旋转地质导向技术在水平井中的应用及体会——以昭通页岩气示范区为例

位干四川盆地南缘的云南昭通国家级页岩气示范区具有强构造改造、过成熟热演化、复杂山地人文的地质特点,页岩气井长水平段储层钻遇率和井眼轨迹平滑控制是影响页岩气产能的重要因素。为此,在分析该示范区内黄金坝页岩气建产区水平井钻井技术难点的基础上,引入了旋转地质导向技术。通过不断探索优质页岩储层展布规律、改进钻井工具性能、优选技术方案,确立了水平井的地质设计定靶点、钻前分析定轨迹、着陆段定曲率、水平段定钻遇率的"四定"工作思路;形成了稳斜探顶、复合入窗的着陆方法和地质模型指导、成像精确定位的轨迹控制技术。现场实践结果表明,旋转地质导向技术使井眼轨迹平滑、优质页岩储层钻遇率达到100%、平均机械钻速提高至10.1 m/h,实现了页岩气水平井优质井身质量和高储层钻遇率。所形成的"双向互动式"页岩气地质工程一体化综合研究和三维地质模型成果可有效指导类似地区旋转地质导向技术的应用。

Application of rotary geosteering technology in horizontal wells and its implication : A case study of the Zhaotong shale gas demonstration area of Yunnan

The Zhaotong national shale gas demonstration area in Yunnan Province,also close to the southern margin of the Sichuan Basin,is geologically characterized by strong tectonic reworking, over mature evolution and complex mountainous topography, and its shale gas productivity is mainly influenced by reservoir encountering ratio of long horizontal sections and smoothing control of well paths. In this paper, rotary geosteering technology was introduced to solve the difficulties in horizontal well drilling in the Huangjinba shale gas development block in this demonstration area. Distribution rules of high-quality shale reservoirs were explored, performance of drilling tools was improved and technical programs were optimized. In this way, a work approach was defined to determine targets based on geologic design, well path based on pre-drilling analysis, curvature based on landing section and encountering ratio based on horizontal section. Landing methods were established, including hole angle holding and top exploring and complex window entering. Moreover, well path control technologies were developed, such as geologic model guiding and accurate image positioning. Practical applications indicate that well patch was smooth, encountering ratio of high-quality shale reservoirs could reach 100% and average ROP rose to 10.1 m/h. The rotary geosteering drilling technique can guarantee high quality of horizontal shale gas wells and significantly improve the high-quality shale reservoir encountering ratio. The comprehensive study results of two-way interactive shale gas geologic engineering integration and the 3D geologic model results in this paper can provide effective guidance for the application of rotary geosteering technologies in similar areas.