延长油田水平井地质导向技术及其应用

Horizontal Geosteering and Its Application in Yanchang Oilfield

延长油田水平井施工中地质导向存在地震资料缺乏、井间构造不明、油层预测误差较大等地质风险,针对以上技术难点,结合延长油田水平井地质导向现有的基础数据、目的任务,形成了相应的技术对策。钻前通过资料分析对比,对构造、储层和连通性的不确定性进行研究,采用大构造趋势与砂体形态相结合的方法确定微构造及储层连通性,进行地质风险分析,提出技术对策,作出预案。入窗前精细地层对比,入窗时实时调整井斜和垂深确保中靶。通过调整钻头与储层间的位置关系实现水平段轨迹跟踪与监控,同时作出自然伽马、气测等数据随斜深和垂深变化的关系图,根据钻遇情况实时修正地质模型指导钻进。总结为:实时对比,提前着陆,稳斜找层,着陆重模,稳斜钻进。通过现场应用与不断改进,取得了较好的效果。

In Yanchang oilfield, construction of horizontal well is accompanied by some geological risks which contains lack of seismic data, unclear interwell structure, forecast of oil layer with big error, etc. Aimed at these technical difficul- ties, a technical countermeasure has been put forward based on basic data existing and current objective about horizontal geosteering in Yanchang oilfield. Research the uncertainty of structure, oil layer and connectivity between them by analy- zing and comparing data existing before drilling. Ascertain the micro-structure and connectivity of oil layer by a method which combine structural trend and silt body shape, analyze geological risks, propose technical countermeasure and the fol- lowing plan. To ensure hitting the target, two principle has to be comply： fne strata correlation before drilling into the oil layer; adjust the hole deviation and vertical depth currently while drilling into the oil layer. Tracking and monitoring the horizontal trajectory by adjusting the relative position between the bit and oil layer, and making the scheme of data of gam- ma logging and gas logging which vary with hole deviation and vertical depth, revising the geological model by analyzing ac- counting status to guide drilling. All can be summarized as follows： comparing currently; reducing the hole deviation rela- tively earlier; keeping the hole deviation to search the target; adjust hole deviation after hitting the target; keeping the hole deviation and drilling horizontally. Through applied in oilfield and improved, this technology has acquired preferably effect.