2014 Volume 79 Issue 6 Pages 391-397
Enhanced oil recovery (EOR) processes have been applied to improve mobility of heavy oil and bitumen. This article has introduced three topics on numerical models for heavy oil and bitumen productions based on laboratory measurements and their scaling up to field reservoir simulations using CMG STARS™.
First one is CO2 gas foaming by depressurizing after immiscible CO2 dissolution in heavy oil. Saturated CO2 solubility and apparent swelling after foaming were measured on decreasing pressure processes using PVT apparatus and a high pressure cell. The numerical models of apparent viscosity and swelling ratio for foamy heavy oil have been proposed based on the measurement data and applied to a field scale oil-reservoir by Huff-n-Puff production method
The second one is bitumen emulsion (water in oil) formed by the Steam Assisted Gravity Drainage (SAGD) method for oil-sands layers, because condensed fine water-droplets diffuse into bitumen at the steam-chamber boundary. The characteristic of heavy-oil viscosity was measured against water/oil ratio (W/O) and temperature. The model of viscosity ratio (emulsion/original) vs. W/O has been presented and investigated its effect on bitumen-production from a typical oilsands reservoir by SAGD method. Finally, it has been shown that cumulative bitumen-production increases with bitumen swelling function of W/O.
The third one is heavy oil recovery by in-situ combustion with injecting air or O2 gas. Recently, the Toe-to-Heal Air Injection (THAI) method using a vertical injector and a horizontal producer is expected to be able to keep stable combustion front and oil drainage flow into the producer. Based on our numerical history-matching study on the tube combustion test for bitumen sands-pack, the reaction model consists from 3 major reactions were screened from 8 chemical reactions on Maltenes, Asphaltenes and Coke. Finally, the model was successfully applied to a heavy-oil in-situ production from a typical field oil reservoir.