, a natural gas hydrate reaction system, a data monitoring and processing system, and a gas-liquid separation and metering system. Among them, the gas injection system provides gas source for the synthesis of natural gas hydrate; the power system provides current to promote the decomposition of natural gas hydrate; the natural gas hydrate reaction system provides the required ambient temperature and pressure for the formation and decomposition of natural gas hydrate; data monitoring and processing The system is used to measure the flow rate of produced gas and the saturation of natural gas hydrate in the device; the gas-liquid separation metering system is used to separate natural gas and water produced by the decomposition of natural gas hydrate. According to the principle that current passes through the conductor to generate heat, the present invention realizes the experimental device and working method of gas hydrate exploitation with electric heating assisted depressurization in double horizontal wells. It has a simple structure and strong applicability, and provides tools for the efficient development of natural gas hydrate reservoirs and methods.

Description

Experimental device and working method for natural gas hydrate recovery with electric heating and depressurization in dual horizontal wells

technical field

The invention relates to a method in the field of natural gas hydrate development, in particular to an experimental device and a working method for exploiting natural gas hydrate with electric heating-assisted depressurization in double-horizontal wells.

Background technique

Natural gas hydrates are combustible solids composed of small molecular gases such as water and methane. Today, as conventional energy is increasingly scarce, natural gas hydrate, as a relatively clean new energy with huge reserves, has attracted much attention.

At present, the mining methods of natural gas hydrate are mainly traditional mining methods, such as thermal stimulation mining method, depressurization mining method, chemical agent injection mining method and CO ₂ replacement mining method, etc. Among them, the thermal stimulation mining method mainly injects thermal fluids such as hot water and steam into the reservoir, and its heat utilization efficiency is usually low and difficult to control; the chemical agent used in the chemical agent injection mining method is expensive, the mining speed is slow, and the gas recovery is comparatively low. Difficulties, but also bring some environmental pollution problems; CO ₂ displacement mining method requires a stable CO ₂ gas source, and its application is relatively limited. The exploitation of natural gas hydrate by electric heating can convert electrical energy into thermal energy for developing natural gas hydrate reservoirs. The equipment is simple and the energy utilization rate is high, so it has attracted more and more attention. However, there is still no experimental device and working method for simulating the electric heating-assisted depressurization of natural gas hydrate in the laboratory, which seriously restricts the research progress of natural gas hydrate reservoir development.

Contents of the invention

Aiming at the above technical deficiencies, the present invention provides an experimental device and working method for exploiting natural gas hydrate with electric heating-assisted depressurization in dual-horizontal wells.

Technical scheme of the present invention is as follows:

An experimental device for exploiting natural gas hydrate with electric heating and depressurization in dual horizontal wells is characterized in that it includes a gas injection system, an electric power system, a natural gas hydrate reaction system, a data monitoring and processing system, and a gas-liquid separation metering system. The gas injection system consists of a natural gas cylinder (1), a pressure reducing valve (2), a gas mass flow meter (3), a pressure gauge (4) and a two-way valve (5), and the natural gas cylinder (1) passes through The pressure reducing valve (2), the gas mass flowmeter (3), the pressure gauge (4) and the two-way valve (5) are connected to the high pressure reactor (6), and the gas mass flowmeter (3) is connected to the computer (32); The power system is mainly composed of a power supply (13), an input cable (14), an output cable (15), an input electrode (11), and an output electrode (10). The power supply (13) connects the input cable (14) and the input electrode (11) connection, the output electrode (10) is connected to the power supply (13) through the output cable (15), the input electrode (11) is placed in the lower horizontal steel conduit (8), and the output electrode (10) is placed in the upper horizontal steel conduit ( 9); the natural gas hydrate reaction system consists of a high-pressure reactor (6), a constant temperature container (12), an upper horizontal steel conduit (9), a lower horizontal steel conduit (8), and a sodium lauryl sulfate solution tank ( 16), an advection pump (17), a two-way valve (18), a two-way valve (19) and a recovery tank (20), the high-pressure reactor (6) is placed in a constant temperature container (12), and the upper horizontal steel conduit (9) Placed at 10-20cm away from the top of the autoclave (6), the lower horizontal steel conduit (8) is placed at 10-20cm away from the bottom of the autoclave (6), the sodium lauryl sulfate solution tank (16) link to each other with high-pressure reactor (6) by advection pump (17) and two-way valve (18), recovery tank (20) links to each other with high-pressure reactor (6) by two-way valve (19); data monitoring processing system It consists of a TDR probe (7), a data acquisition device (31) and a computer (32). The TDR probe (7) is placed in a high-pressure reactor (6) to monitor the change of natural gas hydrate saturation. ) is connected to the computer (32) through the data acquisition device (31); the gas-liquid separation metering system consists of a two-way valve (21), a two-way valve (22), a pressure reducing valve (23), a hand pump (24), a separation device (25), two-way valve (26), gas mass flow meter (27), natural gas collection bottle (28), two-way valve (29), measuring cylinder (30), hand pump (24) and pressure reducing valve (23) connect to each other, pressure reducing valve (23) links to each other with high pressure reactor (6) by two-way valve (22), two-way valve (21), separator (25) is by two-way valve (26) and gas mass flow rate Meter (27) links to each other with natural gas collecting bottle (28), gas mass flow meter (27) links to each other with computer (32), and measuring cylinder (30) links to each other with separator (25) by two-way valve (29).

In the present invention, 20 to 30 holes are evenly distributed on the walls of the upper horizontal steel conduit (9) and the lower horizontal steel conduit (8) in the natural gas hydrate reaction system; the power system input electrode (11) and The lower horizontal steel conduit (8) is in contact, and the output electrode (10) is in contact with the upper horizontal steel conduit (9); in the data monitoring and processing system, 9 to 18 TDR probes (7) are placed in a high-pressure reactor ( 6) is used to monitor the change of natural gas hydrate saturation.

A working method for using the above-mentioned device to simulate double-horizontal well electric heating to assist depressurization to exploit natural gas hydrate, including the following steps:

(1) Simulate the natural depositional environment of natural gas hydrate formation: tightly fill the high-pressure reactor (6) with quartz sand with a particle size of 0.09-0.26 mm;

(2) Open the two-way valve (18) and the two-way valve (19), inject the sodium lauryl sulfate solution into the autoclave (6) with the speed of 0.1～1mL/min with the horizontal flow pump (17), two After the solution flows out of the pipeline where the through valve (19) is located, continue to inject for 30-60 minutes;

(3) Close the advection pump (17), the two-way valve (18) and the two-way valve (19), open the two-way valve (5) and the pressure reducing valve (2), and control the injected natural gas pressure to be 10-12MPa. The gas cylinder (1) injects natural gas with a purity of 99.99% into the high-pressure reactor (6); The pressure valve (2) makes the pressure in the autoclave (6) constant; the mass m of natural gas injected into the autoclave (6) is read by the gas mass flow meter (3) and the computer (32), when the gas mass flow meter (3 ) is less than 0.0001g/min, close the pressure reducing valve (3) and the two-way valve (5), leave the autoclave (6) for 3 to 7 days, and pass the TDR probe (7), data acquisition A device (31) and a computer (32) monitor changes in natural gas hydrate saturation;

(4) Open the back pressure valve (23), two-way valve (22), two-way valve (21), two-way valve (26) and two-way valve (29), control the hand pump (24), adjust the return The pressure of the pressure valve (23) is 3 to 6 MPa, simulating the depressurization of natural gas hydrate;

(5) When the output gas mass flow rate shown by the gas mass flow meter (27) is less than 0.0001g/min, turn on the power supply (13) and start simulating the exploitation of natural gas hydrate by electric heating in a double-horizontal well;

(6) When the output gas mass flow rate shown by the gas mass flow meter (27) is less than 0.0001g/min, the natural gas hydrate exploitation ends, and the total mass m _of the output gas is read;

(7) Calculate the recovery factor of natural gas hydrate:

The advantage of the present invention is that it can simulate the process of natural gas hydrate formation under the condition of natural gas hydrate deposition, natural gas hydrate depressurization production, and double horizontal well electric heating assisted depressurization production of natural gas hydrate. The device is simple and easy to operate. The development provides simulation tools and methods.

Description of drawings

Fig. 1 is a schematic structural view of the experimental device of the present invention.

Among them, 1. Natural gas cylinder; 2. Pressure reducing valve; 3. Gas mass flowmeter; 4. Pressure gauge; 5. Two-way valve; 6. High pressure reactor; 7. TDR probe; 8. Lower horizontal steel conduit ;9, upper horizontal steel conduit; 10, output electrode; 11, input electrode; 12, constant temperature container; 13, power supply; 14, input cable; 15, output cable; 16, sodium lauryl sulfate solution tank; 17 , Convection pump; 18, Two-way valve; 19, Two-way valve; 20, Recovery tank; 21, Two-way valve; 22, Two-way valve; 23, Back pressure valve; 24, Hand pump; 25, Separator; 26. Two-way valve; 27. Gas mass flow meter; 28. Natural gas collection bottle; 29. Two-way valve; 30. Measuring cylinder; 31. Data acquisition device; 32. Computer.

detailed description

The present invention will be described in detail below in conjunction with the embodiments and the accompanying drawings, but it is not limited thereto.

Embodiment one

As shown in Figure 1

An experimental device for exploiting natural gas hydrate with electric heating and depressurization in dual horizontal wells is characterized in that it includes a gas injection system, an electric power system, a natural gas hydrate reaction system, a data monitoring and processing system, and a gas-liquid separation metering system. The gas injection system consists of a natural gas cylinder (1), a pressure reducing valve (2), a gas mass flow meter (3), a pressure gauge (4) and a two-way valve (5), and the natural gas cylinder (1) passes through The pressure reducing valve (2), the gas mass flowmeter (3), the pressure gauge (4) and the two-way valve (5) are connected to the high pressure reactor (6), and the gas mass flowmeter (3) is connected to the computer (32); The power system is mainly composed of a power supply (13), an input cable (14), an output cable (15), an input electrode (11), and an output electrode (10). The power supply (13) connects the input cable (14) and the input electrode (11) connection, the output electrode (10) is connected to the power supply (13) through the output cable (15), the input electrode (11) is placed in the lower horizontal steel conduit (8), and the output electrode (10) is placed in the upper horizontal steel conduit ( 9); the natural gas hydrate reaction system consists of a high-pressure reactor (6), a constant temperature container (12), an upper horizontal steel conduit (9), a lower horizontal steel conduit (8), and a sodium lauryl sulfate solution tank ( 16), an advection pump (17), a two-way valve (18), a two-way valve (19) and a recovery tank (20), the high-pressure reactor (6) is placed in a constant temperature container (12), and the upper horizontal steel conduit (9) Placed at 10-20cm away from the top of the autoclave (6), the lower horizontal steel conduit (8) is placed at 10-20cm away from the bottom of the autoclave (6), the sodium lauryl sulfate solution tank (16) link to each other with high-pressure reactor (6) by advection pump (17) and two-way valve (18), recovery tank (20) links to each other with high-pressure reactor (6) by two-way valve (19); data monitoring processing system It consists of a TDR probe (7), a data acquisition device (31) and a computer (32). The TDR probe (7) is placed in a high-pressure reactor (6) to monitor the change of natural gas hydrate saturation. ) is connected to the computer (32) through the data acquisition device (31); the gas-liquid separation metering system consists of a two-way valve (21), a two-way valve (22), a pressure reducing valve (23), a hand pump (24), a separation device (25), two-way valve (26), gas mass flow meter (27), natural gas collection bottle (28), two-way valve (29), measuring cylinder (30), hand pump (24) and pressure reducing valve (23) link to each other, pressure reducing valve (23) links to each other with high pressure reactor (6) by two-way valve (22), two-way valve (21), separator (25) is by two-way valve (26) and gas mass flow rate Meter (27) links to each other with natural gas collecting bottle (28), gas mass flow meter (27) links to each other with computer (32), and measuring cylinder (30) links to each other with separator (25) by two-way valve (29).

In the present invention, 25 holes are evenly distributed on the walls of the upper horizontal steel conduit (9) and the lower horizontal steel conduit (8) in the natural gas hydrate reaction system; The steel conduit (8) is in contact, and the output electrode (10) is in contact with the upper horizontal steel conduit (9); in the data monitoring and processing system, 16 TDR probes (7) are placed in the middle of the autoclave (6) , used to monitor changes in gas hydrate saturation.

Embodiment two,

A working method for using the above-mentioned device to simulate double-horizontal well electric heating to assist depressurization to exploit natural gas hydrate, including the following steps:

(1) Simulate the natural deposition environment of natural gas hydrate formation: tightly fill the high-pressure reactor (6) with quartz sand with a particle size of 0.13-0.20 mm;

(2) Open the two-way valve (18) and the two-way valve (19), inject the sodium lauryl sulfate solution into the autoclave (6) with the speed of 0.5mL/min by the horizontal flow pump (17), and the two-way After the pipeline where the valve (19) is located has solution flowing out, continue to inject for 30 minutes;

(3) Close the advection pump (17), the two-way valve (18) and the two-way valve (19), open the two-way valve (5) and the pressure reducing valve (2), control the injected natural gas pressure to be 11MPa, and utilize the natural gas cylinder (1) Injecting the natural gas with a purity of 99.99% in the high-pressure reactor (6); after the pressure gauge (4) shows a stable value, adjust the temperature in the constant temperature container (12) to be 1°C, and simultaneously adjust the pressure reducing valve (2 ) to make the pressure in the high-pressure reactor (6) constant; when the indication of the gas mass flowmeter (3) was less than 0.0001g/min, read and inject the high-pressure reactor ( 6) natural gas quality m=0.1560g; Close pressure reducing valve (3) and two-way valve (5), leave standstill autoclave (6) 5 days, and pass TDR probe (7), data acquisition device (31 ) and computer (32) monitor the change of natural gas hydrate saturation;

(4) Open the back pressure valve (23), two-way valve (22), two-way valve (21), two-way valve (26) and two-way valve (29), control the hand pump (24), adjust the return The pressure valve (23) has a pressure of 4MPa, simulating the depressurization of natural gas hydrate;

(5) When the output gas mass flow rate shown by the gas mass flow meter (27) is less than 0.0001g/min, turn on the power supply (13) and start simulating the exploitation of natural gas hydrate by electric heating in a double-horizontal well;

(6) When the mass flow rate of the produced gas shown by the gas mass flow meter (27) is less than 0.0001g/min, the natural gas hydrate production ends, and the total mass of the produced gas is read as m ₁ =0.1055g;

(7) Calculate the recovery factor of natural gas hydrate:

.

Claims (6)

1. the experimental provision of dual horizontal well electrical heating secondary buck exploitation of gas hydrate, it is characterised in that include gas injection system, power system, Gas hydrates response system, data monitoring processing system and gas-liquid separate measurement system, described gas injection system is by natural gas cylinder (1), decompression Valve (2), mass-flow gas meter (3), Pressure gauge (4) and two-port valve (5) composition, natural gas cylinder (1) pass sequentially through air relief valve (2), Mass-flow gas meter (3), Pressure gauge (4) are connected with autoclave (6) with two-port valve (5), mass-flow gas meter (3) and calculating Machine (32) is connected；Power system is mainly by power supply (13), input cable (14), output cable (15), input electrode (11), output electrode (10) composition, power supply (13) is connected with input electrode (11) by input cable (14), and output electrode (10) passes through output cable (15) Being connected with power supply (13), input electrode (11) is placed in lower horizontal steel conduit (8), and output electrode (10) is placed in upper level steel In conduit (9)；Gas hydrates response system is by autoclave (6), thermostatic container (12), upper level steel conduit (9), bottom Horizontal steel conduit (8), sodium dodecyl sulfate solution groove (16), constant-flux pump (17), two-port valve (18), two-port valve (19) and recovery Groove (20) forms, and autoclave (6) is placed in thermostatic container (12), and upper level steel conduit (9) is placed in away from autoclave (6) At top 10～20cm, lower horizontal steel conduit (8) is placed at autoclave (6) bottom 10～20cm, and sodium lauryl sulphate is molten Liquid bath (16) is connected with autoclave (6) with two-port valve (18) by constant-flux pump (17), and accumulator tank (20) passes through two-port valve (19) It is connected with autoclave (6)；Data monitoring processing system is by TDR probe (7), data acquisition unit (31) and computer (32) group Becoming, TDR probe (7) is placed in the change of monitoring gas hydrates saturation in autoclave (6), and TDR probe (7) passes through data acquisition Acquisition means (31) is connected with computer (32)；Gas-liquid separation metering system is by two-port valve (21), two-port valve (22), air relief valve (23), hands Shake pump (24), separator (25), two-port valve (26), mass-flow gas meter (27), natural gas receiving flask (28), two-port valve (29), amount Cylinder (30) composition, hand pump (24) is connected with air relief valve (23), and air relief valve (23) is by two-port valve (22), two-port valve (21) and height Pressure reactor (6) is connected, and separator (25) is by two-port valve (26) and mass-flow gas meter (27) and natural gas receiving flask (28) phase Even, mass-flow gas meter (27) is connected with computer (32), and graduated cylinder (30) is connected with separator (25) by two-port valve (29).

2. according to the experimental provision of the dual horizontal well electrical heating secondary buck exploitation of gas hydrate described in claim 1, it is characterised in that The wall of described gas hydrates response system middle and upper part horizontal steel conduit (9) and lower horizontal steel conduit (8) is uniformly distributed perforation 20～30 Individual.

3. according to the experimental provision of the dual horizontal well electrical heating secondary buck exploitation of gas hydrate described in claim 1, it is characterised in that During in described power system, input electrode (11) is placed in lower horizontal steel conduit (8), input electrode (11) and lower horizontal steel conduit (8) Contact, output electrode (10) is positioned in upper level steel conduit (9), and output electrode (10) contacts with upper level steel conduit (9).

4. according to the experimental provision of the dual horizontal well electrical heating secondary buck exploitation of gas hydrate described in claim 1, it is characterised in that For simulation gas hydrates naturally occur environment, in autoclave (6), filling granularity is the quartz sand of 0.09～0.26mm；It is simultaneously Accelerate the formation speed of gas hydrates, use the sodium dodecyl sulfate solution of 0.02%～0.04% to replace water.

5. according to the experimental provision of the dual horizontal well electrical heating secondary buck exploitation of gas hydrate described in claim 1, it is characterised in that In described data monitoring processing system, 9～18 TDR probes (7) are placed in autoclave (6), are used for monitoring gas hydrates and satisfy Change with degree.

6. utilize a method of work for unit simulation dual horizontal well electrical heating secondary buck exploitation of gas hydrate as claimed in claim 1, It is characterized in that, comprise the following steps that

(1) the crude sedimentation environment that simulation gas hydrates generate: the quartz sand that granularity is 0.09～0.26mm is closely filled out in reaction under high pressure In still (6)；

(2) open two-port valve (18) and two-port valve (19), by constant-flux pump (17) with 0.1～1mL/min speed to autoclave (6) Middle injection sodium dodecyl sulfate solution, the pipeline at two-port valve (19) place has solution to continue after flowing out to inject 30～60min；

(3) close constant-flux pump (17), two-port valve (18) and two-port valve (19), open two-port valve (5) and air relief valve (2), control to inject sky So atmospheric pressure is 10～12MPa, and utilizing natural gas cylinder (1) to inject purity in autoclave (6) is the natural gas of 99.99%；Treat pressure After table (4) registration is stable, the temperature in regulating thermostatic container (12) is 0～3 DEG C, regulates air relief valve (2) simultaneously and makes autoclave (6) interior Pressure is constant；Read quality of natural gas m injecting autoclave (6) by mass-flow gas meter (3) and computer (32), work as gas When the registration of mass flowmenter (3) is less than 0.0001g/min, close air relief valve (3) and two-port valve (5), stand autoclave (6) 3～7 My god, and by TDR probe (7), data acquisition unit (31) and the change of computer (32) monitoring gas hydrates saturation；

(4) open back-pressure valve (23), two-port valve (22), two-port valve (21), two-port valve (26) and two-port valve (29), control hand pump (24), regulation back-pressure valve (23) pressure is 3～6MPa, the blood pressure lowering exploitation of simulation gas hydrates；

(5) when output gas mass flow shown in mass-flow gas meter (27) is less than 0.0001g/min, turn on the power (13), start mould Intend dual horizontal well electrical heating exploitation of gas hydrate；

(6) when output gas mass flow shown in mass-flow gas meter (27) is less than 0.0001g/min, exploitation of gas hydrates terminates, Read output gas gross mass m1；

(7) recovery ratio of calculating gas hydrates:

$R_1=\frac{m_1}{m}\×100\%.$