--> Petrophysic Behavior of Reservoirs and Seals in Cuban Economic Exclusive Zone in the Gulf of Mexico and its Surroundings

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Petrophysic Behavior of Reservoirs and Seals in Cuban Economic Exclusive Zone in the Gulf of Mexico and its Surroundings

Abstract

Abstract

Cuban reservoirs and seals, because of different scenarios they are developed, have many factors which impact on its behavior. The most important genetic type of reservoirs are carbonates. To the North of Cuban Island, into different Cretaceous scenarios within the Cuban Economic Exclusive Zone in the Gulf of Mexico (CEEZ-GoM), carbonate reservoirs (limestone and dolomites) were drilled in some exploration wells, the values of complex porosity types are up to 25%.

To the South of this CEEZ-GoM, naturally fractured carbonates are widespread in the Northern Cuban Heavy Oil Belt, they have been producing oil and gas for more than 50 years. In these oil fields, many extended-reached wells are today drilled from northern shoreline into the folded and thrust belt, within Upper Jurassic to Lower Cretaceous carbonate reservoirs facies. Petrophysical and lab studies of these reservoirs show mix porosities between 6-20% and high oil saturations, where fractures always improve permeability.

Into Jurassic section, Constancia Formation, from Oxfordian to Lower Kimmeridgian, was detailed studied; and both reservoir, seal and source rocks facies were founded. This unit can be comparable with some sandstone oil fields, and in some cases with greater thickness it could have good hydrocarbon saturations, well preserved by clayey interbedded rocks.

Many seal types which could be founded and their qualities as cap rocks were analyzed. The laboratory studies, the well log analysis and the developed methodologies, have allowed a better approach to the quantitative evaluation of these reservoirs and seals for a better understanding and modeling.