● Upstream · Subsurface Carbonate Reservoir Reservoir Mapping 2002 — 2005

Unswept oil distribution
in Kais carbonate

Field Plan of Development study mapping the spatial distribution of remaining unswept oil across the Kais carbonate formation in an Eastern Indonesia field — identifying infill drilling targets for an international E&P operator.

Kais
Carbonate formation
5
Map types generated
FPOD
Deliverable type

The problem with mature carbonate fields

Mature carbonate reservoirs present a specific challenge: heterogeneous porosity and permeability distribution means that water flooding sweeps unevenly, leaving significant pockets of unproduced oil in locations that are not obvious from well-level data alone.

The Kais carbonate formation in this Eastern Indonesia field had been on production for several years. The operator needed to understand where the remaining moveable oil was — to prioritize infill drilling and optimize water injection patterns.

  • Formation-scale reservoir characterization
  • Subsurface mapping across Kais formation
  • Integration of well data & production history
  • Identification of unswept oil accumulations
  • FPOD (Field Plan of Development) support

Five-map approach to localize remaining oil

The study regenerated and cross-referenced five distribution maps across the formation, each providing a different lens on the reservoir state:

  • Depth structure map — current structural framework and reservoir top
  • Porosity distribution map — heterogeneity and quality variation across the field
  • Water-cut (WC) distribution map — identifying swept vs. unswept zones
  • Cumulative oil distribution map — historical production contribution by area
  • Latest BOPD distribution map — current production rate distribution

Overlaying these five maps allows a systematic identification of areas with high porosity, low water cut, and low cumulative production — the combination that indicates unswept, moveable oil remaining in place.

Localized residual oil targets for infill drilling

The integrated mapping exercise identified specific structural areas within the Kais carbonate where unswept oil was concentrated. These locations formed the basis for the infill drilling program in the Field Plan of Development, prioritized by estimated recoverable volumes and drilling accessibility.

The work was conducted in association with an international E&P operator active in Eastern Indonesia during the 2002–2005 period.