Experimental Investigation of Reservoir Fluid Interlayer Crossflow Through Fracture During the Drainage Stage of Coal Measure Gas Well

Wang, Qian; Su, Xinming; Jin, Yi; Sun, Changyin; Yu, Shiyao; Zhao, Weizhong; Feng, Yue

doi:10.1007/s11053-023-10187-3

Cited by 13 publications

(4 citation statements)

References 37 publications

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“…The pores in shale reservoirs display a broad range of sizes, varying from several microns to a few nanometers . Their characteristics are significantly influenced by the shale compositions, especially organic matter (OM), brittle minerals, and clay minerals. , The properties, size scale, and development degree of pores play a vital role in determining the gas adsorption capacity, gas occurrence state, and gas flow behavior within shale reservoirs. − Consequently, accurate and effective characterization of the full-scale pore structure is of crucial importance for shale reservoir evaluation.…”

Section: Introductionmentioning

confidence: 99%

Scale-Dependent Fractal Properties and Geological Factors for the Pore Structure in Shale: Insights from Field Emission Scanning Electron Microscopy and Fluid Intrusion

Feng,

Li,

Zhu

et al. 2023

Energy Fuels

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Cost-effective pore characterization is essential for understanding gas storage and flow in shale reservoirs. Herein, we thoroughly investigated the pore structure of Qiongzhusi shale from Northeastern Yunnan, China, utilizing field emission scanning electron microscopy, high-pressure mercury intrusion porosimetry (HP-MIP), and low-pressure gas adsorption (LP-N 2 /CO 2 GA). Scale-dependent fractal properties were identified to evaluate the applicability of fluid intrusion methods. Furthermore, geological factors controlling the pore structure were analyzed. Fractal analysis via the Menger sponge model and the Frenkel−Halsey− Hill model revealed scale-dependent fractal features that act as a "fingerprint" to identify sequential stages during measurements. Mercury intrusion was identified in three stages: pore volume filling, matrix compression, and pore structure damage. Matrix compression appeared at approximately 25 MPa, corresponding to 50 nm in pore size; thereby, HP-MIP is unreliable for characterizing pores below 50 nm. Likewise, N 2 adsorption was identified in four stages: micropore filling, monolayer adsorption, multilayer adsorption, and capillary condensation. As the fractal dimensions from the micropore filling stage are invalid for certain samples, LP-N 2 GA is inadequate for micropore characterization. To cover full-scale pore size distribution (PSD), LP-CO 2 GA, LP-N 2 GA, and HP-MIP were employed to characterize micropores (<2 nm), mesopores (2−50 nm), and macropores (>50 nm), relatively. The resulting PSDs are unimodal or bimodal, with peaks at 0.3−1.0 and 5−20 nm. The Qiongzhusi shale contains interparticle pores along brittle mineral edges and within clay interlayers, intraparticle pores within pyrite framboids and dissolutionrelated minerals, and organic matter (OM) pores with varying morphologies influenced by surrounding minerals. OM and quartz were found to promote pore development, with quartz-based frameworks protecting internal OM pores from compaction-induced damage. However, clays demonstrate a multifaceted impact on pore structure, with interlayer pores between illite−smectite mixed layers contributing to pore volume, while illites negatively affect pore volume. This study provides valuable insights into full-scale pore characterization and shale reservoir evaluation.

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Section: Introductionmentioning

confidence: 99%

Scale-Dependent Fractal Properties and Geological Factors for the Pore Structure in Shale: Insights from Field Emission Scanning Electron Microscopy and Fluid Intrusion

Feng,

Li,

Zhu

et al. 2023

Energy Fuels

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“…In CBM development, it is crucial to implement measures to increase production in low-efficiency areas. Revitalizing low-yield and low-efficiency CBM wells have become vital in restricting the effective development of the Qinshui Basin and the CBM industry in China . By studying the geological conditions and identifying the critical factors behind the low productivity and efficiency of CBM wells, effective measures can be taken to increase single-well production.…”

Section: Effective Revitalization Measuresmentioning

confidence: 99%

Geological Characteristics of Low-Yield and Low-Efficiency CBM Wells and Practical Measures for Production Increase in the Qinshui Basin

Zhang,

Ren,

Zhao

et al. 2023

ACS Omega

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Many low-production and low-efficiency wells in the Zhengzhuang, Fanzhuang, Lu’an, and Yangquan blocks of the Qinshui Basin seriously hinder the development of coalbed methane in China. Through in-depth research on the geological conditions and development technology of coalbed methane, it was found that the main reasons for the existence of a large number of low-production and low-efficiency wells are the fragmentation of coal structure, poor adaptability of vertical well types, sizable well spacing, and mismatched stimulation measures. On this basis, it is proposed to adopt an L-shaped horizontal well and staged Fracking technology in the block with a complete coal structure but low permeability. For stress–concentration areas, the first fracturing of a vertical well has a single crack and a small coverage area; After a period of drainage and production, the use of repeated fracturing technology can increase the complexity of fractures and increase gas production; For the fractured area of coal structure, the use of roof fracturing technology effectively solves the problem of coal fragmentation. In natural fracture development areas, new fractures are formed using fracture turning technology to achieve the effect of increasing production. The above technologies have achieved good results in the Qinshui Basin engineering experiment. Therefore, in-depth research on the geological conditions of coalbed methane and matching related development technologies are the main ways to solve low-efficiency and low-production wells in coalbed methane development blocks.

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“…It is also situated in a typified arid and semi‐arid fragile ecological environment in China, making the harmonious development of high‐strength coal production and ecological preservation a crucial area of research. Given the unique challenges posed by the limited water resources and delicate ecological environment in the arid and semi‐arid regions of Yangjiacun Coal Mine, this study proposes the approach and foundational principles for implementing sustainable mining practices by examining the hydrogeological characteristics of the mining area and the various coal seam structures 23–25 …”

Section: Stability Analysismentioning

confidence: 99%

Characteristics of overlying strata and mechanisms of arch beam failure in shallowly buried thick bedrock coal seams: A case study in western China

Wang,

Li,

Zhang

et al. 2023

Energy Science & Engineering

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The Yangjiacun coal mine, located in western China, exhibits distinctive characteristics, such as its shallow depth, thick bedrock, thin loose layer, and unique roof strata breaking movement. In this research, a comprehensive analysis of previous exploration data, subsequent mechanical testing, key stratum theory, natural equilibrium arch theory, and simulation tests and numerical simulations has been conducted to investigate the failure behavior of the overlying rock strata in the Yangjiacun Coal Mine. Specifically, the load‐bearing capacity of the key stratum structure in the bedrock and the morphological properties of the arch‐beam structure have been thoroughly examined. A mechanical model of the roof rock arch‐beam structure has been established, and an analytical formula for the limit size and stability criterion of the arch‐beam structure has been derived. The mining‐induced rock arch‐beam structure plays a crucial role in transferring the load of the upper strata to the surrounding goaf, thereby preventing subsidence and deformation of the overlying strata. However, the arch‐beam structure periodically experiences instability during the advancement of the working face, gradually progressing towards the upper layer until the main key stratum is breached and the arch‐beam structure collapses. Based on the characteristics of weathered rock and the arch‐beam failure model in the Yangjiacun Coal Mine, quantitative backfilling mining methods have been proposed to either compensate for the mining void created by coal extraction or limit the size of exposed key strata through strip mining, ensuring the stability of the R6 key stratum. This study represents a significant contribution to understanding the intricate failure behavior of overlying rock strata in coal mines and provides a valuable framework for the responsible and efficient extraction of coal resources in similar environments.

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Experimental Investigation of Reservoir Fluid Interlayer Crossflow Through Fracture During the Drainage Stage of Coal Measure Gas Well

Cited by 13 publications

References 37 publications

Scale-Dependent Fractal Properties and Geological Factors for the Pore Structure in Shale: Insights from Field Emission Scanning Electron Microscopy and Fluid Intrusion

Scale-Dependent Fractal Properties and Geological Factors for the Pore Structure in Shale: Insights from Field Emission Scanning Electron Microscopy and Fluid Intrusion

Geological Characteristics of Low-Yield and Low-Efficiency CBM Wells and Practical Measures for Production Increase in the Qinshui Basin

Characteristics of overlying strata and mechanisms of arch beam failure in shallowly buried thick bedrock coal seams: A case study in western China

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