LIAO Songlin, XIA Yang, CUI Yinan, et al. Variation of crude oil properties with multi-cycle CO2 huff-n-puff of horizontal wells in ultra-low permeability reservoir[J]. Petroleum Reservoir Evaluation and Development, 2022, (5): 784-793.
DOI:
LIAO Songlin, XIA Yang, CUI Yinan, et al. Variation of crude oil properties with multi-cycle CO2 huff-n-puff of horizontal wells in ultra-low permeability reservoir[J]. Petroleum Reservoir Evaluation and Development, 2022, (5): 784-793. DOI: 10.13809/j.cnki.cn32-1825/te.2022.05.010.
Variation of crude oil properties with multi-cycle CO2 huff-n-puff of horizontal wells in ultra-low permeability reservoir
huff-n-puff after fracturing of horizontal wells can effectively improve the properties of crude oil and increase the oil recovery of ultra-low permeability reservoirs. Combined with the geology and fluid characteristics of a typical ultra-low permeability reservoir
Block H
the mechanism of multi-cycle CO
2
injection in horizontal wells and the variat
ion of crude oil properties in ultra-low permeability reservoirs are studied by means of laboratory experiment and numerical simulation. The results show that after CO
2
injection
the saturated pressure of crude oil increases
the volume expands
the viscosity decreases
and the system becomes lighter. And the main action mechanism of different stages of CO
2
huff-n-puff are different: in the injection stage
the main mechanism is to supplement the formation energy
dissolve in crude oil
and reduce the crude oil viscosity; in the soaking and the initial stage of production
the main mechanism is to reduce the crude oil viscosity and expand the scope of CO
2
; in the middle and late period of well opening production
the light hydrocarbons and a small amount of intermediate component hydrocarbons in the oil phase are extracted. The CO
2
content in oil phases at different distances in the reservoir is analyzed by the method of fixed time and fixed point
and it is deduced that the lateral sweep radius of CO
2
injection along the fracture in H block is 24~40 m. With the increase of the huff-n-puff cycle
the increase of molar content of CO
2
in the oil phase decreased from 451 times in the first cycle to 0.44 times in the third cycle. The dissolved amount of injected CO
2
in crude oil decreases relatively
and the effect on the properties of crude oil also gradually decreases. The above research provides a new analysis method for understanding the mechanism of CO
2
huff-n-puff
and provides some theoretical support for further popularizing the multi-cycle CO
2
huff-n-puff technology of horizontal wells in ultra-low permeability reservoirs.
关键词
Keywords
references
Mingchen Ding,Yefei Wang,Yang Wang,Miao Gao,Dexin Liu,Wuhua Chen.Experimental investigation of bypassed-oil recovery via CO 2 soaking and huff and puff injection: Effects of miscibility and bypassed-oil size[J].Fuel,2019.
Xiang Zhou,Qingwang Yuan,Yizhong Zhang,Hanyi Wang,Fanhua Zeng,Liehui Zhang.Performance evaluation of CO 2 flooding process in tight oil reservoir via experimental and numerical simulation studies[J].Fuel,2019.
Runxuan Sun,Wei Yu,Feng Xu,Hui Pu,Jijun Miao.Compositional simulation of CO 2 Huff-n-Puff process in Middle Bakken tight oil reservoirs with hydraulic fractures[J].Fuel,2019.
Tang Yong,Su Zhengyuan,He Jibo,Yang Fulin.Numerical Simulation and Optimization of Enhanced Oil Recovery by the In Situ Generated CO2 Huff-n-Puff Process with Compound Surfactant[J].Journal of Chemistry,2016.