Lessons Learned From Carbon Capture and Storage Projects in South East Asian Depleted Reservoirs

Abstract

The aging of oil and gas reservoirs in South East Asia (SEA) presents opportunities for their repurposing for use in Carbon Capture and Storage (CCS); to our knowledge, there are currently no operational CCS projects in SEA. Multiple CCS projects have been announced recently in SEA, targeting storage in depleted reservoirs. In this paper, we share technical lessons learned while working on CCS projects in SEA. The paper first provides an overview of engineering factors that should be considered for the transport and storage of CO2 in depleted reservoirs. We will then focus our discussion on four of the challenges faced while assessing these factors. Firstly, we highlight the impact that regional geothermal gradients have on storage capacity; particularly, we show that higher geothermal gradients due to the proximity to the ring of fire reduces storage capacity in reservoirs in SEA. Secondly, challenges surrounding the dynamic modelling of Carbon Dioxide (CO2) injection into depleted reservoirs will be discussed; the large difference between the composition of the injected gas and native reservoir gas necessitates the use of compositional dynamic models. In this regard, many depleted reservoirs either do not have dynamic models at all, or only have black oil models; both circumstances will require significant time and resource investments to construct compositional dynamic models. Next, we will discuss the reusability of regional gas pipelines for CCS projects; we discuss factors that may prevent a pipeline from being convertible for CO2 transport. Finally, we will discuss the challenge of managing CO2 phase transitions at injection sites. The phase transitions are a result of CO2 being transported at high pressures and then injected into depleted reservoirs with low pressures and high temperatures. We argue in the paper that the phase transition should be engineered to occur in the reservoir to minimize facilities costs.