Water sorption behaviour of gas shales: II. Pore size distribution

Zolfaghari, Ashkan; Dehghanpour, Hassan; Xu, Mingxiang

doi:10.1016/j.coal.2017.05.009

Cited by 109 publications

(37 citation statements)

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“…The formation characteristics of HFN are difficult to obtain because of the extremely low permeability and complex stress state of shale reservoirs [9,10]. Some main factors have been studied in detail in previous studies, such as the presence of clay minerals in clay-rich shales, pore size distribution, rock brittleness, viscosity of the fracturing fluid and injection rate [11][12][13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

“…According to these results, the interaction between HF and weak surfaces, such as BP, can be divided into two categories, namely HF cross through BP (the first row in Figure 1) or propagate along BP (the second row in Figure 1). studied in detail in previous studies, such as the presence of clay minerals in clay-rich shales, pore size distribution, rock brittleness, viscosity of the fracturing fluid and injection rate [11][12][13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

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Experimental Investigation of Fracture Propagation Behavior Induced by Hydraulic Fracturing in Anisotropic Shale Cores

Chong

Yao

2019

Energies

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Hydraulic fracturing is a key technology for the development of unconventional resources such as shale gas. Due to the existence of numerous bedding planes, shale reservoirs can be considered typical anisotropic materials. In anisotropic shale reservoirs, the complex hydraulic fracture network (HFN) formed by the interaction of hydraulic fracture (HF) and bedding plane (BP) is the key to fracturing treatment. In this paper, considering the anisotropic angle, stress state and injection rate, a series of hydraulic fracturing experiments were conducted to investigate the effect of anisotropic characteristics of shale reservoirs on HFN formation. The results showed that the breakdown pressure increased first and then decreased when the anisotropic angle changed at 0°–90°, while the circumferential displacement had the opposite trend with a small difference. When θ = 0°, fracturing efficiency of shale specimens was much higher than that under other operating conditions. When θ ≤ 15°, the bedding-plane mode is ubiquitous in all shale reservoirs. While θ ranged from 30°–45°, a comprehensive propagation pattern of bedding-plane and crossing is presented. When θ ≥ 60°, the HFN pattern changes from comprehensive mode to crossing mode. The propagation pattern obtained from physical experiments were verified by theoretical analysis. The closure proportion of the circumferential displacement was the highest when the propagation pattern was the bedding-plane mode (θ ≤ 15°), following by crossing. The closure proportion was minimum only when the bedding-plane and crossing mode were simultaneously presented in the HFN. The results can provide some basic data for the design in hydraulic fracturing of tight oil/gas reservoirs.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Experimental Investigation of Fracture Propagation Behavior Induced by Hydraulic Fracturing in Anisotropic Shale Cores

Chong

Yao

2019

Energies

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“…The YY shale with peaks near 2 nm and 100 nm and the GZ shale with peaks near 2 nm and 10 nm are shown in Figures 7(a) and 7(c). The pore size distributions of the raw YY and GZ shale were different from those of the Barnett shale in North American shale plays and Otter-Park shale in the Horn River Basin [41,42]. It was observed that the pore size distributions of the YY shale increased significantly after slick water treatment (Figure 7(a)), especially the mesopores (Figure 7(b)).…”

Section: Geofluidsmentioning

confidence: 96%

Pore Structure Alteration Characteristics of Different Mineralogical Composition Shale during Shale-Fracturing Fluid Physical-Chemical Interactions

et al. 2019

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Hydraulic fracturing is widely applied to economic gas production from shale reservoirs, but the effect of the shale mineral composition on the physical-chemical reactions during hydraulic fracturing is still poorly understood. To develop a foundational understanding of chemical interactions occurring on shale with different mineralogical compositions, two different types of mineral composition marine shale (carbonate-poor and carbonate-rich) from the Niutitang Formation were reacted with slick water fracturing fluid in a laboratory reactor at 100°C and 50 MPa for three days. To identify the changes of the pore structure characteristics during hydraulic fracturing, the field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), low-temperature nitrogen adsorption, and porosity measurement were performed on the original and treated shale samples. After the slick water treatment, the dissolution of pyrite in carbonate-poor shale (obtained from Youyang County, labeled as YY) was observed by FE-SEM and XRD analyses, while in carbonate-rich shale (obtained from Guzhang County, labeled as GZ), the carbonate dissolution was observed. Results from the low-temperature N2 adsorption and porosity measurement demonstrated that the variation trend of pore structure characteristics for the YY and GZ shale samples was quite different after reacting with slick water fracturing fluid. For YY shale, the specific surface area, total pore volume, and porosity increased after the reaction, whereas an opposite trend was observed in the GZ shale. Moreover, the fractal dimension analysis illustrated that the pore surface became less rough and the pore structure became more complex in the YY shale, whereas the degree of pore surface roughness and pore structure complexity of the GZ shale was reduced. The results demonstrated that the initial mineralogical composition of shale played an important role in pore structure alteration during hydraulic fracturing.

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“…Most water vapor adsorption experiments use an oversaturated solution in a tightly closed container to maintain one level of RH (Hu, Trautz, & Wang, 2004;Zolfaghari et al, 2017), but this has the following disadvantages: (a) it is time consuming to reach equilibrium and much space is needed for many containers; (b) it is difficult to reach the target RH by saturated salt solution, especially a low one such as 10% RH; and (c) it is disruptive to the equilibration process to take and return the samples to weigh periodically, and thus equilibration must be reestablished. In this study, the dynamic water vapor adsorption isotherm was obtained using a gravimetric water vapor adsorption analyzer (Aquadyne DVS, Quantachrome/Anton Parr).…”

Section: Water Vapor Adsorptionmentioning

confidence: 99%

Changes in water vapor adsorption and water film thickness in clayey materials as a function of relative humidity

Lin

Chen

et al. 2020

Vadose Zone Journal

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Soil water, with adsorbed water being an important component, plays an important role in fluid flow and chemical movement in the unsaturated zone. The adsorbed water consists of water film and interlayer water, and its content is related to the relative humidity (RH). This study theoretically and experimentally focuses on the variation in adsorbed water content in clayey materials as the RH changes. Based on a slit-pore model, three types of water (water film, interlayer water, and capillary water) could be present in the water vapor adsorption process. The variation of water film is obtained from the analysis of interfacial forces, and then the total water content can be quantitatively subdivided into these three types of water for different RH values. The slit-pore adsorption model was used with experimental measurements (water vapor adsorption and N 2 physisorption) to quantify the amounts and interrelationships of these three different types of water to six clayey materials, namely three clay minerals (kaolinite, montmorillonite, and illite-smectite mixed layer) and three clay-rich sediments from the Jianghan Plain in China. The main results are that (a) the volumes of water vapor adsorption are much greater than those of N 2 adsorption except for kaolinite; (b) interlayer water largely dominates the growth of total water content in montmorillonite and results in a concentration of 0.090 ml g −1 at 95% RH; and (c) the minimum thickness of water film is calculated to be 0.23 nm, and the maximum value is one-third of the pore width by considering the interfacial forces. 1 INTRODUCTION Soil water supports plant growth, affects nutrient transport, and is involved in many geophysical and geochemical

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Water sorption behaviour of gas shales: II. Pore size distribution

Cited by 109 publications

References 50 publications

Experimental Investigation of Fracture Propagation Behavior Induced by Hydraulic Fracturing in Anisotropic Shale Cores

Experimental Investigation of Fracture Propagation Behavior Induced by Hydraulic Fracturing in Anisotropic Shale Cores

Pore Structure Alteration Characteristics of Different Mineralogical Composition Shale during Shale-Fracturing Fluid Physical-Chemical Interactions

Changes in water vapor adsorption and water film thickness in clayey materials as a function of relative humidity

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