Reservoir forming and developing simulated experiment system and method for submarine natural gas hydrate

Abstract

The invention relates to a reservoir forming and developing simulated experiment system and method for submarine natural gas hydrate. The reservoir forming and developing simulated experiment system and method for submarine natural gas hydrate consists of a fluid injection part, a hydrate synthesis/decomposition part and a withdrawal fluid metering part, wherein the fluid injection part comprisesa high-pressure displacement pump, a natural gas cylinder, a middle container and a seawater storage tank; the hydrate synthesis/decomposition part comprises a high-low-temperature test box, a high-pressure reaction kettle, a simulating straight well pipeline, a simulating horizontal well pipeline, a temperature sensor, a pressure sensor and a computer, wherein the high-pressure reaction kettle ispositioned in the high-low-temperature test box; fluid injection and withdrawal interfaces are uniformly distributed in the end cover and the wall surfaces of a kettle body; the pressure sensor and the temperature sensor are connected to the computer through guide-out wires; and the withdrawal fluid metering part comprises a back-pressure valve, a gas-liquid separator, a measuring barrel and a gas meter. The system can be utilized to perform experiments such as submarine natural gas hydrate synthesis simulation or submarine natural gas hydrate exploitation, is simple and convenient in operation, and can provide important support for submarine natural gas hydrate reservoir development technical evaluation and establishment.

Description

technical field [0001] The invention belongs to the field of marine natural gas hydrate development, in particular to a marine natural gas hydrate accumulation-development simulation experiment system and method. Background technique [0002] Natural gas hydrate is composed of water, hydrocarbons (mainly methane), non-hydrocarbons (CO 2 、H 2 S) An ice-like non-stoichiometric cage crystal compound formed by small molecular gases under low temperature and high pressure conditions. Most of the natural gas hydrates are distributed in the permafrost zone and the shallow deep sea. Today, the total proven natural gas hydrate reserves in the world are about twice the existing natural gas and oil reserves. Only the South my country Sea has proven natural gas hydrates. Reserves have reached 64970 billion m 3 , under standard conditions, 1m 3 Natural gas hydrate can release 150-200m 3 of natural gas. Due to its wide distribution, large reserves, and high gas storage capacity, natu...

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Problems solved by technology

The high-pressure reactor is different from the seabed sediment layer. The pore water in the sediment layer in the reactor cannot flow freely, so that the relative permeability of the injected natural gas is very low. After the natural gas is injected into the autoclave, it can only form natural gas hydrate with water on the surface of the sediment layer. The formation of gas hydrate will further reduce the seepage ability of natural gas in the sedimentary layer, making the generated gas hydrate uneven in the sedimentary layer, and the conversion rate of water to hydrate is low.

Lang Xuemei (Lang Xuemei, Cao Yuan, Fan Shuanshi, Wang Yanhong. A method and device for the formation and replacement of natural gas hydrate [P].CN106544070A, 2017-03-29) proposed to freeze the water-containing sedimentary solid particles first, so that the water was evenly dispersed in the Natural gas is re-injected between solid particles, so that a more uniformly distributed hydrate reservoir can be synthesized, but the rate of ice and natural gas combining to form gas hydrate is very low

However, the decompression and injection of hydrates directly from the top or bottom of the autoclave cannot effectively simulate the actual process. The fact that the development well is drilled inside the reservoir

Moreover, the reported experimental systems basically do not consider the influence of water intrusion characteristics in the hydrate development process.

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