超临界CO2压裂裂缝特征研究现状与展望

为加强对超临界CO2压裂裂缝特征的认识,指导超临界CO2压裂技术的发展,总结了前人对超临界CO2起裂、扩展和导流能力特征的研究.结果表明:超临界CO2压裂裂缝起裂压力比液态和清水压裂低,其主导原因是超临界CO2的低黏度和高扩散性使孔隙压力增大起裂压力降低;超临界CO2压裂裂缝扩展影响因素复杂,主要受CO2相变、岩石弱面...

Current Status and Prospect of Study on Supercritical CO2 Fracturing Characteristics

Previous studies on the characteristics of supercritical CO₂ fracture initiation, propagation and conductivity were summarized in order to enhance the understanding of the fracture characteristics of supercritical CO₂ fracturing and guide the development of supercritical CO₂ fracturing technology. The results showed that the fracture initiation pressure in supercritical CO₂ fracturing was lower than that of both liquid and water fracturing, which was mainly caused by that the low viscosity and high diffusivity of supercritical CO₂ increased the pore pressure and reduced the fracture initiation pressure; the influencing factors of fracture propagation were complex, mainly dominated by CO₂ phase change, rock weak surface structure and the weak surface structure of the rock, but the specific mechanism was not yet clear, and it was necessary to develop experimental devices and establish a three-dimensional model of fracture propagation for more microscopic and detailed study; compared with water fracturing, the roughness, tortuosity and length of fractures in supercritical CO₂ fracturing were greater, but the fracture width was smaller and the fracture effectiveness was insufficient; in the supercritical CO₂ fracturing, natural and artificial fractures could be sheared in a staggered manner, and CO₂ could enter the micro-fractures and pores to destroy the cementation of rock and minerals, causing rock and minerals to fall off to generated unpropped fractures that were conductive, but a study was required for the formation mechanism and maintenance mode. This study provides a reference for the study of fracture characteristics of supercritical CO₂ fracturing.