Simultaneous Gas Production and CO2 Recycling for Sequestration in an Integrated Field and Storage Development Plan (FSDP): A Case Study
Authors: Khanifar Ahmad , Deo Tewari Raj , Masoudi Rahim , Bin Sedaralit Mohd Faizal , MousaviMirkalaei Seyed Mousa 
Published: October 2023

Abstract
Development and monetization of the gas fields with high carbon dioxide (CO2) content is one of the Petronas’s strategies to support their sustainability agenda and meet the gas demand. The key challenge associated with this type of development is producing massive amount of CO2 which will exceed the step-wised targeted limit of GHG & CO2 emission reduction towards net zero carbon emission by 2050. Decarbonization seems crucial for sustainable development and, hence, sequestration of produced CO2 is identified as the most pragmatic solution going forward.
In this paper feasibility of recycling the produced CO2 for sequestration purpose as part of field development plan for a Malaysian gas field with initial ~60% of CO2 content was studied. The main objective of this study was to investigate the possibility of simultaneous gas production and CO2 injection in the same geological formation during field development. The impact of CO2 sequestration back into the same field on important parameters including hydrocarbon reserve, recovery factor, production profile, CO2 breakthrough time, produced gas quality, and overall project cost were investigated, and the cumulative gas production and effective CO2 storage volume as main objective parameters were optimized.
A full compositional dynamic model with proper CO2 storage features was constructed. The recycling option of produced CO2 was activated between gas producers and CO2 injectors in the model. Two CO2 tracers for each well were introduced into model to distinguish the CO2 from different sources (i.e., reservoir and injection stream). The results of these tracers will be monitored and evaluated to estimate and manage CO2 breakthrough time to each producer and hence applying the chock-back or shutdown constrain to the affected producers and optimize the field parameters.
The results of pure depletion case as the basecase scenario without CO2 injection shows ~73% recovery factor. The CO2 mole fraction in the production well stream and CO2 separation efficiency of the surface facilities were the two key constraints introduced during sequestration modeling. The overall finding from this study verifies recycling of produced CO2 could be a techno-economically viable option for such high CO2 gas field development. An optimization study was conducted to concurrently maximizing the net hydrocarbon production and the CO2 storage capacity. It shows full gas stream CO2 separation with 80% CO2 mole fraction cutoff scenario in the topside processing and separation facilities could be chosen as an optimized development scenario. The simultaneous gas production and CO2 injection case provide a solution to manage CO2 in-situ by permanent CO2 sequestration to the same geological formation although it gives about 14% less RF compared to the pure depletion case without CO2 injection.
This paper presents an innovative technique for demonstrating the possible development of the high CO2 gas field with sequestration for achieving net zero carbon emission target and avoiding transporting CO2 into flaring stream. Moreover, it introduces a well-chosen concept of having an integrated field and storage development plan (FSDP) for maximizing asset value by developing fields and unlocking additional gas reserves with appropriate CO2 management arrangement.