A Developed Screening Workflow for Preliminary Ranking Viable Onshore & Nearshore CO2 Storage Sites in Sarawak Area
Authors: Ab Rahman M Zahari Bin , Trianto Adi , Hendraningrat Luky , Mohamad M Naim Bin , Yakup M Hamzi Bin , Che Mat M Noor Fajarimi Bin , M Ali Siti Syareena Bt , Widyanita Ana , Jones Ernest A 
Published: October 2023

To reduce CO2 emissions by 2050, most of the international oil and gas firms are rushing to undergo decarbonization. It is well-known that several gas resources in Malaysia contain significant amounts of CO2 gas, with some reservoirs having up to 90% CO2 by weight. Since gas flaring is no longer a possibility, the monetization of the high CO2 field necessitates the cost-effective removal and secure storage of the CO2 and other contaminants. This paper presents a developed screening workflow for ranking viable CO2 storage in Malaysia basin.

A multi-criteria evaluation was developed that considers the distance to the nearest onshore facility, the type of field, the volume of hydrocarbons, the type of reservoir, the completeness of the data, as well as other factors like field status, ownership, contract expiry, and data gathering. A total of 73 fields were looked at in this screening investigation. To rank the fields based on these 5 key criteria, a score system was developed. The first round of screening required that the fields on the list be filtered within a radius of less than 100 kilometres from the coast. Following the distance, the list will be filtered by field type, volume placed, and reservoir type. Due to their impact on the expense and risk of the possible research sector, these three factors were taken into account. The data completeness criteria were chosen as the last criterion since they will have a significant impact on the examined field's uncertainty as well as the fields that are chosen based on the storage development plan.

The top three fields were chosen after the aforementioned screening. Weighting was used to establish the score system for the screening criteria to balance the parameter uncertainty. For instance, data completeness has the highest weight of 0.4, followed by volume, distance, and then field and reservoir type criteria, each with a weight of 0.02. It is generally believed that data completion contributes the most weight because it can reduce the risks and uncertainties for a field's subsequent study. Volume is given the second-highest weight since it affects how much data can be stored during the study. This is to guarantee that the long-term CO2 storage plan is carried out. To further examine the suitability of the top 3 fields as CO2 storage possibilities, a feasibility study has been conducted. It entails simple modeling for CO2 injection simulation, well integrity analysis, geo-pressure and gas chromatography analysis, preliminary potential storage calculation based on the layer cake assumption. The high-level traffic light analysis conducted to risk rank the potential reservoir candidates of the top 3 fields based on reservoir, seal/overburden and well integrity criteria. The initial estimates of three field's theoretical CO2 storage capacity range from 0.9 to 1.2 Tscf.

According to the findings of this study, it is crucial to develop the chosen candidates as possible CO2 storage facilities in accordance with the storage development plan's standards. Additionally, this study can identify and develop domestic and foreign investment opportunities for the CCUS portfolio.