The Baram Delta Operations (BDO), located offshore Sarawak Malaysia, consists of 9 fields with an estimated STOIIP of about 4 BSTB. 6 of the major fields in BDO have been on production for more than 30 years. Average recovery factor to date is about 30%. EOR has been planned as an effort to boost the production as well as prolong the life of the field. A preliminary EOR screening study shows that water-alternating-gas (WAG) is the most amenable EOR process for BDO. A PETRONAS and Shell joint study team was tasked to further extend the screening study conducted in 2005 by developing an EOR Big Picture for BDO. The objective of the study was to quantify the EOR potential in BDO and to develop a holistic areal implementation plan to mature the EOR potential. Scenarios evaluated involved a combination of three gas processes; immiscible hydrocarbon (HC) WAG as well as immiscible and miscible carbon dioxide (CO2) WAG. All reservoirs in BDO were first screened and ranked. Eligible reservoirs were then characterized into a few groups according to fluid, rock type as well as aquifer and gas cap size. Optimized EOR performance was evaluated using full field models as well as smaller scale, detailed prototype models of a few selected reservoirs. The prototype models were developed using field analogue data which were representative of a particular reservoir group. The performance prediction of the remaining reservoirs not modeled was STOIIP scaling of representative dimensionless curves. The HC WAG reservoirs were all immiscible while the potential CO2 WAG was a combination of miscible and immiscible cases. The subsurface EOR evaluation also included an estimation of infill and water flood potential, associated well count, well cost as well as the net gas import required and the total gas handling required. This paper presents the details of the systematic approach used to assess the subsurface EOR potential in the BDO fields.

Gas injection, both Hydrocarbon Water Alternating Gas (HC WAG) and Carbon Dioxide (CO2) WAG, are possible Enhanced Oil Recovery (EOR) technologies to further develop and extend the field life of the Baram Delta Operations (BDO), located offshore Sarawak Malaysia. BDO consists of nine fields with an estimated STOIIP of about 4 BSTB. Over 100 reservoirs are in production within the cluster, with many wells operating as dual completions. The 6 largest fields in BDO have been on production for more than 30 years with an average recovery factor to date around 30%, mainly through natural depletion and aquifer support. Most of the fields contain light, undersaturated oil and after initial screening, gas injection is the most likely technology to extend the life of BDO and boost its recovery. The size, geological complexity of BDO, the number existing and aging offshore platforms and facilities; and then to design and execute a large scale, technically and economically optimal gas injection project, makes producing a fully integrated basin wide forecast challenging. From a reservoir engineering perspective, simulation of miscible and near miscible gas injection requires compositional characterization and fine model gridding, compared with the size of reservoir, to be able to capture the physics (mass transfer, mixture properties and reduce numerical dispersion) to produce reliable results. Moreover, the economical assessment needs to have reliable estimates of incremental recovery, gas breakthrough times, gas utilization and gas recycling. Hence, small scale sector models rather than full field simulations are preferred so more robust results can be generated. The small scale model predictions, essentially building blocks, can then be scaled-up to generate full field forecasts. Likewise, the implementation of a gas injection project requires an appropriate balance between enhancing oil recovery and facility constraints. The size and cost of facilities, the cost of gas supply, and the acceleration in oil production control the economic viability, and a good design comes from a balance between these variables. Consequently, there is the need to create multiple scenarios of how the gas injection will be managed not only for each reservoir and/or each field, but also the integration and timing of injection of neighboring fields. Rapid forecasting of dozens of reservoirs and 6 fields is required to adequately assess optimal staging and economical viability before selecting a final concept. This paper presents the methodology used to build robust full field forecasts capturing key physics for the Baram Delta gas injection study. In addition to the methodology employed, a brief description will be given of the models developed and used as input into the full field forecasts, a brief description of the scale-up tool used, examples of forecasts developed will be shown and a summary of strengths and future enhancements.