天然气工业2025，Vol.45Issue(9)：104-113,10.DOI:10.3787/j.issn.1000-0976.2025.09.009
超临界CO2复合压裂页岩裂缝扩展及增渗机理
Fracture propagation and permeability enhancement mechanisms in shale under supercritical CO2 compound fracturing
摘要
Abstract
Supercritical CO2 compound fracturing,which takes supercritical CO2 as the pad fluid and guar gum fracturing fluid as the sand-carrying fluid,has been verified to be effective in field tests.However,the synergetic effect of the two-stage fluids on the final fracture morphology and conductivity in the process of supercritical CO2 compound fracturing has not been experimentally studied and understood systematically.To understand the mechanisms of supercritical CO2 compound fracturing,this paper adopts the indoor triaxial fracturing experiment method to compare the morphological characteristics of fracture propagation in three modes,i.e.,guar gum fracturing,supercritical CO2 fracturing,and supercritical CO2 compound fracturing,and quantitatively characterize the key parameters like fracture width,complexity and permeability.In addition,the fracture network enhancement and permeability enhancement mechanisms under compound fracturing are revealed from the perspective of experimental study.The following results are obtained.First,compared with guar gum fracturing,supercritical CO2 fracturing is more likely to connect discontinuities such as bedding,to form more branch fractures,producing a more complex fracture morphology.Second,as the bedding inclination increases,supercritical CO2 compound fracturing will form a complex fracture network more easily.And when the bedding inclination reaches 90°,compound fracturing can extensively connect the bedding and natural fractures within the rocks,so as to increase the stimulated volume.Third,in supercritical CO2 compound fracturing,guar gum fracturing can significantly increase the complexity and width of the fractures formed during the supercritical CO2 fracturing stage,with the fracture complexity increased by 33.6%,the width increased by 7.08 times,and the permeability increased by an order of magnitude.In conclusion,the research results reveal the pad fluid fracturing,fracture network propagation and synergetic permeability enhancement mechanisms of two-stage fluids in supercritical CO2 compound fracturing,which can provide theoretical basis and technical support for efficient fracturing stimulation of unconventional reservoirs of shale gas,CBM and tight gas.关键词
超临界二氧化碳/压裂/页岩/裂缝扩展/裂缝宽度/渗透率/增渗机理Key words
Supercritical CO2/Fracturing/Shale/Fracture propagation/Fracture width/Permeability/Permeability enhancement mechanism分类
能源科技引用本文复制引用
蔡灿,冯彪,陈浩,张烈辉,杨显鹏..超临界CO2复合压裂页岩裂缝扩展及增渗机理[J].天然气工业,2025,45(9):104-113,10.基金项目
国家自然科学基金重点项目"海相页岩水平井超临界二氧化碳压裂机理与一体化模拟研究"(编号:52234003)、国家自然科学基金面上项目"深井高压气体射流辅助钻井破岩机理及携岩特性研究"(编号:42472383)、四川省自然科学基金青年基金项目"复杂裂缝内水驱CO2多相流动机理及支撑剂运移规律"(编号:25QNJJ2040). （编号:52234003）
