A Thermal Maturity Analysis of the Effective Cretaceous Petroleum System in the Southern Persian Gulf Basin

Abstract

Commercial hydrocarbon discoveries in the Cretaceous of the southern Persian Gulf basin provide direct evidence that there is an effective petroleum system associated with the Cretaceous series. The revised models of thermal maturity in this region are needed to investigate lateral and stratigraphic variations of thermal maturity, which have not so far been addressed in detail for this part of the Persian Gulf. Such thermal maturity models are required to delineate the existing play assessment risks and to predict properties in more deeply buried undrilled sections. This study uses two dimensional basin modeling techniques to reconstruct maturity evolution of the Cenomanian Middle Sarvak source rock, presumably the most likely source for these hydrocarbons. The results indicate that an estimated 900 meter difference in the depth of burial between the southeastern high and the adjacent trough tends to be translated into noticeable variations at both temperature (135 °C versus 162 °C) and vitrinite reflectance (0.91% versus 1.35%). Since the organic matter in the mentioned source rock is of reactive type II, these could cause a shift of about 18 million years in the onset of hydrocarbon generation over respective areas.