Performance of Hankel Transform Filters for Marine Controlled-Source Electromagnetic Surveys: A Comparative Study

Abstract

For the numerical calculation of electromagnetic responses by an arbitrary source in a one-dimensional model, integral-equation based approaches can be the best method since they are semi-analytic and thus very fast and accurate. In the numerical computation of the integral-based approaches, digital linear filters (e.g., Anderson’s filter, Kong’s filter and Mizunaga’s filter) play a key role. Using a closed-form solution of the Hankel transform in transverse magnetic mode for a homogeneous half-space model, we can assess the accuracy of digital linear filters for evaluating the Hankel transform. In this paper, we conduct comparative performance tests on the linear filter with known integral transforms. We examine three kinds of filters developed by Anderson, Kong and Mizunaga, which are known to be suitable for marine controlled-source electromagnetic (CSEM) applications. Kong’s filters perform best in the three kinds of filters over a practical range of offset distances in marine CSEM surveys. While the relative error versus distance appears as a V-shaped curve in semi-log scale, Mizunaga’s filters are the shortest in length and have a performance comparable to Kong’s filters. Anderson’s filters have a quite similar performance between the J0 and J1 filters, although these are somewhat inferior to Kong’s and Mizunaga’s filters when computing marine CSEM fields.