EOR for California Diatomites: CO₂, Flue Gas and Water Corefloods, and Computer Simulations

This paper describes a research project to determine oil recovery potential by CO₂/flue gas injection for the Lost Hills diatomite reservoir. Gas injection into the diatomites may provide an altemale recovery method to waterflood and primary depletion. The present study is aimed at the possibility of future CO₂ supplies becoming available from pipeline or from large-scale CO₂ separation facilities.

The laboratory results reported here arc from a series of long coreflood studies for gas and water injection into a diatomitc rock. Coreflood models were matched to the experimental data to validate PVT data and develop numeric models for prediction of overall oil recovery for a five-spot pattern element. The hybrid streamtube method was used in the pattern simulation, Coreflood results and computer simulation indicate that CO₂-flooding the diatomite reservoir after primary depletion may be technically feasible and can recover incremental oil over waterflood, both as secondary or tertiary processes with 2 to 3 times the injectivity of water.