Estrutura térmica da Bacia de Barreirinhas, margem equatorial brasileira

Abstract

This study characterizes the thermal regime of the Barreirinhas Basin, located in the central sector of the Brazilian Equatorial Margin (BEM), based on 592 temperature records obtained from 85 exploratory wells, encompassing both onshore and offshore areas. Bottom-hole temperature (BHT), drill-stem test (DST), and extrapolated temperature (ET) measurements have been corrected using conventional methods, including the American Association of Petroleum Geologists (AAPG) and a Linear Fit methods, developed in this study. The AAPG method exhibited the best performance for BHT data (R² = 0.8463), while the Linear Fit Method showed consistent results in DST data correction. Corrected temperatures ranged from 45°C to 165°C across the Barreirinhas basin, associated with geothermal gradients from 19°C/km to 40°C/km. The geothermal gradient decreases sharply down to 800 m, stabilizing around 30°C/km and decreasing to 20°C/km at depths greater than 5,000 m. Thick sedimentary layers act as thermal insulators, limiting heat dissipation to the surface and reducing the geothermal gradient by the blanket effect. These thermal conditions indicate potential for liquid hydrocarbon generation between 1,500 and 3,500 m depth, whereas gas generation may occur at depths greater than 3,550 m. The correlation between the thermal regime and the internal architecture of the basin is consistent with patterns observed in Asian transform margins, as well in the conjugate African Equatorial Atlantic margin, reinforcing the relevance of the Barreirinhas Basin as a potential reservoir for energy resource production.