Effect of Large Capillary Pressure on Fluid Flow and Transport in Stress-sensitive Tight Oil Reservoirs

2015 ◽  
Author(s):  
Yi Xiong ◽  
Phil Winterfeld ◽  
Cong Wang ◽  
Zhaoqin Huang ◽  
Yu-Shu Wu
Keyword(s):  
Fluid Flow ◽  
Capillary Pressure ◽  
Oil Reservoirs ◽  
Tight Oil ◽  
Flow And Transport ◽  
Tight Oil Reservoirs

Numerical modeling of fluid flow in tight oil reservoirs considering complex fracturing networks and Pre-Darcy flow

2021 ◽  
Vol 207 ◽  
pp. 109050
Author(s):  
Linkai Li ◽  
Xiao Guo ◽  
Ming Zhou ◽  
Zhangxin Chen ◽  
Lin Zhao ◽  
...  
Keyword(s):  
Numerical Modeling ◽  
Fluid Flow ◽  
Oil Reservoirs ◽  
Darcy Flow ◽  
Tight Oil ◽  
Tight Oil Reservoirs

scholarly journals Nanopore Confinement Effect on the Phase Behavior of CO2/Hydrocarbons in Tight Oil Reservoirs considering Capillary Pressure, Fluid-Wall Interaction, and Molecule Adsorption

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
Zhixue Zheng ◽  
Yuan Di ◽  
Yu-Shu Wu
Keyword(s):  
Phase Behavior ◽  
Pore Size ◽  
Capillary Pressure ◽  
Confinement Effect ◽  
Oil Reservoirs ◽  
Co2 Injection ◽  
Tight Oil ◽  
Tight Reservoirs ◽  
Tight Oil Reservoirs ◽  
Nanopore Confinement

The pore sizes in tight reservoirs are nanopores, where the phase behavior deviates significantly from that of bulk fluids in conventional reservoirs. The phase behavior for fluids in tight reservoirs is essential for a better understanding of the mechanics of fluid flow. A novel methodology is proposed to investigate the phase behavior of carbon dioxide (CO2)/hydrocarbons systems considering nanopore confinement. The phase equilibrium calculation is modified by coupling the Peng-Robinson equation of state (PR-EOS) with capillary pressure, fluid-wall interaction, and molecule adsorption. The proposed model has been validated with CMG-Winprop and experimental results with bulk and confined fluids. Subsequently, one case study for the Bakken tight oil reservoir was performed, and the results show that the reduction in the nanopore size causes noticeable difference in the phase envelope and the bubble point pressure is depressed due to nanopore confinement, which is conductive to enhance oil recovery with a higher possibility of achieving miscibility in miscible gas injection. As the pore size decreases, the interfacial tension (IFT) decreases whereas the capillary pressure increases obviously. Finally, the recovery mechanisms for CO2 injection are investigated in terms of minimum miscibility pressure (MMP), solution gas-oil ratio, oil volume expansion, viscosity reduction, extraction of lighter hydrocarbons, and molecular diffusion. Results indicate that nanopore confinement effect contributes to decrease MMP, which suppresses to 650 psi (65.9% smaller) as the pore size decreases to 2 nm, resulting in the suppression of the resistance of fluid transport. With the nanopore confinement effect, the CO2 solution gas-oil ratio and the oil formation volume factor of the oil increase with the decrease of pore size. In turn, the oil viscosity reduces as the pore size decreases. It indicates that considering the nanopore confinement effect, the amount of gas dissolved into crude oil increases, which will lead to the increase of the oil volume expansion and the decrease of the viscosity of crude oil. Besides, considering nanopore confinement effect seems to have a slightly reduced effect on extraction of lighter hydrocarbons. On the contrary, it causes an increase in the CO2 diffusion coefficient for liquid phase. Generally, the nanopore confinement appears to have a positive effect on the recovery mechanisms for CO2 injection in tight oil reservoirs. The developed novel model could provide a better understanding of confinement effect on the phase behavior of nanoscale porous media in tight reservoirs. The findings of this study can also help for better understanding of a flow mechanism of tight oil reservoirs especially in the case of CO2 injection for enhancing oil recovery.

scholarly journals Mechanism of Permeability and Oil Recovery during Fracturing in Tight Oil Reservoirs

Processes ◽  
2020 ◽  
Vol 8 (8) ◽  
pp. 972
Author(s):  
Yujie Bai ◽  
Guangsheng Cao ◽  
Guanglei Wei ◽  
Xiaohan Nan ◽  
Qingchao Cheng ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Crude Oil ◽  
Oil Recovery ◽  
Oil And Gas ◽  
Oil Reservoirs ◽  
Dynamics Simulation ◽  
Tight Oil ◽  
Fracturing Fluid ◽  
Flow Through ◽  
Tight Oil Reservoirs

In this study, the effect of fracturing fluid on the permeability of tight oil reservoirs is analyzed through oil absorption. The mechanism of permeation and absorption in tight oil reservoirs was studied using the molecular dynamics simulation of fluid flow through fractures in porous media containing crude oil. The influence of surfactants on the adsorption characteristics of crude oil formations on rock walls was also examined. The research results show that the introduction of the appropriate surfactant to the fracturing fluid could accelerate the rate of percolation and recovery as well as improve the recovery rate of absorption. The optimal concentration of polyoxyethylene octyl phenol ether-10 (OP-10) surfactant in the fracturing fluid was 0.9%. When the percolation reached a certain stage, the capillary forces in the crude oil and percolation medium in the pore stabilized; accordingly, the crude oil from the pore roar should be discharged at the earliest. The fluid flow through the fracture effectively carries the oil seeping out near the fractured wall to avoid the stability of the seepage and absorption systems. The surfactant can change the rock absorbability for crude oil, the result of which is that the percolating liquid can adsorb on the rock wall, thus improving the discharge of crude oil. The results of this study are anticipated to significantly contribute to the advancement of oil and gas recovery from tight oil reservoirs.

scholarly journals Stimulation and Sequestration Mechanism of CO2 Waterless Fracturing for Continental Tight Oil Reservoirs

ACS Omega ◽  
2021 ◽  
Author(s):  
Jiaping Tao ◽  
Siwei Meng ◽  
Xu Jin ◽  
Jianguo Xu ◽  
Qinghai Yang ◽  
...  
Keyword(s):  
Oil Reservoirs ◽  
Tight Oil ◽  
Tight Oil Reservoirs ◽  
Waterless Fracturing
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