Novel method for conducting hot dry rock drilling through liquid nitrogen

Abstract

The invention discloses a novel method for conducting hot dry rock drilling through liquid nitrogen. According to the method, the liquid nitrogen is used as drilling fluid to conduct hot dry rock drilling, tensile stress is generated on the surface of hot dry rock through the low temperature effect of the liquid nitrogen, and microcracks are induced to be produced and extended, so that the strength of the hot dry rock is lowered, and the rock breaking efficiency of a drill bit is improved. After the liquid nitrogen is gasified at a shaft bottom, nitrogen returns from an annulus, and rock debris formed by rock breaking is carried to the ground. According to the novel method, the cold shock effect of the liquid nitrogen and the advantage of nitrogen unbalanced drilling are combined, so that the mechanical drilling speed of hot dry rock drilling is greatly improved, the well leakage problem in hot dry rock drilling is effectively solved, and the hot dry rock drilling cost is greatly lowered. The novel method is expected to provide new technological reserve for development of hot dry rock resources in China.

Description

technical field [0001] The invention relates to a new method for drilling hot dry rock by using liquid nitrogen, which belongs to the fields of oil and gas well engineering and geothermal resource development. Background technique [0002] Geothermal is a renewable and clean energy buried deep in the earth's crust and existing in the form of thermal energy. Geothermal energy resources are abundant, which can be used for residential heating, hot spring development and steam power generation. Geothermal energy exists in many forms, among which hot dry rock has the greatest development potential. Hot dry rock refers to the crustal rock mass with a buried depth of more than 3 km, a temperature between 200 and 650 °C, and basically no natural fluids. The lithology is mainly gneiss and granite. Statistics show that the potential of hot dry rock resources in my country is huge, and CO2 will not be produced during the development process. 2 , dust particles and waste water and ot...

AI Technical Summary

Problems solved by technology

[0005] Aiming at the problems of high difficulty and high cost of dry hot rock drilling, the present invention proposes a new method of using liquid nitrogen for dry hot rock drilling

The high-pressure liquid nitrogen jet and the cutting teeth of the drill bit carry out hydraulic-mechanical combined rock breaking at the bottom of the well, which improves the mechanical penetration rate; after the liquid nitrogen is gasified, the nitrogen returns from the annular space to carry the cuttings to the ground, solving the problem of serious lost circulation in dry hot rock drilling question

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