Article
Energy & Fuels
Mingyu Cai, Yuliang Su, Shiyuan Zhan, Derek Elsworth, Lei Li
Summary: This study proposes a relative permeability model that incorporates complex interactions between fluids and solids in reservoirs. The model predicts the relative permeability to CO2 flooding in the near-miscible region using Gibbs free energy interpolation. The thermodynamic phase behavior of fluids in nanopores is considered by applying critical shifts in temperatures and pressures. The model can be integrated with a compositional simulator to address macroscopic problems in unconventional reservoirs.
Article
Biotechnology & Applied Microbiology
Jie Chi, Xing Zhang
Summary: With the increasing global demand for oil and gas fuels, the development of extremely low permeability oil and gas reservoirs has become increasingly important. The immiscible displacement method can achieve better development effect, while stress sensitivity factors also impact the recovery degree of reservoirs.
ENVIRONMENTAL TECHNOLOGY & INNOVATION
(2021)
Article
Energy & Fuels
Qian Wang, Jian Shen, Piroska Lorinczi, Paul Glover, Shenglai Yang, Hao Chen
Summary: Miscible CO2-SAG flooding, by adding a CO2 soaking process after CO2 breakthrough, improves the recovery and permeability variation during CO2 flooding, especially in areas with low permeability and high residual oil saturation. The soaking process leads to more homogeneous distribution of permeability decline and a greater increase in permeability decline, with significant improvement in recovery observed in lower permeability cores.
JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING
(2021)
Article
Geochemistry & Geophysics
Anlun Wang, Xiaoqing Zhao, Jianguang Wei, Lisha Zhao, Guangliang An, Xiaofeng Zhou, Jiangtao Li, Xuedong Shi, Ying Yang, Gen Li
Summary: Miscible CO2 flooding is an effective method for oil recovery, but the heterogeneity at the pore level can significantly affect its efficiency. This study proposes a method based on NMR T-2 spectrum to determine the distribution of residual oil in sandstone without the need for additional agents. The results show that the residual oil is mainly distributed in small pore throats, and the heterogeneity of pore size affects the displacement efficiency. There are also unswept areas with residual oil that can be targeted for further improvement.
Article
Thermodynamics
Tong Zhang, Ming Tang, Yankun Ma, Guangpei Zhu, Qinghe Zhang, Jun Wu, Zhizheng Xie
Summary: The investigation of CO2/water flooding mechanism in ultralow-permeability oil reservoir is crucial for enhanced oil recovery. The study conducted core flooding experiments under different in situ stresses and used online LF-NMR technology to monitor multiphase flow and pore-fracture behavior. The findings showed that percolation pore dominated volumetric sweep efficiency, capillary pressure influenced oil recovery in adsorption pore, and viscosity fingering and thief channeling occurred in migration pore. CO2 flooding mainly relied on percolation pore and migration pore for oil recovery, while water flooding saw contributions from all pores. The research also observed decreased oil recovery in pore core with increased in situ stress during CO2/water flooding. The fracture and fracture-connected pore were displaced first in CO2 flooding, and the evolving residual oil showed increased fractal dimension with higher in situ stress in both CO2 and water flooding. The oil recovery rate in CO2 flooding was about 10 times that in water flooding. The peak oil recovery occurred at 25 MPa in CO2/water flooding, and the influence of fractures was more significant in water flooding. These findings provide valuable guidance for enhanced oil recovery in ultralow-permeability reservoirs.
Article
Geosciences, Multidisciplinary
Sen Yang, Yangmengzhe Xu, Zhiwei Huang, Qunshuang Zhang, Ting Liu, Xuelei Li
Summary: This study conducted experimental evaluation and numerical simulation research on the adaptability of CO2 flooding in beach-bar sand reservoirs in the Dongying Sag. The results showed that the recovery factor of CO2 flooding is higher than that of water flooding, and the displacement distance of CO2 in the reservoir is significantly larger than that of water injection development. Therefore, CO2 flooding can effectively increase the oil recovery and economic benefits of this type of reservoir.
FRONTIERS IN EARTH SCIENCE
(2022)
Article
Energy & Fuels
Yuxia Wang, Qinghua Shang, Lifa Zhou, Zunsheng Jiao
Summary: The study found that macroscopic permeability heterogeneity in tight sandstone reservoirs can impact the efficiency of CO2-EOR technology, while a high-low permeability model can improve CO2 injectivity, maintain high pressure levels, and increase oil displacement efficiency.
JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING
(2021)
Article
Energy & Fuels
Dali Hou, Jinghui Li, Hongming Tang, Jianchun Guo, Xueni Xiang
Summary: This paper investigates the application of CO2-water co-injection in low-permeability near-critical volatile reservoirs through experiments and simulations. The results show that CO2-water co-injection can improve oil recovery and increase displacement efficiency, mainly due to the dissolution of CO2 in water, effectively inhibiting gas channeling.
Article
Energy & Fuels
Mohammed Abdalla Ayoub, Bennet Nii Tackie-Otoo, Siti Hidmayati Binti Zulkefli
Summary: This study investigates the minimum miscibility pressure (MMP) of carbon dioxide (CO2) flooding using a simulation approach and compares different correlations for determining MMP. The impact of MMP and injection rate on oil recovery by CO2 flooding is evaluated using a synthetic reservoir model. The results show that miscible flooding is more effective in improving oil recovery, but immiscible CO2 flooding is a feasible option.
JOURNAL OF PETROLEUM EXPLORATION AND PRODUCTION TECHNOLOGY
(2022)
Article
Energy & Fuels
Ran Lin, Zhihao Yu, Jinzhou Zhao, Caili Dai, Yongpeng Sun, Lan Ren, Mengke Xie
Summary: This study investigates the impact of CO2 flooding on tight sandstones, revealing that the corrosion process enhances porosity and liquid permeability while reducing the pore and throat diameter for movable fluids. XRD analysis indicated main corrosion minerals to be calcite, dolomite, and feldspar, with significantly increased corrosion pores post-reaction. These findings suggest improved formation petrophysical properties associated with CO2 flooding in tight sandstones, providing a theoretical basis for the efficient development of tight oil reservoirs.
Article
Geosciences, Multidisciplinary
Chenjun Zhang, Xu Jin, Jiaping Tao, Bo Xiong, Zhijian Pan, Siwei Meng, Bin Ding, Ying Wang, Lihao Liang
Summary: This study comprehensively characterized the microscopic pore throat structure of unconventional tight sandstone reservoirs and prepared a new nanofluid with excellent performance in enhancing oil recovery. The nanofluid remained stable and matched well with the pore throat size, increasing sweep volume effectively and reducing oil-water interfacial tension. Core imbibition experiments demonstrated the superiority of the nanofluid over generic oil-displacing agents in achieving a higher recovery rate for unconventional reservoirs.
FRONTIERS IN EARTH SCIENCE
(2021)
Article
Energy & Fuels
Mukhtar Elturki, Abdulmohsin Imqam
Summary: It is essential to investigate gas injection methods to produce the trapped oil in unconventional resources. However, the injection process can cause asphaltene depositions inside the reservoir, leading to plugging of pores and oil recovery reduction. This study examines the significance of CO2 injection in oil recovery and identifies the critical parameters that could impact the effectiveness of CO2 huff-n-puff operation in unconventional formations.
Article
Thermodynamics
Hao Chen, Xiliang Liu, Chao Zhang, Xianhong Tan, Ran Yang, Shenglai Yang, Jin Yang
Summary: This study focuses on the impact of supercritical CO2 injection on oil recovery in reservoirs, showing that the decrease in gas relative permeability leads to a similar ultimate oil recovery between near-miscible flooding and miscible flooding. A new threshold pressure gradient is proposed as an indicator of reservoir fluids' seepage capacity, emphasizing the importance of CO2-SAG flooding in enhancing oil recovery.
Review
Energy & Fuels
Narendra Kumar, Marcio Augusto Sampaio, Keka Ojha, Hussein Hoteit, Ajay Mandal
Summary: This review extensively discusses the various technical aspects of enhancing oil production through the application of miscible CO2, identifying significant research gaps. It covers multiple aspects from theoretical analysis to laboratory experiments and field applications, providing valuable information for a better understanding of this topic.
Article
Chemistry, Multidisciplinary
Fan Yang
Summary: The study investigates the acidizing problems in the sandstone reservoir of Shanshan oilfield and proposes a combined system of multinanoscale stimulation fluid and mud acid. The research provides a scientific basis for acidizing and stimulation of ultra-low permeability sandstone reservoirs.