Effects of pore-throat structure on gas permeability in the tight sandstone reservoirs of the Upper Triassic Yanchang formation in the Western Ordos Basin, China

Huang, Hexin; Sun, Wei; Ji, Wenming; Zhang, Ronghui; Du, Kun; Zhang, Shaohua; Ren, Dazhong; Wang, Youwei; Chen, Lei; Zhang, Xi

doi:10.1016/j.petrol.2017.10.076

Cited by 101 publications

(83 citation statements)

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“…However, the actual pore structures are more complex than those of the ideal formation. Several scholars have found that an exponential relationship, rather than a linear relationship, exists between the T2 spectrum (ms) and the pore radius (µ m) [23,27,42]: this finding is also supported by Figure 2b,c; the relationship can be expressed as follow:…”

Section: Combining Nmr and Hpmi Methodsmentioning

confidence: 52%

“…The NMR-derived PSD has been determined with imaging methods (e.g., casting thin sections and field emission scanning electro microscopy (FE-SEM)) using a large amount of statistical multi-scale pore radii data [21]. The combination of the throat size distribution of rate controlled porosimetry (RCP) and PSD of NMR has been attempted, but the integrated parts of two techniques requires further study [11,[22][23][24]. Besides, the integration of nitrogen adsorption and NMR to recover the total PSD of tight sandstones only effectively investigates the configuration of pores <50 nm.…”

Section: Introductionmentioning

confidence: 99%

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Multi-Scale Quantitative Characterization of Pore Distribution Networks in Tight Sandstone by integrating FE-SEM, HPMI, and NMR with the Constrained Least Squares Algorithm

Zhou

Shi

et al. 2019

Energies

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The goal of this study was to investigate the impacts of various sedimentary-diagenetic conditions on the macroscopic petrophysical parameters and microscopic pore structures of tight sandstones from the Lower Jurassic Badaowan Formation in the Southern Junggar Basin, China. Based on the traditional methods for establishing pore size distribution, including integrating the results of high-pressure mercury injection, nuclear magnetic resonance, and scanning electron microscopy, the constrained least squares algorithm was employed to automatically determine the porosity contributions of pore types with different origins. The results show that there are six genetic pore types: residual intergranular pores (RIPs), feldspar dissolution pores (FDPs), rock fragment dissolution pores (RFDPs), clay mineral intergranular pores (CIPs), intercrystalline pores of kaolinite (IPKs), and matrix pores (MPs). Four lithofacies were identified: the quartz cemented-dissolution facies (QCDF), carbonate cemented facies (CCF), authigenic clay mineral facies (ACMF), and matrix-caused tightly compacted facies (MCTF). Modified by limited dissolution, the QCDF with a high proportion of macropores (RIPs, FDPs, and RFDPs) exhibited a slightly higher porosity and considerably higher permeability than those of others. A large number of micropores (MPs, CIPs, and IPKs) in MCTF and ACMF led to slightly lower porosities but considerably lower permeabilities. Due to the tightly cemented carbonates in the CCF, its porosity reduced sharply, but the permeability of the CCF remained much higher those of the MCTF and ACMF. The results highlight that a high proportion of macropores with large radii and regular shapes provide more effective percolation paths than storage spaces. Nevertheless, micropores with small radii and complex pore structures have a limited contribution to flow capability. The fractal dimension analysis shows that a high proportion of MPs is the major reason for the heterogeneity in tight sandstones. The formation of larger macropores with smooth surfaces are more conductive for oil and gas accumulation.

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Section: Combining Nmr and Hpmi Methodsmentioning

confidence: 52%

Section: Introductionmentioning

confidence: 99%

Multi-Scale Quantitative Characterization of Pore Distribution Networks in Tight Sandstone by integrating FE-SEM, HPMI, and NMR with the Constrained Least Squares Algorithm

Zhou

Shi

et al. 2019

Energies

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“…Archaean and lower Proterozoic crystalline rocks formed the basin basement. 23,[26][27][28] Permian Shihezi Formation is one of the main pay zones of the Sulige Gas Field, the largest gas field in the basin. It consists of a series of sediments of the deltaic plain subfacies, among which the channel sand body is the target for gas exploration and exploitation.…”

Section: Samples and Experimental Methodologymentioning

confidence: 99%

“…Hence, it is inappropriate to simply treat pores and throats as a whole. 28,35 The shapes of the 20 constant-rate mercury capillary pressure curves can be generally divided into three types. The first type is the pore type, which shows that in the large-throat rock, the mercury injection volume of pores rises rapidly and always exceeds that of throats, even after the mercury injection approaches the equilibrium (Fig.…”

Section: Constant-rate Mercury Injectionmentioning

confidence: 99%

Pore-Throat Structure and Fractal Characteristics of Shihezi Formation Tight Gas Sandstone in the Ordos Basin, China

et al. 2018

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In order to better understand the impact of fractal features of pore-throat structures on effective physical properties of tight gas sandstones, this paper carried out constant-rate mercury ‡ ‡ Corresponding authors. This is an Open Access article published by World Scientific Publishing Company. It is distributed under the terms of the Creative Commons Attribution 4.0 (CC-BY) License. Further distribution of this work is permitted, provided the original work is properly cited. 1840005-1Fractals 2018.26. Downloaded from www.worldscientific.com by 13.66.222.141 on 04/01/19. Re-use and distribution is strictly not permitted, except for Open Access articles. H. Huang et al.injection tests, gas-water permeability analyses, helium-based porosity and nitrogen pulse decay permeability measurements, and SEM and casting thin-section analyses on 20 sandstone samples of the Shihezi Formation from 16 wells of the Sulige Gas Field in the Ordos Basin, China. The fractal dimensions of pores corresponding to two pore radius ranges, namely fractal dimensions D p2 and D p3 , and those of throats also corresponding to two throat radius ranges, namely fractal dimensions D t1 and D t2 , were then calculated using the constant-rate mercury injection data. Fractal dimensions D p2 and D p3 are negatively correlated with the average pore radius and pore volume as well as quartz content, and they are positively related to contents of clay minerals and lithic fragments. Compared with pore fractal dimensions, throat fractal dimensions have lower correlations with throat structural parameters, and show vague relations with mineral compositions. Although the effects imposed by mineral compositions upon throat structures are similar to those upon pore structures, the flake-like and curved shapes of throats result in irregularity of fractal dimensions. Tight gas sandstones, with smaller fractal dimensions D p2 and D p3 , have larger effective porosity, indicating that more gas volumes can be replaced by liquids. As for tight gas sandstones with lower fractal dimensions D p3 and D t2 , the effective gas permeability is relatively high. In such cases, gas can flow more easily through the reservoir.

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“…Tight gas reservoirs have been the highest potential exploration and development field of natural gas in China [1,2]. The resources of tight gas reservoirs are abundant in China, and mainly distributed in Sichuan, Ordos, Songliao, Qaidam, Bohai Bay, Tarim and Junggar basins [3,4]. In recent years, the productions of tight gas reservoirs in China have been increasing year by year, and nearly 80% of the newly proved reserves of PetroChina are in tight gas reservoirs [5].…”

Section: Introductionmentioning

confidence: 99%

Threshold Pore Pressure Gradients in Water-Bearing Tight Sandstone Gas Reservoirs

et al. 2019

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Tight gas reservoirs commonly occur in clastic formations having a complex pore structure and a high water saturation, which results in a threshold pressure gradient (TPG) for gas seepage. The micropore characteristics of a tight sandstone gas reservoir (Tuha oilfield, Xinjiang, China) were studied, based on X-ray diffraction, scanning electron microscopy and high pressure mercury testing. The TPG of gas in cores of the tight gas reservoir was investigated under various water saturation conditions, paying special attention to core permeability and water saturation impact on the TPG. A mathematical TPG model applied a multiple linear regression method to evaluate the influence of core permeability and water saturation. The results show that the tight sandstone gas reservoir has a high content of clay minerals, and especially a large proportion of illite-smectite mixed layers. The pore diameter is distributed below 1 micron, comprising mesopores and micropores. With a decrease of reservoir permeability, the number of micropores increases sharply. Saturated water tight cores show an obvious non-linear seepage characteristic, and the TPG of gas increases with a decrease of core permeability or an increase of water saturation. The TPG model has a high prediction accuracy and shows that permeability has a greater impact on TPG at high water saturation, while water saturation has a greater impact on TPG at low permeability.Energies 2019, 12, 4578 2 of 13 nanometer, which strongly affects the seepage ability of gas in tight gas reservoirs [6]. In addition, it also has a characteristic of high water saturation in tight gas reservoirs, the influence of water saturation on gas seepage is very significant, and a complex relationship between water and gas will be formed [7]. The water in the pores of tight gas reservoirs forms a thin hydration film at the small pore throats, or small water droplets gather and block at the throats to produce the Jamin effect of gas seepage, which will increase the seepage resistance of gas [8][9][10]. These make gas seepage show a characteristic of non-linear seepage and a threshold pressure gradient (TPG) phenomenon in water-bearing tight gas reservoirs [11,12]. Therefore, on the basis of recognizing their micropore structures, it is necessary to study the TPG characteristic of gas in water-bearing tight gas reservoirs.The TPG of gas in water-bearing tight gas reservoirs has been accepted by most scholars, and a lot of researches have been carried out. Wojnarowski et al. [13] performed lots of liquid and gas permeability measurements on rock samples, contrasted the values of water and corrected-gas permeability, and found that water permeability was overestimated by Klinkenberg permeability, with difference in range of 11-24%. Tanikawa et al. [14] studied intrinsic permeability of sedimentary rocks using nitrogen gas and distilled water, found that gas permeability was greater than water permeability, increasing with an increase of pore pressure. Song et al. [15] investigated the influences ...

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Effects of pore-throat structure on gas permeability in the tight sandstone reservoirs of the Upper Triassic Yanchang formation in the Western Ordos Basin, China

Cited by 101 publications

References 31 publications

Multi-Scale Quantitative Characterization of Pore Distribution Networks in Tight Sandstone by integrating FE-SEM, HPMI, and NMR with the Constrained Least Squares Algorithm

Multi-Scale Quantitative Characterization of Pore Distribution Networks in Tight Sandstone by integrating FE-SEM, HPMI, and NMR with the Constrained Least Squares Algorithm

Pore-Throat Structure and Fractal Characteristics of Shihezi Formation Tight Gas Sandstone in the Ordos Basin, China

Threshold Pore Pressure Gradients in Water-Bearing Tight Sandstone Gas Reservoirs

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