Experimental Investigation of Oil Recovery Performance and Permeability Damage in Multilayer Reservoirs after CO2 and Water-Alternating-CO2 (CO2-WAG) Flooding at Miscible Pressures
Experimental Investigation of Oil Recovery Performance and Permeability Damage in Multilayer Reservoirs after CO2 and Water-Alternating-CO2 (CO2-WAG) Flooding at Miscible Pressures
复制标题
混相压力 CO2 与水交替 CO2 (CO2-WAG) 驱后多层油藏采收率及渗透率损害实验研究
DOI：
10.1021/acs.energyfuels.9b02786
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发表时间：
2020
期刊：
影响因子：
5.3
通讯作者：
Lei Hao
中科院分区：
文献类型：
--
作者：
Wang Qian;Yang Shenglai;Lorinczi Piroska;Glover Paul;Lei Hao
沥青质沉积和无机相互作用导致的储层堵塞是一个严重的问题，可能会加剧非均质多层砂岩储层驱油特征的复杂性，并影响co2和CO2-WAG驱油过程中的原油采收率。在本研究中，在混相条件下（70°C, 18 MPa），在相同的多层体系上进行了co2和CO2-WAG驱油实验。对两种驱油方式的产油性能和储层损害进行了评价。实验结果表明：co2驱油后，整个体系的采收率（RF）较低，为27.6%，原油主要从高渗透层产出（91.4%），剩余油主要集中在中、低渗透层。CO2-WAG驱注压高，但co2突破（BT）时间较晚，整个体系的油收率达到44.5%。中、低渗透层产油量贡献率分别提高到3.8%和17.1%。co2驱后，高渗透层渗透率降低16.8%，主要是沥青质析出所致。而CO2-WAG驱后，各层渗透率均显著降低，分别降低29.4%、16.8%和6.9%。沥青质沉淀仍是主要影响因素，但co2 -盐水-岩石相互作用导致的渗透率下降也不容忽视，特别是在高渗透层（6.1%）。因此，对于高非均质多层油藏，CO2-WAG驱油驱油效果较好，但更需要采取沥青质沉淀防治措施。
Blockage in reservoirs caused by asphaltene deposits and inorganic interactions is a serious problem that may exacerbate the complexity of displacement characteristics in heterogeneous multilayer sandstone reservoirs and affect crude oil recovery performance during CO2and CO2–WAG flooding. In this study, experiments of both CO2and CO2–WAG flooding were carried out on the same multilayer systems under miscible conditions (70 °C, 18 MPa). The two flooding methods were evaluated for oil production performance and reservoir damage. The experimental results indicate that, after CO2flooding, the entire system has a low oil recovery factor (RF) of 27.6%, and oil is produced mainly from the high permeability layer (91.4%), while the residual oil remains predominantly in the medium and low permeability layers. The injection pressure of CO2–WAG flooding is high, but the timing of CO2breakthrough (BT) is late, and the oil RF of the entire system reaches 44.5%. The contribution rate of oil production in medium and low permeability layers is improved to 3.8% and 17.1%, respectively. Furthermore, the permeability of the high permeability layer decreases by 16.8% after CO2flooding, which is mainly due to asphaltene precipitation. However, after CO2–WAG flooding, the permeability of each layer is significantly reduced, namely by 29.4%, 16.8%, and 6.9%, respectively. Asphaltene precipitation is still the main factor, but permeability decline caused by CO2–brine–rock interactions cannot be ignored, especially in the high permeability layer (6.1%). Therefore, for multilayer reservoirs with high heterogeneity, CO2–WAG flooding provides the better oil displacement performance, but prevention and control measures for asphaltene precipitation are more necessary.