A New Depositional Model for the North Kutei Basin

Vendrell-Roc, Jaume; White, Roger; Reader, Joanne
Salamander Energy Plc, Singapore, Singapore.

The northern Kutei Basin is generally considered to be a sand poor region. The main mouth of the Mahakam Delta lies approximately 100 km's to the south and it is generally assumed that the delta's major distributary channels failed to reach the northern Kutei area. This argument appears to be supported by a series of wells drilled in the 1980's and 1990's that failed to encounter significant reservoir sands within the Miocene to Pliocene sedimentary succession. Salamander Energy Plc has recently acquired 2 large 3D seismic surveys in the Bontang and SE Sangatta PSC's. The recent interpretation and integration of these datasets with sub-regional 2D mapping and regional tectonic models has led to the development of a new gross scale depositional model for the northern Kutei Basin. The model demonstrates that this region was the recipient of large volumes of Late Miocene to Early Pliocene sediments which is clearly demonstrated by the presence of significant large scale Mio-Pliocene sedimentary feeder systems on the paleoslope. The drilling of the Angklung-1 well has also confirmed the presence of gas charged sands within one of these feeder systems and has thus proved all of the required elements for a deepwater slope to basin floor turbidite play in this area.

The recently shot 3D seismic surveys in the Northern Kutei show excellent geomorphologies consistent with an overwhelming sediment source from the north-west. It is postulated that the bulk of sedimentation in this region has been sourced from a Paleo-Mahakam delta diverted to the north and south in response to regional tectonics inverting the central parts of the basin. An updated tectono-stratigraphic framework has allowed a greater understanding of the relative impact of eustatic sea level changes and the repeated pulses of tectonic inversion on deep water sedimentation. Recent 3D seismic has provided a clear image of deepwater depositional morphologies and highlights the increased reservoir potential within the underexplored northern Kutei Basin.

AAPG Search and Discovery Article #90155©2012 AAPG International Conference & Exhibition, Singapore, 16-19 September 2012