文摘
Resistivity logging through casing is a kind of logging technique obtaining formation resistivity by measuring casing potential and current. Measurement results are affected by formation parameters, logging tool precision, etc. Based on casing potential and current formula, as well as boundary conditions, longitudinal step-formation model of limited thickness in whole space is established to realize numerical simulation of Russian resistivity logging through casing. Simulation results have lamination ability for formation of different thickness and the approximate degree between apparent and real formation resistivity decreases as the formation thickness decreases. According to actual measuring limitation, numerical simulation is realized again under approximate conditions. The latter simulation results have the similar lamination ability with the former. For thin layer, the approximate degree of the latter is a little worse than the former. Measured data process verifies the feasibility of approximate calculation method.