浅薄稠油油藏水平井CO_2吞吐机理及影响因素
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摘要
针对浅薄稠油油藏,通过将长岩心组合模型的水平和竖直放置对比实验,研究水平井CO_2吞吐相比于直井吞吐对油藏开发的改善效果,探明其增油机理。通过平行实验研究注入压力、注入时间及焖井时间对多轮次水平井CO_2吞吐开发浅薄稠油油藏效果的影响。结果表明:稠油油藏CO_2吞吐最主要的驱油机理是CO_2对原油的溶解膨胀作用及降黏作用;在浅层稠油的地层条件下,重力引起的CO_2对阁楼油动用规模以及CO_2-原油体系接触空间和时间的差异是水平井CO_2吞吐的采收率显著高于直井的成因;稠油油藏中进行多轮次水平井CO_2吞吐,其最终采收率随注入压力的升高而升高,随焖井时间的增长而升高,第1和第2周期为主力产油阶段;采收率与注入时间的关系有待进行更深入的实验研究。
For shallow thin heavy oil reservoir, a pair of contrast experiments with a long composite core plug model was conducted to determine the improvement of oil recovery and demonstrate the mechanisms. Then a series of parallel experiments were carried out to study the effects of operation pressures, injection time, and soaking periods. The results show that the dissolution of CO_2 swells the oil and reduces its viscosity, thus improving the oil recovery tremendously; in thin shallow reservoir, the volume of attic oil motivated by gravity and the contacting space and time are much larger in horizontal flooding than vertical flooding, which are the dominant mechanisms of horizontal CO_2 huff and puff; in cyclic CO_2 huff and puff in horizontal wells, the ultimate recovery increases noticeably with the increase of operation pressure, and it also benefits from the longer soaking period; the first and second cycles contribute the majority of oil recovery; besides, to investigate the influence of injection time on the cyclic CO_2 huff and puff test, it is recommended that such tests be performed on a larger experimental model.
For shallow thin heavy oil reservoir, a pair of contrast experiments with a long composite core plug model was conducted to determine the improvement of oil recovery and demonstrate the mechanisms. Then a series of parallel experiments were carried out to study the effects of operation pressures, injection time, and soaking periods. The results show that the dissolution of CO_2 swells the oil and reduces its viscosity, thus improving the oil recovery tremendously; in thin shallow reservoir, the volume of attic oil motivated by gravity and the contacting space and time are much larger in horizontal flooding than vertical flooding, which are the dominant mechanisms of horizontal CO_2 huff and puff; in cyclic CO_2 huff and puff in horizontal wells, the ultimate recovery increases noticeably with the increase of operation pressure, and it also benefits from the longer soaking period; the first and second cycles contribute the majority of oil recovery; besides, to investigate the influence of injection time on the cyclic CO_2 huff and puff test, it is recommended that such tests be performed on a larger experimental model.
引文
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[2]刘文章.稠油注蒸汽热采工程[M].北京:石油工业出版社,1997:13-29.
[3]ROSTAMI B,POURAFSHARY P,FATHOLLAHI A,et al.A new approach to characterize the performance of heavy oil recovery due to various gas injections[J].International Journal of Multiphase Flow,2018,99:273-283.
[4]吴光焕,夏志增,时凤霞,等.CO2对超稠油物性影响的实验研究[J].油田化学,2015,32(1):67-71.
[5]廉黎明,秦积舜,刘同敬,等.修正混合规则的BWRS型状态方程及其在CO2-原油体系相态计算中的应用[J].中国石油大学学报(自然科学版),2013,37(2):81-88.
[6]杨胜来,魏俊之.油层物理学[M].北京:石油工业出版社,2015:33-39.
[7]WANG X,GU Y.Oil recovery and permeability reduction of a tight sandstone reservoir in immiscible and miscible CO2flooding processes[J].Industrial&Engineering Chemistry Research,2011,50(4):2388-2399.
[8]LEI H,YANG S,ZU L,et al.Oil recovery performance and CO2storage potential of CO2water-alternating-gas injection after continuous CO2injection in a multilayer formation[J].Energy&Fuels,2016,30(11):8922-8931.
[9]王海涛,伦增珉,骆铭,等.高温高压条件下CO2/原油和N2/原油的界面张力[J].石油学报,2011,32(1):177-180.
[10]李孟涛,单文文,刘先贵,等.超临界氧化碳混相驱油机理实验研究[J].石油学报,2006,27(3):80-83.
[11]李康宁,宫厚健,王冲,等.N2对CO2最小混相压力的影响[J].断块油气田,2016,23(6):763-767.