The Cantarell and Sihil fields are located in a complex system of compressive structures in the offshore Campeche Bay province in Mexico. The geometry of the Cantarell-Sihil structure varies along trend from a simple fault-related structure in the south to a duplex consisting of the Cantarell and Sihil structures in the central part to a more complex system consisting of compressive blocks separated by Tertiary normal faults in the north. The Cantarell-Sihil structures formed during three main episodes of deformation: (1) Jurassic to Early Cretaceous extension, resulting in the formation of normal faults that displace Tithonian, Kimmeridgian, and Lower Cretaceous units; (2) Miocene compression, during which the Cantarell-Sihil thrust system was formed; and (3) Pliocene to Holocene extension, during which several of the preexisting Jurassic normal faults were reactivated. The Cantarell field produces out of three separate fault-bounded allochthonous blocks: the Akal, Nohoch, and Kutz blocks. The main field is located in the Akal structure. 'Secondary fields in the allochthonous block include Kutz, which formed on the crest of a downthrown fault block, and Nohoch, which formed above a west-vergent backthrust. The recently discovered Sihil field is located in a subthrust-compressive structure and consists of two structural lobes formed above the sub-Sihil fault. The Chac structure is formed at the updip edge of a tilted fault block in the autochthonous block. The detailed three-dimensional structural model is being used for future production of the remaining reserves in the Cantarell field as well as for the delineation of the Sihil field.