基于声波变密度测井信息识别水平井压裂裂缝的方法

摘要

In order to resolve the difficulties in identifying the fractures in horizontal wells,the method of identifying fractures with acoustic variable density log (VDL) data has been studied.VDL simulation tests have been conducted to find the VDL response to fractures in horizontal wells,and then VDL data acquired before and after actual fracturing was used to identify the fracturing section and evaluate the results.Research results showed that when the casing wave amplitude is low,and formation wave amplitude high in non—fracture section when first and second interface have a good cement bond,with thick and clear VDL plots.With an increase of fracture number between receiving and launching detectors at fracturing interval,amplitude of casing wave was increased,and formation wave amplitude was decreased.While formation wave in VDL plot was fuzzy white grayish,with large curvature and V-shape.At the same time,formation compressional wave time difference was increased and energy reduced.Both simulation test and field application indicated that the VDL could be used to identify transverse fractures in horizontal wells,which can provide a basis for the identification of fractures and an assessment of fracturing effects in horizontal wells.%针对水平井压裂裂缝难以识别的问题,研究了基于声波变密度测井(VDL)信息的水平井压裂裂缝识别方法.首先进行水平井压裂裂缝的VDL模拟试验,研究压裂裂缝的VDL响应特征,然后用实际井压裂前后的VDL资料进行压裂井段识别与效果评价.研究表明:当第一、二界面胶结良好时,非裂缝段套管波的波幅很小、地层波的波幅较大,VDL图中地层波相线粗而明显;随着裂缝段接收与发射探头间裂缝数量增多,套管波的波幅增大、地层波的波幅减小,VDL图中地层波呈灰白色而模糊不清、弯曲率大、成“人”字形,其地层纵波时差增大、能量降低.模拟试验和现场应用均验证了利用VDL识别水平井横向压裂裂缝的可行性,可见VDL信息可为水平井压裂裂缝检测与压裂效果评价提供依据.