Publications

Fluvial and tidal-influenced reservoirs are one of the most important hydrocarbon-bearing units. Therefore, a better understanding particularly in the lateral and vertical connectivity for predicting internal heterogeneities of sandbodies is essential in study of field development and production. The conventional stratigraphic approach, lithostratigraphy and more recently sequence stratigraphy have been introduced and applied for several decades. However, determining the elements of these models are be challenging in some intervals. The aim of this study is to reconstruct subsurface correlation using a near-synchronous correlation framework called cyclostratigraphy that deals with cyclicity related to earth’s orbital parameters. The “S” Field located in the Northern part of the Kutai Basin will be the basis for this study, it has a complex subsurface correlation due to it being dominated by multilayered shaly-sand resulting from mixed fluvial-tidal influenced system. Sequence stratigraphy observes a vertical succession of sediment as a genetic unit, where as cyclostratigraphy is observing a vertical succession trend as well but corresponding to climatic change.Integrated Prediction Filter Analysis (INPEFA) log transformation was derived using a unique equation from Gamma Ray log and could represent a proper trend as a climate cycle. The INPEFA trend contributes to recognizing accumulations of conductive minerals and dispersed clay distribution as causes of low resistivity reservoir in several wells in the “S” Field. It could be useful for determining stratigraphic elements in the shaly-sand interval with bias trend of GR log and provide a better correlation. A new subsurface correlation using Cyclostratigraphy-INPEFA performs a more detailed depositional pattern of the fluvial-tidal influenced system. Based on analysis, there are eleven higher correlations rather than previous conventional correlation. In addition, the positive trend of INPEFA or warming phase sequence allows distribution of dispersed and high accumulation of conductive minerals that are essential for low resistivity reservoir assessment. Keywords: cyclostratigraphy, INPEFA log, Low resistivity reservoir