The Whole-Aperture Pore Structure Characteristics and Their Controlling Factors of the Dawuba Formation Shale in Western Guizhou

Yuan, Kun; Huang, Wenhui; Chen, Xianglin; Cao, Qian; Fang, Xingxing; Lin, Tian; Chunshuang, Jin; Li, Shizhen; Wang, Chao; Wang, Ting

doi:10.3390/pr10040622

Cited by 4 publications

(3 citation statements)

References 18 publications

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“…The obtained results displayed favorable agreement with field monitoring outcomes. Moreover, the opening of hydraulic fractures can cause compression of the surrounding reservoir, leading to alterations in pore pressure and stress fields adjacent to the fracture [20,21]. Sun et al [22] employed the finite element method (FEM) to investigate hydraulic fracturing parameters in porous media, revealing a gradual decrease in fluid pressure within the fracture as the fracture length increases.…”

Section: Introductionmentioning

confidence: 99%

Study on the Fracture Propagation in Multi-Horizontal Well Hydraulic Fracturing

et al. 2023

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Multi-horizontal well hydraulic fracturing is a widely employed and highly effective method for stimulating tight and shale reservoirs. However, most existing studies primarily focus on investigating the impact of intra-well interference on fracture propagation while neglecting the influence of inter-well interference. Here, a multi-well hydraulic-fracture-propagation model is established to examine the effects of inter-well interference on fracture propagation within a multi-well system. In this study, based on the bilinear T-S criterion, the stiffness degradation is used to describe the damage and evolution process of fracture, the coupling process of fluid flow and solid damage and deformation is realized, and the dynamic distribution of inter-fracture flow is realized by using Kirchhoff function on the basis of the cohesive zone method (CZM) finite element model. Finally, the fracture-propagation model of multiple horizontal wells is established. Based on this model, the mechanism of inter-well interference on fracture propagation is studied, and the influence law of Young’s modulus and fracture displacement on fracture propagation in multi-wells is investigated. The results show that the reservoir can be divided into self-influence area, tension area and compression area according to the stress distribution state in the hydraulic fracture propagation of multi-wells. The propagation rate of hydraulic fractures in horizontal wells is significantly accelerated when they propagate to the local tension area generated by the fracture tip of neighboring wells, and rapidly decreases as the hydraulic fractures continue to propagate to the compression area of neighboring wells. Rocks with a lower Young’s modulus tend to be more plastic, forming hydraulic fractures with usually lower fracture lengths and usually larger fracture widths. The hydraulic fracture has an inhibitory effect on the propagation of fractures closer to each other in neighboring wells, and this inhibitory effect gradually increases as the distance decreases. The dominance of the dominant fracture to propagate in the self-influence area gradually decreases under inter-well and intra-well interference. As the dominant fracture propagates into the tension and compression areas of the neighboring well fractures, the feed fluid will show a brief rise and then eventually stabilize. This study quantifies the effect of inter-well interference on fracture propagation and lays the foundation for treatment optimization of small well spacing hydraulic fracturing.

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Section: Introductionmentioning

confidence: 99%

Study on the Fracture Propagation in Multi-Horizontal Well Hydraulic Fracturing

et al. 2023

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“…Since 2014, the Oil and Gas Resources Survey Center of the China Geological Survey has been working in South China to advance geological knowledge and engineering technologies, with an emphasis on discovering Paleozoic shale gas [7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Carboniferous Shale Gas Accumulation Characteristics and Exploration Directions in South China

et al. 2023

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China has focused on the exploration and development of shale gas resources to reduce its reliance on coal and shift to cleaner energy sources. While significant progress has been made in the Sichuan Basin, unlocking the shale gas potential in other regions of South China has proven challenging due to the complex geology and mountainous terrain. In 2021, Well QSD-1 was deployed in southwestern Guizhou and achieved a daily shale gas flow of 11,011 m3 in the Dawuba Formation, marking the first time an industrial gas flow had been obtained from shale gas drilling in the marine strata of the Upper Paleozoic in China. This breakthrough has deepened the understanding of the southern China Carboniferous marine strata and highlighted key aspects of the formation: (1) Sedimentation occurred in alternating platforms and basins, with most organic-rich shale developed in sloping and basin areas; (2) the formation exhibits favorable static indicators, with a relatively thick section (over 200 m), and an organic carbon content of approximately 1%; (3) the intercalation of argillaceous limestone and shale intervals is conducive to the preservation of shale gas within the formation. These results demonstrate the potential for the Upper Paleozoic in South China to become a significant shale gas producer, which could contribute significantly to China’s energy security. Furthermore, exploring shale gas in the region may have positive economic and environmental impacts, including reducing China’s dependence on coal and decreasing greenhouse gas emissions.

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“…Influenced by multi-stage geological tectonics, the reservoir lithological assemblages and pore structure are complex, and they are characterized by multiple layers, thin layers, large cumulative thicknesses, frequent interbedding, abundant organic matter, low maturity, and high clay mineral content. Though the existing literature has covered the shale pore structure characteristics [6,8,9,[16][17][18], studies exploring areas such as low-mature marine-continental transitional shale pore structure characteristics and the dominant factors controlling shale pore development are lacking. In this research, the Longtan Shale core samples from the HP3 and YL4 wells in western Guizhou were selected.…”

Section: Introductionmentioning

confidence: 99%

Factors Controlling the Pore Development of Low-Mature Marine–Continental Transitional Shale: A Case Study of the Upper Permian Longtan Shale, Western Guizhou, South China

Zhang,

Hu,

Wei

et al. 2023

JMSE

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The Upper Permian Longtan Shale is a significant reservoir in western Guizhou. To clarify the main factors controlling the low-mature marine–continental transitional shale pore development in western Guizhou, pore types were classified with scanning electron microscopy (SEM), and the pore developmental stages and morphological structures were quantitatively characterized by nitrogen adsorption isotherm analyses. Additionally, the qualitative or semi-quantitative relationships between the pore developmental stages and the main controlling factors were established via geochemical analysis. The results showed that the Longtan Shale pores include intergranular pores, intragranular pores, organic pores, and microfractures. The intergranular pore structures were categorized into ink-bottle, slit, layered, and irregular types. The intragranular pores were found to be of the elliptical, nearly circular, ink-bottle, and irregular varieties. The organic pores were categorized into elliptical, bubble-like, and irregular polygonal variants. The microfractures were only of the elongated type. The clay-mineral-related intergranular pores were the predominant pore type. The organic pores were found to be poorly developed. The mesopores were predominant, followed by macropores. The shale pore diameters ranged between 1 nm and 100 nm, and they are characterized by multiple peaks. The specific surface area (SSA) was primarily provided by nanopores in the range of 5 nm to 10 nm, such that the smaller pores provided a greater contribution to the SSA, and they are more conducive to shale gas adsorption and accumulation. Clay mineral content was the dominant internal factor controlling pore development and the SSA, with the illite–smectite mixed layer being the most obvious controlling factor. While too low or too high clay mineral content is adverse to macropore development, brittle mineral content, carbonate mineral content, and total organic carbon (TOC) content are adverse to pore development and the SSA. Thermal maturity has no remarkable control effect on pore volume and the SSA of non-organic pores.

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The Whole-Aperture Pore Structure Characteristics and Their Controlling Factors of the Dawuba Formation Shale in Western Guizhou

Cited by 4 publications

References 18 publications

Study on the Fracture Propagation in Multi-Horizontal Well Hydraulic Fracturing

Study on the Fracture Propagation in Multi-Horizontal Well Hydraulic Fracturing

Carboniferous Shale Gas Accumulation Characteristics and Exploration Directions in South China

Factors Controlling the Pore Development of Low-Mature Marine–Continental Transitional Shale: A Case Study of the Upper Permian Longtan Shale, Western Guizhou, South China

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