压裂改造技术在页岩气储层中的应用

Stimulation technology application in shale gas reservoir

目前水平井完井、大规模分段压裂改造已经成为实现页岩气商业化开发的主体技术措施。页岩储层根据其岩石矿物类型和天然裂缝发育程度不同可以定性地分为脆性页岩和塑性页岩,在脆性页岩地层中压裂液主要有减阻水或减阻水＋线性胶体系,塑性地层中一般采用高黏度交联冻胶、泡沫压裂液体系等。经过30年的发展,北美页岩气已经实现了效益开发,而国内页岩气勘探开发则刚刚起步,尚处于勘探评价阶段。W201井是国内第1口为勘探页岩气钻的井,其基质渗透率极低（0.00018×10-3μm2）,脆性矿物含量较高,裂缝较发育,吸附气含量较高。结合国外页岩气开发经验,通过对W201井储层评价、液体优选、工艺措施优化,成功实现了页岩储层大规模减阻水压裂施工,标志着国内在页岩气压裂施工工艺、液体体系、裂缝监测等方面实现突破。

Shale with a rich organic is not only hydrocarbon source but also can be the storage and conservation of natural gas in shale gas reservoir. In nowadays, horizontal well completion and large-scale staged fracturing and stimulated reservoir volume（SRV） with staged fracturing and cluster perforation and drillable bridge has already became mainly shale gas development technologies. According to mineral types and different development degree of natural fractures, the shale can be divided into brittle shale and plastic shale. The fracturing fluids used in the former mainly include slick-water or slick-water combined with linear rubber system, meanwhile, the high viscosity cross-linking gel and foam fracturing fluids are often adopted in the brittle shale reservoir. With the 30 years development, China just began to explore and develop the unconventional gas reservoir when those in North American have achieved commercial development. Well W201 was the first pilot test well for shale reservoir exploration in domestic, which possess a formation with extremely low permeability, high brittle mineral content, well-developed nature fracture, high absorption gas content and easily to fracture network. Large scale slick-water fracturing was arranged in Well W201 based on the reservoir evaluation, fluid optimizing and selective treatment; and many breakthroughs in treatment technology, fluid system and fracture monitor were obtained through the operation.