2.5D Finite Element Forward Modeling of the Induction Log Responses in Carbonate Reservoirs with Drilling Fluid Invasion

Summary Traditionally, to analyze the resistivities of the virgin zone (Rt) and depth of invasion (di), a step or piston profile is assumed, which is the simplest model, since it does not consider the presence of a transition zone or gravitational effects of fluids. In this study, we studied the response of the medium (ILM) and deep (ILD) induction logs to a piston and annulus models. To do this, these responses were simulated utilizing a finite element numerical approach for 2.5D or axial symmetry and, using as a comparison for the modeling ILM and ILD logs collected in Santos Basin, Southeast Brazil. The responses indicate that it is possible to model with a good fit on both piston and annulus models, having found that the R2 of these induction logs has a better value at low resistivities. In the modeling of the annulus, it was verified that its presence influences the log responses, therefore it must be considered when the oil reserves are estimated in the reservoir.