Comparison of electrical image log with core in a fractured carbonate reservoir

Abstract

Borehole image logs are kind of the modern logs which are frequently used to detect small-scale fractures intersecting well in fractured reservoirs. Electrical imaging tools like FMS (Formation MicroScanner) and FMI (Fullbore Formation MicroImager), electrically scan the borehole wall and deliver a pseudo-picture of the formation. Characteristics of fractures such as type, aperture and orientation can be determined by interpreting these logs.In this paper, we attempt to evaluate the ability of electrical image logs in detecting fractures and other geological features of a carbonate reservoir (Asmari) and explain the possible reasons of mismatch between the image log and core. To achieve this goal, we have compared the FMS of a well with the core. The results are verified with FMI and core data from seven nearby wells.Comparison of the FMS with the core revealed that FMS, as representative of electrical image logs, is robust in detecting open fracture and anhydrite; it is average in detecting bedding plane and flexural slip and is weak in detecting filled fracture, fault and compactional feature in carbonate reservoirs.