Ek-Balam field: A structure related to multiple stages of salt tectonics and extension

Abstract

The Ek-Balam field is a major oil and gas field in the offshore Campeche Bay, Mexico. The structure was formed as a result of multiple episodes of salt tectonics and associated extension. Salt movement into the core of the structure initiated in the Jurassic–Early Cretaceous and continued until the Miocene. The most prominent normal faults are of Jurassic–Early Cretaceous age and detach in the Jurassic salt. These faults mostly dip to the west, although in the vicinity of the Ek-Balam structure, some east-dipping faults are also present. Some of these faults were subsequently reactivated in the Late Cretaceous and Tertiary. Separating the Ek and Balam structures is a set of Upper Cretaceous faults, which drop the eastern part of the structure down. Tertiary faults are related to continued uplift of the salt and are symmetrically distributed with respect to the central uplift. Seismic time maps, three-dimensional depth models of the top of the Cretaceous breccia and the Kimmeridgian, and balanced structural cross sections provide accurate details of the structural geometry and fault patterns in the Ek-Balam structure. At the level of the Cretaceous breccia, many of the faults have small throws and are discontinuous along trend. The top of the Kimmeridgian, however, is cut by faults of different ages, many of which have significant throw and extend for longer distances. The detailed structural geometry and fault patterns will be useful for identifying compartments within the Ek-Balam field and for identifying secondary traps within Kimmeridgian and Oxfordian reservoirs.