Workflow for improvement of 3D anisotropic CSEM resistivity inversion and integration with seismic using cross-gradient constraint to reduce exploration risk in a complex fold-thrust belt in offshore northwest Borneo

  • Max A. Meju, Ahmad Shahir Saleh, Randall L. Mackie, Federico Miorelli, Roger V. Miller, Noor Kartini S. Mansor
  • Interpretation, June 2018, Society of Exploration Geophysicists
  • DOI: 10.1190/int-2017-0233.1

Structure-controlled 3D anisotropic CSEM inversion with crossgradient criterion

What is it about?

Conventional 3D anisotropic CSEM resistivity inversion typically produces models of horizontal and vertical resistivity that are completely different in structure and inconsistent with geological structure. This poses major challenges in frontier exploration for hydrocarbons. Now, by using the crossgradient criterion and statistically independent a priori information (resistivity well logs and seismic horizons), we produce models that are structurally similar, conform to seismic structure and match resistivity well logs (hence more accurate) than otherwise possible. We demonstrate the usefulness of this workflow in a deepwater exploration campaign.

Why is it important?

1) This approach help reduce uncertainty in subsurface exploration for hydrocarbons and reserve estimation, especially in complex terrains. 2) The resulting models can be used to build low- frequency seismic velocity models, via appropriate rockphysics transform, for subsequent processing of PSDM data or seismic full waveform inversion (FWI).

Perspectives

Max Meju

3D CSEM anisotropic inversion is bedeviled by model inconsistency, making geological interpretation a difficult proposition. This new approach significantly reduces model ambiguity and improves the user's confidence especially when taking "drill or drop" decisions in frontier exploration for hydrocarbons.

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http://dx.doi.org/10.1190/int-2017-0233.1

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