天然气水合物开采方法研究现状及展望

Current status and prospects on natural gas hydrate exploitation methods

摘要:

天然气水合物是一种储量巨大的固态清洁能源，因此被认为是传统化石燃料的接替能源而备受关注。由于其赋存于低温、高压的海洋及冻土环境中，采用经济、高效的方法将天然气从天然气水合物储层中开采出来是实现天然气水合物商业开采的关键。根据实验室研究、数值模拟和现场试验等方面的研究现状，本文分析了降压法、注热法、注化学抑制剂法、CO₂置换法、联合法等方法的开采效果，并对各种方法的优点和局限性进行了论述。已有的开采方法主要受到储层渗透率低、导热性能差等限制，未能实现长期连续产气。针对以上问题，提出储层原位电阻加热法提高热利用率；并认为水力压裂増透技术是提高储层渗透率以辅助降压法等开采方法实现高效产气的一种有效措施；关于水合物开采可能导致储层失稳等问题，认为利用CO₂置换法可以加固储层，并且通过超临界CO₂喷射技术能够提高CO₂置换率。

Abstract:

Natural gas hydrate is a type of solid clean energy with huge reserve， which is therefore considered as a substitute for traditional fossil fuels and have attracted much attention around the world. Due to its occurrence in low-temperature and high-pressure marine and permafrost environments， the key to achieving commercial exploitation is to find out economical and efficient exploitation methods. Based on the current research status of laboratory research， numerical simulation， and on-site experiments， the exploitation effects of methods such as depressurization， heat injection， chemical inhibitor injection， CO₂ displacement and combination method were analyzed， and the advantages and limitations of each method were discussed. The existing exploitation methods are mainly limited by low reservoir permeability and poor thermal conductivity， and have not been able to achieve long-term continuous gas production. To address the above issues， the in-situ resistance heating method for reservoirs is proposed to improve thermal utilization efficiency， and it is believed that hydraulic fracturing and permeability enhancement technology is an effective measure to increase reservoir permeability and assist in efficient gas production through production methods such as depressurization； Regarding the potential instability of reservoirs caused by hydrate exploitation， it is believed that the use of CO₂ replacement method can strengthen the reservoir， and the use of supercritical CO₂ injection technology can improve the CO₂ replacement rate.