Prospectivity evaluation with 3D CSEM

Abstract

Evaluation of the prospectivity potential of hydrocarbon exploration ventures is a process of integration. Information provided by different technologies needs to be integrated into a single evaluation. This paper details a method for embedding the additional information provided by 3D Controlled Source Electromagnetic (CSEM) surveys into existing (or independently generated) prospect evaluations. Workflows are designed to leverage the primary value of the CSEM information in exploration (sensitivity to hydrocarbon volume), while minimizing the disruption and potential increase in risk associated with the adoption of a new technology. This is achieved through a focus on maintaining the independence of information sources and visibility of measurement uncertainties, along with adoption of standard performance-tracking methodologies. Previously-described workflows for embedding CSEM information in a prospect evaluation process (e.g., Buland et al., 2011; Baltar and Roth, 2013) focus either on updates to the Probability of Success (PoS), or volume assessment. In contrast, we show that the nature of the information provided by CSEM is more suited to a coupled reassessment of both risk and volumes. This generates a more robust update not prone to the shortcomings associated with existing stand-alone approaches. Workflows are illustrated with the use of realistic synthetic examples; a published prediction using the methodology is also reviewed in light of recent drilling results. When applied systematically across a CSEM-sensitive portfolio, the new information provided by 3D CSEM has the effect of polarising existing evaluations, making CSEM a valuable tool in exploration venture evaluation.