Publications

Tangguh gas discoveries are located in the Bintuni and Berau Bays, Birds head, Papua Barat, Indonesia. The fields subject to this study are: Vorwata, Wiriagar Deep, Roabiba and Ofaweri. The primary reservoir is the Middle Jurassic Roabiba formation (informally named, part of Lower Kembelangan Group (Visser and Hermes, 1962, Dow et al., 1988)). It is divided into 3 members informally named: Lower, Middle and Upper Roabiba. Based upon high resolution biostratigraphy and sedimentology, these members are subdivided into 15 zones: 5, 1 and 9 respectively. These zones are not always present as they occur partially eroded and/or pinching-out. Roabiba formation consists of sandstones and mudstones deposited within tidal influenced braided rivers and deltas (Lower Roabiba), tidal dominated delta and tidal-shoreface (Upper Roabiba), delta front and offshore settings (Middle Roabiba).The geocellular model was constructed using RMS Version 2009, following 6 steps:1. Structural model: basis for building 3D grid, consist of top and base formation horizons, reservoir zone horizons and numerous normal and strike-slip faults.2. Facies model: stochastic population using core and non-cored wells facies proportion.3. Petrophysical model: porosity (core and logs data) and permeability (core data only) stochastically populated and conditioned to facies model.4. Water saturation model: based upon capillary pressure data and vertical trend function curves per facies.5. Volumetrics: calculated using parameters in the grid.6. Scale-up for dynamic simulation.This integrated approach, using various types and vintages of datasets, allowed us to account for geological and petrophysical trends, which in the past were not captured by building separate models of each field. A set of connected workflows which included quality control steps, was created in order to speed up the modelling process. Therefore we were able to pay more attention to quality control (QC) of the intermediate results (i.e. petrophysical model compared to well data) and ultimately to gain confidence on static volumetric calculations.