TY - JOUR
T1 - Experimental investigation of foam-assisted N2 huff-n-puff enhanced oil recovery in fractured shale cores
AU - Xiong, Xiaofei
AU - Sheng, J. J.
AU - Wu, Xiaofeng
AU - Qin, Jianghua
N1 - Funding Information:
The support by the Fundamental Research Funds for the Central Universities of China and China Scholarship Council and the Strategic Cooperation Technology Projects of CNPC and CUPB (ZLZX2020-XX) is appreciated.
Publisher Copyright:
© 2021 Elsevier Ltd
PY - 2022/3/1
Y1 - 2022/3/1
N2 - Gas huff-n-puff is an effective method of improving recovery factor from shale reservoirs. However, due to the existence of fractures in shale reservoirs, the gas easily flows along the fractures, and the efficiency of enhancing the oil recovery factor is low. In this paper, the foam-assisted N2 huff-n-puff experiment and the N2 huff-n-puff experiment are carried out in fractured shale cores. Compared with the N2 huff-n-puff experiment, the foam-assisted experiment inhibited the gas channeling of fractured cores, prolonged the gas channeling time, and expanded the N2 swept area. At the same time, the foam also has the advantage of viscosity and changing the interfacial tension due to the presence of surfactants, all of which help to improve the oil recovery. From the perspective of microscopic pores, foam-assisted N2 huff-n-puff not only produced oil in macropores, but also produced a small amount of oil in micropores and mesopores. The oil production in the macropores and mesopores contributes the most to the recovery factor. The cumulative recovery factor increased as the cycle number increased.
AB - Gas huff-n-puff is an effective method of improving recovery factor from shale reservoirs. However, due to the existence of fractures in shale reservoirs, the gas easily flows along the fractures, and the efficiency of enhancing the oil recovery factor is low. In this paper, the foam-assisted N2 huff-n-puff experiment and the N2 huff-n-puff experiment are carried out in fractured shale cores. Compared with the N2 huff-n-puff experiment, the foam-assisted experiment inhibited the gas channeling of fractured cores, prolonged the gas channeling time, and expanded the N2 swept area. At the same time, the foam also has the advantage of viscosity and changing the interfacial tension due to the presence of surfactants, all of which help to improve the oil recovery. From the perspective of microscopic pores, foam-assisted N2 huff-n-puff not only produced oil in macropores, but also produced a small amount of oil in micropores and mesopores. The oil production in the macropores and mesopores contributes the most to the recovery factor. The cumulative recovery factor increased as the cycle number increased.
KW - Enhanced oil recovery
KW - Foam-assisted N huff-n-puff
KW - Gas channeling
KW - Shale oil
UR - http://www.scopus.com/inward/record.url?scp=85120308953&partnerID=8YFLogxK
U2 - 10.1016/j.fuel.2021.122597
DO - 10.1016/j.fuel.2021.122597
M3 - Article
AN - SCOPUS:85120308953
VL - 311
JO - Fuel
JF - Fuel
SN - 0016-2361
M1 - 122597
ER -