oa Source Rock Potential and Thermal Maturity of the Coqueiros Formation Shales, Campos Basin, Brazil

This study investigates the source rock potential of organic-rich shales within the Early Cretaceous Coqueiros Formation, Campos Basin, Brazil. X-ray diffraction (XRD), scanning electron microscopy (SEM), and Raman spectroscopy were applied to cuttings from two wells (3-BP-11-RJS and 6-DEV-18P-RJS). XRD reveals a mixed mineralogy of calcite, quartz, dolomite, and clay, with varying proportions between wells, suggesting differing depositional environments. Pyrite, indicative of anoxic conditions favorable for organic matter preservation, was observed. Raman spectroscopy indicates high thermal maturity (Ro% 1.03–1.40), placing the shales within the condensate wet gas window. SEM imaging of 6-DEV-18P-RJS shows evolving textures with depth and the presence of authigenic minerals and intergranular porosity, potentially facilitating hydrocarbon migration. While the high maturity and mineralogical indicators suggest good source rock potential, further geochemical analyses (TOC, Rock-Eval) are needed for definitive assessment. The potential impact of drilling mud contamination (barite) requires further evaluation.