Integrated Containment Analysis for CO2 Sequestration in High-CO2 Content Gas Fields: Decarbonization and Optimizing Asset Value
Authors: Razali Nur Myra Rahayu , Majidaei Saeed , Mazeli Abd Hakim , Mohamad M Naim , Trianto Adi , Khanifar Ahmad 
Published: February 2025

The development and monetization of gas fields with high CO2 content is a key strategy for PETRONAS to support sustainability goals and meet gas demand. However, a major challenge in this type of development is the significant CO2 emissions exceeding targeted limits for greenhouse gases and CO2 reduction towards achieving net zero emissions by 2050. Therefore, decarbonization becomes essential for sustainable development, leading to the consideration of sequestering produced CO2 as a practical solution. This paper examines the feasibility of recycling produced CO2 for sequestration purposes in a Malaysian gas field containing approximately 60% CO2 content, aiming to explore simultaneous gas production and injection of CO2 into the same geological formation during field development.

High-level integrated containment analysis was conducted to verify containment for the shortlisted potential targets in Z field through typical geology process which mostly related to reservoir characterization, reservoir correlation, sedimentology, and structural configuration. The integrated containment analysis results were identified 14 non-associated gas (NAG) potential targets, 11 normal-pressure zones and 3 over-pressure zones with different level of risks. A field cross-section scenario map was established by considering three different possible cases and three different risk levels from integrated containment analysis to address complexity field geological structure and the plan for subsurface development. The injection and development scenarios were included two options, in-situ CO2 sequestration scenario through simultaneous injection & production plan for gas zones and CO2 injection in pure saline aquifers.

The capacity estimation results for Z field shows there is an approximately 3 TSCF potential theoretical storage capacity. Also, the capacity estimation results using analogue analyses shows there is an approximately 754 BSCF potential effective storage capacity. However, it is decided to exclude saline aquifer option during development with only 3% contribution to effective storage volume and it is due to higher uncertainties, less well penetration/data availability, and need for considering water producer and making artificial depletion to make desire injection as per plan. CCUS-EOR can be an option for oil rim development with ~ CR=7.6 MMstb, potential oil recovery of ~3.8 MMstb, RF=50%. It requires to produce all gas/oil together and plan for proper re-recycling the injected CO2 to maximize the oil gain from CCUS.

The study's overall conclusion validates the feasibility of recycling produced CO2 as a cost-effective option for developing high CO2 gas fields. This paper introduces groundbreaking approach to demonstrate the potential development of high CO2 gas fields with sequestration, aiming to achieve a net-zero carbon emission target and eliminate the need for transporting CO2 into flaring streams. Additionally, it proposes an integrated field and storage development plan that maximizes asset value by unlocking additional gas reserves and implementing appropriate CO2 management arrangements.