Experimental evaluation of Carbon Dioxide-Assisted Gravity Drainage process (CO2-AGD) to improve oil recovery in reservoirs with strong water drive
Experimental evaluation of Carbon Dioxide-Assisted Gravity Drainage process (CO2-AGD) to improve oil recovery in reservoirs with strong water drive
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DOI：
10.1016/j.fuel.2022.124409
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发表时间：
2022-05-11
期刊：
影响因子：
7.4
通讯作者：
Al-Jawad, Mohammed S.
中科院分区：
文献类型：
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作者：
Al-Obaidi, Dahlia A.;Al-Mudhafar, Watheq J.;Al-Jawad, Mohammed S.
气体辅助重力泄油（GAGD）技术已被开发出来，用于改善和提高二次和三次采油阶段的产油量。在GAGD工艺中，通过油水界面上方的水平井采油。因此，高水位的峰值可能正在发生，特别是在具有活跃含水层的水库中。然而，以往所有的GAGD可行性实验研究都没有涉及到活动含水层的存在。因此，本研究旨在验证非混相GAGD工艺在具有强水侵倾向的棕色油藏中提高采收率、降低含水率的可行性。Hele-Shaw模型由两个平行的玻璃板组成，其中填充了硅砂，以直观地识别工艺性能。具体而言，在大、中、无底水驱动的物理模型上，研究了CO2-AGD工艺与自由落体重力排水（FFGD）机制的可行性。实验结果表明，由于GAGD的采油速度快、采收率高，特别是在没有底水驱动的油藏上实施时，GAGD工艺在所有运行中都优于FFGD工艺。不混相的CO2-AGD过程不仅在提高采收率方面很重要，而且还显著推迟了天然气的突破。含水层强度与气侵时间成反比，含水层强度越大，产油越快，气侵越早。此外，非混相GAGD实验表明，在无底水驱动模型下，FFGD和GAGD过程的原油采收率分别提高到OOIP的35%和47%。然而，在相同的FFGD和GAGD过程中，对于具有大底水驱动的模型，石油采收率分别提高到OOIP的61%和63%。具体来说，在大底水驱的GAGD过程中，最终采收率仅比FFGD高2%；而在无底水驱的情况下，该模型的最终采收率提高了约12%。因此，在底水驱动有限或无底水驱动的油藏中，GAGD工艺可以更有效地提高采收率。
The Gas-Assisted Gravity Drainage (GAGD) process has been developed to improve and enhance oil production in both secondary and tertiary recovery stages. In the GAGD process, oil is produced through horizontal wells above the oil-water contact. Therefore, high levels of water cresting are probably happening, especially in reservoirs with active water aquifers. However, all the previous GAGD feasibility experimental studies have never been addressing the existence of active water aquifers. Consequently, the current research was conducted to test the immiscible GAGD process feasibility to improve oil recovery and minimize water cut in brown reservoirs with strong water coning tendencies. A Hele-Shaw model consists of two parallel glass plates packed with silica sand to visually discern the process performance. Specifically, the CO2-AGD process feasibility versus the Free Fall Gravity Drainage (FFGD) mechanism was investigated on the physical model with large, moderate, and without bottom water drive. The experimental results indicated that the GAGD process performance is higher performance than the FFGD in all runs because of its fast high oil recovery, especially when implemented on the reservoir without a bottom water drive. The immiscible CO2-AGD process is not only important in terms of increasing oil recovery, but it also significantly delays the gas breakthrough. The strength of the aquifer inversely impacts the gas breakthrough time as increasing the aquifer strength results in fast oil production and early gas breakthrough. Additionally, the immiscible GAGD experiments illustrated that oil recoveries in the FFGD and GAGD processes improved to 35% and 47% of OOIP for the model without bottom water drive, respectively. However, the oil recovery increased in the same FFGD and GAGD processes to 61% and 63% of OOIP for the model with a large bottom water drive, respectively. Specifically, the ultimate oil recovery during the GAGD process with a large bottom water drive was higher than the FFGD run with only 2%; while there is increasing in ultimate oil recovery for the model without the bottom water drive of about 12%. Consequently, the GAGD process is more efficient to improve oil recovery in reservoirs with limited or without bottom water drive.