Structural geometry and evolution of the Ku, Zaap, and Maloob structures, Campeche Bay, Mexico

The Ku, Zaap, and Maloob structures consist of an arcuate series of fold-thrust structures, which change orientation from approximately east-west to north-northwest–south-southeast along a structural salient in the offshore Campeche Bay, Mexico. The structures are related to a series of thrust faults, which merge into the Maloob thrust. The Ku, Zaap, and Maloob fields located on these structures together constitute an important complex of fields with proven remaining reserves of approximately 1850 MMBOE. The structures formed during three main periods of deformation: (1) a Jurassic–Cretaceous extensional episode; (2) a Miocene compressive phase, during which the main trap-forming structures were formed; and (3) a Pliocene to Holocene extensional episode, resulting in several listric growth faults. Three-dimensional (3-D) models of the main reservoir unit (Upper Cretaceous breccia), and other prospective reservoir units (Eocene and Kimmeridgian) constructed by integrating 3-D seismic interpretation, well data, and a series of balanced structural cross sections, provide an understanding of the geometry and evolution of the structures. The Zaap, Maloob, and sub-Maloob structures are interpreted as a series of faulted detachment folds, detaching within salt and other Jurassic ductile units. The front limbs of these structures are typically cut by thrust faults with small displacements, terminating in the lower Tertiary section. The Ku and Pakal structures also originated as a detachment fold, but was faulted relatively early in its deformational history. The frontal zone of this structure is marked by a closely spaced thrust system consisting of the Ku, Pakal-1, and Maloob thrusts. The 3-D models provide an accurate picture of the structural geometry of the principal reservoir units, which will be useful for future production from the fields and for exploration in adjacent areas in the basin.