Formation resistivity measurement method that eliminates effects of lateral tool motion

Abstract

A method of compensating for tool motion is disclosed. In one embodiment, the method includes passing a logging tool through a borehole, obtaining a series of tool response measurements, and obtaining a series of tool position measurements associated with the tool response measurements. The tool position measurements preferably indicate the distance between the tool axis and the borehole axis. The tool position measurements are preferably examined to determine if the tool was moving while the tool was making measurements. For measurements made while the tool was moving, the measurement time interval is preferably divided into subintervals each having a corresponding tool position. A formation property (such as resistivity) is estimated, and the expected tool response for each tool position is calculated. The expected tool responses are combined to form a model tool response, that is, the tool response that might be expected for a tool in motion. The model tool response is then compared to the measured tool response. The estimate of the formation property is adjusted and the process is repeated until the model tool response is substantially equal to the measured tool response.

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