Experimental investigation of the pore structure characteristics of the Garau gas shale formation in the Lurestan Basin, Iran

Vafaie, Atefeh; Habibnia, Bahram; Moallemi, Seyed Ali

doi:10.1016/j.jngse.2015.06.029

Cited by 35 publications

(8 citation statements)

References 37 publications

(94 reference statements)

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“…Generally, shale is dominated by nanoscale pores, and pores of 2‐50 nm are typically developed. Therefore, the IUPAC classification scheme has a good adaptability to quantitatively evaluate the pore size distribution of shale and is widely used by different researchers 22,26,57‐60 …”

Section: Resultsmentioning

confidence: 99%

“…Many laboratory analysis techniques have been used to qualitatively and quantitatively characterize the complex pore structure of shale. The commonly used experimental methods include mercury injection capillary pressure (MICP), nitrogen gas adsorption, scanning electron microscopy (SEM), nuclear magnetic resonance (NMR), and micro computed tomography (CT) 14,21‐28 . These methods have given important insights into understanding the pore structure of shale rock, but they also have some limitations.…”

Section: Introductionmentioning

confidence: 99%

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A 3D FIB‐SEM technique for quantitative characterization of oil shale's microstructure: A case study from the Shahejie Formation in Dongying Depression, China

Zhao

Dong

Zhang

et al. 2020

Energy Science & Engineering

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Investigating the pore structure of shale rocks plays an important role in understanding the mechanism of shale oil accumulation and migration; thus, it has a notable influence on the exploration and development of shale oil resources. In the present study, the microstructure of oil shale samples extracted from the Shahejie Formation in the Dongying Depression was investigated through the joint usage of focused ion beam (FIB) and scanning electron microscopy (SEM). Herein, we selected four representative samples. The SEM images of the sample surfaces milled by FIB indicated that pores were found in both the organic and inorganic matter. Organic pores were less developed in the samples because of the low thermal maturity of the organic matter. Continuous 3D digital rock images of shale samples were generated by FIB grinding and SEM in situ imaging. Based on multithreshold segmentation, the shale rocks were separated into different parts including kerogen, inorganic matter, and pores. The pore connectivity and pore size distributions were analyzed via Avizo software and in‐house developed MATLAB scripts. The pore size and corresponding volume distributions suggested that mesoscale pores (2‐50 nm) were abundant in the samples but they contributed limitedly to the total pore volume. Macropores (>50 nm) accounted for a small proportion but they had a greater contribution to the overall pore space volume. The coordination numbers of the subject four samples were mainly 0 and 1, which means that isolated pores accounted for the vast majority of the pores. These observations are critical to conduct reliable petrophysical simulations in the oil shales and understand their intrinsic properties accurately.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A 3D FIB‐SEM technique for quantitative characterization of oil shale's microstructure: A case study from the Shahejie Formation in Dongying Depression, China

Zhao

Dong

Zhang

et al. 2020

Energy Science & Engineering

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“…In comparison with North America, a few research studies have been conducted on shale gas resources in the Middle East [32]. Recent investigations of shale gas reservoirs in Iran led to the recognition of two main organic-rich shale formations (S1 and S2) within the Lurestan area [32][33][34][35][36][37]. is prospect is a part of the Zagros fold-thrust belt and is confined with Zagros reverse fault and Dezful embayment [34,38,39].…”

Section: Case Studymentioning

confidence: 99%

Integrated Technical and Economical Methodology for Assessment of Undeveloped Shale Gas Prospects: Applying in the Lurestan Shale Gas, Iran

Abdollahi¹,

Motahhari²,

Esfandyari

2021

Mathematical Problems in Engineering

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Shale gas resources can supply the substantial growing demand for clean energy. In comparison with conventional reservoirs, shale gas reservoirs have lower production potential, and selecting the most favorable areas from the broad region of shale gas prospect is very crucial in commercial development. These areas are screened regarding some key evaluation indicators that affect the ultimate recovery of shale gas reservoirs. Many attempts have been made to screen sweet spots by applying the different evaluation indicators. These studies mainly focus on geological sweet spot identification without considering the economic indicators that may influence the order of geological sweet spots for development. The current study introduces a methodology for selecting the best techno-economic spots in undeveloped shale gas regions by integrating the technical and economic criteria. The techno-economic areas are defined as the geological sweet spots with the highest rate of return under the currently employed technology. The economic objective functions for selecting these areas are net present value, internal rate of return, and payback time. To estimate the unknown features for integrating the technical and economic criteria in undeveloped areas, an analogy study is applied. Due to the large number of unknowns and uncertainties in shale gas evaluation and low confidence of deterministic results, a probabilistic approach is used. As the first attempt in shale gas assessment in Iran, the Lurestan shale gas region is evaluated by applying this approach. The results indicate that no selected geological sweet spots in this region are commercial regarding the current cost rates and the available technology in Iran, and it can be considered as a future affordable source of energy.

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“…Pore structure refers to the geometry, size, distribution, and connectivity of the pores and throats and the characteristic relationships between the pore and throat . With shale being a complex and heterogeneous porous medium, its pore structure parameters, such as pore morphology, pore size distribution, pore volume, and specific surface area, are essential for evaluating adsorption, storage capacity, and flow mechanisms . Therefore, it is very important to thoroughly study the pore structure characteristics of shales.…”

Section: Introductionmentioning

confidence: 99%

“…2 With shale being a complex and heterogeneous porous medium, its pore structure parameters, such as pore morphology, pore size distribution, pore volume, and specific surface area, are essential for evaluating adsorption, 3 storage capacity, 4 and flow mechanisms. 5 Therefore, it is very important to thoroughly study the pore structure characteristics of shales. Currently, to elucidate the complex pore structure in shale reservoirs, different methods are applied, including image analysis (e.g., thin section and FE-SEM), 6,7 fluid injection (e.g., gas adsorption and mercury injection), 7−9 and nonfluid injection (e.g., NMR, Micro-Nano CT, and small-angle neutron scattering) 10−13 with some techniques down to a nm-scale resolution.…”

Section: Introductionmentioning

confidence: 99%

Applying Fractal Theory to Characterize the Pore Structure of Lacustrine Shale from the Zhanhua Depression in Bohai Bay Basin, Eastern China

et al. 2018

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The complexity of the shale pore structure, which can be assessed by the fractal dimension, will affect the percolation and reservoir capability of a shale; thus, the pore structure is important for shale reservoir evaluation. For the pore structure and fractal characteristics of lacustrine shale to be investigated, a combination of X-ray diffraction (XRD), total organic carbon (TOC), scanning electron microscopy (SEM), mercury-injection capillary pressure (MICP), nuclear magnetic resonance (NMR), and Nano-CT experiments were performed on shale samples from the lower submember of the third member of the Eocene Shahejie Formation (Es3 L) in the Zhanhua Depression, Bohai Bay Basin. On the basis of fractal theory, the NMR fractal dimensions of the analyzed shale samples were determined by the transversal relaxation time (T 2) spectrum from the NMR experiment. The relationships between the NMR fractal dimension and mineral content, TOC, and pore structure parameter were discussed. The results indicate that the pore structure of the lacustrine shale in the study area is complex and exhibits strong heterogeneity. The pore types mainly include intergranular pores, intragranular pores, and some dissolved pores and microfractures. Calcite and clay are the dominant minerals, ranging from 9 to 91% (average 52.23%) and from 1 to 48% (average 18.63%), respectively. The TOC contents are relatively high with values from 0.06 to 9.32%. The calculated NMR fractal dimension (D) values are between 2.2544 and 2.439, which exhibit positive correlations with TOC content, quartz content, and clay mineral content. In contrast, a negative relationship occurs between the NMR fractal dimension and calcite content, indicating that the development of large, dissolved pores in shale samples could reduce the heterogeneity of the pore size distribution. Negative correlations are observed between the NMR fractal dimension and the T 2 cutoff value, T 2 geometric mean, porosity, and average pore throat radius, whereas the NMR fractal dimension exhibits a positive correlation with the displacement pressure (P d) and has no obvious relationship with permeability. The different relationships suggest that the NMR fractal dimension is closely related to the pore structure; namely, the smaller the NMR fractal dimension is, the better the pore structure is in the shale samples. Four typical samples were chosen to verify the relationship between the NMR fractal dimensions and the shale pore structure in the logging profile of Well L69. Excellent application results were obtained, suggesting that the NMR fractal dimension can be used to indicate the effectiveness of the reservoir in the study area.

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Experimental investigation of the pore structure characteristics of the Garau gas shale formation in the Lurestan Basin, Iran

Cited by 35 publications

References 37 publications

A 3D FIB‐SEM technique for quantitative characterization of oil shale's microstructure: A case study from the Shahejie Formation in Dongying Depression, China

A 3D FIB‐SEM technique for quantitative characterization of oil shale's microstructure: A case study from the Shahejie Formation in Dongying Depression, China

Integrated Technical and Economical Methodology for Assessment of Undeveloped Shale Gas Prospects: Applying in the Lurestan Shale Gas, Iran

Applying Fractal Theory to Characterize the Pore Structure of Lacustrine Shale from the Zhanhua Depression in Bohai Bay Basin, Eastern China

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