Evaluating subtle stratigraphic traps: prospect to portfolio

Abstract

AbstractA compilation of 85 stratigraphic traps demonstrates the variety of trapping mechanisms and the scope for developing new concepts by matching geological models with features in 3D seismic volumes. However, aspects of quantitative evaluation may discourage exploration. Investors require assurance in the form of probabilistic evaluations of risk and value but information critical to the evaluation of new stratigraphic concepts is likely to be lacking. As estimates of risk and uncertainty vary with information, prospects evaluated with radically different levels of information must be ranked with care. The requirements for quantitative project ranking and portfolio optimization have to be reconciled with the need to ‘venture into the unknown’. The character of stratigraphic prospects dictates different evaluation methods from those used to evaluate structural prospects. This, together with the high degree of sensitivity of value to evaluation methodology, can also lead to inconsistencies in ranking.Within the context of a company’s overall strategy and risk tolerance, organizational and cultural factors may influence prospect selection. In particular over-emphasis on quantitative methods may not have the intended effect. A common understanding, amongst technical and commercial disciplines and decision makers, of the background to quantification is essential.Factors which encourage the progression of stratigraphic prospects include a dedicated geoscience effort, a separate ‘growth’ portfolio of new concepts, a formal structure for progressing these and a stable organization.