Petroleum Drilling Techniques, Issue 4, 2018

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Surrounding Rock Influence Correction for Array Laterolog Responses with Borehole Eccentricities in Horizontal Wells

Abstract

The response of the array lateral logging tool is influenced by the surrounding rock. Therefore, a surrounding rock correction needs to be performed. In this paper, a 3D layered medium model of horizontal well was established as the first step. The forward response characteristics of array laterolog under various borehole eccentricities were studied by using the 3D finite element method, and the correction plate of surrounding rock was obtained. The nonlinear analysis of the numerical simulation plate was carried out, and the fast correction formula and correction plate of the surrounding rock/layer thickness were obtained. Research showed that the deeper the instrument detection depth, the more they are affected by surrounding rock. When the borehole eccentricity was lower than 20%, borehole eccentricity changes had little effect on the response of array lateral logging. However, when the borehole eccentricity was greater than 40%, the response of array laterolog logging was significantly affected by borehole eccentricity, and the maximum change range of apparent resistivity could reach 44. 8%. It was found that the fast correction plate was in good agreement with the numerical simulation plate and the relative error of sampling points between the two plates was lower than 5. 3%. As shown by the comprehensive study, the fast correction plate could be used for fast and real-time correction of array lateral well response in horizontal wells.