川南海相深层页岩气水平井钻井关键技术与实践

Key technology and practice of horizontal drilling for marine deep shale gas in southern Sichuan Basin

贾利春 李枝林 张继川 陶怀志 李雷 黄崇君 魏萧

JIA Lichun LI Zhilin ZHANG Jichuan TAO Huaizhi LI Lei HUANG Chongjun WEI Xiao

川庆钻探工程有限公司钻采工程技术研究院

Drilling & Production Technology Research Institute, CNPC Chuanqing Drilling Engineering Co. Ltd., Guanghan 618300, Sichuan, China

川南海相深层页岩气资源丰富，是当前及未来页岩气开发的重要接替领域。由于深层页岩气具有层序多、井底温度高、地层压力高、优质储层薄等地质工程特征，在钻井中面临着导向仪器和钻井液耐温性不足、井眼轨迹控制难度高、工具井眼清洁困难、钻速慢及井下复杂风险高的难题。通过优选耐165 ℃高温旋转导向系统提升钻井时效降低趟钻次数，研制高效破岩PDC钻头提高机械钻速，采用降密度控压钻井降低井底钻井液密度，研发岩屑动态称重装置及可降解携砂纤维实现井眼高效清洁，利用钻井液地面降温系统保障井下工具正常作业，采用地质工程一体化导向钻井模式精准识别钻遇岩性和层位，形成了深层页岩气水平井钻井关键技术。现场应用结果显示，L203井区单井钻井周期由199 d缩短至82.6 d，Z201井区单井钻井周期由239.5 d缩短至118 d，实现深层页岩气铂金靶体平均钻遇率92.8%，对今后深层页岩气钻井提速提效具有示范指导作用。

The southern Sichuan Basin has abundant marine deep shale gas resources, which is a critical replacement for the current and future shale gas development. However, drilling of deep shale gas faces numerous challenges, such as inadequate thermal tolerance of steering instruments and drilling fluids, high difficulties in well trajectory control and clean-up of wells and tools, low penetration rate, and high risks of downhole complex issues, due to the geologic characteristics of deep shale gas (numerous sequences, high formation temperature, high formation pressure, and thin high-quality reservoirs). Given this, we managed to develop the key technology for horizontal drilling of deep shale gas through multiple efforts. The 165ºC-tolerant rotary steerable system was selected to reduce runs and facilitate time-efficient drilling, and moreover, the drilling fluid surface cooling system was deployed to ensure the normal functioning of downhole tools. The PDC bit with efficient rock-breaking was developed to raise the penetration rate. The managed pressure drilling was adopted to reduce the drilling fluid density. The dynamic weighting device of cuttings and degradable cutting-laden fibers were developed for efficient well clean-up. At last, the geology-engineering-integrated steering mode was introduced to accurately identify the lithology and stratigraphy of formations at the bit. The field application shows the drilling cycle of a well in the L203 well district is shortened from 199 d to 82.6 d; that of the Z201 well district, from 239.5 d to 118 d; the encounter ratio with the platinum target averages 92.8%. The proposed key technology for the deep shale gas horizontal drilling provides guidance and demonstration for future ROP-enhancing and efficiency-improvement of deep shale gas drilling.

10.13639/j.odpt.2022.02.002