A Method of Moments Solution to the Conductive Steel Casing Problem - Theory, Validation and Model Studies
C. Kohnke, L. Liu, R. Streich and A. Swidinsky
Event name: 79th EAGE Conference and Exhibition 2017
Session: Electromagnetics A
Publication date: 12 June 2017
Info: Extended abstract, PDF ( 1.5Mb )
Price: € 20
We present a thoroughly tested modeling algorithm using a Method of Moments approach to calculate the controlled-source electromagnetic response of multiple 3D pipelines or steel-cased boreholes of arbitrary geometry in a layered earth host. To validate the algorithm, we compare results with a simpler Method of Moments approach for a single vertical casing in a halfspace. We also compare results with a finite-element solution using Comsol Multiphysics for both a single vertical and single tilted well crossing a subsurface boundary. Our tests show a very good match between these different approaches. We then apply our algorithm to a realistic synthetic marine model with three casings (one vertical and two deviated) extending into a layered earth model containing the classic thin resistive layer. This example illustrates how the algorithm can be used to compute the electromagnetic response of multiple steel casings, as well as how signal can be enhanced at depth through a casing with suitable transmitter geometry.