William C. Dawson1,
William R. Almon1,
Terrell H. Tankersley2,
Peter J. Janele2
(1) Texaco, Inc, Houston, TX
(2) Caltex Pacific, Indonesia
Abstract: Reservoir management guided by high-resolution sequence stratigraphy: Central Sumatra Basin, Indonesia
Sedimentologic analyses of conventional cores, wire-line log analysis, facies mapping, and production data have been integrated within the context of high-resolution sequence stratigraphy to optimize reservoir management of mature fields within the Central Sumatra Basin, Indonesia. Reservoir architecture and heterogeneity are related to position within depositional cycles and are predictable. Chronostratigraphic correlations reveal that sandstones associated with fluvial incision along the 22 ma and 21 ma sequence boundaries are excellent (high permeability) reservoirs throughout Central Sumatra. A stochastic approach has been attempted to model lithofacies distributions (Kotabatak field). Sandstones associated with the 22 ma sequence boundary represent a marginal marine (estuarine-braid delta) depositional setting. Reservoirs associated with the 21 ma sequence boundary represent estuarine-tidal delta (basal transgressive) lithofacies. Offshore marine (sheet) sandstones developed along the 17.5 ma and 16.5 ma sequence boundaries are low permeability reservoirs. Lithofacies successions in Mesozoic outcrops of France provide working analogs for the architecture of central Sumatra reservoirs.
The recognition and delineation of channelized estuarine-tidal lithofacies are keys to developing an improved understanding of reservoir compartmentalization in Miocene strata in the Central Sumatra Basin. Changes in reservoir management approach guided by an improved understanding of facies distribution have resulted in dramatic improvements (40%) in daily production rates where reservoirs have been re-interpreted within a chronostratigraphic framework. Predictions of reservoir architecture and heterogeneity made on the basis of position within a depositional cycle can assist in the prioritization of reservoirs for detailed characterization studies and in focusing of mature field revitalization strategies.
AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana