随钻聚焦电阻率测井仪响应特性分析与应用

Response Characteristics Analysis and Application of Focusing Resistivity Logging While Drilling Tool

随钻聚焦电阻率测井是随钻测井系列的重要组成部分,其仪器本体属于钻具的一部分。相比于传统电缆测井,随钻测井在大斜度井/水平井等复杂井眼工况时,能够在钻井过程中实时采集接近裸眼井原状地层的电性资料,具有低作业风险和高作业时效等显著优势。通过采用软硬件聚焦的形式,提出一种无硬电极电流型聚焦电阻率测井仪,能够提供深、浅电阻率曲线和井壁微电阻率成像,可用于随钻过程中实时泥浆侵入评价以及钻后地层电阻率和井壁附近地层电阻率成像评价。介绍了该仪器的电极系结构和测量原理,由数值模拟结果可知该仪器具有良好的径向探测深度、纵向分层能力和较小的井眼影响等探测特性。实验样机在现场实际测井中取得了良好的测井效果,满足了现场测井需求,为储层评价提供有力的支持。

Focusing resistivity logging while drilling is an important part of logging while drilling(LWD)series.The measuring instrument body is part of the drilling tool.Compared with traditional wireline logging,LWD can acquire electrical property data of undisturbed formation near open hole well in complex borehole conditions such as high-angle and horizontal wells in real time during drilling,which has significant advantages such as low operation risk and high operation efficiency.By adopting software and hardware focusing,a current type focusing resistivity logging tool without hard electrode is proposed,which can provide deep and shallow resistivity curves and borehole micro-resistivity imaging,and can be used for real-time mud invasion evaluation while drilling,as well as formation resistivity evaluation and resistivity imaging evaluation near wellbore after drilling.The electrode structure and measuring principle of the instrument are introduced.The numerical simulation results show that the instrument has detection characteristics such as good performance on radial detection and vertical stratification as well as small influence by borehole.The experimental prototype has achieved good logging results in the field logging,meeting the needs of field logging and providing strong support for reservoir evaluation.