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Study of the Casing Effect on Borehole-to-surface Onshore CSEM
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 78th EAGE Conference and Exhibition 2016, May 2016, Volume 2016, p.1 - 5
Abstract
Monitoring the resistivity changes occurred in reservoirs during hydrocarbon production or CO2 sequestration is essential to determine fluid distribution and to optimize resources and efforts. Several modeling or theoretical studies have demonstrated the capability of the CSEM method to monitor onshore reservoirs. However there exist few published studies reporting experimental results from real CSEM experiments. Realistic modeling studies are needed to understand real data and to identify and characterize different effects affecting them. In this paper we investigate the sensitivity of the borehole-to-surface configuration using a deep VED. In order to study the influence of the source position and the effect of the steel casing on the data, we present numerical examples and a comparison with real results. The effect of the casing has been studied from two different approaches: a realistic modeling of the casing or replacing the casing by dipoles simulating the current induced along the casing. Both approximations can qualitatively reproduce the experimental data. In the first case, the vertical separation of the VED and the bottom of the casing is the key factor to be determined. In the second case, a precise determination of the current induced in the bottom of the casing is required.