海上丛式井领眼井预防浅层气技术

Technology of Pilot Hole in Preventing Shallow Gas Applied to Offshore Cluster Wells

为降低浅层气对海洋钻井危害,小尺寸领眼井被用于勘察油田开发区域浅层气以降低浅层气井喷风险。在丛式井组中优选出一口井,改变井轨迹造斜点设计,表层井段不造斜;使用钻头扩眼减少卡钻及井组防碰风险;结合浅层气地震资料对丛式井组中表层井段井轨迹分布评估领眼井对浅层气探测能力,论证浅层气对丛式井组的影响。该技术解决了表层造斜的海上丛式井组领眼井存在易出新井眼、易水泥卡钻等问题,其在渤海某浅层气区域的实际应用证明其能够有效探明浅层气情况。如遇浅层气溢流该技术能够快速处理,避免浅层气井喷。

Small-sized pilot hole is an effective technology to investigate shallow gas of an oil field, but this technology used in drilling offshore cluster wells has the problems of being easy to create a new borehole and high risk of adjacent wells collision. A well from the wells of the platform is selected in this research, its KOP changed, the first spudding section straight, the bit is used to ream the pilot hole instead of the reamer, the risk of pipe stuck as well as adjacent wells collision can be reduced. The seismic data of shallow gas and first spudding well tracks of the well group are analyzed, the shallow gas detecting effect of pilot well is evaluated. Successful use in drilling Bohai offshore cluster wells in an oilfield proves that the pilot hole technology has the ability to detect the shallow gas and can treat the shallow gas faster to avoid the shallow gas blowing out. The paper can provide guidance and reference for drilling operation in offshore cluster wells in shallow gas area.