Publications

Historically, reservoir review methods in the Rokan Block have focused on structural play and layered stratigraphy, leading to significant oil production. However, challenges such as high-water cuts and economic viability arise as these asset ages. High-frequency stratigraphy (HFS) is a data-centric approach that examines detailed characteristics of rock strata within higher-order classifications, offering enhanced reservoir understanding and the potential to identify untapped oil opportunities in mature fields.

This paper underscores the significance of high-frequency stratigraphic analysis in defining reservoir unit zonation in fluvial to shallow marine environments. It leverages outcrop analogs and integrates static and dynamic well data to establish a fifth-order stratigraphic framework of the reservoir, leading to reservoir unit zonation and fluid contact analysis. Cased-hole reservoir saturation log data was acquired to reduce uncertainty about oil presence. The initial pilot execution at a well in the flank area of the Kerning Field targeted Frankfurt Reservoir revealed oil saturation up to 70% and a depth 7 feet deeper than the estimated oil-water contact. This success led to broader implementation in other primary fields starting in late 2022. Approximately ~77 workover/well intervention jobs have been conducted across nine oil fields, involving various unique stratigraphic cases (i.e., unconnected reservoirs in wells located in the flank structure area; oil and water reservoirs are located adjacent to each other and have the same structural position; reservoirs have remained idle for over 20 years due to a perceived lack of potential). It resulted in an additional production of approximately ~494 thousand barrels of oil and reduced fluid production by about ~48 thousand barrels per day. Further, this methodology can be applied to idle wells in less attractive areas, thereby enhancing the value and economics of these wells.