A method and system for improving recovery of shale gas wells

Abstract

The invention relates to a method and a system for improving recovery efficiency of a shale gas well. The method includes that paving pipelines; filling high-pressure CO2 into the pipeline in a horizontal well, enabling the high-pressure air to knock to form a series of high-pressure air pulse vibration to puncture the hollow pipe wall and horizontal well wall, and forming a primary seam in a shale layer; pressing liquid CO2 to the primary seam position of the shale layer through the pipeline, heating the rock at the primary seam position of the shale layer, and enabling the liquid CO2 to change phase to vaporize quickly to generate a series of high-pressure air pulse vibration to crack the primary seam in the shale layer again; dividing the pipeline in the horizontal well into several segments through a plurality of dividers, and using said method to produce seams segment by segment for the shale layer segments corresponding to the pipeline segments. According to the method for improving the recovery efficiency of the shale gas well, by means of the CO2 phase change mode, the crack degree of the shale layer is effectively improved, and the recovery efficiency of the shale gas well is improved.

Description

technical field [0001] The invention relates to the technical field of shale gas acquisition, in particular to a method and system for improving the recovery rate of shale gas wells. Background technique [0002] Shale gas refers to unconventional natural gas that occurs in organic-rich mudstone and its interlayers, mainly in the form of adsorption or free, and its main component is methane. In recent years, the United States has made technological breakthroughs in shale gas exploration and development, and its production has grown rapidly, realizing its "natural gas revolution", which has had a major impact on the international natural gas market and the world's energy structure, and has greatly rewritten the world's energy structure. [0003] There are multiple sets of coal measures and dark mud and shale formations developed in many basins in China. There are large sets of interbedded tight sandstones, which have favorable conditions for the development of source gas / shal...

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Problems solved by technology

[0005] 1. The water consumption is huge. Generally, more than 10,000 cubic meters of water is required to fracturing a well, which limits its application. For example, in southern my country, there are many mountains and hills, and water supply is very difficult, so this method cannot be applied

[0006] 2. The fracturing fluid pollutes the groundwater seriously and does not meet the current environmental protection requirements

[0007] 3. Staged fracturing of horizontal wells During water fracturing, only a few fractures are produced in each stage, and the gas production efficiency is low

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