Tracing Oil Migration Pathways Using Integrated Modeling and Nitrogenous Compound Data in the X Block, Oriente Basin, Ecuador

ABSTRACT Successfully predicting effective migration pathways can greatly improve the accuracy of trap risk evaluations, increase the drilling success rate, and reduce the costs of exploration in general. Combined with modeling, a total of 47 crude oil samples and 24 source rock samples were analyzed to study oil migration pathways in the Cretaceous Napo Fm M1ss member in the X block in the Oriente Basin of Ecuador. The vitrinite reflectance values of 24 source rock samples show that the source rock in the southwest zone is in the oil maturity window and was capable of supplying oil to the X block. The nitrogenous compound ratios of 1,8‐/2,6‐dimethylcarbazole and 1,5‐/2,7‐dimethylcarbazole have a consistent decreasing trend which indicates that oils migrated within the M1ss member from southwest to northeast. Basin modeling of M1ss carrier shows that different oil supply areas have different migration pathways. The migration pathways associated with oil supplies from the southwest region of Block X are restricted to the southwest and central areas. In contrast, those linked to oil supplies from the Fanny fault extend across both the hanging wall and footwall of this fault. Meanwhile, the migration pathways connected to oil supplies from the MariannN and MariannM faults are confined solely to the hanging walls of these two faults. Basin modeling combined with nitrogenous compounds analysis verified the migration pathway distribution in X block which could explain the formation of most accumulations. The traps in the southwest and eastern areas of X block appear to be favorable for future exploration as they are located on a migration pathway.