RESERVOIR CHARACTERIZATION OF THE THICK IVF CYPRESS SANDSTONE IN NOBLE FIELD, ILLINOIS, FOR NONCONVENTIONAL CO2-EOR
Historically, oil production from the IVF Cypress is comparatively poor due to excessive water coning that occurs almost immediately. The IVF Cypress at Noble accounts for 50% of the field’s total production, with a 20 ft (6 m) thick oil column in the top of a 151 ft (46 m) thick sandstone, and an estimated 100 million bbl of original oil in place. Despite decades of waterflooding, recovery efficiency is low at around 25%, leaving a significant development opportunity, especially if an unrecognized ROZ is found. Nonconventional CO2 enhanced oil recovery (EOR) in the IVF Cypress may provide economic incentive to mitigate CO2 emissions by storing more CO2 rather than recycling CO2 as is typical of conventional CO2-EOR floods.
Detailed reservoir characterization provides a better understanding of reservoir architecture and heterogeneity and is a crucial step in building representative geocellular models for reservoir simulation to reduce CO2-EOR uncertainty. Findings from this study have broad implications, as analogous nonconventional CO2-EOR target reservoirs are common in other Carboniferous strata in the ILB and elsewhere. Detailed characterization may provide industry with data needed to begin targeting nonconventional reservoirs for CO2-EOR.