Natural gas hydrate CO2 substitution extraction method combined with depressurization

Abstract

The invention discloses a natural gas hydrate CO2 substitution extraction method combined with depressurization. The method includes: using alow-density mud drilling technology to depressurize natural gas hydrate reservoir so as to decompose part of the natural gas hydrate; using heterogeneous alcohol ethoxylate as an emulsifier and liquid CO2 as dispersion phase water and a continuous medium to prepare a CO2 emulsifier in a high-pressure container with controlled pressure and temperature; drilling a CO2 emulsifier filling passage, and filling the CO2 and a water emulsifier into a natural gas hydrate reservoir through an emulsifier filling opening; controlling reservoir pressure through the emulsifier filling opening to be in the CO2 hydrate phase balance pressure range corresponding to the reservoir temperature so as to promote the reaction of the CO2 and the natural gas hydrate, and generating CO2 hydrate and gaseous CH4. By the method, CO2 emission reduction is achieved, extraction safety is increased, reservoir seepage characteristics can be improved effectively, the emulsifier is prompted to seep into the reservoir, and the efficiency of the CO2 substitution extraction method is increased.

Description

technical field [0001] The invention belongs to the technical field of petroleum exploitation, and relates to a CO-based 2 The extraction method of natural gas hydrate by displacement method. Background technique [0002] With the sharp reduction of traditional fossil energy reserves, countries around the world have paid special attention to the utilization and development of new energy. Among them, natural gas hydrate, as a new type of energy with high efficiency and large reserves, is generally considered to have broad development prospects in the world. Moreover, the United States, Japan and other countries have discovered and exploited natural gas hydrates in their respective sea areas. At present, the traditional natural gas hydrate production methods mainly include thermal shock method, depressurization method, inhibitor method and so on. But they are all in the stage of experimental research and trial mining. [0003] The depressurization method is a production me...

AI Technical Summary

Problems solved by technology

However, due to the existence of gas hydrates, the permeability characteristics of porous media in the reservoir have no effect on CO 2 The injection of the emulsion has a great influence

Images