Method for efficiently developing deep geothermal reservoir through liquid nitrogen circulating fracturing

• Main Authors: WEN HAITAO, HUANG ZHONGWEI, HU XIAOLI, MA FENG, YANG RUIYUE, HONG CHUNYANG, HOU LEI, WU XIAOGUANG
• Format: Patent
• Language: Chinese; English
• Published: 05.04.2022
• Subjects: BLASTING; EARTH DRILLING; EARTH DRILLING, e.g. DEEP DRILLING; FIXED CONSTRUCTIONS; GEOTHERMAL COLLECTORS; GEOTHERMAL SYSTEMS; HEATING; LIGHTING; MECHANICAL ENGINEERING; MINING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR ASLURRY OF MINERALS FROM WELLS; RANGES; VENTILATING; WEAPONS

The invention provides a method for efficiently developing a deep geothermal reservoir through liquid nitrogen circulating fracturing. On the basis of the method, liquid nitrogen is periodically injected in a small-displacement injection-pause mode, under the action of alternating thermal stress-fluid pressure, a stress field around a rock crack of the deep geothermal reservoir is periodically changed, fatigue failure of the rock can be induced, the crack initiation pressure is further reduced, crack initiation and expansion of a crack are induced, and finally a three-dimensional crack net is formed. Meanwhile, as the liquid nitrogen injection displacement is small, the overall injection amount is low, and the pump pressure is low, the cycle index can be selected according to the crack scale, and the earthquake risk can be reduced. Therefore, the problems that conventional hydraulic fracturing is high in crack initiation pressure, single in crack, small in heat exchange area, frequent in microseism and the li