干旱区生态环境知识资源中心

This study is a trial to predict the relationship between the formation resistivity data and some petrophysical properties of rocks in Tut and Khalda oil fields at the northern Western Desert, Egypt. First, the deep resistivity (deep laterolog (LLD)) and gamma ray (GR) logs are smoothed by a linear combination of simple fitting functions that satisfy the smoothness criteria, and consequently the behavior of both logs can be simulated. Next, the smoothed log data are divided into branches, where high and frequent excursions in GR and LLD logs occur. In subsequent steps, the Dar-Zarrouk parameters are calculated and followed by a smoothing process for each branch. Based on a visual inspection of these parameters with effective porosity logs, the Dar-Zarrouk parameters are divided into zones and then interpreted in terms of shale content and the potentiality of the two oil fields. The permeability trend observed in core samples showed that the calculated parameters provide an adequate qualitative prediction for the petrophysical properties including the overall permeability trends. Despite the fact that the predicted permeability trends in Khalda oil field coincides with those measured from core samples, a weak correlation is observed, which can be attributed to the reservoir heterogeneity with dominance of laminated and dispersed shale and/or iron oxides. The potentiality of the proposed method lies in its simplicity, requiring only GR, LLD, and effective porosity logs. However, it would be more meaningful if the above method is tested in areas with diverse geological environment.