Dennis W. Dull1
(1) Texaco Upstream Technology, Houston, TX
Abstract: Integrating sequence stratigraphy and multiple 3-D geostatistical realizations in constructing a reservoir model of the “Second Eocene”, Wafra Field, Partitioned Neutral Zone, Kuwait
The integration of the 3-D geostatistical computer modeling with sequence stratigraphic principles has significantly enhanced the ability to accurately build a reservoir model of the “Second Eocene”. The “Second Eocene” has produced over 330 million barrels and is one of the prolific reservoirs located in the giant Wafra oil field. The “Second Eocene” of Paleocene Age, is a stacked series of complex ramp, dolomite reservoir units.
The recognition of four high frequency sequences established the sequence stratigraphic framework for the 3-D geostatistical model that controls the vertical and horizontal spatial distribution of facies, porosity, water saturation and permeability unique to each sequence.
The ability to generate multiple versions or realizations of a reservoir parameter provided an opportunity to evaluate whether a single model could be used as “the reservoir model”. 30 equally probable models of each facies, porosity, and water saturation were made. Statistical models were generated then compared to a single version statistically, visually, and volumetrically. The “Second Eocene” particularly showed low variance within the known productive stratigraphic intervals with little difference between the mean and P50 for each reservoir parameter. The single realization hydrocarbon pore volume was compared to the mean and mode indicating only minor variation. In addition, the single realization showed excellent agreement between grainstone facies distribution, hydrocarbon pore volume, high oil cumulative production and the depositional model for the “Second Eocene”. The 3-D geostatistical model also potentially explains the pressure depletion and water encroachment problems in the field.
AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana