Optimizing field development of Deep Cretaceous fractured reservoirs, Lake Maracaibo, Venezuela

The Deep Cretaceous carbonate reservoirs of Lake Maracaibo, Venezuela, produce mainly from openfractures. Any improvement in production rate requires optimal access of the wellbore to open fractures. Well tracks with maximum rates of open fracture interception have been calculated using computer models for a structure defined by the Icotea fault in Block IX. Optimum well tracks are towards azimuth 330° with deviation 60° in the West Flank and towards azimuth 030° with deviation 60° in the East Flank. The open fracture networks consist of incompletely cemented or leached fractures which contain a "channel and island" structure of interconnected porosity. This structure, in combination with the high rock matrix strength and the subparallel strike of the open fractures relative to the E-W trend of the present-day maximum horizontal stress, indicate that it is unlikely that the conductivity of individual fracture will be reduced drastically upon pressure depletion. The reservoir geological model established for Block IX is consistent with data obtained from the West Flank of Block I, some 40 km to the north and therefore has regional validity.