scholarly journals Effect of stress sensitivity on displacement efficiency in CO2 flooding for fractured low permeability reservoirs

2009 ◽  
Vol 6 (3) ◽  
pp. 277-283 ◽  
Author(s):  
Rui Wang ◽  
Xiang’an Yue ◽  
Renbao Zhao ◽  
Pingxiang Yan ◽  
Dave Freeman
Keyword(s):  
Stress Sensitivity ◽  
Low Permeability ◽  
Co2 Flooding ◽  
Displacement Efficiency ◽  
Low Permeability Reservoirs

scholarly journals Study on Prevention of Gas Channelling of Acid-resistant Gel Foam in CO2 Flooding of Low Permeability Reservoir

2020 ◽  
Vol 194 ◽  
pp. 01041
Author(s):  
Zhaoxia LIU ◽  
Ming GAO ◽  
Shanyan ZHANG ◽  
Wanlu LIU
Keyword(s):  
Oil Recovery ◽  
Retention Rate ◽  
Crosslinking Agent ◽  
Water Soluble ◽  
Oil Reservoirs ◽  
Low Permeability ◽  
Co2 Flooding ◽  
Water Separation ◽  
Co2 Gas ◽  
Low Permeability Reservoirs

With the shortage of recoverable reserves in conventional oil reservoirs, the development of low-permeability oil reservoirs has received more and more attention. The oil recovery of low-permeability reservoirs can be significantly improved by CO2 flooding, as it can effectively supply formation energy. CO2 flooding is an effective technology for increasing oil production in low-permeability reservoirs. However, because of the heterogeneity of the reservoir and the effect of natural fractures, CO2 gas channelling easily occurs during CO2 flooding, seriously reducing CO2 flooding effect. In this study, the gas channelling technology of acid-resistant gel foam was investigated. Preferred acid-resistant gel foam system formula was found as 0.1% by mass of AOS foaming agent with 0.3% to 0.4% by mass of instant HPAM polymer and 1% to 2% by mass of water-soluble phenolic resin crosslinking agent. This system still has a good foaming ability and blocking performance under at pH=2 and a salinity of 10×104 mg/L. After 60 days of aging under oil reservoir conditions, there is no obvious water separation, and the plugging strength retention rate reached more than 60%. The gel foam channelling system can be applied to highly heterogeneous and low permeability reservoirs with a permeability gradient higher than 14 and can increase the recovery rate by more than 20% based on the CO2 flooding. Acid-resistant gel foam channelling technology can effectively inhibit CO2 gas channelling and improve CO2 flooding effect in low permeability reservoirs.

scholarly journals Low-tension gas process in high-salinity and low-permeability reservoirs

2020 ◽  
Vol 17 (5) ◽  
pp. 1329-1344
Author(s):  
Alolika Das ◽  
Nhut Nguyen ◽  
Quoc P. Nguyen
Keyword(s):  
Oil Recovery ◽  
High Salinity ◽  
Oxidative Degradation ◽  
Qualitative Assessment ◽  
Low Permeability ◽  
Displacement Efficiency ◽  
Fractional Flow ◽  
Hydrocarbon Gases ◽  
Low Tension ◽  
Low Permeability Reservoirs

Abstract Polymer-based EOR methods in low-permeability reservoirs face injectivity issues and increased fracturing due to near wellbore plugging, as well as high-pressure gradients in these reservoirs. Polymer may cause pore blockage and undergo shear degradation and even oxidative degradation at high temperatures in the presence of very hard brine. Low-tension gas (LTG) flooding has the potential to be applied successfully for low-permeability carbonate reservoirs even in the presence of high formation brine salinity. In LTG flooding, the interfacial tension between oil and water is reduced to ultra-low values (10−3 dyne/cm) by injecting an optimized surfactant formulation to maximize mobilization of residual oil post-waterflood. Gas (nitrogen, hydrocarbon gases or CO2) is co-injected along with the surfactant slug to generate in situ foam which reduces the mobility ratio between the displaced (oil) and displacing phases, thus improving the displacement efficiency of the oil. In this work, the mechanism governing LTG flooding in low-permeability, high-salinity reservoirs was studied at a microscopic level using microemulsion properties and on a macroscopic scale by laboratory-scale coreflooding experiments. The main injection parameters studied were injected slug salinity and the interrelation between surfactant concentration and injected foam quality, and how they influence oil mobilization and displacement efficiency. Qualitative assessment of the results was performed by studying oil recovery, oil fractional flow, oil bank breakthrough and effluent salinity and pressure drop characteristics.

scholarly journals Profile improvement during CO2 flooding in ultra-low permeability reservoirs

2014 ◽  
Vol 11 (2) ◽  
pp. 279-286 ◽  
Author(s):  
Fenglan Zhao ◽  
Lei Zhang ◽  
Jirui Hou ◽  
Shujun Cao
Keyword(s):  
Low Permeability ◽  
Co2 Flooding ◽  
Low Permeability Reservoirs

scholarly journals Nonlinear Flow Characteristics and Horizontal Well Pressure Transient Analysis for Low-Permeability Offshore Reservoirs

2015 ◽  
Vol 2015 ◽  
pp. 1-13 ◽  
Author(s):  
Jianchun Xu ◽  
Ruizhong Jiang ◽  
Wenchao Teng
Keyword(s):  
Horizontal Well ◽  
Flow Characteristics ◽  
Stress Sensitivity ◽  
Nonlinear Flow ◽  
Absolute Permeability ◽  
Low Permeability ◽  
Threshold Pressure Gradient ◽  
Pressure Transient ◽  
Permeability Modulus ◽  
Low Permeability Reservoirs

Threshold pressure gradient (TPG) and stress sensitivity which cause the nonlinear flow in low permeability reservoirs were carried out by experiments. Firstly, the investigation of existing conditions of TPG for oil flow in irreducible water saturation low-permeability reservoirs was conducted and discussed, using the cores from a real offshore oilfield in China. The existence of TPG was proven. The relationship between TPG and absolute permeability was obtained by laboratory tests. TPG increases with decreasing absolute permeability. Then, stress sensitivity experiment was carried out through depressurizing experiment and step-up pressure experiment. Permeability modulus which characterizes stress sensitivity increases with decreasing absolute permeability. Consequently, a horizontal well pressure transient analysis mathematical model considering threshold pressure gradient and stress sensitivity was established on the basis of mass and momentum conservation equations. The finite element method (FEM) was presented to solve the model. Influencing factors, such as TPG, permeability modulus, skin factor, wellbore storage, horizontal length, horizontal position, and boundary effect on pressure and pressure derivative curves, were also discussed. Results analysis demonstrates that the pressure transient curves are different from Darcy’s model when considering the nonlinear flow characteristics. Both TPG and permeability modulus lead to more energy consumption and the reservoir pressure decreases more than Darcy’s model.

Potential to enhance CO2 flooding in low permeability reservoirs by alcohol and surfactant as co-solvents

2019 ◽  
Vol 182 ◽  
pp. 106305 ◽  
Author(s):  
Mingchen Ding ◽  
Yefei Wang ◽  
Wei Wang ◽  
Hailong Zhao ◽  
Dexin Liu ◽  
...  
Keyword(s):  
Low Permeability ◽  
Co2 Flooding ◽  
Low Permeability Reservoirs

scholarly journals Study on three phase foam for Enhanced Oil Recovery in extra-low permeability reservoirs

2018 ◽  
Vol 73 ◽  
pp. 55 ◽  
Author(s):  
Ming Zhou ◽  
Juncheng Bu ◽  
Jie Wang ◽  
Xiao Guo ◽  
Jie Huang ◽  
...  
Keyword(s):  
Enhanced Oil Recovery ◽  
Oil Recovery ◽  
Foam Stability ◽  
Temperature Tolerance ◽  
Resistance Coefficient ◽  
Low Permeability ◽  
Displacement Efficiency ◽  
Three Phase ◽  
Profile Control ◽  
Low Permeability Reservoirs

Poly (MSt-MMA) nanosphere as foam stabilizing agent was synthesized by emulsion polymerization. The three phase foam was prepared with Disodium 4-Dodecyl-2,4′-Oxydiben Zenesulfonate (DOZS) as foaming agent, Hydrolyzed Polyacrylamide (HPAM) and synthesized poly (MSt-MMA) nanospheres as the mixed foam stabilizing agents. It had outstanding foaming performance and foam stability. The optimal three phase foam system consisting of 0.12 wt% HPAM, 0.04 wt% poly (MSt-MMA) nanospheres and 0.12 wt% DOZS by orthogonal experiment, had high apparent viscosity, which showed that three components had a very good synergistic effect. The three phase foam’s temperature tolerance and salt tolerance were researched in laboratory tests. Flooding oil experiment showed that the average displacement efficiency of three phase foam system was 16.1 wt% in single core experiments and 21.7 wt% in double core experiments. Resistance coefficient of low permeability core was more than those of high permeability core, but their residual resistance coefficients were small. The results of core experiment and pilot test indicated that the three phase foam had good profile control ability and generated low damage to the low permeability layer for extra-low permeability reservoirs. Three phase foam flooding has great prospects for Enhanced Oil Recovery (EOR) in extra-low permeability reservoirs.

Smart mobility control agent for enhanced oil recovery during CO2 flooding in ultra-low permeability reservoirs

Fuel ◽  
2019 ◽  
Vol 241 ◽  
pp. 442-450 ◽  
Author(s):  
Yan Zhang ◽  
Mingwei Gao ◽  
Qing You ◽  
Hongfu Fan ◽  
Wenhui Li ◽  
...  
Keyword(s):  
Enhanced Oil Recovery ◽  
Oil Recovery ◽  
Control Agent ◽  
Mobility Control ◽  
Low Permeability ◽  
Co2 Flooding ◽  
Smart Mobility ◽  
Low Permeability Reservoirs

Study on Gas Channeling Characteristics and Suppression Methods in CO2 Flooding for Low Permeability Reservoirs

2011 ◽  
Author(s):  
Rui Wang ◽  
Cheng Yuan Lv ◽  
Zengmin Lun ◽  
Xiang-an Yue ◽  
Renbao Zhao ◽  
...  
Keyword(s):  
Low Permeability ◽  
Co2 Flooding ◽  
Gas Channeling ◽  
Low Permeability Reservoirs
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