Abstract
Multi-component thermal fluid (MCTF) huff and puff technology is an innovative heavy oil development technology widely used in China offshore oilfields. MCTFs mainly include steam, N2 and CO2. Under high temperature and high pressure, the physical and chemical reactions between thermal fluids and rocks occur, damaging the reservoir permeability and production effect. In this paper, 16 groups of core comparison experiments were carried out by MCTF device, the influence of original permeability, temperature and component on reservoir damage was quantitatively studied, and a mathematical model was established. Finally, the influence of reservoir damage on heavy oil development was investigated through numerical simulation. The experimental study reveals that MCTF has an obvious damage effect on the reservoir, where temperature and PV dominate the damage degree; with the increase of MCTF injection volume (PV), the core permeability rapidly decreases initially and stabilizes later (>6 PV). The numerical simulation results show that reservoir damage could lead to a recovery drop by 6.9% during MCTF development; on the premise of considering reservoir damage, MCTF huff and puff will further improve oil recovery by 9.68% compared with pure steam. The research is of great significance for understanding the production law of MCTF huff and puff and helpful for promoting the development of offshore heavy oil reservoir.
Highlights
At present stage, the potential of conventional sandstone reservoirs has gradually declined, and heavy oil reservoirs have become one of the key areas to increase production in China (Jiang et al, 2020; Li, 2021; Yang, 2021)
To determine the key influencing factors, we study the influence of original permeability level, temperature and thermal fluid component proportion on reservoir damage degree
This paper quantitatively studies the influence of multiple factors on reservoir damage through core experiments
Summary
The potential of conventional sandstone reservoirs has gradually declined, and heavy oil reservoirs have become one of the key areas to increase production in China (Jiang et al, 2020; Li, 2021; Yang, 2021). Offshore heavy oil development platform has been seeking a new thermal recovery method, where injection material is easy to obtain, transport and store, and the equipment is light and able to produce enough heat. These requirements coincide with the target of. The compaction and cementation of offshore heavy oil reservoir are usually poor Under such high temperature and pressure environment, complex physical and chemical reactions will occur between hot steam, CO2, N2, formation fluid and rock, which will cause continuous damage to the reservoir in the process of long-term huff and puff production, making it difficult to accurately predict, evaluate and adjust reservoir development. Simulation method to compare the development effect considering reservoir damage on oilfield scale
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