A Hybrid Simulation Study of the Windalia Sand Waterflood

Abstract

ABSTRACT The Windalia reservoir is a 22,000 acre, 600 well oil reservoir with a 25 year waterflood history, complicated by stress induced fracturing and a major pattern realignment. The reservoir recovery performance was studied by an integrated combination of geostatistical, finite difference, and stream tube models. The methodology is an extension of previously published work1 to larger and more complex reservoir problems. The basis of the approach is a geostatistical reservoir description derived from well logs and core data. Fine grid 2-D and 3-D models are developed to correlate sweep efficiency as a function of characteristic reservoir stratigraphies. These correlations are translated into fractional flow functions and pseudo relative permeabilities which are used in full field stream tube models and 2-D areal finite difference models. The stream tubes provide recovery calculation and front tracking and the areal model provides a calculation for pressure and well productivity. The methodology provided a reasonable representation of the reservoir and its well histories for an efficient expenditure of labor and computer time. Model construction, well history matching and forecasts were completed in four months, a significant improvement over previous attempts to model this reservoir. Refinement, update and sensitivities continue as a reservoir management process.