Validating of the Reservoir Connectivity and Compartmentalization with the CO2 Compositional Gradient and Mass Transportation Simulation Concepts

More than 40% of the world's conventional gas reserves are in re servoirs that contain significant amounts of H 2S and CO 2. The presence of these gases results in a number of challenges f or the Field Development Plan (FDP). For a field with mul tiple fault blocks with unknown fault transmissivity, a key challenge is to understand the field connectivity and compartmentaliza tion which impacts the ability to drain their reserves. This paper presents a comprehensive study to understand reservoir co nnectivity in a gas and oil fields located in South East Asia. This particular field has variation of the CO 2 even in the same zone ranging from less than 10% to more tha n 80%wt. A key for production strategy and facility design is to b e able to accurately quantify CO 2 in each reservoir is. Initially, the CO 2 study aimed to quantify the CO 2 content for each reservoir using an advanced Downhole Fluid A nalyzer (DFA), and then to use the DFA measurement as well as the available PVT data from nearby wells to understand reservoir connectivity through the use of a compositional gradient concept. Reservoi r fluids that deviated from the compositional gradient wer e considered to not be in equilibrium. In addition, the use of a PVT ther modynamic calculation with a non-isothermal solution resulted in a possible identification of the CO 2 charging location. Although the geochemistry study was conducted to understand the source of CO 2 and hydrocarbon isotopes, it did not provide a conclusive result of the reservoir connectivity. As expecte d the hydrocarbon had a different charge source compared to the non hydrocarbon gases. Since the geochemistry study was inconclus ive, a mass transportation simulation was performed to understand the reservoir connectivity and this information has had a great impact on understanding the production mechanism of this field. This paper provides a systematic process to understand t he reservoir connectivity by using the integrated reservoir dat a such as pressure, DFA, PVT fluid properties, geochemistry, as wel l as the geological and geophysical interpretations of the r eservoir. This paper offers an efficient way for reservoir character ization for proper field management for an important hy drocarbon discovery in South East Asia.