Integrated Decarbonization Assessment of CO2-Rich Gas Injection for Pathway to Net Zero Carbon Emission 2050
Authors: Tauphy Raja M. Amirul Raja Kamal , Razak M. Firdaus , Seah Yong Han , Mahmood Nor Azman Che , Rahim M. Shamir A. , Fuaddin Noor Amalina , Mazlan Rifhan Nabihah Bt , Jamaludin Maisarah 
Published: February 2025

This paper describes the study of decarbonizing 0.5 Mtpa of Green-House Gas (GHG) emissions in field development planning. Field S is an under-developed brownfield with 12 years of production history, located 145 km offshore Peninsular Malaysia. It consists of four main areas: North, North-West, Graben, and South, having an East-West elongated anticline field structure. The field holds a huge amount of oil in place; however, its recovery factor (RF) from existing wells is less than 5%, and full Field Development Plan (FDP) is advancing to fully uncover its true potential.

Aligning with PETRONAS Pathway to Net Zero Carbon Emissions 2050 aspiration through energy transition, the team is committed to achieving the ideal decarbonization plan for field development. Notable challenges include: 1) With the field being underdeveloped, hundreds of development scenarios were evaluated, including recovery strategies, sensitivities on facilities handling limit, and determining optimum development sequence. 2) Currently, the field gas production is at 8 MMscf/d, having a produced gas mixture containing high CO2 content up to 68% mole (gas phase). Nevertheless, there is no gas disposal method in place at present, making flaring or venting the only option available. The flare gas will rise higher in the coming years due to: a) well-to-well (i.e., gas producer to oil producers) gas lift operation; b) less stringent Reservoir Management Plan (RMP) due to high Gas-Oil-Ratio producing wells; c) power generation by diesel fuel instead of utilizing produced gas; d) full FDP envisioned to produce 50 MMscf/d of gas production that will be utilized for production operation (i.e., fuel and gas lift).

To achieve decarbonization, the team proposed the injection of CO2-rich gas into gas cap as an alternative to flaring or venting. The assessments included techno-commercial evaluation between gas injection concept against flaring concept, PVT fluid analysis and characterization, CO2 tracking with partial pressure through sector modelling, injectivity study, and risk assessment. Leveraging on digital cloud technologies and solutions with scalable High-Performance Computing (HPC), the dynamic compositional CO2 modeling study has enabled optimum sizing design of Acid Gas Removal Unit (AGRU). In addition, the assessments safeguard wells and facilities' integrity via optimal materials selection. The application of gas injection strategy is envisaged to significantly improve oil recovery in this underdeveloped field, address pressure depletion and achieve Zero Flaring Zero Venting philosophy.

This work offers comprehensive assessments of gas injection to achieve decarbonization, providing a range of potential solutions to address carbon emissions: 1) Forecasted to improve RF from 17% (with natural depletion) to 27% (with CO2-rich gas injection); 2) Eradicate 0.5 Mtpa of GHG emissions; 3) Material design ensures integrity and avoids CO2 leakage; 4) Sizing optimization of AGRU is expected to save US$10 million; 5) OPEX improvement by 20%. The cloud HPC environment accelerates subsurface studies, and facilitates a broader spectrum of development scenarios to be investigated for well-informed decision making. The team observed over 4-5 times speed enhancement on simulation run performance using high-resolution reservoir simulator together with cloud computing compared to virtual machine and on-premise infrastructure.