Production Performance of Gas Condensate Reservoirs: Compositional Numerical Model - A Case Study of Hai Thach - Moc Tinh Fields

Abstract The approach focuses on the use of analytical and 3D dynamic compositional numerical models to physically describe the condensate banking phenomenon and to better understand the real deliverability in terms of gas and condensate production. The model is also built to compare the benefits of hydraulic fracturing over the horizontal well in Bien Dong POC development campaign. In this study, an analysis of pressure transient test data is conducted to investigate the condensate bank radius. Construction of a radial model is used as a benchmark model to compare it to an equivalent Cartesian grid model in term of productivity. The paper is focused on the development of a workflow for the analysis and selection of grid size and methods used in the 3D compositional model. Then the model is used for horizontal and hydraulic fracturing designs. When the flowing bottomhole pressure falls below dew point, the condensate dropouts in the near wellbore reduce permeability to gas through relative permeability effects; hence the well productivity is reduced significantly. The prediction of gas condensate well production will strongly depend on condensate banking evaluation and modeling. It is important that a model is built to describe the condensate banking phenomenon accurately to avoid over-estimating well performance. It is shown that an integrated model which incorporates Generalized Pseudo Pressure (GPP) and Local Grid Refinement (LGRs) can reproduce almost exactly with the benchmark model. The presented procedure and analysis can serve as a guideline for full field gas condensate reservoir modeling. The study also suggests that un-fractured horizontal well is not attractive compared to hydraulic fractured vertical well. Fractured half-length optimization design should be based on economic criterion. The study addresses the complexity of gas condensate behavior around the near wellbore region. The workflow of building an accurate 3D compositional model allows Bien Dong POC to have a reliable resource in reservoir development and management plans. The applicability of this work is confirmed by actual field case study in offshore Vietnam. It contributes to the knowledge of performance of gas condensate reservoirs and supports representative modeling of detailed model and recovery processes.