宜昌地区五峰-龙马溪组页岩气水平井钻井复杂情况地质原因分析

Geological Cause Analysis of Drilling Incident in Shale Gas Horizontal Wells in Wufeng-Longmaxi Formation in Yichang Area

宜昌地区上奥陶五峰组-下志留系龙马溪组页岩气为下步勘探开发潜力区,第一口水平井XX2HF井在钻井过程中发生多次井垮、卡钻,多次打捞未果导致提前完钻。为了厘清发生钻井复杂情况的地质原因,从构造、裂缝、岩石、地应力、井眼轨迹等多方面进行了地质特征分析,认为钻遇地层破碎带是本井卡钻的主要原因,观音桥段易垮塌、地应力差异大、层间裂缝发育等多种因素综合导致多次井垮、卡钻。结合区域地质特征分析结果,强化地震资料精细化解释、井眼轨迹优化等改进,可有效降低区域内复杂故障发生。

The upper ordovician Wufeng-lower silurian Longmaxi formation of Yichang Area is the potential area for the next shale gas exploration and development.During the drilling process,the first horizontal well,XX2HF Well,broke down and stuck for many times,and failed to salvage for many times,leading to the drilling completion early.In order to clarify the geological causes of the complicated drilling situation,this paper analyzes the geological characteristics from many aspects such as the structure,the fracture,the rock,the crustal stress and the well track and believes that the formation fracture zone is the main reason for the stuck drilling in this well.The occurrence of complex faults in the region can be effectively reduced by combining with the analysis results of regional geological characteristics and strengthening detailed interpretation of seismic data and the optimization of borehole trajectory.