scholarly journals Material balance approach for determining oil saturation at the start of carbon dioxide enhanced oil recovery

2018 ◽  
Author(s):  
Mahendra K. Verma
SPE Journal ◽  
2019 ◽  
Vol 24 (03) ◽  
pp. 1139-1153 ◽  
Author(s):  
S. B. Fredriksen ◽  
Z. P. Alcorn ◽  
A.. Frøland ◽  
A.. Viken ◽  
A. U. Rognmo ◽  
...  

Summary An integrated enhanced-oil-recovery (EOR) (IEOR) approach is used in fractured oil-wet carbonate core plugs where surfactant prefloods reduce interfacial tension (IFT), alter wettability, and establish conditions for capillary continuity to improve tertiary carbon dioxide (CO2) foam injections. Surfactant prefloods can alter the wettability of oil-wet fractures toward neutral/weakly-water-wet conditions that in turn reduce the capillary threshold pressure for foam generation in matrix and create capillary contact between matrix blocks. The capillary connectivity can transmit differential pressure across fractures and increase both mobility control and viscous displacement during CO2-foam injections. Outcrop core plugs were aged to reflect conditions of an ongoing CO2-foam injection field pilot in west Texas. Surfactants were screened for their ability to change the wetting state from oil-wet using the Darcy-scale Amott-Harvey index. A cationic surfactant was the most effective in shifting wettability from an Amott-Harvey index of –0.56 to 0.09. Second waterfloods after surfactant treatments and before tertiary CO2-foam injections recovered an additional 4 to 11% of original oil in place (OIP) (OOIP), verifying the favorable effects of a surfactant preflood to mobilize oil. Tertiary CO2-foam injections revealed the significance of a critical oil-saturation value below which CO2 and surfactant solution were able to enter the oil-wet matrix and generate foam for EOR. The results reveal that a surfactant preflood can reverse the wettability of oil-wet fracture surfaces, lower IFT, and lower capillary threshold pressure to reduce oil saturation to less than a critical value to generate stable CO2 foam.


2021 ◽  
Vol 7 ◽  
pp. 960-967
Author(s):  
Mohammad Hossein Ahmadi ◽  
S.M. Alizadeh ◽  
Dmitry Tananykhin ◽  
Saba Karbalaei Hadi ◽  
Pavel Iliushin ◽  
...  

2021 ◽  
Author(s):  
Yongsheng Tan ◽  
Qi Li ◽  
Liang Xu ◽  
Xiaoyan Zhang ◽  
Tao Yu

<p>The wettability, fingering effect and strong heterogeneity of carbonate reservoirs lead to low oil recovery. However, carbon dioxide (CO<sub>2</sub>) displacement is an effective method to improve oil recovery for carbonate reservoirs. Saturated CO<sub>2</sub> nanofluids combines the advantages of CO<sub>2</sub> and nanofluids, which can change the reservoir wettability and improve the sweep area to achieve the purpose of enhanced oil recovery (EOR), so it is a promising technique in petroleum industry. In this study, comparative experiments of CO<sub>2</sub> flooding and saturated CO<sub>2</sub> nanofluids flooding were carried out in carbonate reservoir cores. The nuclear magnetic resonance (NMR) instrument was used to clarify oil distribution during core flooding processes. For the CO<sub>2</sub> displacement experiment, the results show that viscous fingering and channeling are obvious during CO<sub>2</sub> flooding, the oil is mainly produced from the big pores, and the residual oil is trapped in the small pores. For the saturated CO<sub>2</sub> nanofluids displacement experiment, the results show that saturated CO<sub>2</sub> nanofluids inhibit CO<sub>2</sub> channeling and fingering, the oil is produced from the big pores and small pores, the residual oil is still trapped in the small pores, but the NMR signal intensity of the residual oil is significantly reduced. The final oil recovery of saturated CO<sub>2</sub> nanofluids displacement is higher than that of CO<sub>2</sub> displacement. This study provides a significant reference for EOR in carbonate reservoirs. Meanwhile, it promotes the application of nanofluids in energy exploitation and CO<sub>2</sub> utilization.</p>


2008 ◽  
Vol 16 (3) ◽  
pp. 343-353 ◽  
Author(s):  
Edgar G. Hertwich ◽  
Martin Aaberg ◽  
Bhawna Singh ◽  
Anders H. Strømman

2021 ◽  
pp. 131-143
Author(s):  
F. A. Koryakin ◽  
N. Yu. Tretyakov ◽  
O. B. Abdulla ◽  
V. G. Filippov

Nowadays the share of hard-to-recover reserves is growing, and to maintain oil production on necessarily level, we need to involve hard-to-recover reserves or to increase oil production efficiency on a brownfields due to enhanced oil recovery. The efficiency of enhanced oil recovery can be estimated by oil saturation reduction. Single-well-chemical-tracer-test (SWCTT) is increasingly used to estimate oil saturation before and after enhanced oil recovery application. To interpret results of SWCTT, reservoir simulation is recommended. Oil saturation has been calculated by SWCTT interpretation with use of reservoir simulator (CMG STARS). Distribution constants has been corrected due to results of real core sample model, and core tests has been successfully simulated. Obtained values of oil saturation corresponds with real oil saturation of samples. Thus, SWCTT as a method of oil saturation estimation shows good results. This method is promising for enhanced oil recovery efficiency estimation.


Author(s):  
B. A. Suleimanov ◽  
S. J. Rzayeva ◽  
U. T. Akhmedova

Microbial enhanced oil recovery is considered to be one of the most promising methods of stimulating formation, contributing to a higher level of oil production from long-term fields. The injection of bioreagents into a reservoir results in the creation of oil-displacing agents along with a significant amount of gases, mainly carbon dioxide. Earlier, the authors failed to study the preparation of self-gasified biosystems and the implementation of the subcritical region (SR) under reservoir conditions. Gasified systems in the subcritical phase have better oil-displacing properties than nongasified systems. In a heterogeneous porous medium, the filtration profile of gasified liquids in the SR should be more uniform than for a degassed liquid. Based on experimental studies, the superior efficiency of oil displacement by gasified biosystems compared with degassed ones has been demonstrated. The possibility of efficient use of gasified hybrid biopolymer systems has been shown.


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