oa Geochemical Characteristics and Computational Modeling of Source Rocks in Deep-Water Regions of the Ceará Basin, Brazil

Petroleum systems with Cretaceous source rocks are globally recognized for their relevance. On the Brazilian Equatorial Margin, the Ceará Basin stands out for hosting organic-rich source rocks deposited during the Aptian, Albian, and Cenomanian stages. This study integrates geochemical data and one-dimensional modeling to reconstruct the thermal evolution, subsidence history, and kerogen transformation rates in two deepwater wells (1-BRSA-1080-CES and 1-BRSA-1114-CES). The results reveal high total organic carbon (TOC) contents, elevated S2 values, and hydrogen indices (HI), with a predominance of type I, II, and II/III kerogen. Thermal maturity data indicate that the Aptian and Aptian–Albian intervals reached the oil and wet gas generation windows, while the Albian–Cenomanian interval remains immature. Modeling shows variable transformation rates, particularly in the Aptian–Albian interval, where lower, less organic-rich sections experienced higher thermal gradients and more advanced maturation. The Aptian interval underwent deep and continuous burial, resulting in complete organic matter transformation. The Albian–Cenomanian interval exhibited significant transformation only in well 1-BRSA-1114-CES. Regional contrasts highlight differing thermal and burial responses across basin compartments, underscoring the value of integrated approaches. Modeling results proved essential in identifying transformation patterns that conventional geochemical data alone would not have fully revealed.