CO2 huff-n-puff process to enhance heavy oil recovery and CO2 storage: An integration study

In this study, experimental and mathematical studies were carried out to investigate heavy oil pro-duction performance using the carbon dioxide (CO2) huff-n-puff process, as well as the potential of CO2 storage in abundant reservoirs. Five experiments were conducted under different injection pressures and different pressure depletion rates. The components in the produced heavy oil were measured using a gas chromatography-mass spectrometry system to investigate the influence of CO2 extraction under different injection pressures in different cycles. The experimental results indicate that (a) heavy oil recovery factor increases with increasing injection pressure. (b) CO2 extraction of the light/medium components in heavy oil affect heavy oil production. (c) With different pressure depletion rates, an optimized pressure depletion rate can be identified as 4 kPa/min. And (d) the relationship between heavy oil and gas pro-duction can be predicted using the developed equation with high agreements. Mathematically, the po-tential of CO2 storage and CO2 capacity were calculated, and the investigations show that the most significant influences on CO2 capacity are CO2 stored in the available space and dissolving into the remaining heavy oil. An objective function was developed to optimize the heavy oil recovery factor and the CO2 storage factor in the CO2 huff-n-puff process. The influences of weights between heavy oil production and CO2 storage were investigated, and the optimized case with the same weight (0.5) was studied. (c) 2021 Elsevier Ltd. All rights reserved.

Automated summary

This study investigated heavy oil production performance using the CO2 huff-n-puff process and the potential of CO2 storage in abundant reservoirs through experimental and mathematical studies. The results showed that increasing injection pressure and optimizing pressure depletion rates can improve heavy oil recovery factor, and an equation has been developed to predict the relationship between heavy oil and gas production. The significant influences on CO2 capacity were found to be CO2 stored in available space and dissolved into remaining heavy oil.