AUTHOR=Thorkildsen Vemund S. , Gelius Leiv-J. 

TITLE=Resolution enhancement of 2D controlled-source electromagnetic images by use of point-spread function inversion

JOURNAL=Frontiers in Earth Science

VOLUME=Volume 11 - 2023

YEAR=2023

URL=https://www.frontiersin.org/journals/earth-science/articles/10.3389/feart.2023.1101228

DOI=10.3389/feart.2023.1101228

ISSN=2296-6463

ABSTRACT=Marine Controlled Source Electromagnetic (CSEM) is employed both in large-scale geophysical  applications as well as within exploration of hydrocarbons and gas hydrates. Due to the diffusive character of the EM field only very low frequencies are used leading to inversion results with rather low resolution. In this paper, we calculate the resolution matrix associated with the inversion and derive the corresponding Point Spread Functions (PSFs). The PSFs give information about how much the actual inversion has been blurred, and use of space-varying deconvolution can therefore further improve the inversion result. The actual deblurring is carried out by use of the Non-Negative Flexible  Conjugate Gradient Least-Squares (NN-FCGLS) algorithm, which is a fast iterative restoration technique. For completeness, we also introduce results obtained by use of a blind deconvolution algorithm based on maximum likelihood estimation (MLE) with unknown PSFs. The potential of the proposed approaches have been demonstrated using both complex synthetic data as well as field data acquired at the Wisting oil field in the Barents Sea. In both cases, the resolution of the final inversion result has improved and shows better agreement with the known target area.