A Compositional Model for Gas Injection IOR/EOR in Tight Oil Reservoirs Under Coupled Nanopore Confinement and Geomechanics Effects

2019 ◽  
Author(s):  
Ye Tian ◽  
Yi Xiong ◽  
Lei Wang ◽  
Zhengdong Lei ◽  
Yuan Zhang ◽  
...  
Keyword(s):  
Gas Injection ◽  
Oil Reservoirs ◽  
Tight Oil ◽  
Compositional Model ◽  
Tight Oil Reservoirs ◽  
Nanopore Confinement

scholarly journals Optimization of triple-alternating-gas (TAG) injection technique for enhanced oil recovery in tight oil reservoirs

2021 ◽  
Author(s):  
Mvomo Ndzinga Edouard ◽  
Pingchuan Dong ◽  
Chinedu J. Okere ◽  
Luc Y. Nkok ◽  
Abakar Y. Adoum ◽  
...  
Keyword(s):  
Enhanced Oil Recovery ◽  
Oil Recovery ◽  
Gas Injection ◽  
Oil Reservoirs ◽  
Recovery Factor ◽  
Injection Technique ◽  
Tight Oil ◽  
Compositional Model ◽  
Injection Scheme ◽  
Tight Oil Reservoirs

AbstractAfter single-gas (SG) injection operations in tight oil reservoirs, a significant amount of oil is still unrecovered. To increase productivity, several sequencing gas injection techniques have been utilized. Given the scarcity of research on multiple-gas alternating injection schemes, this study propose an optimized triple-alternating-gas (TAG) injection for improved oil recovery. The performance of the TAG process was demonstrated through numerical simulations and comparative analysis. First, a reservoir compositional model is developed to establish the properties and composition of the tight oil reservoir; then, a suitable combination for the SG, double alternating gas (DAG), and TAG was selected via a comparative simulation process. Second, the TAG process was optimized and the best case parameters were derived. Finally, based on the oil recovery factors and sweep efficiencies, a comparative simulation for SG, DAG, and TAG was performed and the mechanisms explained. The following findings were made: (1) The DAG and TAG provided a higher recovery factor than the SG injection and based on recovery factor and economic advantages, CO2 + CH4 + H2S was the best choice for the TAG process. (2) The results of the sensitivity analysis showed that the critical optimization factors for a TAG injection scheme are the injection and the production pressures. (3) After optimization, the recovery factor and sweep efficiency of the TAG injection scheme were the best. This study promotes the understanding of multiple-gas injection enhanced oil recovery (EOR) and serves as a guide to field design of gas EOR techniques.

scholarly journals Simulation of High Water-Cut in Tight Oil Reservoirs during Cyclic Gas Injection

2019 ◽  
Author(s):  
Chi Zhang ◽  
Ye Tian ◽  
Yizi Shen ◽  
Bowen Yao ◽  
Yu-Shu Wu
Keyword(s):  
Gas Injection ◽  
High Water ◽  
Oil Reservoirs ◽  
Tight Oil ◽  
Tight Oil Reservoirs ◽  
High Water Cut ◽  
Water Cut

scholarly journals Experimental Study on EOR Performance of Natural Gas Injection in Tight Oil Reservoirs

2019 ◽  
Vol 252 (5) ◽  
pp. 052021
Author(s):  
Haiyang Yu ◽  
Zhewei Chen ◽  
Xin Lu ◽  
Shiqing Cheng ◽  
Youan He ◽  
...  
Keyword(s):  
Experimental Study ◽  
Natural Gas ◽  
Gas Injection ◽  
Oil Reservoirs ◽  
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 Hydrocarbon Gas Flooding Optimization considering Complex Fracture Networks through Numerical Simulation in the Tight Oil Reservoirs

Lithosphere ◽  
2021 ◽  
Vol 2021 (Special 4) ◽  
Author(s):  
Yong Qin ◽  
Haochuan Zhang ◽  
Chang Liu ◽  
Haifeng Ding ◽  
Tianyu Liu ◽  
...  
Keyword(s):  
Oil Recovery ◽  
Gas Injection ◽  
Oil Reservoirs ◽  
Tight Oil ◽  
Oil Reservoir ◽  
Fracture Networks ◽  
Complex Fracture ◽  
Gas Flooding ◽  
Hydrocarbon Gas ◽  
Tight Oil Reservoirs

Abstract Field data indicates that oil production decline quickly and the oil recovery factor is low due to low permeability and insufficient energy in the tight oil reservoirs. Enhanced oil recovery (EOR) is required to improve the oil production rates of tight oil reservoirs. Gas flooding is a good means to supplement formation energy and improve oil recovery factor, especially for hydrocarbon gas flooding when CO2 is insufficient. Due to the permeability in some areas is too low, the injected gas cannot spread farther, and the EOR performance is poor. So multifractured horizontal well (MFHW) are usually used to assist gas injection in oilfields. At present, there are few studies on the optimization of hydrocarbon gas flooding parameters especially under the complex fracture network. This article uses unstructured grids to characterize the complex fracture networks, which more realistically shows the flow of formation fluids. Based on actual reservoir data, this paper establishes the numerical model of hydrocarbon gas flooding under complex fracture networks. The article conducts numerical simulation to analyze the effect of different parameters on well performance and provides the optimal injection and production parameters for hydrocarbon gas flooding in the M tight oil reservoir. The optimal injection-production well spacing of the M tight oil reservoir is about 800 to 900 m. The EOR performance is better when the total gas injection rates are about 0.45 HCPV, and gas injection rates of each well are about 3000 to 3500 m3/d (0.021 to 0.025 HCPV/a). The recommended injection-production ratio is about 1.1 to 1.2. This work can offer engineers guidance for hydrocarbon gas flooding of the MFHW with complex fracture networks. Hydrocarbon gas flooding in tight oil reservoirs can enhance oil recovery. The findings of this study can help for a better understanding of the influence of different parameters on hydrocarbon gas flooding in the M tight oil reservoir. This work can also offer engineers guidance for hydrocarbon gas flooding of the MFHW with complex fracture networks.

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