DE-RISKING FOLD AND THRUST BELT HYDROCARBON PLAYS WITH STRUCTURAL MODELING

In recent years, fold and thrust belts have re-emerged as an important exploration target. While there are numerous historical examples of prolific hydrocarbon systems in this setting, the risk from structural complexity can be considerable. High quality 3D seismic imaging can help mitigate this risk to an extent, but is of limited utility in intensely deformed areas in fold forelimbs and near large faults. Often, critical decisions must be made based on structural interpretations that are constrained by little more than the intuition of the geologist. Experience, critical thinking and understanding of regional geology are typically sufficient for a reasonable ‘first pass’ interpretation. However, while technically and geologically correct, this is just one among a family of admissible interpretations. Rarely are the range of possibilities given equal consideration, largely due to the time and effort required. Here, we begin by reviewing cases where considering a suite of alternate interpretations resulted in business success. We then discuss a more fluid, quantitative approach to structural interpretation that can make the extended family of admissible interpretations much more accessible. Essentially, this involves building a kinematic forward model based on a first pass manual interpretation, and systematically generating variations on the kinematic model that still satisfy the constraints. Examples of the application of this approach are presented for fold and thrust belt structures in the Niger Delta, Gulf of Mexico, Alberta Foothills and Southern California.