Non-hydrocarbon Migration Model in Petroleum System Analysis - An Integrated Procedure for Accurate Risk Assessment

How to estimate the risk of the occurrence of non-hydrocarbon components (nonHC) such as carbon dioxide (CO2), hydrogen sulfide (H2S) or nitrogen (N2), is one of the main issues in the field of petroleum exploration. Numerical models can provide valuable tools to predict the occurrence and distribution of such components. Different approaches exists to this end, starting from the simplest ones, relying onto geometrical considerations, up to those based on a fully physical description of the migration and accumulation processes.In this work, a procedure for efficient coupling of petroleum system analysis withmultiphase Darcy flow simulations is developed to obtain 3D time dependent representation of the migration paths and accumulation volumes of nonHC at basin scale on a geological timescale. We focus on the tests carried out to prove that is technically feasible to run simulations of very deep geological formations (high P, T, salinity) even if considering a very detailed picture of the transport phenomena (buoyant, viscous and capillary forces). The challenge is to find the right compromise between the needs to honor fine-scale hydrostratigraphic details of the structure and the size of the numerical model in its discretized form.