多维天然气水合物开采模拟试验系统的研制与初步应用

Development of multi-dimensional production simulation test system for natural gas hydrate and its primary application

为研究天然气水合物的合成及分解特性、储层的开采特性以及开采过程中的出砂防砂等问题,自主研制了一套多维天然气水合物开采模拟试验系统。该试验系统主要由气体注入系统、稳压供液系统、蒸汽或热水注入系统、一维/二维/三维模型、回压控制系统、出口计量系统、数据采集控制处理系统等组成。该试验系统的主要特色如下:(1)将高压玻璃做成的一维反应釜外壁和高清摄像头结合达到可视化的目的,监测中低压力下水合物的合成、分解情况以及开采过程中砂粒的运移情况;(2)采用自主研发的双缸恒速恒压泵控制回压阀,使得整个降压开采过程中反应釜中的压力能够实现高精度的均匀减小,达到分段缓慢降压的目的,避免水合物的二次生成,使产气速度更加均匀。以不同粒径的石英砂、去离子水和纯度为99.9%的甲烷气为原材料,开展了一维相平衡试验和二维降压开采试验,通过以上初步应用验证了该试验系统的可靠性。

In order to study the synthesis and decomposition characteristics of natural gas hydrates,the exploitation performance of the reservoir,and the sand production and control during the mining process of natural gas hydrates,a set of multi-dimensional natural gas hydrate production simulation test system has been developed.The test system is mainly composed of gas injection system,constant pressure liquid supply system,steam or hot water injection system,1D,2D&3D model,back pressure control system,outlet metering system,data acquisition and control processing system and corresponding auxiliary systems.The main innovations of the experimental system are as follows:(1)The one-dimensional reactor wall made of high-pressure glass and the high-definition camera are combined to achieve visualization for monitoring the synthesis and decomposition of hydrate and the sand migration in the production process under medium and low pressure;(2)The self-developed double-cylinder constant speed and pressure pump is used to control the back pressure valve,so that the pressure in the reactor can be uniformly reduced at a decrement of higher precision during the entire depressurization production process.Consequently,the gas hydrate reformation is greatly reduced,and the gas production rate becomes more uniform.Using quartz sand of different particle sizes,deionized water and methane gas with a purity of 99.9%as raw materials,the one-dimensional phase equilibrium test and two-dimensional depressurization production test are conducted.The reliability of the test system is verified based on the primary application results from these tests.