Electromagnetic Logging Tool with Toroidal Coils for the Study of Vertically Inhomogeneous Macroanisotropic Formations
M. Epov, I. Mikhaylov, V. Glinskikh, M. Nikitenko and I. Surodina
Event name: 81st EAGE Conference and Exhibition 2019
Session: WL & LWD Processing and Interpretation
Publication date: 03 June 2019
Info: Extended abstract, PDF ( 917.9Kb )
Price: € 20
The research work is dedicated to studying the electrical macroanisotropy of laminated sand-shale reservoirs for their reliable saturation evaluation, by using an unconventional signal excitation-observation system implemented in a new wireline electromagnetic logging tool with toroidal coils on a metal stem. The multi-coil multi-frequency toroidal tool has two operating modes for the detection of formation boundaries and determination of the resistivity anisotropy coefficient. We performed extensive 2D finite-difference simulation of the electromagnetic signals, conducted physical experiments on the tool in artificial and natural water reservoirs, developed data inversion algorithms and software, as well as created a petrophysical interpretation technique with an estimate of oil saturation from the tool data and petrophysical relationships. We present the results of successful field tests of the tool in oil wells penetrated complex geological sections in the Volga-Ural oil and gas province. Account of shale interlayers during the quantitative interpretation of the toroidal tool data leads to an increase in the determined oil saturation coefficient, compared to that obtained by conventional resistivity logging methods. The research results show that the developed tool is a reasonably good alternative to multi-component induction logging tools, characterized by sophisticated data processing and inversion algorithms.