Reservoir Characterization of Lower Roabiba Sandstone in FA Field, Bintuni Bay, West Papua, Indonesia

Abstract

Abstract

FA field is situated on the northern shore of the Bintuni Bay, Bird's head region, West Papua, Eastern Indonesia. The field has two Middle Jurassic gas reservoirs, Upper Roabiba and Lower Roabiba Sandstone reservoirs. The field has not been producing commercially due the complexity and the heterogeneity of the reservoirs. Considering the fact that many literatures study on the Upper Roabiba Sandstone as the main target, this study will be focusing on Lower Roabiba Sandstone as the new prospective reservoir.

This study main aim is to characterize the Lower Roabiba Sandstone in FA Field by integrating geology, petrology, biostratigraphy and petrophysics data. This study will identify the reservoir quality of Lower Roabiba Sandstone and its distribution in the field as the new potential reservoir target in FA field.

Facies were defined on the basis of prominent grain size, sedimentary structures and biogenic structures analysis from observations of the core data. The study has recognized six major facies and grouped into three facies associations, which are organic-rich mud deposits, stacked channel-fill sandstone, and non-channelize sandstone.

Lower Roabiba sandstone was deposited in tidal-dominated estuarine comprises of series of bioturbated stacked tidal channels, non-channelized tidal bar sand bodies, brackish embayment mudstone and capped by thin transgressive surface with average porosity 12% and permeability 165 mD.

Diagenesis has altered Lower Roabiba sandstone by mechanical compaction, cementation from quartz overgrowths, calcite cementation, grain-coating/pore lining clay development, and K-fledspar dissolution. Porosity and permeability were enhanced by dissolution and reduced by cementation and compaction. Bioturbation both could enhance and also reduce the reservoir properties.

The results of this analysis will act as the basis of the future 3-D static geocellular models construction in the future to establish the quantitative distribution of the fluid and rock properties and its uncertainties according to their spatial variability.

AAPG Datapages/Search and Discovery Article #90260 © 2016 AAPG/SEG International Conference & Exhibition, Cancun, Mexico, September 6-9, 2016