DIGITAL OUTCROP MODEL (DOM) AND HIGH-RESOLUTION SEDIMENTOLOGY OF BALIKPAPAN DELTAIC SANDSTONE: PERSPECTIVE OF HETEROGENEITIES IN THIN-BED RESERVOIR

摘要

Geological analogue plays critical roles towards contributing to comprehensive information in many application areas. The lack of resolution on subsurface datasets (i.e., seismic and well) can be problematic in predicting production performance during development and optimization stages. This paper demonstrates the combination of terrestrial photo-scanning and photogrammetry techniques to aid understanding of thin-bed architecture and the implications on reservoir behavior in a deltaic system. The outcrop area covers approximately 0.2 km~2, comprised of three lithofacies deposited in tidal-flat and mouth-bar environments. The outcrop exposure was of geological interest as an analogue to the existing reservoir in the Mahakam Delta. Detailed sedimentary sections were measured in order to investigate temporal and spatial changes within a stratigraphic framework. Photomontage correlation and architectural element analysis were performed, and a 3D Digital Outcrop Model (DOM) was generated, constrained by field observation to reduce geological uncertainty. In addition, samples were also collected to measure rock properties. Different grain size values were assigned to each lithofacies and populate variability within the mini-model. Photorealistic and outcrop intensity attributes formed the basis for key sedimentary surfaces and build up a full 3D geo-cellular volume. The results indicate that distribution of lithofacies and facies association holds primary control of variation on reservoir properties. In addition, the ability to capture geometry of small-scale features with DOMs as representative subsurface analog has been useful in improving understanding in reservoir modeling, identifying the remaining potential as well as being applied in future development strategies (i.e., injection, infill, horizontal) to enhance oil recovery, particularly in mature hydrocarbon fields.