  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 nonnegative flexible
conjugate gradient algorithm for least squares problem (NN-FCGLS), 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.
