Article
Energy & Fuels
Xian Shi, Caiyun Xiao, Hongjian Ni, Qi Gao, Lei Han, Dianshi Xiao, Shu Jiang
Summary: In order to apply supercritical carbon dioxide (ScCO2) fracturing on tight sandstone properly, the effects of ScCO2 on pore structure were investigated. ScCO2 treatment was applied to three sets of tight sandstone samples, and the pore structure was characterized using high-pressure mercury intrusion porosimetry and nuclear magnetic resonance. The results showed that after SCCO2 treatment, the number of transitional pores decreased significantly, while the number of mesopores and macropores increased. The fractal dimension characteristics indicated that the pore structure became more complicated and heterogeneous, and large pores had a higher fractal dimension than small pores. The content of calcite sharply decreased while clay, feldspar, and plagioclase content had a slight drop after ScCO2 treatment, affecting the alternation of pore structure. Thus, the accumulative pore volume and pore connectivity do not always increase after ScCO2 exposure due to potential pore and channel clogging from re-precipitation and fine migration.
Article
Engineering, Chemical
Mingyang Yang, Shijun Huang, Kuiqian Ma, Fenglan Zhao, Haoyue Sun, Xinyang Chen
Summary: This paper investigates the effects of injecting CO2 into tight oil reservoirs for enhanced oil recovery and CO2 sequestration. The study develops a pore size correction model and conducts experiments to analyze the displacement behaviors in different pore scales. The results reveal the impact of different pore scales on the efficiency of CO2 flooding and huff-n-puff processes.
Article
Geosciences, Multidisciplinary
Jingdong Liu, Cunjian Zhang, Youlu Jiang, Shuai Hou
Summary: The pore structure of ultra-tight reservoirs plays a key role in controlling quality and fluid flow. The relationship between pore types and rock types was identified, with different types of sandstone reservoirs having distinct pore characteristics. High-pressure mercury intrusion and fractal theory were used for quantitative assessment.
MARINE AND PETROLEUM GEOLOGY
(2022)
Article
Chemistry, Multidisciplinary
Haiming Gao, Wanfen Pu
Summary: The study concludes that supercritical CO2 plays a positive role in improving recovery in tight conglomerate reservoirs. The optimal injection volume, soaking time, and throughput cycles were determined to be 0.50 PV, 2 hours, and 3 cycles respectively.
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
Geosciences, Multidisciplinary
Wentong Zhang, Hai Huang, Zhengfu Ning, Juhao Cao, Jun Ni, Zejiang Jia, Bing Yang, Zhilin Cheng, Fangtao Lyu
Summary: This study investigates the effect of direct current (DC) stimulation on oil recovery in tight sandstone reservoirs. It is found that the size and number of nanopores increase with increasing DC voltage. Low DC voltage can transform submicropores to micropores, while high voltage has the opposite effect. These findings provide valuable insights for the development of DC voltage-related technologies in hydrocarbon recovery from porous media.
JOURNAL OF APPLIED GEOPHYSICS
(2023)
Article
Energy & Fuels
Jianmeng Sun, Ping Feng, Peng Chi, Weichao Yan
Summary: Through experiments and numerical simulations, it is found that pore structure parameters of tight sandstone have a significant influence on the electrical properties. Constructing a saturation model can improve the calculation accuracy.
Article
Chemistry, Multidisciplinary
Lei Liu, Jun Yao, Hai Sun, Lei Zhang, Kai Zhang
Summary: Studying the influence of fractures on the rock topological structure and flow characteristics in tight sandstone reservoirs is crucial. This study utilizes digital rock analysis technology to reveal the impact of fracture aperture and length on pore throat structure, permeability, and fluid flow in different directions. The findings highlight the importance of fracture characteristics in determining the properties and behavior of tight sandstone reservoirs and showcase the usefulness of digital rock analysis technology in understanding complex microstructures.
APPLIED SCIENCES-BASEL
(2023)
Article
Geosciences, Multidisciplinary
Quanpei Zhang, Yicang Liu, Botao Wang, Jinfeng Ruan, Na Yan, Hua Chen, Qin Wang, Gangwei Jia, Ruinan Wang, Hong Liu, Chengwei Xue, Feilong Liu, Huan Yang, Yushuang Zhu
Summary: The pore-throat structure of tight sandstone reservoirs plays a crucial role in determining the mobility of reservoir fluids, with different pore-throat structure types having significant impact on the saturation and permeability of movable oil.
MARINE AND PETROLEUM GEOLOGY
(2022)
Article
Geosciences, Multidisciplinary
Qing Guo, Mancang Dong, Hengbo Mao, Jiangtao Ju
Summary: Quantitatively characterizing the micro-scale heterogeneity of pore throats is essential in accurately describing the influence of pore structures on fluid occurrence characteristics in tight sandstone reservoirs. This study systematically investigated the pore throat heterogeneity of a specific reservoir and its impact on fluid occurrence state using various testing methods. The research found that intergranular pores and feldspar dissolution pores were the main pore types in the target layer. The study also revealed that the uniformity of throat development and pore radius played significant roles in determining the reservoir permeability. Additionally, different pore types exhibited distinct movable fluid saturations.
FRONTIERS IN EARTH SCIENCE
(2022)
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.
Article
Energy & Fuels
Hongping Liu, Yang Luo, Yujing Meng, Gaojian Xiao, Yanchao Zhao, Sibin Zhou, Longkan Shao
Summary: Tight oil sandstones have large oil reserves but low waterflooding efficiency and oil recovery. The movable oil saturation (MOS) is critical for evaluating oil recovery in these reservoirs. This study found that factors like porosity and permeability do not have a significant relationship with MOS, while parameters like S apex, R-max/R-50, and MFS show a linear relationship with MOS. The key factor controlling MOS is the volume of well-connected pores regardless of rock type.
JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING
(2021)
Article
Energy & Fuels
Qiang Guo, Jing Ba, Cong Luo, Mengqiang Pang
Summary: This study introduces a novel reservoir parameter inversion method for tight sandstone reservoirs, which builds the forward operator to directly invert observed seismic data for reservoir parameters, and iteratively updates pore aspect ratios to address the complex pore structure. By utilizing Bayesian inversion with the prior Gaussian mixture model, the method stabilizes the inversion process and achieves optimal solutions by considering the complex prior distributions of reservoir parameters in different lithofacies.
JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING
(2021)
Article
Environmental Sciences
Zhiqi Guo, Xiaoying Qin, Cai Liu
Summary: This study proposes a rock-physics-based approach to compute the pore-microfracture indicator (PMI) from elastic properties for pore structure evaluation in tight sandstones. Seismic characterization of pores and microfractures provides valuable information in predicting high-quality tight gas sandstone reservoirs. The computed PMI using seismic data can predict permeable zones and provide valuable information for sweet spot characterization in tight gas sandstone reservoirs.
Article
Geosciences, Multidisciplinary
Wenjun Xu, Jinzhou Zhao, Jianguo Xu
Summary: This paper introduces a new Fracability Index (FI) model, which evaluates the potential candidate layers for hydraulic fracturing in unconventional reservoirs by considering the possibilities of complex hydraulic fracture network and large stimulation reservoir volume. The model takes into account essential factors like brittleness, fracture toughness, natural fractures, and in situ stresses, providing a useful tool for selecting the most suitable candidates for fracturing treatments.
NATURAL RESOURCES RESEARCH
(2021)
