Curvature analysis applied to the Cantarell structure, southern Gulf of Mexico: implications for hydrocarbon exploration

The middle Miocene Cantarell structure is host to the largest hydrocarbon field in Mexico. It has been variously interpreted as a fold-and-thrust or a dextral transpressional structure and the hydrocarbons are generally located in fold culminations adjacent to major faults. The host rocks are predominantly latest Cretaceous-earliest Paleogene breccias, but also include early middle Miocene sedimentary rocks. Primary factors favourable for hydrocarbon traps include porosity and permeability of the rocks, which may be augmented by subsequent fracturing. Such fracturing generally correlates with the intensity of deformation, one measure of which is curvature of fold structures, where curvature can be expressed as the inverse of the radius of an inscribed circle. We have derived a mathematical algorithm to calculate the greatest local curvature of a contoured surface in any of four directions at 45° to one another. Applying this algorithm to the structure contour map at the top of the Cretaceous-Paleocene breccia in the Cantarell structure shows that the highest curvatures occur adjacent to faults and associated folds, and greater values coincide with the largest hydrocarbon fields.