Effects on heterogeneity on waterflooding in a San Andres-Grayburg carbonate reservoir, West Texas

Conference · Fri Jan 01 04:00:00 EST 1988

OSTI ID:6502311

Fogg, G E

Simulation of waterflooding in Section 15 of the Duane field, a San Andres-Grayburg reservoir in west Texas, illustrates the effect of heterogeneity on sweep efficiency. Two cross-sectional models with vertical and horizontal grid spacings of 1.2 and 30.48 m represent detailed permeability patterns that were mapped using log and core data from wells spaced approximately 395 m apart. Permeability patterns between wells were estimated by interpolation. A 2-year simulation of model A, in which permeability is laterally discontinuous, shows a rapid decline in oil production and a corresponding rise in the producing ratio of water to oil, which agrees with the production data. Computed saturations show the cause to be (1) rapid initial production of oil in high-permeability (greater than or equal to 10 md) grainstone facies and (2) increasing cycling of injected water through grainstone facies connecting the injection and production wells. Aided by gravity, water injected at perforations near the top of the 30-m thick reservoir model flows across strata and exits at perforations in a production well near the bottom of the model. Thus, substantial vertical fluid migration occurs in spite of the pronounced horizontal stratification of high and low permeability. Oil near the top of the higher permeability layers tends to be bypassed by the waterflood. In simulation of model A, 27% of the movable oil in the cross section was produced. In contrast, the more continuous permeability pattern of model B supports much more uniform flooding, which leads to production of 46% of the movable oil over the simulation period.

• OSTI ID: 6502311
• Report Number(s): CONF-880301-
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020300* -- Petroleum-- Drilling & Production
CARBONATE ROCKS
ENERGY SOURCES
ENHANCED RECOVERY
FEDERAL REGION VI
FLUID INJECTION
FOSSIL FUELS
FUELS
GEOLOGIC MODELS
HETEROGENEOUS EFFECTS
MATHEMATICAL MODELS
NORTH AMERICA
OIL WELLS
PERMEABILITY
PETROLEUM
RECOVERY
RESERVOIR ROCK
ROCKS
SEDIMENTARY ROCKS
STIMULATION
SWEEP EFFICIENCY
TEXAS
USA
WATERFLOODING
WELL SPACING
WELL STIMULATION
WELLS