WO2017080353A1

WO2017080353A1 - Device for testing characteristics of sand production during mining of natural gas hydrate

Info

Publication number: WO2017080353A1
Application number: PCT/CN2016/102872
Authority: WO
Inventors: 卢静生; 李栋梁; 梁德青
Original assignee: 中国科学院广州能源研究所
Priority date: 2015-11-12
Filing date: 2016-10-21
Publication date: 2017-05-18
Also published as: CN105301200A; CN105301200B

Abstract

A device for testing characteristics of sand production during mining of a natural gas hydrate comprises a sand production simulating system, a pressure system, and a measurement system. The sand production simulating system comprises a reaction kettle body (7), a reaction kettle flange cover (6), and an overburden pressure loader (17). The pressure system comprises an overburden pressure loading system (18), a natural gas charging and pressurizing system, a bottom liquid injection system (19), and a visual gas-liquid-solid separator (14). The measurement system comprises a data acquisition system (15), a first pressure sensor (4), a second pressure sensor (9), a third pressure sensor (11), and a temperature sensor (8). The device can realize in-situ simulation of the characteristics of sand production during mining under the conditions of high pressure and low temperature, thereby broadening the application scope of conventional devices, and improving the measurement precision.

Description

Natural gas hydrate mining sanding characteristic testing device

Technical field

The invention relates to a device for in-situ synthesis of natural gas hydrate deposits and a test for sand production characteristics in the production thereof, in particular to a device for simulating the sand production characteristics in situ under high pressure and low temperature.

Background technique

Natural gas hydrate is an ice-like solid formed by gas (or volatile liquid) and water under certain temperature and pressure conditions. It is commonly known as flammable ice. It is widely distributed in the seabed of 200-2100 meters below the surface of the tundra and the seabed of the continental margin. The sediments below 0-1100 meters have huge natural gas storage capacity, and methane hydrate contains 164 times of natural gas under standard conditions. Enormous world reserves of natural gas hydrate, the gas hydrate is estimated resource of 2 × 10 ¹⁶ cubic meters, the equivalent of 2 × 10 ⁵ tons of oil equivalent, is 2 times the total amount of carbon global conventional fuels. Natural gas hydrates have been listed as an important alternative energy source in the post-oil era by developed countries. China has also included it in the medium and long-term development plan and conducted trial mining during the 13th Five-Year Plan period.

However, the exploitation of natural gas hydrate reservoirs will cause large decomposition of natural gas hydrates, which will lead to changes in the mechanical properties of hydrated formations, which may lead to engineering and geological disasters such as wellbore instability, sand production, stratum collapse, submarine landslides and even tsunami. Sand production as a phenomenon of reservoir sand migration from the reservoir during the oil and gas exploitation process cannot be avoided in the natural gas hydrate mining process. From the perspective of conventional oil and gas production, the sand-spinning mechanism is caused by the original pressure balance of the reservoir near the bottom of the well being broken, causing the reservoir sediment to yield and causing its original structure to be destroyed. In conventional offshore oil and gas exploration, the hazards of sand production mainly include the following aspects: 1. Erosion of oil recovery equipment. 2. The formation and the borehole are unstable. 3. Sand plugging and damaging equipment. 4. In marine oil and gas fields, the disposal of abandoned formation sand will pollute the environment.

Therefore, before the natural gas hydrate is mined, only the accurate understanding of the sand production properties of the production wellbore can guide the smooth progress of natural gas hydrate mining in the future, and reduce the possibility of sand blast accidents caused by natural gas hydrate exploitation. However, the existing sand discharging device is mainly designed under normal temperature and normal pressure, and cannot meet the in-situ measurement of natural gas hydrate under the condition of low temperature and high pressure. In summary, the research and development of sand characterization test equipment for natural gas hydrate mining, in-depth study of natural gas hydrate and reservoir sand production characteristics, explore the response mechanism of different influencing factors on sand production characteristics in hydrate mining, analysis of hydrate mining process The risk of sand production and the establishment of an evaluation model are of great significance for the development of natural gas hydrates.

Summary of the invention

The object of the present invention is to provide a device for in-situ synthesis of natural gas hydrate deposits and a test for sand production characteristics in the process of mining, in particular, a device for simulating the sand production characteristics in situ under high pressure and low temperature, and expanding the current There is a range of use of the device to improve measurement accuracy.

In order to achieve the above object, the present invention proposes the following technical solutions:

A natural gas hydrate mining sanding characteristic testing device, characterized in that it comprises:

Simulating a sand discharging system, comprising: a reaction vessel body, a reaction vessel flange cover, and an overlying pressure loader, wherein the reactor flange cover is fixedly mounted on the upper end surface of the reaction vessel body; a wellbore, a sand control mechanism, and a sample reservoir chamber, wherein the production wellbore is a hollow cylindrical structure having an opening in a side wall, the sample reservoir chamber is located outside the production wellbore, and the sand control mechanism is located in the sample reservoir chamber and the production wellbore The lower end of the overlying pressure loader is in communication with the sample reservoir chamber.

a pressure system, the pressure comprising an overburden pressure loading system, a natural gas injection pressurization system, a bottom liquid injection system, and a visualization gas-liquid-solid separator; wherein the upper end of the overlying pressure loader passes through the reactor flange cover Thereafter, the gas injection pressurization system and the bottom liquid injection system are both in communication with the sample reservoir chamber, and the visual gas-liquid-solid separator is connected to the bottom of the production wellbore; The gas-liquid-solid separator is provided with an air outlet and a liquid outlet;

a measurement system comprising a data acquisition system, a first pressure sensor, a second pressure sensor, a third pressure sensor, and a temperature sensor; the first pressure sensor being installed in a natural gas injection pressurization system and a sample reservoir chamber The temperature sensor and the second pressure sensor are both mounted on the reaction vessel flange cover, and the third pressure sensor is installed on the pipeline between the visualization gas-liquid-solid separator and the production wellbore, A pressure sensor, a second pressure sensor, a third pressure sensor, a temperature sensor, and a fourth pressure sensor carried by the overlying pressure loader are all connected to the data acquisition system.

The main body of the reactor is a special pressure vessel, which can withstand high pressure, low temperature, no leakage, no deformation, and can promote porous medium, natural gas and water to synthesize hydrated porous medium samples in the pressure chamber under the specified high pressure and low temperature range. Meet the requirements required for the test.

The porous medium of the present invention may be various types of deposits such as seafloor sediments, lake sediments, frozen soils, and the like. However, since the sample requires fidelity for simulated mining during the test, the hydrate sample needs to be effectively measured under high pressure and low temperature conditions. Therefore, in the field mining, not only the test sampling cost is high but also has a large safety risk, and most of the time It is difficult to obtain fidelity samples for testing. Therefore, the present invention After the sediment in the target area is selected, the deposit is sampled around the production wellbore by an overlying pressure loader. Sediment preparation is an important part of the test process and directly affects the test results, so the process must be carried out in strict accordance with the operating procedures.

The natural gas injection boosting system includes a gas source, a gas boosting pump, and a buffer tank, wherein the gas source is sequentially connected to the sample reservoir chamber through the gas source pump through the gas boosting pump and the buffer tank, A first pressure sensor and a safety valve are installed on the air supply line.

The natural gas injection pressurization system is in communication with a side of the sample reservoir chamber, the bottom injection system being in communication with the bottom of the sample reservoir chamber.

The sand control mechanism comprises a sand control pipe and a sand control net, the sand control pipe is a porous hollow cylindrical structure, and the mining wellbore is located in the sand control pipe, and the sand control net is located between the mining wellbore and the sand control pipe.

The natural gas hydrate production sanding characteristic testing device further comprises a temperature control system comprising a constant temperature circulating water bath, a reaction kettle outer water jacket and a reaction vessel built-in heat exchange tube, and the reaction kettle outer water jacket Located on the outer side of the sample reservoir chamber and conforming to the sample reservoir chamber, the reaction tube has a built-in heat exchange tube installed in the sample reservoir chamber and is jacketed with the outer water of the reaction kettle, and the constant temperature circulating water bath passes through the connection pipeline and reacts The water outside the kettle is connected to the jacket. The liquid in the constant temperature circulating water bath is respectively passed through the connecting pipe, the heat exchange tube built in the reaction kettle and the outer water jacket of the reaction kettle, and then flows back to the constant temperature bath through the connecting pipe to complete the cycle, and the temperature of the reaction kettle is kept constant.

The reaction vessel flange cover is fixedly connected to the upper end surface of the reaction vessel main body through the reaction vessel flange bolt, and is sealed by a sealing ring between the reaction vessel flange cover and the reaction vessel main body.

The data collected by the data acquisition system includes overlying loading pressure, pore pressure, temperature, and gas flow. The temperature, and pressure are transmitted to the data acquisition and control system via the corresponding sensors, which are read by the measurement and control acquisition system and transmitted to a computer for display, recording, and analysis of the data. The amount of sand produced and the amount of sand produced are separated and collected in a visual gas-liquid-solid separator. The amount of effluent from the effluent is taken by the weighing gas-liquid-solid separator. The amount of sand is dried and sanded and weighed. It was dried by a gas-liquid-solid separator, measured by a gas flow meter, and recorded.

The steps for using this device are as follows:

(a) Check the airtightness of the equipment: connect the corresponding drainage exhaust pipe, close and seal the production reaction kettle, the temperature is normal temperature, use the side air pipe to pass nitrogen gas, and use the detergent water to detect the airtightness along the seam. Good air tightness goes to the next step.

(b) Sample filling: open the reaction vessel flange cover, fill it with sand with water containing sand, compact it, close The upper flange cover is sealed.

(c) Hydrate synthesis: the overlying pressure loading system is opened, the initial overburden pressure is applied, the temperature is gradually reduced to the initial temperature (usually at 20 °C), and the gas injection pressurization system supplies methane gas from the side intake pipe to generate natural gas hydration. The material is fully aired and stabilized 24 hours after the air pressure is stabilized. Then cool down to the desired hydrate synthesis temperature, record the overlying loading pressure every 10 seconds (measured by the fourth pressure sensor attached to the overlying pressure loader), temperature (the temperature inside the reactor body, measured by the temperature sensor) ), pore pressure (measured by the second pressure sensor), intake air volume (the amount of natural gas injected into the sample reservoir chamber by the natural gas injection booster system), and the amount of liquid (the amount of water injected into the sample reservoir chamber by the bottom injection system) . If there is a need for gas saturation or liquid saturation experiments, it is also necessary to perform side injection or bottom injection for sample preparation after sample synthesis.

(d) Pressure chamber mining sand: The bottom of the production wellbore is subjected to depressurization/injection mining at a set pressure reduction rate/heat injection rate, etc., and the overburden pressure, temperature, and porosity are recorded at regular intervals. Pressure, intake air volume and liquid intake amount, until the solidification of the gas-liquid-solid separator occurs, or a certain amount of sand production or mining is completed. The amount of sand produced and the amount of sand produced are separated and collected in a visual gas-liquid-solid separator. The amount of effluent from the effluent is taken by the weighing gas-liquid-solid separator. The amount of sand is dried and sanded and weighed. It was dried by a gas-liquid-solid separator, measured by a gas flow meter, and recorded.

Compared with the prior art, the present invention has the beneficial effects that the present invention provides a device for synthesizing and simulating the sand extraction characteristics in situ under high pressure and low temperature, and expands the use range of the existing devices and improves the measurement accuracy.

DRAWINGS

1 is a structural block diagram of a sand characterization test device for natural gas hydrate production according to the present invention;

Figure 2 is a view showing the cooperation structure of the reaction vessel flange cover and the overlying pressure loader of Figure 1;

Figure 3 is a layered view of the interior of the reactor body of Figure 1.

Description of the reference signs:

1. Gas source; 2. Gas booster pump; 3. Buffer tank; 4. First pressure sensor; 5. Safety valve; 6. Reaction vessel flange cover; 7. Reaction kettle body; 8. Temperature sensor; , second pressure sensor; 10, pressure reducing valve; 11, third pressure sensor; 12, air outlet; 13, liquid outlet; 14, visual gas-liquid-solid separator; 15, data collector; 16, constant temperature circulating water bath ; 17, overpressure loader; 18, overburden pressure loading system; 19, bottom injection system; 20, mining wellbore; 21, sand control tube; 22, sample reservoir room; 23, the outer water jacket of the reaction kettle; 24, the reaction tube built-in heat exchange tube; 25, the reactor flange bolt; 26, sand control net.

detailed description

The content of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

Example:

Natural gas hydrate is an envelope crystal formed by gas or a volatile liquid and water. Natural gas hydrate needs to exist at high pressure and low temperature, so it is necessary to measure its physical properties in situ.

The invention is based on the above principle, and provides a device for simulating the sand production characteristics in situ under high pressure and low temperature, thereby improving the measurement precision. As shown in Fig. 1, a device for in-situ synthesis of natural gas hydrate deposits and test for sand production characteristics in the production includes a pressure system, a simulated sand production system, a measurement system, and a temperature control system.

The simulated sand production system is composed of the reaction vessel main body 7, the reaction vessel flange cover 6 and the overlying pressure loader 17, and can realize natural gas hydrate in-situ synthesis and sand production simulation. The reactor main body 7 and the reaction vessel flange cover 6 are made of a special pressure vessel made of stainless steel material, which are connected by a flange cover bolt 25 and sealed with a seal ring.

Referring to Figures 1 and 3, the reactor body 7 is comprised of a production wellbore 20, a sand control tube 21, and a sample reservoir chamber 22. The production wellbore 20 and the sand control pipe 21 are made of a stainless steel pipe, and the sand control pipe 21 is composed of two porous steel pipes (a large hole pipe and a small hole pipe) and a sand control net 26 sandwiching a multi-size filter screen, and is placed around the production wellbore 20. And replace it according to the experimental needs; the sample reservoir chamber 22 surrounds the sand control tube 21, can fill different types of sediment samples, and simulate the reservoir in the mining area.

The pressure system is divided into an overburden pressure loading system 18, a bottom infusion system 19, and a gas pressure system. among them:

The overburden pressure loading system 18 mainly provides the overburden pressure required for the experiment to simulate the formation stress. Referring to FIG. 2, the overlying pressure loader 17 passes through the reactor flange cover 6 from the top and is sealed with a sealing ring. One end of the pressure loader 17 is connected to the overlying pressure loading system 18, and is pressurized by the overlying pressure loading system 18 for stress loading; the other end of the overlying pressure loader 17 has a hollow cylindrical shape for loading the sample reservoir chamber. Pressure; the top opening of the reaction vessel flange cover 6 is connected to the overlying pressure loader 17, the second pressure sensor 9, and the temperature sensor 8 for the overburden pressure and temperature measurements in the experiment.

The bottom liquid injection system 19 mainly includes a booster pump, a liquid injection system, an inlet pipe, and the like, and mainly provides an experiment. The high pressure liquid required is mainly water.

The gas pressure system comprises a natural gas injection pressurization system and a vacuum system: the natural gas injection pressurization system comprises a gas source 1, a gas booster pump 2, a buffer tank 3, and the gas source 1 is sequentially passed through a gas booster pump 2 and a buffer. The tank 3 is further connected to the sample reservoir chamber 22 through the gas source pipeline. The first pressure sensor 4 and the safety valve 5 are installed on the gas source pipeline, and a gas pressure regulating valve and a gas flow meter are also installed on the gas source pipeline. It mainly supplies high pressure gas required for synthesizing natural gas. The vacuum system consists of a suction vacuum pump and a vacuum controller, a vacuum regulator and a transparent connecting hose, which mainly provide the vacuum environment required for the experiment.

Three inlets and outlets are opened at the bottom of the main body of the reaction vessel, wherein two inlets and outlets at the bottom of the sample reservoir chamber are connected to the bottom liquid injection system 19, and the bottom inlet and outlet of the production wellbore 20 are connected to the visualization gas-liquid-solid separator 14 through a pipeline for Separating the gas-liquid solid matter in the production: the gas-liquid-solid separator 14 is provided with an outlet port 12 and a liquid outlet 13 through which the gas is discharged, the liquid passes through the liquid outlet 13 and the solid is inside the separator. Separation.

The temperature control system is composed of a constant temperature circulating water bath 16 controlled by a high and low temperature program, a heat exchange tube 24 built in the reactor, and a water jacket 23 for the reaction vessel. The constant temperature circulating water bath 16 is provided with a circulating water pump, and is connected to the reaction vessel internal heat exchange tube 24 and the reaction vessel outer water jacket 23 through corresponding pipes. The liquid in the constant temperature bath is circulated through the reaction tube internal heat exchange tube 24, the reaction water outer jacket 23 and the corresponding connecting pipe back to the constant temperature circulating water 16 to maintain the temperature of the main body of the reactor constant.

The measurement system mainly includes a data acquisition system 15, a third pressure sensor 11, a temperature sensor 8, and a pressure sensor attached to the overpressure loader 17. The temperature, pressure and displacement are transmitted to the data acquisition system through the corresponding sensors and displayed, recorded and analyzed by the computer. The temperature and pressure are transmitted to the data acquisition system 15 via the temperature sensor 8, the pressure sensor attached to the overlying pressure loader 17, and the third pressure sensor 11, respectively, and the data is collected by the data acquisition system 15 and processed for transmission to a computer. Display and storage.

In this embodiment, the main processes for initiating the sanding property test include:

(a) Check the airtightness of the equipment: connect the corresponding drainage exhaust pipe, close and seal the production reaction kettle 7, the temperature is normal temperature, use the side air pipe to pass nitrogen gas, and use the detergent water to detect the airtightness along the slit. Good air tightness goes to the next step.

(b) Sample filling: The reactor flange cover 6 was opened, filled with water-containing sand into the sample reservoir chamber 22, and the reactor flange cover 6 was closed.

(c) Hydrate synthesis: aligning the overlying pressure loader 17, loading the initial overburden pressure, the temperature is gradually reduced to the initial temperature (usually at 20 ° C), and the natural gas injection booster system supplies methane gas from the side intake manifold to generate Natural gas hydrate, fully aired, and stabilized 24 hours after the pressure is stabilized. The temperature was lowered to the desired hydrate synthesis temperature, and the overlying loading pressure, temperature, pore pressure, intake air amount, and liquid input amount were recorded every 10 seconds.

(d) Pressure chamber mining sand: set the simulated mining temperature, such as 4 °C. The bottom production port is subjected to pressure reduction mining, such as a set pressure reduction rate or a rated outlet pressure, such as 2.5 MPa (the phase equilibrium pressure of methane hydrate at 4 ° C is 3.9 MPa). The overlying loading pressure, temperature, pore pressure, intake air amount, and liquid intake amount are recorded every 10 seconds until the solidified gas-liquid-solid separator 14 appears solid or reaches a certain amount of sand production or mining. The amount of sand produced and the amount of sand produced are separated and collected in the visible gas-liquid-solid separator 14 , and the amount of effluent from the water is obtained by the weighing gas-liquid-solid separator 14 , and the amount of sand is dried and sanded and weighed. The outgas volume was dried by a gas-liquid-solid separator, measured by a gas flow meter, and recorded.

The materials involved in this example are mainly gases (methane, carbon dioxide, mixed gas, etc.), water and solids (marine sediment samples, etc.).

Different overburden pressures, pore pressures, temperatures, wellhead pressures, intake air, water inflow, gas production, water production, and sand production can be recorded during this process. In the continuous growth phase of hydrate, the amount of natural gas hydrate formed can be calculated by temperature and pressure.

The above embodiments are only intended to illustrate the technical concept and the features of the present invention, and the purpose of the present invention is to enable those skilled in the art to understand the contents of the present invention and to implement the present invention. Equivalent changes or modifications made in accordance with the spirit of the invention are intended to be included within the scope of the invention.

Claims

A natural gas hydrate mining sanding characteristic testing device, characterized in that it comprises:

Simulating a sand production system comprising a reactor body (7), a reactor flange cover (6) and an overburden pressure loader (17), the reactor flange cover (6) being fixedly mounted on The upper end surface of the reaction vessel body (7); the reaction vessel body (7) includes a production wellbore (20), a sand control mechanism, and a sample reservoir chamber (22), the production wellbore (20) having an opening for the side wall a hollow cylindrical structure, the sample reservoir chamber (22) is located outside the production wellbore (20), and the sand control mechanism is located between the sample reservoir chamber (22) and the production wellbore (20), the overlying pressure loader (17) The lower end of the ) is in communication with the sample reservoir chamber (22);

a pressure system comprising an overburden pressure loading system (18), a natural gas injection boosting system, a bottom liquid injection system (19), and a visualization gas-liquid-solid separator (14); wherein the overlying pressure loading The upper end of the device (17) passes through the reactor flange cover (6) and is in communication with an overburden pressure loading system (18); the natural gas injection pressurization system and the bottom injection system (19) are both connected to the sample reservoir The chamber (22) is in communication, the visualization gas-liquid-solid separator (14) is in communication with the bottom of the production wellbore (20); the visualization gas-liquid-solid separator (14) is provided with an air outlet (12) and an outlet Liquid port (13);

a measurement system comprising a data acquisition system (15), a first pressure sensor (4), a second pressure sensor (9), a third pressure sensor (11), and a temperature sensor (8); the first pressure The sensor (4) is installed on a pipeline between the natural gas injection pressurization system and the sample reservoir chamber (22), and the temperature sensor (8) and the second pressure sensor (9) are both mounted on the reaction vessel flange cover ( 6) The third pressure sensor (11) is mounted on a pipeline between the visualization gas-liquid-solid separator (14) and the production wellbore (20), the first pressure sensor (4) and the second pressure sensor (9) The third pressure sensor (11), the temperature sensor (8), and the fourth pressure sensor provided by the overlying pressure loader (17) are all connected to the data acquisition system (15).
The apparatus for testing sand production characteristics of natural gas hydrate according to claim 1, wherein the natural gas injection pressurization system comprises a gas source (1), a gas boosting pump (2), and a buffer tank (3). The gas source (1) is sequentially connected to the sample reservoir chamber (22) through the gas source pipeline through the gas pressure increasing and lowering pump (2) and the buffer tank (3), and the first is installed on the gas source pipeline. Pressure sensor (4) and safety valve (5).
The apparatus for testing sand production characteristics of natural gas hydrate according to claim 1 or 2, wherein said natural gas injection pressurization system is in communication with a side portion of a sample reservoir chamber (22), said bottom portion The injection system (19) is in communication with the bottom of the sample reservoir chamber (22).
The apparatus for testing sand production characteristics of natural gas hydrate according to claim 1, wherein the sand control mechanism comprises a sand control tube (21) and a sand control net (26), and the sand control tube (21) is a porous hollow cylindrical structure. The production wellbore (20) is located within the sand control tube (21), which is located between the production wellbore (20) and the sand control tube (21).
The apparatus for testing sand production characteristics of natural gas hydrate according to claim 1, wherein said gas hydrate production sanding characteristic testing device further comprises a temperature control system comprising a constant temperature circulating water bath (16) ), the outer water jacket (23) of the reaction kettle and the heat exchange tube (24) built in the reactor, the outer water jacket (23) of the reactor is located outside the sample reservoir chamber (22) and with the sample reservoir chamber ( 22) laminating, the reaction tube built-in heat exchange tube (24) is installed in the sample reservoir chamber (22) and communicates with the outer water jacket (23) of the reaction kettle, and the constant temperature circulating water bath (16) passes through the connecting tube The road is connected to the outer water jacket (23) of the reaction kettle.
The apparatus for testing sand production characteristics of natural gas hydrate according to claim 1, characterized in that the reaction vessel flange cover (6) is fixedly connected to the upper end surface of the reaction vessel main body (7) through a reactor flange bolt (25). , sealed between the reactor flange cover (6) and the reactor body (7) by a sealing ring.