Leakage-proofing process for exploiting hot-dry-rock geothermal resource by injecting CO2 (supercritical carbon dioxide)

Abstract

The invention relates to the field of geothermal exploitation and provides a leakage-proofing process for exploiting a hot-dry-rock geothermal resource by injecting CO2 ( supercritical carbon dioxide). According to the leakage-proofing process, four inorganic salt precipitation generating mechanisms including (1) mixing a high-concentration salt solution with a precipitation inducer; (2) mixing a high-concentration inorganic salt solution with weak-acid / weak-base gas; (3) mixing a high-concentration inorganic salt solution with another high-concentration inorganic salt solution; (4) evaporating and carrying residual stratum water in surrounding rocks by the supercritical CO2 when the supercritical CO2 flows are adopted, the supercritical CO2 is injected into front slugs / rear slugs of a hot-dry-rock reservoir stratum alternatively, the slugs are displaced by the supercritical CO2 till to the position close to surrounding rocks in a leaking area, the solutions in the slugs are mixed to generate certain physical-chemical reactions so as to generate precipitation, and the generated precipitation is used to block off rock pore cracks. By the aid of combination of evaporating and carrying functions of the supercritical CO2, the rock pore cracks are further blocked off by the precipitation. The leakage-proofing process for exploiting the hot-dry-rock geothermal resource by injecting the supercritical CO2 is good in effect after being verified by experiments.

Description

technical field

[0001] The invention relates to the field of geothermal development, in particular to a supercritical CO injection 2 The invention discloses a technological method for preventing leakage of hot dry rock geothermal energy. Background technique

[0002] Geothermal is a clean and renewable energy with abundant reserves. However, fossil fuels such as coal and petroleum are still the main components of the world's energy consumption structure. CO 2 Resource utilization and geological storage technology are considered to be an effective measure to reduce greenhouse gas emissions and mitigate climate warming. will CO 2 The idea of ​​resource utilization is applied to geothermal development, that is, the use of supercritical CO 2 Replacing conventional water as the working medium, carrying geothermal heat or displacing underground hot water is a novel geothermal development technology that has attracted widespread attention. In 2000, Brown first proposed the use ...

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