超临界CO2+水力携砂复合体积压裂工艺对陆相页岩储层的改造机理及效果

中国陆相页岩油气资源潜力巨大,但由于陆相页岩具有黏土矿物含量高、非均质性强等特点,很难实现大规模体积压裂。由于缺乏针对性储层体积改造技术,中国陆相页岩油气领域一直未获得实质性突破。为解决这一关键技术难题,综合利用压裂模拟、微观分析等实验手段对松辽盆地青山口组一段富含油页岩层系进行研究。结果表明,超临界CO₂复合体积压裂具有降低页岩储层破裂压力、形成复杂缝网和溶蚀改善储层渗流通道的优势。在陆相页岩油领域设计并使用超临界CO₂复合体积压裂工艺,对吉页油1HF井成功实施了21段/1 431 m水平井压裂,并采用人工裂缝反演、不稳定试井、微地震监测、返排液分析、油源对比等技术进行压后效果评价。现场实践证实,该项技术效果显著,有效改造体积是常规水力压裂的2倍,实现了高黏土矿物含量强非均质性陆相页岩层系大型体积压裂,支撑吉页油1HF井获得稳产16.4 m³/d的高产工业页岩油流。

The stimulation mechanism and performance analysis of supercritical CO2 and hydraulic sand-carrying composite volume fracturing technology on continental shale reservoirs

Continental shale oil and gas has huge development potential in China. However, due to the high content of clay minerals in continental shale with strong heterogeneity, large-scale volume fracturing is very difficult to be implemented. The lack of a targeted technology for reservoir stimulation has led to a failure to make a real breakthrough in the exploration and exploitation of continental shale oil and gas. To solve this key technical difficulty, taking the oil-rich shale formations in the Member 1 of Qingshankou Formation in Songliao Basin as the research object, through the comprehensive use of experimental means such as fracturing simulation and micro analysis, it is found that the supercritical CO₂ composite volume fracturing technology has the advantages of reducing the fracture pressure of shale reservoirs, forming complex fracture network, and improving the reservoir seepage channel by corrosion. Under the guidance of the above research results, the supercritical CO₂ composite volume fracturing process has been innovatively designed and applied in the exploitation of continental shale oil, and the fracturing construction of 21 stages with a total horizontal section length of 1 431 m has been successfully completed in Well Jiye 1HF. Through the post-fracturing effect evaluation by means of artificial fracture inversion, unstable well test, microseismic monitoring, flowback fluid analysis and oil source comparison, it is confirmed that this technology has a significant stimulation effect on the reservoir, and the effective reconstruction volume is twice as large as that of conventional hydraulic fracturing, realizing the large-scale volume fracturing of the highly heterogeneous continental shale series with high clay content. Supported by this technology, the high-yield industrial shale oil flow with daily stable production of 16.4 m³ was obtained in Well Jiye 1HF.