Preparation method and device of natural gas hydrate with uniform high saturability in sediment

[0026] Example one:

[0027] See figure 1 with figure 2 As shown, a device for preparing uniform and high-saturation natural gas hydrates in sediments includes a high-pressure reactor, and a stabilized gas supply module for adjusting and controlling the gas content in the high-pressure reactor, for real-time adjustment and control of system pressure The constant pressure liquid supply module for the supplement of the solution is used to provide a constant temperature water bath module for the high-pressure reactor. The constant temperature water bath module includes a constant temperature water bath 11, which is used to control the automatic operation of the constant pressure gas supply module and the constant pressure liquid supply module. The control module is used to collect the sediment porosity, target three-phase saturation, target generation pressure and temperature data acquisition and processing module of the high-pressure reactor, the stabilized gas supply module, the constant pressure liquid supply module, and the constant temperature water bath module. The reactor is composed of an inner reactor 1 and an outer reactor 2. The inner reactor 1 is connected with a temperature sensor 21, and the inner reactor 1 and the outer reactor 2 are fixedly connected by positioning pillars 4, and the inner reactor The kettle 1 is filled with sediments. A wall gap cavity 3 is provided between the outer wall of the inner reactor 1 and the inner wall of the outer reactor 2. The outer reactor 2 consists of a cylinder 5, an upper flange 6 and a lower method. Lan 7 is sealed, the inner reaction kettle wall 22 of the inner reaction kettle 1 is provided with a number of micropores and filter screens 18, and the wall gap cavity 3 communicates with the inner cavity of the inner reaction kettle 1 through the micropores and the filter screen 18. The top and bottom ends of the layered reactor 2 are respectively provided with an upper gas-liquid port 9 and a lower gas-liquid port 10, and the stabilized gas supply module and the constant-pressure liquid supply module are connected to the upper gas-liquid port 9 and the lower gas-liquid port 10, respectively. Gas and solution are injected into the kettle body through the upper gas-liquid port 9 or the lower gas-liquid port 10 through the high-pressure gas source 13 in the constant pressure gas supply module and the constant pressure advection pump 16 in the constant pressure liquid supply module.

[0028] The pressure-stabilized gas supply module includes a high-pressure gas source 13 for inputting gas into the high-pressure reactor. The high-pressure gas source 13 is provided with a pressure reducing valve 14 and a gas flow meter 15; The constant pressure advection pump 16 pumped into the high pressure reactor, the automatic control module includes a computer 19 and a PID controller 20 connected to each other. The constant pressure advection pump 16 is connected to the PID controller 20, and the PID controller 20 is connected with pressure Sensor 12. The constant pressure advection pump 16 is adjusted and controlled by the computer 19 and the PID controller 20 in the automatic control module. The solution 17 is continuously and stably injected into the wall gap cavity 3 under a constant pressure state, and the solution is in the wall gap cavity 3 It spreads evenly into the sediment pores in the inner reactor 1 through the micropores and the filter screen 18. The data acquisition and processing module includes various sensors, data acquisition system and post-processing software.

[0029] The gap between the inner reactor 1 and the outer reactor 2 is 1~5mm. The inner shape of the inner reactor 1 and the outer reactor 2 can be cylindrical, square or spherical, respectively. The cavity volume is 5~2000L.

[0030] The high-pressure reactor is located in a constant temperature water bath, the temperature control range is -15~30℃, and the temperature control accuracy is ±0.1℃; the inlet of the high-pressure reactor is connected with the stabilized gas supply module and the constant pressure liquid supply module. The stabilized gas supply module can accurately inject the required gas volume into the reactor, and the constant pressure liquid supply module can adjust and control the system pressure and solution supplement in real time

[0031] The micropores and the micropore area of ​​the filter screen 18 are 1~10mm 2 , The opening density is 1~100/100cm 2 The wall, the micropores and the sediment are separated by a pressure-resistant filter; during the automatic continuous liquid injection process of the constant pressure liquid supply module, the injected solution can fill the gap cavity between the inner and outer kettle bodies, and then pass through the inner kettle body wall. The micropores evenly diffuse into the sediment to ensure that the gas and the solution are fully contacted and uniformly distributed in the sediment pores, thereby forming a sediment system with uniformly distributed hydrates.

[0032] When the device of the present invention is in use, the specific operation steps are as follows:

[0033] 1. Fix the inner reactor 1 filled with porous sediments in the outer reactor 2, and seal the outer reactor 2 with the cylinder body 5, upper flange 6 and lower flange 7, and start the constant temperature water bath 11 and A constant temperature is set, and the inner reactor 1 and the outer reactor 2 are evacuated.

[0034] 2. According to the measured sediment porosity, target three-phase (hydrate/water/gas) saturation, target generation pressure and temperature, the actual gas state equation and the principle of mass conservation can accurately calculate the total gas required before hydrate formation And the standard condition volume of the solution, the calculation method of the total gas and solution volume required is as follows:

[0035] Set the target three-phase (hydrate/water/gas) saturation respectively as S H , S A And S G , The sediment porosity is φ, the total volume of the inner reactor is V (ml), the generation end pressure P (MPa), the generation temperature T (K), the gas molar volume V at this temperature and pressure m (ml/mol), hydrate molar mass M H (g/mol), hydrate density ρ H (g/ml), the volume of the gap between the inner and outer vessels ΔV (ml). Obtain the required gas volume V according to the conservation of mass G (L) and solution volume V A (ml) are:

[0036] V G = 22.4 ( φVS G V m + φVS H ρ H M H )

[0037] V A = φVS A + φVS H ρ H ( 1 - 16 M H ) + ΔV

[0038] Gas molar volume V m It is calculated from the temperature and pressure and the existing actual gas state equation.

[0039] 3. Open the inlet valve of the outer reactor 2 and the outlet valve of the high-pressure gas source 13, adjust the pressure reducing valve 14, and inject the gas into the reactor through a gas flow meter. After the specified gas volume is completely injected, close the outlet valve of the high-pressure gas source 13.

[0040] 4. Set the working pressure and liquid injection rate of the constant pressure advection pump 16, open the outlet valve of the constant pressure advection pump 15, and the solution 17 is stably injected into the wall gap cavity 3 at a certain rate, and then uniformly diffused through the micropores and the filter 18 In the sediment of the inner tank body 2, when the pressure in the reactor rises to the hydrate formation pressure, the advection pump 16 automatically suspends liquid injection; when the system pressure decreases by a predetermined difference (such as 0.1 MPa) due to hydrate formation, advection The pump 16 is automatically started and continues to inject the solution into the reaction kettle until the system pressure rises to the predetermined generation pressure again.

[0041] 5. When the cumulative liquid injection volume of the advection pump 16 reaches the required theoretical total solution volume, the advection pump 16 stops working, and the system pressure will continue to decrease with the formation of hydrates. When it drops to the target formation pressure, the hydrate formation process ends , The three-phase saturation of the system is consistent with the target value.