Publications

Outcrops in the Samarinda area have a key role in understanding the petroleum system in the Mahakam Delta. The producing interval down to subsurface in several producing fields is the best and most beneficial method to know the model for reservoir characteristics. Understanding of the heterogeneity reservoir from the outcrop analogue can significantly improve the reservoir modeling process. Ampera outcrops are a good representative area of stratigraphic significance in deltaic facies in vertical and lateral distribution. Detailed study of these outcrops has been performed by stratigraphic measured section and rock properties analysis, which included porosity, porosity type and mineralogy. The outcrops represent a 200m thick succession of deltaic/shallow marine sediments. There are nine distinct facies associations classifications: (1) prodelta, (2) interdistributary delta front, (3) distributary mouth bar, (4) tidal distributary channel, (5) fluvial distributary channel, (6) mud flat, (7) delta swamp, (8) splay bar/overbank deposit, and (9) storm deposit. The vertical stacking pattern of sediment shows fourteen deltaic cycles are recognized and represent high-frequency parasequence cycles. The three types of sandstone deposition can have similar thickness, but different characteristic and porosity. Petrography analysis shows that pore type is intergranular porosity as the primary porosity. The porosity mouth-bar sand ranges up to 6-12% and maximum values of distributary channel sand is up to 10-26%. Based on sand characteristic in distributary mouth bar and distributary channel, there are high differences of vertical and lateral distribution. The back-filled distributary sandstones deposits in mouth bar and distributary channel have significantly different sand body geometries and connectivity. Integrating the sedimentary processes in the Mahakam Delta deposits with outcrop analogue data leads to the variation of heterogeneity in completed deltaic system in vertical succession.