Publications | Indonesian Petroleum Association

Low Quality Reservoir Development of Upper Talang Akar Formation Shaly Sand Reservoir in Widuri Field, Southeast Sumatra

Year: 2025 Authors: Ravizon, Y., Nugroho, P., Dondo, M., Tumanggor, P., Winiarti

Keywords: Fluvial-deltaic, Low permeability, Mature fields, Shaly sand, hydrocarbon potential, oil production, reservoir, sandstone, water cut,

basins:

Proceedings Title : Proc. Indon. Petrol. Assoc., 49th Ann. Conv., 2025

W Field is located within the A Basin about 90 km offshore of North Jakarta operated by PT Pertamina Hulu Energi Offshore Southeast Sumatra (PT PHE OSES). W is a very mature oil field that has been produced since 1990 until now with cumulative oil production of almost 400 MMSTB (Figure1). The existing reservoirs came from the fluvial-deltaic sandstones of Upper Talangakar Formation (TAF) mainly from the Gita Member and Upper Zelda sandstones comprises of 33-4, 33-6, 34-1, 34-2, 35-1, 35-2, and 36-1 sands.
Most of the zones in W field were clean, blocky pattern, high-quality part of the multi-storey amalgamated fluvial braided – meandering channel reservoirs. Hundreds of wells have been drilled from these type of reservoirs 30 years and producing more than 99% watercut, which can be assumed that the oil has been drained or swept from most of the wells.
The assumption is that there is still hydrocarbon potential remaining in the shaly sand reservoir, the quality is low with low porosity and permeability. This paper will discuss further about this type of reservoir which is quite different and unique from the clean sand reservoirs.