井周地层纵横波慢度径向分布反演方法研究进展

Advances of the inversion of radial slowness profile near borehole with array acoustic logging

井壁周围地层的慢度信息对石油勘探开发有着重要的意义,可以有效反映地层岩石的性质.由于泥浆滤液侵入、井壁应力分布、钻井机械损坏、压裂施工等原因,导致井周地层在径向上呈非均质性,具体表现为井壁周围地层慢度在径向上发生变化.通过声波测井反演提取地层径向慢度剖面,可以在识别侵入深度、评价井眼稳定性、指导完井设计、压裂效果评价等方面有重要的应用价值.本文针对目前学者们开发的不同井周慢度径向分布反演方法进行分析,将其分为三类:基于到时信息的慢度剖面反演方法、基于慢度-时间相关的慢度剖面反演方法和基于波频散的慢度剖面反演方法.通过分析发现这些反演方法由于采用算法以及目标模式波不同,其适用情况和反演结果也存在差异.在此基础上,总结了目前国内外在井周慢度径向分布反演方法上的研究进展,展示了不同方法慢度反演效果.

The slowness information of near-wellbore formation is of great significance to oil-gas exploration and development,which can reflect the properties of rock.However,the near-wellbore formation presents radial heterogeneity with a variable slowness profile,due to the effects from mud filtrate invasion,wellbore stress,drilling machinery damage and fracturing operation.Accordingly,extracting radial slowness profile from acoustic logging inversion has important application value in identifying invasion depth,evaluating wellbore stability,guiding well completion design,and evaluating fracturing effect.Therefore,we have investigated the current inversion methods constructed by researchers in this paper and divided them into three categories:the inversion with arrival time of waves,the inversion with slowness-time coherence(STC),and the inversion with wave dispersion.After comprehensive research and analysis,we found that the usability and performance of the methods is different due to the difference of target mode waves and their algorithms.Based on the obversions,we further concluded the advances of the methods in extracting the slowness profile near a wellbore from array acoustic logging data,and compared their performances in real applications.