Research paperEvolution of temperature, maturation level and realization of hydrocarbon potential in subtrappean sedimentary complex of the Bombay offshore - Results of 1-D basin modeling

•Thermal history of the Bombay offshore sedimentary basin was reconstructed.•Vitrinite reflectance with depth was computed in subtrappean complexes.•Maturation level of organic matter depends strongly on duration of trap formation.•Hydrocarbon generation by probable source rocks was estimated numerically.

The modified GALO program package for basin modeling is used to calculate the temperature and vitrinite reflectance distributions with depth at any time before, during and after the Decan Trap formation. An assessment of hydrocarbon generation by kerogen of type III is carried out for burial history of probable source rocks in the subtrappean sedimentary complex of the western passive margin of India near the Bombay offshore. Duration of trap formation is most critical and indefinite parameter in construction of maturity aureole in the subtrappean sedimentary complex. The analysis in the frame of the model of continuous formation of traps suggests that a maturation level of organic matter in sedimentary rocks under the trap depends strongly on duration of the trap formation. Even for traps thickness of 1.5 km or more, maturity level of organic matter in the rocks located on the 100-500 m below the base of the trap can be rather moderate if the trap has been formed over fairly a long time.