Pore-Scale Characterization of Gas Flow Properties in Shale by Digital Core Analysis

Ma, Jingsheng

doi:10.1016/b978-0-12-802238-2.00004-3

Cited by 6 publications

(4 citation statements)

References 64 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The pore structure of shale gas reservoir is complex along with certain amorphous characteristics. Abundant scanning electron microscopy (SEM) images studies indicate that the pore structures in shale contain various shapes. − The adsorption and desorption hysteresis loop is the most prevalent and significant feature to characterize the microscopic pore structures in the microporous media, , which has been classified into four types by the International Union of Pure and Applied Chemistry (IUPAC). According to the shale hysteresis loops gained from the N 2 adsorption and desorption isotherms, the major pore structures can be divided into four types, such as cylinder-shaped pores, bottleneck pores, wedge-shaped pores, and slit-shaped pores. , Based on experimental methods, previous scholars have discovered that all of these four kinds of pore structures exist in shale reservoirs , as shown in Figure .…”

Section: Introductionmentioning

confidence: 99%

Influence of Pore Structure on Shale Gas Recovery with CO₂ Sequestration: Insight Into Molecular Mechanisms

et al. 2019

View full text Add to dashboard Cite

Although the focus of shale gas recovery has shifted to CO 2 sequestration with enhanced gas recovery (CS-EGR) for overcoming the low recovery efficiency, the adsorption and recovery mechanism of methane (CH 4 ) and carbon dioxide (CO 2 ) considering the effect of pore structures remains to be revealed. In this work, we focus on the influence of pore structures on adsorption behaviors of CH 4 and CO 2 at different geological depths and recovery process in different pore structures with various injection gas pressures. The results demonstrate that the excess adsorption capacity of CH 4 and CO 2 is in the order of cylinder-shaped > bottleneck > wedge-shaped > slit-shaped. The adsorption capacities of both CH 4 and CO 2 increase initially with geological depth until reaching maximum and then decrease with the depth going deeper. As for competitive adsorption of CH 4 and CO 2 , the pore structures do not have much influence on the selectivity. However, the pore structures have significant impact on shale gas recovery, and the difficulty of CH 4 molecules being displaced in various pore structures is ordered as cylinder-shaped > bottleneck > slit-shaped > wedge-shaped pores, which is consistent with the system resistance. The displacement efficiency of CH 4 in cylinder-shaped pores is about 59%, much less than in other pore structures. The injection pressure has a negative effect on the speed of shale gas recovery and displacement efficiency of CH 4 for the reason that more molecules aggregate into clusters near the pore throat and the flow blocking effect become more obvious when the injection pressure increases. Based on this actuality, we proposed a probable reliable method for CS-EGR: lower injection pressure is initially set to improve recovery efficiency, and higher pressure is finally used to increase CO 2 sequestration amount.

show abstract

Section: Introductionmentioning

confidence: 99%

Influence of Pore Structure on Shale Gas Recovery with CO₂ Sequestration: Insight Into Molecular Mechanisms

et al. 2019

View full text Add to dashboard Cite

show abstract

“…In shale gas reservoirs, organic nanopores are important gas storage spaces. Because the real molecular structure for the shale is complicated, − the organic pores were simulated widely using carbon-based models. − In fact, the cross-sectional shape of the organic pores is different, − including circle, triangle, square, slit, etc. However, if only the vicinity of the organic pores is considered, all organic pore surfaces of different shapes can be approximated as a plane.…”

Section: Methodology and Simulation Methodsmentioning

confidence: 99%

Heterogeneous Effect of Organic Matter on Accumulation Behaviors of Shale Gas in Water

Zhang

Hao

et al. 2022

Energy Fuels

View full text Add to dashboard Cite

Hydraulic fracturing technology is widely used in unconventional oil and gas exploitation. The existence of water makes the interactions between oil and gas and the interface more complex. Therefore, it is important to understand the interaction between gas and solid in a water environment. In the paper, we construct a generalized charged plate to study the accumulation and diffusion of shale gas on the solid interface in a water environment. The atomic arrangement of the charged interface has an essential influence on the state of the gas accumulation. With the increase of the interfacial bond length, the accumulation ability of the gas is reduced. The accumulation of the gas and water on the interface shows a mutually competitive relationship. The law of change is attributed to the interaction between water molecules and the interface. The longer bond length of the interface makes the water molecules near the interface more orderly, and it is difficult for gas molecules to stay at the interface.

show abstract

“…In order to obtain useful images of the pore structures, the field of view (FOV) needs to be selected so that the pore-space components are resolved into more than one pixel/voxel [58]. Macroscopic structures and properties of interest for a sample can be characterized effectively if the size of the field of view (FOV) and corresponding reconstructed model is large enough.…”

Section: Ct Scanning Setupmentioning

confidence: 99%

Microstructure Imaging and Characterization of Rocks Subjected to Liquid Nitrogen Cooling

Wu,

Zou,

et al. 2024

Processes

View full text Add to dashboard Cite

Liquid nitrogen (LN2) fracturing is a potential stimulation method in unconventional hydrocarbon recovery, showing its merits in being water free, creating low formation damage and being environmentally friendly. The microstructure evolution of rocks subjected to LN2 cooling is a fundamental concern for the engineering application of LN2 fracturing. In this paper, pore-scale imaging and characterization were performed on two rocks, i.e., tight sandstone and coal specimens subjected to LN2 cooling using computed tomography scanning. The digital core technique was employed to reconstruct the microstructures of rocks and give a quantitative analysis of the pore structure evolution of both dry and water-saturated rocks. The results indicate that LN2 cooling has a great effect on the pores’ morphology and their spatial distribution, leading to a great improvement in pore diameter and aspect ratio. When compared to the sandstone, coal is more sensitive to LN2 cooling and thermal stresses, having a more noticeable growth in pore–throat size. The porosity growth of coal is 291% higher than that of sandstone. There is a growing trend in the irregularity and complexity of pore structures. After LN2 cooling, the fractal dimensions of the pores of sandstone and coal grow by 11.7% and 0.87%, respectively, and the proportion of pores with a shape factor > 100 increases. More bundle-like and strip-shape pores with multiple branches are generated, which causes a significant growth in the throat size and the proportion of connected pores with a coordination number ≥ 1, enhancing the complexity and connectivity of pore structures dramatically. Additionally, pore water plays an important role in aggravating rock damage during LN2 cooling, enhancing the pore space and connectivity. The porosities of the saturated sandstone and coal samples grow by 22.6% and 490.4%, respectively, after LN2 cooling, which are 5.6% and 186.6% higher than dry samples. The generation of macropores ≥ 70 μm is the primary contributor to porosity growth during LN2 cooling, although such pores account for only a small proportion of the total. These findings contribute to our understanding of the microscopic mechanism of LN2 cooling on rock damage and may provide some guidance for the engineering application of LN2 fracturing.

show abstract

Pore-Scale Characterization of Gas Flow Properties in Shale by Digital Core Analysis

Cited by 6 publications

References 64 publications

Influence of Pore Structure on Shale Gas Recovery with CO₂ Sequestration: Insight Into Molecular Mechanisms

Influence of Pore Structure on Shale Gas Recovery with CO₂ Sequestration: Insight Into Molecular Mechanisms

Heterogeneous Effect of Organic Matter on Accumulation Behaviors of Shale Gas in Water

Microstructure Imaging and Characterization of Rocks Subjected to Liquid Nitrogen Cooling

Contact Info

Product

Resources

About

Pore-Scale Characterization of Gas Flow Properties in Shale by Digital Core Analysis

Cited by 6 publications

References 64 publications

Influence of Pore Structure on Shale Gas Recovery with CO2 Sequestration: Insight Into Molecular Mechanisms

Influence of Pore Structure on Shale Gas Recovery with CO2 Sequestration: Insight Into Molecular Mechanisms

Heterogeneous Effect of Organic Matter on Accumulation Behaviors of Shale Gas in Water

Microstructure Imaging and Characterization of Rocks Subjected to Liquid Nitrogen Cooling

Contact Info

Product

Resources

About

Influence of Pore Structure on Shale Gas Recovery with CO₂ Sequestration: Insight Into Molecular Mechanisms

Influence of Pore Structure on Shale Gas Recovery with CO₂ Sequestration: Insight Into Molecular Mechanisms