Low-temperature liquid nitrogen fracturing experiment system under confining pressure

Abstract

The invention discloses a low-temperature liquid nitrogen fracturing experiment system under confining pressure. The system is used for simulating the process of high-pressure liquid nitrogen fracturing reservoir rock under the condition of ground stress and researching crack initiation characteristics of rock, fractures formation laws and liquid nitrogen low-temperature assisted rock fracturing effect. The experiment system is composed of three parts, namely a liquid nitrogen supercharging injection apparatus, a liquid nitrogen fracturing experiment apparatus and a confining pressure applying apparatus. The liquid nitrogen supercharging injection apparatus contains an adjustable-speed motor, a vacuum pump and a liquid nitrogen container and a pressure cylinder. The pressure cylinder pumps high pressure liquid nitrogen into a rock sample wellbore for fracturing. Meanwhile, the confining pressure applying apparatus applies radial confining pressure onto a rock sample through hydraulic pressure. A rock sample clamping unit applies axial stress onto the rock sample through mechanical thrust. The system is safe and simple to operate, has high efficiency, can conduct low-temperature liquid nitrogen fracturing experiments under various working conditions, and can be used for fracturing experiments of supercritical CO2, water, oil and other fluids under confining pressure.

Description

technical field [0001] The invention relates to a low-temperature fluid fracturing experiment system, in particular to a low-temperature liquid nitrogen fracturing experiment system under confining pressure, belonging to the technical fields of cryogenic fluid and rock crushing. Background technique [0002] Today's oil and gas exploration and development have gradually moved from conventional reservoirs to low-permeability, ultra-low-permeability and unconventional reservoirs. Among them, in terms of unconventional energy, my country has abundant shale gas and coalbed methane reserves, which are expected to become important alternative energy sources in the 21st century. At present, the mining of shale gas and coalbed methane mainly relies on hydraulic fracturing to increase production, and many problems have been exposed in practical applications, such as difficult flowback of fracturing fluid, serious damage to reservoirs, and large environmental pollution. Efficient deve...

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Problems solved by technology

In addition, liquid nitrogen has the characteristics of low temperature and low viscosity, and the formation law of the fracture network in liquid nitrogen fracturing is still unclear

[0005] Therefore, it is necessary to carry out basic research on the characteristics of liquid nitrogen fracturing rocks under confining pressure, the formation law of fracturing fractures, and low temperature assisted rock fracturing. At present, the research results in this field have not been reported in the literature. Exploratory research on nitrogen fracturing is of great significance

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