“连续管+柔性钻具”超短半径水平井钻井技术研究与现场试验

Research and Field Test of Ultra-Short Radius Horizontal Drilling Technology Combining Coiled Tubing and Flexible BHA

超短半径水平井在油气田老井改造、剩余油挖潜方面作用很大,但常用的柔性钻具超短半径水平井钻井技术存在起下钻周期长、作业成本高的问题。考虑连续管钻井具有钻井效率高、成本低和安全可靠等优点,提出了将连续管与柔性钻具相结合的钻井新思路,并研制了高速和低速大扭矩螺杆、改进了柔性钻具结构、研制了叠加式斜向器和造斜PDC钻头等关键工具,优化了配套施工工艺,初步形成了“连续管+柔性钻具”超短半径水平井钻井技术。该技术在江汉油田陵72-5CZ井开展了首次现场试验,成功完成了长30.21 m的超短半径水平分支井眼,平均机械钻速0.8 m/h,实钻井眼轨迹与设计井眼轨道吻合良好,水平段平均稳斜角为88.17°。现场试验结果验证了“连续管+柔性钻具”超短半径水平井钻井技术的可行性,为剩余油挖潜和低渗油田高效开发提供了一项新技术。

Ultra-short radius horizontal wells play an important role in the stimulation of old oil and gas wells and the potential tapping of remaining oil.The commonly used ultra-short radius horizontal drilling technology with flexible bottom hole assembly(BHA),however,faces the problems of long tripping periods and high operation costs.In contrast,coiled tubing drilling tools feature high drilling efficiency with low costs and are safe and reliable.Hence,this study combined the advantages of coiled tubing and flexible BHA and developed key tools for ultra-short radius horizontal drilling,including large-torque positive displacement motors(PDM)at high and low rotary speed,optimized flexible BHA,stacking whipstock and build-up PDC bit,etc.Moreover,supporting operation processes were optimized.As a result,the ultra-short radius horizontal drilling technology combining coiled tubing and flexible BHA was preliminarily developed.The technology was first applied in a field test in Well Ling 72-5CZ of Jianghan Oilfield,and an ultra-short radius horizontal lateral well of 30.21 m was drilled,with an average rate of penetration of 0.8 m/h.The trajectory was in good agreement with the designed one,and the horizontal section has an average inclination angle of 88.17°.The field test results verify that the ultra-short radius horizontal drilling technology combining coiled tubingand flexible BHA is feasible,and it can provide a new technology for the potential tapping of remaining oil andefficient development of low-permeability oil fields.