Detecting Hydrocarbon Reservoir through Inversion of Broadband Multicomponent CSEM Data and Joint Interpretation with Seismic Constraints

Abstract

This reference is for an abstract only. A full paper was not submitted for this conference. Abstract Description The marine Controlled-Source Electromagnetic (CSEM) method uses electromagnetic waves to detect resistivity contrast in the subsurface which can be used to distinguish between commercial and non-commercial hydrocarbon or brine. One of the limitations of conventional CSEM is depth resolution of subsurface structures. Multicomponent data offers partial remedies to this problem while combining with seismic improves vertical resolution. A stable iterative inversion scheme that permits occam and model based inversions have been developed to investigate these problems. In this paper, joint interpretation of a gas field offshore east Malaysia using CSEM, well bore and seismic data is presented. Firstly, we carried out synthetic studies of multifrequency and multicomponent 1D occam inversion using a model derived resistivity log to determine the improvement in resolution achievable through this approach. Secondly, the similar approach is applied to a field data acquired over a gas field in east Malaysia. A model based constrained inversion approach is applied to the field data to recover improved estimates of model resistivity, not obtainable through Occam inversion. Depth determined from seismic horizons are used as a priori information in the inversion while resistivities are free parameters. Application Establish a working model for the application of the CSEM method specifically in the eastern Malaysia offshore basins. Results The inversion results of CSEM synthetic and field data is presented in detail. The results are validated using existing wellbore and seismic data. Previous work have been mostly concentrated on synthetic data, while some of the work that was presented using field data lack the validation part which requires well bore information. The synthetic studies confirm previous work by Key (2009), that broadband multicomponent inversion significantly improves model resolution. Results from the inversion of field data agree with well log but are a smoothed version. The use of seismic depth control is found to yield resistivities closer to the ground truth and is recommended. The effective sequence of operations is formulated into a workflow that can be used in deepwater exploration surveys.