泥页岩水化对气体钻井井壁稳定性影响规律研究

Effect of shale hydration on wellbore stability in gas drilling

张杰 徐安建 李翠楠 蒋祖军

ZHANG Jie XU Anjian LI Cuinan JIANG Zujun

中国石化西南分公司博士后工作站，四川德阳　618000 中国石化西南工程技术研究院,四川德阳　618000 中石油西南油气田分公司重庆气矿,四川广安　638500

Postdoctoral Workstation of Southwest Subsidiary Company, Sinopec, Deyang 618000, China Southwest Engineering Technology Institute, Sinopec, Deyang 618000, China Chongqing Gas Field, Southwest Oil and Gas Field Company of PetroChina, Guang’an 638500, China

气体钻井钻遇地层水后，井壁岩石力学特征变得复杂，给钻井施工带来较大的安全威胁。从泥页岩水化机理着手，通过实验和理论计算方法，对气体钻井过程中泥页岩水化对井周岩石力学参数的影响规律进行分析研究，给出地层出水条件下泥页岩井段井壁稳定性分析评价方法，结合工程地质特征，对川西特殊复杂地层出水情况下气体钻井井壁稳定性进行定量评价。分析结果表明，由于川西地区中浅～中深井段泥页岩层段较多，且地层水丰富，气体钻井过程中井壁容易发生失稳破坏。因此在气体钻井过程中，应充分认识待钻井段地层出水情况和泥页岩地层的纵向分布规律。

Wellbore rock-mechanics properties become more complicated after the formation water is met in gas drilling, which threatens safe gas drilling greatly. From the perspective of the mechanism of shale hydration, based on the experiment and theoretical calculation, the effect of shale hydration on wellbore rock-mechanics parameters is analyzed. The method for analyzing and evaluating the shale wellbore stability under the condition of formation water production is proposed. Combined with the actual engineering geological characteristics, quantitative evaluation is made on the wellbore stability in gas drilling under the condition that the special and complex formation in western Sichuan produces water. Results obtained from the experiment and the theoretical calculation show that well bore instability and failure easily occurs in gas drilling, because shale is widely distributed in the intervals ranging from the medium shallow one to the medium deep one, and the formation water is abundant in western Sichuan, the problem of wellbore stability is outstanding in the process of gas drilling. The formation water production of the well interval to be drilled and the vertical distribution law of shale formations should be fully recognized during the process gas drilling demonstration, design, and construction.