Difference in pore structure characteristics between condensate and dry shale gas reservoirs: Insights from the pore contribution of different matrix components

Qiu, Hengyuan; Jiang, Zhenxue; Liu, Zhujiang; Chang, Jiaqi; Su, Zhanfei; Yang, Zhanwei; Zhou, Wen

doi:10.1016/j.jngse.2021.104283

Cited by 11 publications

(4 citation statements)

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“…The pore structure of shale condensate gas reservoir is quite different from that of dry gas reservoir. In shale condensate gas reservoir, there are mainly organic matter (OM) pores, clay mineral (CM) pores, intragranular dissolution (ID) pores, and microfractures [7]. Micropores and mesoporous pores are mainly provided by OM and CM pores, while macropores are mainly provided by CM pores and microfractures [7].…”

Section: Reservoir Characteristics Resource Distribution and Exploita...mentioning

confidence: 99%

Progress of Seepage Law and Development Technologies for Shale Condensate Gas Reservoirs

Yang

Qiao

et al. 2023

Energies

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With the continuous development of conventional oil and gas resources, the strategic transformation of energy structure is imminent. Shale condensate gas reservoir has high development value because of its abundant reserves. However, due to the multi-scale flow of shale gas, adsorption and desorption, the strong stress sensitivity of matrix and fractures, the abnormal condensation phase transition mechanism, high-speed non-Darcy seepage in artificial fractures, and heterogeneity of reservoir and multiphase flows, the multi-scale nonlinear seepage mechanisms are extremely complicated in shale condensate gas reservoirs. A certain theoretical basis for the engineering development can be provided by mastering the percolation law of shale condensate gas reservoirs, such as improvement of productivity prediction and recovery efficiency. The productivity evaluation method of shale condensate gas wells based on empirical method is simple in calculation but poor in reliability. The characteristic curve analysis method has strong reliability but a great dependence on the selection of the seepage model. The artificial intelligence method can deal with complex data and has a high prediction accuracy. Establishing an efficient shale condensate gas reservoir development simulation technology and accurately predicting the production performance of production wells will help to rationally formulate a stable and high-yield mining scheme, so as to obtain better economic benefits.

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Section: Reservoir Characteristics Resource Distribution and Exploita...mentioning

confidence: 99%

Progress of Seepage Law and Development Technologies for Shale Condensate Gas Reservoirs

Yang

Qiao

et al. 2023

Energies

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“…The mineral particles and organic matter in shale reservoirs contain large scale range of pores (nano/micro/millimeter scale) and micro-fractures, providing important storage space for shale gas enrichment, and also offered flow channels for shale gas seepage (Zhang et al, 2019;Zhao et al, 2022). By clarify the reasons for the complexity and heterogeneity of pore systems in shale gas reservoir, we can achieve more efficient development of deep shale gas resources (Yang et al, 2016;Zhang et al, 2020;Qiu et al, 2021;Xie et al, 2022;Cui et al, 2024). The characterization of pore structure in shale gas reservoirs involves many aspects, including pore types, pore shape, pore size, pore volume, pore specific surface area, spatial distribution of pore systems, connectivity between pores.…”

Section: Introductionmentioning

confidence: 99%

Characterization and fractal characteristics of nano-scale pore structure in shale gas reservoirs: a case study of the deep Longmaxi Formation, Zigong region, Southern Sichuan Basin, China

Zhao,

Bao,

et al. 2024

Front. Earth Sci.

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Taking the Longmaxi deep-marine shale gas reservoir in Zigong region as the research target, this paper aimed to characterize the nano-scale pore structure and investigate the reservoirs’ heterogeneity based on fractal theory. By conducting a series of experimental studies, mainly including TOC, XRD, gas adsorption (N2 and CH4), we were able to clarify the main controlling factors for the heterogeneity of deep shale pore structure. Our results indicated that the deep marine shale possessed a significant amount of organic matter, as the average TOC value is 3.68%. The XRD analysis results show that quartz and clay were the main mineral types, and the total content of these two minerals averaged 77.5%. Positive correlations were observed between TOC and quartz, while TOC decreases as the clay mineral increases, this discovery indicating that quartz is biogenic. Based on FHH (Frenkele-Halseye-Hill) method, by using the LTNA adsorption isotherms, we took relative pressure P/P0=0.5 as the boundary, then two separate fractal dimension were deduced, D1 and D2 represent the fractal characteristics of small and large pores, respectively. Our study revealed that both D1 and D2 demonstrated positive correlations with N2 adsorption pore volume and adsorption specific surface area, while negatively correlated with the adsorption average pore diameter. Moreover, the two fractal dimensions showed positive associations with TOC and quartz and negative associations with clay. Additionally, D1 and D2 also demonstrated a positive correlation with Langmuir volume. The presence of micropores was found to significantly influence the formation of an irregular pore structure in shale. As the pore size decreased, the adsorption specific surface area increased, resulting in a more intricate pore structure, and the fractal dimension of the pores elevated, ultimately. This intricate structure is beneficial for the accumulation of shale gas. These research findings offer valuable insights for the comprehensive assessment of deep shale gas, and enrich our knowledge of enrichment mechanisms in deep shale gas reservoirs.

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“…Organic-rich shales in China are deposited in marine, terrestrial, and marine-land transitional environments, with significant differences in their geochemical characteristics, reservoir properties, and gas-bearing properties. − Marine shale typically has high total organic carbon (TOC) content, with a high degree of thermal evolution and organic matter dominated by types I and II; sea-land transitional shale exhibits rapid vertical changes in TOC with some cyclicity, moderate thermal evolution, and kerogen mainly type III; terrestrial shale distribution is limited, with higher TOC at the sedimentary center, lower maturity, and dominance of types I and II1 kerogen. − According to the IUPAC, pores in shales are classified as micropores (<2 nm), mesopores (2–50 nm), and macropores (≥50 nm) . Most shale gas is adsorbed in organic nanometer pores or in the surface and interlayer pores of clay minerals. − Low-temperature CO 2 adsorption experiments can quantitatively characterize the micropore characteristics in shale. − The PSD characteristics significantly affect the gas storage capacity of shale. − Research on the genesis of PSD peaks of micropores mainly focuses on coal and transitional shales. − For example, Qu et al found that the micropores in tectonic deformation coal are lamellar pores of aromatic rings or columnar pores formed by stacking . Yu et al combined research on the origin of micropores in coal with micropores in transitional shales and found that the influence of clay minerals on the total micropore volume and pore volume of peak 2 (0.46–0.63 nm) is slightly bigger than that of TOC, whereas the influence on peak 3 (0.82 nm) is the opposite .…”

Section: Introductionmentioning

confidence: 99%

Pore Peak Types and Controlling Factors of Micropores in Different Shale Reservoirs

Nie,

Pan,

et al. 2023

Energy Fuels

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The micropores (<2 nm) developed in shale reservoirs play a crucial role in the adsorption and storage of shale gas. In this study, we investigated the organic geochemistry, mineral constituents, and micropore structure characteristics of transitional shale reservoirs in the Yangquan mining area of the Qinshui Basin, China, using total organic carbon (TOC), quantitative X-ray diffraction (XRD), and low-temperature CO2 adsorption. We analyzed the genesis and dominant factors of micropore structure characteristics in marine, terrestrial, and transitional shales. The results showed: (1) In transitional shale, the pore-size distribution (PSD) exhibited a bimodal distribution, and peaks 2 and 3 in transitional shale were mainly organic pores; the peak value of PSD is affected by sedimentary environment, the micropore volume of shale in tidal-flat facies was greater than that of shale in lagoon facies. (2) Regarding the genesis of the micropores, peak 1 was likely a false peak. The value of peak 1 in marine shale was positively correlated with the clay and Illite–smectite mixed layer (I/S), but the interlayer of Illite–smectite mixed layer was approximately 1 nm, suggesting that peak 1 was not a clay mineral pore. In terrestrial shale, the value of peak 1 was positively correlated with TOC, and we observed peak 1 in some terrestrial shale (CL-3, S-1, S-2, and S-3), suggesting that peak 1 was not an organic pore. (3) Maturity and quartz have different effects on clay minerals in different shales, and we found that maturity (R o = 1.4–2.0%) was conducive to developing clay minerals in terrestrial shale, whereas maturity (R o = 0.52–3.66%) was not conducive to developing clay minerals in marine shale; quartz was not conducive to developing clay minerals in marine and transitional shale, but it promoted the development of clay minerals in terrestrial shale.

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Difference in pore structure characteristics between condensate and dry shale gas reservoirs: Insights from the pore contribution of different matrix components

Cited by 11 publications

References 50 publications

Progress of Seepage Law and Development Technologies for Shale Condensate Gas Reservoirs

Progress of Seepage Law and Development Technologies for Shale Condensate Gas Reservoirs

Characterization and fractal characteristics of nano-scale pore structure in shale gas reservoirs: a case study of the deep Longmaxi Formation, Zigong region, Southern Sichuan Basin, China

Pore Peak Types and Controlling Factors of Micropores in Different Shale Reservoirs

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