四川盆地外缘常压页岩气水平井低成本钻井技术探讨

Discussion on Low-Cost Drilling Technologies of Normal Pressure Shale Gas in the Outer Margin of the Sichuan Basin

  • 摘要: 四川盆地外缘页岩气储层压力系数为0.90~1.20,属于常压页岩气储层,采用高压页岩气钻井技术进行开发,开发成本高。在分析常压页岩气与高压页岩气钻井差异的基础上,分别从井身结构、井眼轨道设计、井眼轨迹控制、钻井液和固井工艺等方面探讨了降低钻井成本的技术措施,提出将三开井身结构优化为二开井身结构,采用"双二维"模型设计井眼轨道、利用旋转导向技术控制二开井眼轨迹、使用低油水比油基钻井液和优化生产套管水泥返高等降低钻井成本的配套技术和措施,以期为实现四川盆地外缘常压页岩气的经济有效开发提供技术支撑。

     

    Abstract: The shale gas reservoirs on the outer margin of the Sichuan Basin have a pressure coefficient of 0.90-1.20,which belongs to the normal pressure shale gas reservoirs and are developed by high-pressure shale gas drilling technology.The cost of per unit gas production is high,which hinders the economic development of shale gas.Therefore,according to the analysis on the differences between the drilling of normal pressure shale gas and high pressure shale gas reservoirs,the low-cost drilling technologies were discussed taking into consideration the casing program,wellbore trajectory design,wellbore trajectory control,drilling fluid and cementing processes.The low-cost drilling technologies and associated measures (i.e.,optimizing the tri-section casing program into the dual-section one,designing the wellbore trajectory with dual-2D model,controlling the second section wellbore trajectory with rotary steering technology,using the low oil-water ratio oil-based drilling fluid,and adopting the low-cost supporting technologies and measures like production casing cement top optimization,etc.) were proposed to provide technical supports for the economic development of normal pressure shale gas reservoirs in the outer margin of the Sichuan Basin.

     

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