四川盆地深层页岩气水平井优快钻井技术——以泸203井为例

泸203井是中国石油天然气集团有限公司部署在四川盆地南部泸县—长宁页岩气区块的1口重点超深页岩气探井,实际完钻井深达5 600 m,测试日产气量为137.9×10~4 m~3,成为目前国内首口单井测试日产量超百万立方米的页岩气井。为了给深层页岩气井优快钻井提供借鉴和经验,以泸203井为例,在分析储层特征对钻井要求的基础上,归纳总结了保障该井页岩气水平井钻井井身质量、优质储层钻遇率、快速钻进以及降低复杂事故率的优快钻井综合配套技术,并对其应用效果进行了评价。研究结果表明:(1)采用旋转导向工具并配合钻柱扭摆系统钻进,减少了滑动定向钻进进尺,成功地控制了钻具托压现象,大幅度降低了定向辅助时间;(2)实施的4种削减钻具振动措施很好地解决了水平段钻进中螺杆故障问题,进一步提高了钻井速度;(3)采用近钻头伽马测量系统实时追踪储层,控制轨迹在优质产层内钻进,保证了优质页岩储层钻遇率;(4)优配钻井装备及高密度的油基钻井液的应用保证了井下动力钻具的动力和井眼携砂的需求以及钻井液性能的净化,确保了井眼畅通、保持了井壁稳定,起到了提高钻井速度的重要作用。结论认为,泸203井按照地质工程一体化的技术思路,采取先打直导眼再侧钻水平井的方式,优质页岩储层钻遇率达到100%,该井的实施进一步完善了四川盆地新区块超深页岩气水平井配套优快钻井技术。

Fast and efficient drilling technologies for deep shale gas horizontal wells in the sichuan Basin: A case study of Well Lu 203

Well Lu 203 is an important ultradeep shale gas exploration well which is deployed by the CNPC in the Luxian–Changning Shale Gas Block of the southern Sichuan Basin. Its total well depth is 5 600 m and its daily gas production during the test is 137.9×104 m3. At present, it is domestic first shale gas well whose single-well daily production is over one million cubic meters. In this paper, Well Lu 203 was taken as an example to provide the technologies and experience for the fast and efficient drilling of deep shale gas wells. After the drilling requirements based on reservoir characteristics were analyzed, the comprehensive support technologies of fast and efficient drilling to ensure the wellbore quality, high-quality reservoir drilling rate and fast drilling of shale gas horizontal wells and reduce the complex accident rate were summarized and their application effects were evaluated. And the following research results were obtained. First, rotary steering tools, combined with drill string torsion system can reduce the sliding directional drilling footage, successfully control the backing pressure of drilling tools and greatly save the orientation assistance time. Second, the four measures which were taken to reduce the vibration of the drilling tools can well solve the problem of screw failure during horizontal section drilling and increase the rate of penetration (ROP) further. Third, the near-bit gamma measurement system is used to track the reservoirs in real time and control the drilling trajectory in the high-quality production layers so as to ensure the high-quality shale drilling rate. Fourth, the application of well-equipped drilling equipment and high-density oil-based drilling fluid ensures the dynamic of the downhole power drilling tool and the purification of the drilling fluid performance, satisfies the need of sand carrying in the wellbore, guarantees the smooth flow of the wellbore, maintains the stability of the wellbore, and plays an important role in ROP improvement. In conclusion, according to the technical idea of geology–engineering integration, Well Lu 203 is drilled in the mode of drilling the vertical pilot hole first and then sidetracking the horizontal well, and its high-quality reservoir drilling rate is up to 100%. The implementation of the Well Lu 203 further improves the support drilling technologies for the fast and efficient drilling of ultradeep shale gas horizontal wells in the new blocks of the Sichuan Basin.