Pore–throat structure and fractal characteristics of tight sandstones in Yanchang Formation, Ordos Basin

Qu, Yiqian; Sun, Wei; Tao, Rongde; Luo, Bin; Chen, Lei; Ren, Dazhong

doi:10.1016/j.marpetgeo.2020.104573

Cited by 60 publications

(59 citation statements)

References 42 publications

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“…Exploration surveys have revealed both the resource potential of and the heterogeneities found within deep clastic reservoirs. To a large extent, the physical properties of the sandstone in the reservoir are dictated by the pore structure (Qu et al, 2020). Therefore, understanding the complexities of the reservoir pore structure is important for both the academic and industrial communities.…”

Section: Introductionmentioning

confidence: 99%

“…Some analytical tools and techniques that have been employed to quantify the reservoir pore type, geometry, connectivity, and structure include thin sections, scanning electron microscopy, mercury intrusion capillary pressure (MIP) experiments, N 2 and CO 2 gas adsorption, and nuclear magnetic resonance (NMR) (Clarkson et al, 2012; Desbois, Urai, Kukla, Konstanty, & Baerle, 2011; R. L. Guo et al, 2020; Nooruddin, Hossain, Hasan, & Okasha, 2014; Qu et al, 2020; Ross & Bustin, 2008; K. Zhang et al, 2018). Due to its efficiency and low cost, MIP is one of the most common methods used to characterize the microscopic pore structure (K. Zhang et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

“…Due to its efficiency and low cost, MIP is one of the most common methods used to characterize the microscopic pore structure (K. Zhang et al, 2018). From a sample preservation and accuracy standpoint, NMR is another popular tool used to describe the reservoir pore structure (Qu et al, 2020). Unsurprisingly, an integrated MIP/NMR approach is a highly effective method for investigating the pore structure of a given reservoir.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, understanding the complexities of the reservoir pore structure is important for both the academic and industrial communities. Some analytical tools and techniques that have been employed to quantify the reservoir pore type, geometry, connectivity, and structure include thin sections, scanning electron microscopy, mercury intrusion capillary pressure (MIP) experiments, N 2 and CO 2 gas adsorption, and nuclear magnetic resonance (NMR) (Clarkson et al, 2012;Desbois, Urai, Kukla, Konstanty, & Baerle, 2011; R. L. Guo et al, 2020;Nooruddin, Hossain, Hasan, & Okasha, 2014;Qu et al, 2020;Ross & Bustin, 2008;K. Zhang et al, 2018).…”

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confidence: 99%

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Micro‐ and nanoscale pore‐throat structure, fractal characteristics, and permeability estimation models in deep sandstones: Palaeogene Shahejie Formation, Nanpu Sag, NE China

et al. 2021

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Long‐term burial and strong diagenesis modification result in highly heterogeneous pore structures in deep clastic reservoirs; these heterogeneities exert a controlling influence over the development of these deep petroleum systems. A clear understanding of the pore structure simplifies the tasks of identifying and modelling reservoirs for the purposes of hydrocarbon exploration. This study characterizes the mineral compositions, physical properties, and pore systems of the first member of the Palaeogene Shahejie Formation (Es1) in the Nanpu Sag using thin section and scanning electron microscope observations, X‐ray diffraction measurements, mercury intrusion capillary pressure, and nuclear magnetic resonance data. Our results show that the Es1 sandstones typically fall into one of three different pore‐throat sizes: mainly 10 μm (type‐I), 1 μm (type‐II), and less than 1 μm (type‐III). Between type‐I and type‐III reservoirs, the pore system changes from residual intergranular pore (InterP) and secondary InterP to secondary intragranular pores (IntraP) and intercrystalline pores. The fractal theory is selected to quantify the heterogeneity of the pore‐throat structure, due to the existence of an irregular and complex pore system (IntraP and intercrystalline pores), the type‐III reservoir has the highest fractal dimension, which indicates that the complex pore‐throat structure is not conducive to the formation of high‐quality deep sandstone reservoirs. Using the fractal dimension and displacement pressure, a novel permeability prediction is proposed, compared with the previous method, the new model is simpler and more effective. Our research can deepen the geological understanding of deep‐burial sandstone reservoirs and further guide petroleum exploration.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Micro‐ and nanoscale pore‐throat structure, fractal characteristics, and permeability estimation models in deep sandstones: Palaeogene Shahejie Formation, Nanpu Sag, NE China

et al. 2021

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“…Recent years, many researches have been carried out on pore segmentation of tight sandstone. From the qualitative evaluation of pores develops into the quantitative evaluation of pore distribution at the micron-nanometer level (Loucks et al, 2009;Andrew et al, 2014;Liu et al, 2018;Zhu et al, 2018;Li et al, 2019;Qu et al, 2020;Shan et al, 2020;, from 2D analysis relying on scanning electron microscopy (SEM) develops into 3D feature analysis using focused ion beam scanning electron microscopy (FIB-SEM) (Curtis et al, 2012;Tartakovsky et al, 2015;Shaina et al, 2016;Alexandra et al, 2020;Chen et al, 2020;Choi et al, 2020;Goral et al, 2020). But most of these researches are focus on imaging technology, the essence of the pore segmentation method is still based on the gray-scale threshold without any significantly improvement (Kang et al, 2019;Shou et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

Dynamic capillary pressure analysis of tight sandstone based on digital rock model

et al. 2020

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In recent studies, dynamic capillary pressure has shown significant impacts on the flow behaviors in porous media under transient flow condition. However, the effect of dynamic capillary pressure effect on tight sandstone is still not very clear. Since lattice Boltzmann method (LBM) is a very promising and widely used method in analyzing flow behaviors, therefore, a two-phase D3Q27 LBM model is adopted in this paper to simulate the flow behaviors and analyze the dynamic capillary pressure effect in tight sandstone. Moreover, a new pore segmentation method for tight sandstone base on U-net deep learning model is implemented in this study to improve the pore boundary qualities of pore space, which is crucial for two-phase LBM simulation of tight sandstone. A total of 3800 3D sub-volume data sets extracted from computed tomography data of 19 tight sandstone samples are selected as ground truth data to train the network and segment the pore space afterward. The simulation results based on the segmented digital rock model, show that nonwetting phase fluid prefer the path with lower dynamic capillary pressure in the seepage process before breaking through the porous model. Furthermore, the increase of injection rate causes the saturation changes more quickly, injection rate also shows apparent positive correlation relationship with capillary pressure, which implies that dynamic capillary pressure effect also exists in tight sandstone, and LBM based two-phase flow simulation could be used to quantitatively analyze such effect in tight sandstone.

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Pore‐throat structure characteristics and fluid mobility analysis of tight sandstone reservoirs in Shaximiao Formation, Central Sichuan

et al. 2023

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The pore‐throat structure and fluid mobility are the key factors of tight sandstone reservoir classification and evaluation. Taking the Jurassic Shaximiao Formation tight sandstone reservoir in Central Sichuan Basin as an example, 19 samples were analysed by casting thin sections, scanning electron microscopy, high‐pressure mercury injection and nuclear magnetic resonance to clarify the pore‐throat structure, the fluid motility and its controlling factors. The results show that the pore type of Shaximiao Formation tight sandstone reservoir consist of intergranular pores, dissolved pores and a few microfractures. Based on the feature of capillary pressure curve, the pore‐throat structure was classified into three types, corresponding to different movable fluid characteristics. The Type I has large pore and throat radius, good pore‐throat connectivity, small fractal dimension, weak reservoir heterogeneity and strong fluid motility. The distribution range of pore‐throat radius is mainly from 0.3 to 1.1 μm and the average movable fluid porosity (MFP) and movable fluid saturation (MFS) are 6.04% and 49.93%. The Type II has poor pore‐throat sorting, weak fluid motility and the distribution range of pore‐throat radius is 0.01–0.03 μm and 0.2–0.8 μm. The average MFP and MFS of Type II are 1.13% and 14.3%. The Type III has the smallest pore‐throat radius and the largest fractal dimension, corresponding to the most complex pore‐throat structure, which lead to the worst fluid mobility. The average MFP and MFS are 0.49% and 12.76%. The fluid mobility of the tight sandstone reservoir is affected by physical properties and pore‐throat structure. The reservoirs with large pore‐throat size, good connectivity between pore and throat, and low heterogeneity have higher MFP and saturation. Moreover, the mineral compositions have different effects on fluid mobility of the tight sandstone. The feldspar positively affects fluid mobility, while the clay minerals negatively affect fluid mobility.

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Pore–throat structure and fractal characteristics of tight sandstones in Yanchang Formation, Ordos Basin

Cited by 60 publications

References 42 publications

Micro‐ and nanoscale pore‐throat structure, fractal characteristics, and permeability estimation models in deep sandstones: Palaeogene Shahejie Formation, Nanpu Sag, NE China

Micro‐ and nanoscale pore‐throat structure, fractal characteristics, and permeability estimation models in deep sandstones: Palaeogene Shahejie Formation, Nanpu Sag, NE China

Dynamic capillary pressure analysis of tight sandstone based on digital rock model

Pore‐throat structure characteristics and fluid mobility analysis of tight sandstone reservoirs in Shaximiao Formation, Central Sichuan

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