The Characterization of the Transgressive Depositional Packages to Aid Reservoir Geometry and Connectivity Prediction: North Kutai Lama Field, East Kalimantan, Indonesia

Eka Putra, Chandra M.; Septama, Erlangga

The depositional based stratigraphic framework of complex multilayer reservoir in Balikpapan Group, Paleo-Mahakam delta, North Kutai Lama (NKL) oil and gas development field, Indonesia has been constructed to elucidate the non-marine to transitional sand facies correlation pattern, reservoir geometry and connectivity prediction. Our study is focused on the transgressive sand packages, which are identified by flooding surfaces marker and their correlative conformity landward. The data used in this study were included wireline log data, formation test, well test data, bore hole imaging, sidewall cores and ditch cuttings from ten key wells, constrained laterally by 3-D seismic data, and outcrop analogs as comparison.

The seaward flooding surface is characterized by a retrogradational distributary channel fill, which is constituted of fine grained sand intercalated with thin calcarenite layers (e.g. NKL-1027 C-03b layers). This layer is marked by the occurrence of the carbonate matrix in the sandstone and the flasser bedding typical of tide-dominated environment, and is represented as serrated gamma log profiles in well. The extension of this flooding surface landward were characterized by either thick amalgamated backfilled fluvial channel (e.g.NKL-1013 A-25, NKL-1016 C-13 and NKL-1022 D-09 layers) or split into several coal seams in non-active depositional area. The channel fill deposit is typically medium to fine sand, interlayering with silt and coal clast with blocky shape gamma log profiles, sharp bed contacts that appear erosional in bottom part. This layer is capped either by a shale drape or coal layers on the top part.

The study suggests that the depositional based correlation significantly aids lateral facies distribution interpretation of the transgressive sand packages. The high sea level condition prevent the seaward detrital supply manifested by backfilled channel in the active depositional area, and eventually, the regional seawater rising will correlate with the high groundwater table suited to swamp and wetland were the coal originally deposited. Both of backfilled fluvial channel fill and distributary channel fill in this transgressive package, depend upon the fault-stratigraphic juxtaposition, have proven to be hydrocarbon prolific with an initial production rate vary from 153 BOPD (distributary channel) to 800 BOPD (A-25 amalgamated fluvial channel).

AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013