Reservoir Evaluation and Development ›› 2018, Vol. 8 ›› Issue (5): 37-41.

• Reservoir Evaluation • Previous Articles     Next Articles

Influence of scale effect on oil displacement efficiency by natural gasiscible-flooding

Yang Xue   

  1. (Research Institute of Exploration and Development of Zhongyuan Oil Field Company, SINOPEC, Puyang, Henan 457000, China)
  • Received:2018-02-09 Online:2018-10-26 Published:2018-12-05


In order to study the influence of the scale effects on the oil displacement efficiency of natural gas miscible-flooding, we proposed to take the volatile reservoir with mid-low permeability of the third section of the Shahejie formation of some block in Zhongyuan oilfield as an example, and carried out the small scaled physical simulation experiment of natural gas flooding by the combination of natural cores with different length to revealed the mechanism of enhanced oil recovery by long core miscible flooding. And then we researched the gas driving development effects with large size by the numerical simulation method based on the actual geological model. The results show that the recovery rate of the natural gas recovery with the core length of 1 800 mm, 950 mm and 500 mm respectively are 90.88 %, 82.89 % and 64.8 %. It is found that the oil displacement efficiency of the long core is about 25 % higher than that of the short one, that is to say, along with the increase of the injection volume at the same injection rate, the miscible section of the long core is longer, the miscible contact is sufficient and there are time lags in gas breakthrough. Meanwhile, it is verified by numerical simulation that the best well spacing range is 300 ~ 350 m. Within this range, the larger the well spacing is, the better the displacement effect will be. But as the well spacing increases, the increasing degree of the recovery efficiency and the economic effect all get worse. Based on this study, the influence of size effect on natural gas displacement is further clarified, which is of great practical significance for the optimization of injection and production parameters and the development of similar reservoirs.

Key words: scale effect, miscible displacement, recovery efficiency, long core, numerical simulation

CLC Number: 

  • TE349