川东红星地区二叠系吴家坪组海相页岩气钻井实践

川东红星地区二叠系吴家坪组富含优质页岩，多口钻井获得高产工业气流，是江汉油田天然气产能的重要接替区块，但由于该区构造、岩性复杂，目的层埋藏深，储层薄产状起伏大等因素，造成井漏、井垮等复杂情况多发，机械钻速低、钻井周期长，优质储层钻遇率难以保证等钻井问题，严重制约了效益开发。通过前期资料总结，分析了钻井难点，开展钻井工程优化设计，优选关键破岩工具，优化钻井液密度及封堵性能，形成了“三开次”井身结构、“异形齿PDC、混合钻头+大扭矩等壁厚螺杆+强化参数钻井”、旋转控制头简易控压、低密度强封堵“漏垮同治”钻井液工艺，建立了“垂深预测、分段控斜、五图一表”地质工程一体化导向技术，提出了下步优化方向。现场应用表明：(1) “三开次”井身结构满足红星地区安全成井需求，为钻井提速奠定了基础，高性能PDC强化参数钻井，各开次机械钻速显著提升，二叠系地层三开造斜段钻速提高15%，水平段提高22%；(2)降密度、纳米封堵钻井液技术有效降低复杂处理次数及时间，复杂时效相比前期实施井减少20.5%；(3)优质储层穿行率大幅提升至93.27%，相比前期提升19.85%。

Drilling practice of marine shale gas in Permian Wujiaping Formation in Hongxing area of eastern Sichuan

Permian Wujiaping Formation in Hongxing area of eastern Sichuan is rich in high-quality shale, and multiple wells have achieved high productivity of industrial gas. It is an important replacement block for the natural gas production capacity of the Jianghan Oilfield. However, due to the complex structure and lithology, deep burial depth of the target layer, and large fluctuations in the attitude of thin reservoirs, complex situations such as well leakage and collapse occuring frequently, low mechanical drilling speed, long drilling cycles, and difficulty in ensuring the drilling rate of high-quality reservoirs seriously restrict the benefit development. Based on the summary of previous data, the drilling difficulties were analyzed, the optimal design of drilling engineering was carried out, and some key rock breaking tools were selected to optimize the density and sealing performance of drilling fluid. The "three opening" wellbore structure with three different diameters, "irregular tooth PDC and mixed drill bits + high torque equal wall thickness screw + reinforced parameter drilling", simple pressure control by a rotary control head, and low density and strong sealing drilling fluid technology for "both leakage and collapse treatment" were formed. We have established a geological engineering integrated guidance technology based on "vertical depth prediction, segmented slope control, and five charts and one table", and proposed the direction for further improvement. The on-site application shows that: (1) the "three opening" wellbore structure with three different diameters meets the safety drilling requirements in Hongxing area, laying the foundation for drilling speed increase. The parameter drilling was enhanced by high-performance PDC, and the mechanical drilling speed of each opening is significantly improved. The drilling speed of the third opening section in the Permian formation increased by 15%, and the horizontal section increased by 22%; (2) The density reduction and nano sealing drilling fluid technology effectively reduced the number and time of complex treatments, and the time for complex treatments was reduced by 20.5% compared to the early implementation of wells; (3) The penetration rate of high-quality reservoirs significantly increased to 93.27%, an increase of 19.85% compared to the previous period.