重庆南川页岩气钻井关键技术与思考

Key Technology and Application of Shale Gas Drilling in Nanchuan Block, Chongqing

重庆南川SY14-3HF井和SY14-4HF井是中石化在国内为钻完井日费制市场化管理试行实施的第一和第二口页岩气井,钻遇地层存在缝洞发育、漏失风险高、倾角大、研磨性强和可钻性差等特点,钻井过程中面临浅表地层坍塌掉块、漏塌同存、蹩跳钻严重、机械钻速低、压裂气窜以及异常高压等诸多复杂难题。通过新技术集成应用,一开井段采用电磁波随钻测量仪器监测井身质量,保障井下安全;二开井段采用高效射流冲击器提高机械钻速,研制“三低两强”钾基聚合醇钻井液体系降低井下复杂风险;三开优选高效破岩钻头,采用旋转导向配合高扭矩低转速螺杆精准控制井眼轨迹,研发低黏高切油基钻井液体系保持井壁稳定,创新性使用高、低速离心机串联回收重晶石清除有害固相,形成安全高效的钻井关键技术;两口井在钻完井周期、复杂情况时效及平均机械钻速等方面实现了突破,SY14-4HF井平均机械钻速10.75 m/h,钻完井周期较同平台其他井缩短11.95%;SY14-3HF井平均机械钻速9.70 m/h,生产时效96.89%,钻完井周期较同平台其他井缩短39.01%,创南川胜页工区井深超过5000 m页岩气水平井钻完井周期最短记录。技术已经在南川工区得到了推广应用,实现了可复制和可推广的目的。

The two shale gas wells SY14-3 HF and SY14-4 HF in Nanchuan,Chongqing are the first and second wells implemented by SINOPEC for the market-oriented management of drilling and completion daily rate system in China.The strata encountered by drilling are characterized by the well developed fractures and caves,high risk of leakage,large dip angle,strong abrasive property and poor drillability.In the process of drilling,there are many complicated problems,such as the collapse of shallow formation,co-existence of leakage and collapse,serious bit bounce,low rate of penetration,fracturing gas channeling and abnormal high pressure.Through the integrated application of new technology,the electromagnetic MWD tool was used to monitor the well quality in the first spudded in section to ensure downhole safety.High efficiency jet impactor was used to improve the rate of penetration,and‘three low and two strong’potassium polyol drilling fluid system was developed to reduce the complex risk in the second spudded in section.Optimized the highly efficient drill bit,adopted rotary steering and high-torque and low-speed PDM to accurately control the wellbore trajectory,developed a low viscosity and high cutting oil-based drilling fluid system to maintain wellbore stability,and innovatively used high and low speed centrifuges in series to recover barite and remove harmful solids,a safe and efficient key drilling technology has been formed.A breakthrough in drilling and completion periode,complex treatment and average ROP has been achieved in these two wells.The average ROP of SY14-4 HF was 10.75 m/h,the drilling and completion period was shortened by 11.95%compared with other wells on the same platform.The average ROP of SY14-3 HF was 9.70 m/h,production efficiency was 96.89%,the drilling and completion period was shortened by 39.01%compared with other wells on the same platform,setting the shortest drilling and completion period of shale gas horizontal well with well depth of more than 5000 meters in Shengye area of Nanchuan.The technology has been popularized and applied in Nanchuan block,which has realized the purpose of replicable and promotable.