3D inversion of time‐lapse CSEM data for reservoir surveillance

Abstract

Recent studies have inferred the feasibility of time‐lapse controlled‐source electromagnetic (CSEM) methods for the surveillance of offshore oil and gas fields. However, quantitative interpretations have not been shown to ascertain what information about the reservoirs that may be recovered. We present a 3D inversion study of synthetic time‐lapse CSEM data for the lateral water flooding of a reservoir unit where the hydrocarbon accumulation is trapped by a thin dome structure. We demonstrate that even with few constraints on the model, the flooding front can be recovered from 3D inversion. In this paper, synthetic time‐lapse CSEM responses are simulated with the threshold about the noise floor and subject to multiple 3D inversion scenarios. The time‐lapse CSEM inverse problem is highly constrained though inherently 3D since the geometry of the reservoir is established prior to production from high resolution seismic surveys; rock and fluid properties are measured from well logs; and multiple history matched production scenarios are contained in dynamic reservoir models.