Experimental apparatus and method for preparing natural gas hydrate rock sample via two-step process

Abstract

The invention an experimental apparatus and method for preparing a natural gas hydrate rock sample via two-step process; the apparatus according to its technical scheme comprises a cold storage, a reactor, a confining pressure pump, a gas supply system, a computer data collection system and the like; all experimental systems are positioned in the low-temperature cold storage, and cold storage temperature is adjusted through a temperature control system of the cold storage; the output end of the confining pressure pump is connected with the reactor; the output end of the gas supply system is connected with the reactor; a gas flowmeter and a temperature sensor are connected with the computer data collection system. The method for preparing the natural gas hydrate rock sample via two-step process comprises the steps of first, generating hydrate in a rock sample; second, decreasing methane gas pressure to around phase equilibrium pressure but slightly higher than phase equilibrium pressure so that the hydrate is recrystallized. By using the apparatus and method, the problem in the preparation of natural gas hydrate rock samples is solved, a hydrate rock sample closer to an actual hydrate reservoir in physical mechanical characteristic can be acquired, and experimental support is provided for the drilling and development of natural gas hydrate resources.

Description

technical field [0001] The invention relates to the field of natural gas hydrate drilling and development, in particular to an experimental device and method for preparing natural gas hydrate rock samples by a two-step method. Background technique [0002] my country is the world's largest energy consumer, with energy consumption accounting for 23% of the world's total. At the same time, my country's energy utilization rate is low and its structure is unbalanced. The proportion of natural gas as a clean energy source is small, and the proportion of oil and coal is relatively high. In recent years In the future, global climate change has attracted people's attention. Low-carbon energy saving, optimization of energy structure, and development of clean energy are imperative. Natural gas hydrate is a crystalline compound formed by the combination of natural gas and water molecules. It has the advantages of large resources, high energy density and low pollution. It is recognized a...

AI Technical Summary

Problems solved by technology

[0003] In recent years, although rock samples containing hydrates have been artificially prepared, the hydrates are formed in the stratigraphic depositional environment for a long period of time, and the depositional environment is complex, and the laboratory preparation is rapid synthesis, and the synthetic conditions are also quite different from the actual strata.

For example, the integrated device for in-situ formation, decomposition and permeability measurement of hydrate deposits published in the invention patent with application number CN201110353136.7 can complete the in-situ synthesis and testing of hydrate deposits, but the preparation of hydrate Pressurize to prepare the rock sample skeleton and then input methane gas and water to generate hydrate in the rock sample pores, which is inconsistent with the actual conditions that some hydrates exist in the form of formation skeleton, and it is also difficult to accurately control the realization of hydrate saturation; When preparing hydrates in this invention, methane and hydrates are quickly crystallized to form hydrates under the condition of extremely large subcooling, while in actual formations, hydrates are slowly formed at a pressure and temperature close to phase equilibrium conditions. The greater the degree of supercooling, the morphology and crystallization type of hydrate crystals will be affected, so that the lattice of the artificial hydrate sample is mechanically cemented, rather than the lattice cemented form of the actual formation, which will lead to The physical and mechanical properties of rock samples are quite different from those of actual reservoirs

Images