Publications

Tertiary Isolated Carbonate Build-Up (ICB) particularly Oligocene-Miocene carbonate reservoirs have served as the backbone of Indonesia’s oil/gas production for many years. Big producing fields such as Arun and Banyu Urip provide insights into existing ICB. These learnings, if optimally used, can create major positive impacts on asset profitability.

In this paper, we utilize historical public data and understanding to present three new insights related to ICB in Indonesia:

(1) ICB shows prominent multiscale pore systems (MPS), ranging from microns to meters, featuring pores of microporosity, a pervasive network of touching vugs, fractures, karst, and karst systems. These features exist in different proportions depending on the dimension of the ICB.

(2) The presence of dual-porosity dual-permeability MPS has resulted in increased pore volume, excess permeability and has influenced reservoir performance and prediction including early water and gas breakthrough, these implications highlight the direct impact of MPS on field development strategies and ultimate hydrocarbon recovery.

(3) Most ICB reservoir models do not accurately represent the full spectrum of MPS. As a consequence, the discrepancy in history matching is often managed by applying big permeability multipliers without conducting detailed reservoir characterization.

(4) An integrated MPS characterization workflow and data acquisition strategy during field appraisal are key in characterizing and properly distributing MPS.

This paper is intended to increase awareness of the existence of MPS and its implications for the life of developed or undeveloped Tertiary ICB reservoirs as well as for carbon capture utilization & storage (CCUS) efforts. Failure to recognize and properly describe the MPS during field development plan is a recurrent cause of poor performance in carbonate fields that significantly reduce the hydrocarbon recovery and reserves.

Furthermore, this paper will demonstrate recent evidence that accurate MPS characterization can successfully extend the hydrocarbon production plateau to support reaching the country’s vision of 1 million BOPD in 2030.