Cooling hydraulic fracturing method for developing hot dry rock thermal energy

Abstract

The invention discloses a cooling hydraulic fracturing method for developing hot dry rock thermal energy. The method belongs to a hot dry rock heat energy utilization technology in an enhanced geothermal power generation system (EGS). According to the method, the hot dry rock stratum is injected with low-sand-ratio thickened water fracturing fluid, the target stratum is cooled, due to injection ofthe low-sand-ratio thickened water fracturing fluid, the temperature of a shaft and the temperature of the fracturing fluid in cracks are gradually lowered, and in order to guarantee the good coolingeffect and achieve the non-waste aim, the injection amount of the low-sand-ratio thickened water fracturing fluid needs to be precisely calculated. The distribution condition of the temperature of the stratum nearby the shaft is different from distribution of the temperature of rock nearby the cracks, the temperature of the stratum nearby the shaft is increased according to the ground temperaturein a gradient mode with change of well depth, the temperature of the reservoir nearby the cracks is a mean value, and therefore temperature change of perforation portions under the shaft and the temperature distribution condition of the fracturing fluid in the cracks need to be calculated so as to achieve a better hot dry rock stratum cooling effect.

Description

technical field [0001] The invention relates to a hot dry rock thermal energy utilization technology in an enhanced geothermal power generation system (EGS), in particular to a cooling and fracturing method for thermal energy development of dry hot rock. Background technique [0002] As a renewable new energy, geothermal energy has huge resource potential, CO 2 Due to the advantages of low emission and wide distribution, it has become a renewable clean energy that is mainly researched and developed by countries all over the world. Geothermal energy can be divided into hydrothermal type and dry-hot rock type. At present, the exploitation and utilization of geothermal resources in the world is mainly hydrothermal type geothermal energy, but the resource potential in the future is the exploitation of dry-hot rock type geothermal energy, that is, the enhanced geothermal power generation system ( EGS), at present, the enhanced geothermal power generation system (EGS) faces a ser...

AI Technical Summary

Problems solved by technology

However, due to the ultra-high formation temperature of geothermal reservoirs, fracturing poses a great challenge to the high temperature resistance of fracturing fluids. At present, the temperature resistance of conventional cross-linked fracturing fluids is below 160 °C. However, commercially used hot dry rocks The temperature of the rock formation is greater than 250°C, even reaching above 300°C

Conventional cross-linked fracturing fluids cannot meet the temperature resistance requirements for construction. If the temperature resistance of fracturing fluids is improved, it will not only greatly increase the development cost, but also face a series of technical challenges

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