ABSTRACT: Multidisciplinary Reservoir Description of the Batu Raja Limestone, Bima Field, Offshore Northwest Java, Indonesia

John G. Kaldi, Gary S. Woodling, Randall C. Roe

Bima field is the largest hydrocarbon reservoir producing from carbonate rocks in the offshore northwest Java area. The giant field has multiple drive mechanisms and high viscosity oil, resulting in rapid gas/oil ratio and water-cut increase after 2 yr of production. Because of high stakes and reservoir complexities, a three dimensional reservoir simulation Model was used to evaluate field development options. An integrated geological, geophysical, and engineering reservoir description was done to provide input for the model. Geologically, the Oligocene-Miocene Batu Raja Limestone was deposited on the Seribu Platform, a basement-controlled, fault-bounded carbonate build-up. The reservoir consists of a series of cleaning-upwards cycles that were exposed to meteoric leachin during a lower Miocene drop in sea level. This diagenetic event enhanced porosity and permeability across the buildup. Based on reservoir quality, the reservoir was zoned into five model layers. Geophysical input included micromodeling sections (a form of seismic inversion) that were generated from a dense grid of seismic data. These were calibrated to well logs and used to define the buildup edge and map the thickness of the entire Batu Raja and the main pay zone. Engineering reservoir description integrated capillary pressure, relative permeability, production, and drill-stem test data. The three-dimensional simulation model required treatments unique to the Bima Field including varying GOC depths to honor separate gas cap closures; making permeability pressure dependent in poorly con olidated zones, and setting up horizontal well completion treatments. The synergistic approach of geological, engineering, and geophysical input into the Bima reservoir study resulted in a reservoir management tool as well as a model to aid regional Batu Raja exploration strategies.

AAPG Search and Discovery Article #91003©1990 AAPG Annual Convention, San Francisco, California, June 3-6, 1990