Simulation experiment system and simulation method of entire natural gas hydrate exploitation process

A simulation device of a natural gas hydrate exploitation process, comprising:

• a hydrate accumulation simulation subsystem simulating a hydrate accumulation process;
• a hydrate formation drilling simulation subsystem simulating a hydrate formation drilling process;
• a hydrate exploitation simulation subsystem simulating a hydrate decomposition and gas production process;
• and
• a produced gas collecting and processing simulation subsystem simulating a produced gas collecting and processing process,
• wherein the hydrate accumulation simulation subsystem comprises:
• a high pressure reaction kettle;
• a hydrate rock core;
• a first high pressure gas cylinder;
• a pressure reducing valve;
• a filter;
• a balance kettle;
• a first pressure control valve, wherein the first high pressure gas cylinder is connected to a gas-liquid inlet of the high pressure reaction kettle through the pressure reducing valve, the filter, the balance kettle and the first pressure control valve in sequence;
• a first electronic balance;
• a constant-flux pump;
• constant temperature water bath, the balance kettle and the high pressure reaction kettle being placed in the constant temperature water bath;
• a first liquid storage tank used for storing deionized water placed in the first electronic balance, the first liquid storage tank being connected to the gas-liquid inlet through the constant-flux pump;
• and
• a first stop valve arranged between the gas-liquid inlet and the constant-flux pump,
• wherein the hydrate formation drilling simulation subsystem comprises:
• a servo motor;
• a connecting gear;
• a drilling column fixed at the upper side of the high pressure reaction kettle;
• a drill pipe inserted in the drilling column and extending into the high pressure reaction kettle, the servo motor driving the connecting gear engaged with the drill pipe to rotate so as to drive rotation of the drill pipe;
• a hydraulic pump connected to the drill pipe to provide a necessary downward pressure for the drill pipe;
• a drill bit located at the bottom of the drill pipe;
• a mining fluid inlet,
• a gas-liquid outlet, the mining fluid inlet and the gas-liquid outlet being located on opposite sides of the drilling column;
• a mud tank provided with a mud cooling device and a stirring device;
• a first mud pump,
• a second mud pump, inlet pipelines of the first mud pump and the second mud pump being connected with the mud tank;
• a heater, an outlet pipeline of the second mud pump being connected with the heater, an outlet pipeline of the first mud pump is jointed with an outlet pipeline of the heater through a tee joint, a first temperature sensor being arranged at an outlet of the tee joint for measuring a drilling fluid temperature, wherein drilling fluid from the first mud pump and the second mud pump is mixed and then divided by the tee joint into two paths;
• an overflow valve;
• a drilling fluid flowmeter;
• and
• a liquid flowmeter, wherein one path of the two paths for the mixed drilling fluid divided by the tee joint is connected with a mud inlet of the drill pipe by the drilling fluid flowmeter through a pipeline, and the other path of the two paths for the mixed drilling fluid divided by the tee joint is connected with the mud tank through the overflow valve,
• wherein the hydrate exploitation simulation subsystem comprises:
• a piston container connected with the constant-flux pump;
• a heating tank, an outlet of the piston container being connected with the heating tank, a second stop valve, and a mining liquid inlet of the high pressure reaction kettle through a pipeline;
• a back pressure valve having an inlet connected with the gas-liquid outlet through a pipeline and an outlet connected to the inlet of the gas-liquid separator;
• a gas-liquid separator having a gas outlet side connected to the produced gas collecting and processing simulation subsystem and a liquid outlet side communicating with an inlet of a second liquid storage tank;
• and
• a second electronic balance the second liquid storage tank being placed on the second electronic balance, and a third stop valve is arranged between the gas-liquid separator and the second liquid storage tank, and
• wherein the produced gas collecting and processing simulation subsystem comprises:
• a dryer;
• a gas flowmeter;
• a gas storage tank;
• a second pressure control valve;
• a booster pump;
• and
• a second high pressure gas cylinder, wherein the gas outlet side of the gas-liquid separator is connected to the second high pressure gas cylinder through the dryer, the gas storage tank, the second pressure control valve and the booster pump in sequence, and the gas flowmeter is arranged on the pipeline between the dryer and the gas storage tank.