Challenges in the Analysis of Surface-Borehole EM Measurements. Reviewing the Field Distortion due to Metallic Casing
N. Cuevas, D. Colombo, G. McNeice and M. Pezzoli
Event name: 81st EAGE Conference and Exhibition 2019 Workshop Programme
Session: WS11 Reservoir Characterization and Monitoring from Inversion and Joint Inversion of Seismic and Non-seismic Methods
Publication date: 03 June 2019
Info: Extended abstract, PDF ( 618.64Kb )
Price: € 20
In this paper a discussion is presented of the main aspects describing the challenges expected and encountered in recording and analyzing STB/BTS data in the presence of the steel casing. To this end, numerical simulations of the casing effect are analysed in relation to the many unknown of the system, i.e. casing, overburden and reservoir properties. The discussion highlights the evident need to either remove the distorting component of the field due to the current flow in the casing, or to directly model the response of the entire system, i.e. including the localized highly conductive anomaly of the metallic casing. In the former case, an estimate of the casing effect could be obtained from the recorded data, but the accuracy may not be enough to remove the casing response while keeping a x100 weaker response of the reservoir. In the later case, aside from the numerical burden of the modelling exercise, the properties of the casing may not be known accurately enough to discriminate the subsurface response from the total field dominated by the casing effect.