Hétérogénéités compositionnelles dans les réservoirs de gaz acides : compréhension et modélisation du rôle d'un aquifère actif

摘要

The H2S occurrence in gas reservoirs is an important factor of economic depreciation. Thus, the knowledge of its content and distribution is a critical parameter when planning field development. Under typical reservoirs conditions of pressure and temperature, H2S is far more soluble than hydrocarbons and other gases. The preferential leaching of H2S by an active aquifer over time could explain the creation of compositional heterogeneities. The thesis aims at illustrating and quantifying this process based on numerical simulations performed with the two-phase transport and geochemical software Hytec, developed by Mines ParisTech (France). This mechanism may be controlled by: Differential solubility of gases, which changes the relative amounts of each gas near the gas-watercontact; Contact with an active aquifer, which can export the dissolved gases thus enhancing dissolution on the long-term; Diffusional transport in the gas phase, which transfers the compositional anomalies farther from the gas-water contact; Geological parameters (type of aquifer, permeability heterogeneities) which can modify the transport scenario.