石油与天然气地质 ›› 2023, Vol. 44 ›› Issue (6): 1378-1392.doi: 10.11743/ogg20230604

• 油气地质 • 上一篇    下一篇

四川盆地不同类型页岩气压裂难点和对策

王光付1,2(), 李凤霞1,2, 王海波1,2, 周彤1,2, 张亚雄1,2, 王濡岳1,2, 李宁1,2, 陈昱辛1,2, 熊晓菲1,2   

  1. 1.中国石化 石油勘探开发研究院,北京 102206
    2.页岩油气富集机理与有效开发国家重点实验室,北京 102206
  • 收稿日期:2023-08-01 修回日期:2023-10-09 出版日期:2023-12-01 发布日期:2023-12-20
  • 第一作者简介:王光付(1965—),男,博士、教授级高级工程师,油气田开发。E?mail:wanggf.syky@sinopec.com
  • 基金项目:
    国家自然科学基金联合基金项目(U23B6004);中国石油化工股份有限公司科技部项目(P21039-3)

Difficulties and countermeasures for fracturing of various shale gas reservoirs in the Sichuan Basin

Guangfu WANG1,2(), Fengxia LI1,2, Haibo WANG1,2, Tong ZHOU1,2, Yaxiong ZHANG1,2, Ruyue WANG1,2, Ning LI1,2, Yuxin CHEN1,2, Xiaofei XIONG1,2   

  1. 1.Petroleum Exploration and Production Research Institute,SINOPEC,Beijing 102206,China
    2.State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development,Beijing 102206,China
  • Received:2023-08-01 Revised:2023-10-09 Online:2023-12-01 Published:2023-12-20

摘要:

四川盆地内部和盆缘页岩气资源丰富,但由于沉积类型多样、构造复杂,页岩气井压裂测试产量差异大,部分高产井压裂工艺技术推广存在局限性,迫切需要探索和形成针对不同类型页岩气特点的压裂对策和模式。从页岩气高效开发角度出发,通过对比四川盆地已探明页岩气区块地质工程参数特征,依据沉积类型及岩相组合特征、埋藏深度和压力系统,划分出6种类型页岩气:海相中-浅层(深度<3 500 m)超压页岩气、海相深层(深度>3 500 m)超压页岩气、海相深层常压页岩气、海相新类型页岩气、海-陆过渡相深层超压页岩气及陆相中-浅层超压页岩气。开展数值模拟和实验研究发现:①天然裂缝发育及复杂的地应力分布会导致压裂裂缝非均匀扩展和裂缝合并,优化射孔参数和采用暂堵工艺可有效调控裂缝形态,增大改造体积;②夹层和纹层影响缝高纵向扩展和支撑剂的运移铺置,提高前置高黏压裂液和小粒径支撑剂用量,有利于裂缝纵向穿层与支撑剂均衡支撑;③高黏土页岩强水化作用会导致页岩力学性质劣化和加剧支撑剂嵌入,优化压裂液体系添加剂类型和用量可抑制页岩水化作用。探索并提出了不同类型页岩气水平井体积压裂优化设计原则及工艺技术对策,并应用于丁山复杂构造应力场的深层高压页岩气、林滩场深层常压页岩气、井研-犍为海相碎屑岩新类型页岩气、普光大隆组海-陆过渡相和千佛崖组湖相页岩气开发,提高单井产能显著,为不同复杂类型页岩气高效压裂和效益开发提供经验和借鉴。

关键词: 压裂机理, 地应力, 黏土矿物, 夹层, 天然裂缝, 页岩气分类, 四川盆地

Abstract:

The Sichuan Basin and its periphery are rich in shale gas resources. However, diverse sedimentary facies and intricate structures result in significant variations in shale gas productivity across shale gas wells during fracturing tests. Consequently, some fracturing techniques that are effective in high-productivity wells may be subjected to limited popularization. Therefore, there is an urgent need to develop specialized fracturing schemes for different types shale gas. To achieve efficient shale gas recovery, we compare the geological and engineering parameters of blocks with proven shale gas reserves within the Sichuan Basin. These parameters, along with the sedimentary facies types, lithofacies assemblages, burial depths, and pressure systems, are used to classify the shale gas into six types: marine overpressured type of medium-shallow burial depth (burial depth less than 3 500 m), deep overpressured marine type (burial depth more than 3 500 m), deep normally pressured marine type, new marine type, deep overpressured type of transition from continental to marine sedimentation, and overpressured continental type of medium-shallow burial depth. Our findings, obtained from numerical simulations and experiments, are as follows: (1) Natural fractures and complex in-situ stress distributions cause uneven fracture propagation and merging. Optimizing perforation parameters and employing the temporary plugging technique can effectively control fracture morphologies and enhance stimulated reservoir volume (SRV); (2) Interlayers and laminae affect vertical fracture height growth, as well as the proppant migration and placement morphology. Increasing the amount of preflush of high viscosity for fracturing and small-particle-size proppant, is conducive to the fracture longitudinal penetration layers and balanced proppant support; (3) Strong hydration of shales with high clay content can lead to the deterioration of shale mechanical properties and exacerbation of proppant embedment, while optimizing the type and dosage of additives in fracturing fluid systems can inhibit shale hydration. We formulate the optimal design principles and techniques for volume fracturing of horizontal wells in various shale gas reservoirs. The methodology has been successfully applied to the development of deep high-pressure shale gas reservoirs with complex tectonic stress field in the Dingshan block, deep normally pressured shale gas reservoirs in the Lintanchang block, the new-type shale gas reservoirs in marine clastic rocks in the Jingyan-Qianwei block, the shale gas reservoirs of the marine-continental transitional facies in the Dalong Formation in Puguang area, and lacustrine shale gas reservoirs in the Qianfoya Formation, resulting in significant improvement in single well productivity. This study provides valuable experience and reference for efficient fracturing and commercial exploitation of various complex shale gas reservoirs.

Key words: fracturing mechanism, in-situ stress, clay mineral, interlayer, natural fracture, shale gas reservoir classification, Sichuan Basin

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