Integrating Geology, 3-D Seismic, and Production Data to Optimize Old Oil Pools in the Lower Cretaceous Glauconite Formation, Southern Alberta

Countess O and F Pools (T.18, R.15,16w4) are part of a 535 km long Glauconitic compound incised valley system. Between Countess and Alderson, a 90 km reach of this trend has produced more than 100 Mmbbls oil and 300 Bcf gas from 122 pools. Although in its twilight years of production, Countess F Pool was chosen for optimization because it shows below-average secondary recovery (45 %) for this part of the trend. Adjacent O Pool, in contrast, enjoys a 64% R.F. at comparable reservoir parameters. lengthy production and pressure histories, combined with recent 3D seismic, core description, petrology, petrophysics, and detailed sequence stratigraphy have helped refine reservoir models.

F Pool has produced 630 103m³ (4MMbbls) oil during the past 27 years, and currently pumps oil at 38 m³/d(240 bopd) with a 93% watercut. Chert-rich sublitharenites were deposited in fluvially-dominated channels. Seismic amplitude and time slice maps helped unravel a complex pool geometry. Pressure and production vary widely between the resulting compartments suggesting a frontal, "fingering" sweep to the waterflood.

Neighbouring O Pool has produced 909 1Q³m³(5.7 Mmbbls) oil in 22 years of operation. Before optimization, O Pool oil production was 46 m³/d(308 bopd) at a 95% watercut. Well-sorted quartz arenites were deposited in stacked, tidally influenced channels. Pool geometry is simple. Pressure and production history support an interpretation of bottom water drive.

Results of the optimization study predict potential increased recoverable reserves of 500 10³m\0.35 Mmbbls) and doubled daily oil production for each pool. Finding and development costs of $2-3/bbl, and 50-70% chance of success make optimization a viable way to balance risk in an oil company portfolio. New exploration leads have evolved from a more detailed understanding of the geological complexity within and between pools. Optimization is a way to breathe new life into mature areas.