Assessment of CO2 Storage Potential Capacity in Depleted Reservoirs of Offshore Malay Basin

Abstract

Abstract Due to concerns about global warming and climate change, storing CO2 using an underground geologic structure has been widely discussed and put into action. Depleted gas reservoirs are one of the most common geological solutions for CO2 storage for a variety of reasons. Depleted gas reservoirs are excellent for storing CO2 when taking into account data accessibility, economic viability, and storage safety. In this research, the appraisal of CO2 storage potential in depleted reservoirs offshore the Malaysian Basin is discussed as part of storage development plan. This study explains the assessment of CO2 storage potential capacity in depleted gas reservoirs which includes dynamic modelling of major reservoir, analytical evaluation of minor reservoirs as well as project risk analysis exercise. For both wet gas and dry gas reservoirs, the material balance equation (MBE) approach was employed to predict hydrocarbon recovery. The MBE considers the natural gas production history and the idea of volumetric balance at reservoir pressure and temperature. The MBE can also be used to calculate the gas injection efficiency for natural gas storage. An integrated subsurface-surface study included geomechanics study was carried out during storage development plan study to establish a notional CO2 storage development plan for a field with few depleted reservoirs of Offshore Malay Basin. The dry and wet gas reservoirs were identified as the fluid phase behaviors of the depleted reservoirs of the Offshore Malaysian Basin, which is extremely suitable to simplify the role of a depleted gas reservoir to only storing CO2 in an underground formation. The historical match for all reservoirs achieved acceptable match between simulated and observed data for dynamic production and pressure that some of those reservoirs require aquifer with varies of size. Four large reservoirs were assessed with potential CO2 storage capacity of these reservoirs, which ranged from 1.6 Tscf to 2.3 Tscf. Upside storage capacity in minor reservoirs could achieve 425 Bscf in the meantime. Based on this study, aquifers are identified as a key element that affects the storage capacity potential. This field is planned to have CO2 injection site ready for injection in near future to monetize the nearby high CO2 gas fields to meet GHG requirement. The key subsurface and surface facilities risk were identified as project risk assessment.