Experimental study on stress-dependent permeability of coal samples with different salinities of water in coal

Lei, Junhuan; Meng, Zhaoping; Tan, Libo; WANG, Yuheng; Wu, Di

doi:10.1016/j.psep.2022.12.025

Cited by 5 publications

(3 citation statements)

References 34 publications

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“…This means that pressurized drilling requires a drilling fluid system with specific abilities, such as suspending and transporting cuttings to clean the borehole, reducing drilling fluid loss by plugging fractures, and forming thin and compact mud cakes to reduce filtration and protect soft walls. Literature research indicates that the majority of coal seams contain clay minerals, such as kaolinite, illite, illite/smectite mixed clays, montmorillonite, chlorite, etc., which means that some coal seams have a certain water sensitivity. ,− Hence, the drilling fluid must additionally inhibit the clay hydration dispersion to prevent borehole instability. After drilling, the drilling fluid and mud cake should be easily degraded and removed to reduce damage to the coal seams and restore permeability.…”

Section: Methodsmentioning

confidence: 99%

Construction and Evaluation of a Degradable Drilling Fluid for Underground Coalbed Methane Extraction Boreholes

Kong,

Tang,

Luo

et al. 2024

ACS Omega

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Gas drainage with bedding boreholes is an efficient method for preventing gas and achieving coal and gas comining in underground mining engineering. An underground pressurized drilling method is proposed to maintain the borehole stability. However, the presence of natural fractures in coal seams poses challenges during pressurized drilling. Therefore, it is crucial to establish a low-leadage degradable drilling fluid system that minimizes coal seam damage. In this study, a degradable drilling fluid system was developed based on the characteristics of coal seams. The performance and influencing factors of the drilling fluid and the degrading capability of cellulase were examined. Moreover, the damage of the drilling fluid on fractured coal seams was investigated using core flow test methods. The results showed that additives significantly improved the rheology, filtration, and inhibition of the drilling fluid. The drilling fluid system exhibited excellent stability, rheological properties, low filtration, and sealing performance in coal seam environments. However, drilling fluid invasion and mud cake blockage negatively affected gas flow in fractured coal seams, and a higher content of filtrate reducer hindered the recovery of the gas flow rate. Cellulase was used to degrade polymers and alleviate the challenge of mud cake removal after drilling. Research on the influencing factors of cellulase indicates that the degradation efficiency of cellulase enzymes is influenced by the temperature, pH, salinity, and solid-phase content. For polluted coal samples, the gas flow rate significantly recovered after treatment with a cellulase solution. This study provides insights into a degradable drilling fluid system that can enhance underground pressurized drilling methods and minimize reservoir damage.

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Section: Methodsmentioning

confidence: 99%

Construction and Evaluation of a Degradable Drilling Fluid for Underground Coalbed Methane Extraction Boreholes

Kong,

Tang,

Luo

et al. 2024

ACS Omega

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“…Subsurface water depicts several dissolved salts at a range of salinities, and the studies on coal wettability, coal adsorption, and coal permeability have therefore investigated a range of salinities. − Similarly, wettability of coal surface in the presence of CO 2 has been evaluated under a range of salinity conditions (Table ). The influence of brine salinity on the wetting characteristics of the coal/CO 2 /water systems has been extensively reviewed, and the collected data are presented in Figure .…”

Section: Coal Wettability Assessment By Contact Anglesmentioning

confidence: 99%

Coal Wettability: A Holistic Overview of the Data Sets, Influencing Factors, and Knowledge Gaps

Arif,

Awan,

Zhang

et al. 2024

Energy Fuels

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Coal seams are naturally occurring geological media offering tremendous potential for gas storage. The wetting characteristics of coals at typical geological formations underpin a diverse array of processes spanning coal resource recovery, combustion, enhanced coal beneficiation, enhanced methane recovery, and CO 2 storage for sustainable energy transition. An accurate characterization of coal wettability is thus crucial and remains an active area of research. The intrinsic heterogeneity of coal surfaces and the presence of multicomponent systems add layers of intricacy to wetting behavior. In particular, coal wettability characterization is challenging because it is a complex and multifaceted function of a range of influencing parameters. These include coal geological parameters (such as coal rank, ash content, and microstructure), operating conditions (e.g., CO 2 injection pressure, coal seam temperature, and salinity), and sample conditioning factors (e.g., surface roughness, polishing, cleaning, etc.). This study develops a repository of the coal wettability data sets (using contact angle measurements, the nuclear magnetic resonance method, and spontaneous imbibition) for a range of conditions. The factors influencing coal wettability are critically analyzed and explained. We also identify potential limitations related to wettability measurement techniques and present the outlook for future research in this area. The findings suggest that the coal/CO 2 /brine systems exhibit wetting characteristics from weakly water-wet to strongly CO 2 -wet. The main factors contributing to the increased CO 2 wettability of coals include but are not limited to high injection pressure, low to moderate temperatures, high salinity, low ash content, and high vitrinite reflectance. Thus, this study offers a succinct analysis of the coal wettability data sets, presents an overview of cutting-edge technologies, and discusses potential future advances in this field to improve the understanding of coal wettability and the associated impact on fluid flow in the coal microstructure.

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“…Experimental studies conducted in the past [4,5] provide evidence of permeability's dependence on stress. Later on, researchers discovered that stress-dependent Fuels 2023, 4 permeability plays important role in a variety of engineering applications, including hydrocarbon production and fluid injection designs [6,7], CO 2 sequestration [8], coal bed methane reservoirs [9,10], geothermal reservoirs [11], and nuclear waste storage in the subsurface.…”

Section: Introductionmentioning

confidence: 99%

Stress-Dependent Petrophysical Properties of the Bakken Unconventional Petroleum System: Insights from Elastic Wave Velocities and Permeability Measurements

Pothana,

Ifrene,

Ling

2023

Fuels

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The net-effective stress is a fundamental physical property that undergoes dynamic changes in response to variations in pore pressure during production and injection activities. Petrophysical properties, including porosity, permeability, and wave velocities, play a critical role and exhibit strong dependence on the mechanical stress state of the formation. The Williston basin’s Bakken Formation represents a significant reservoir of hydrocarbons within the United States. To investigate this formation, we extracted core plugs from three distinct Bakken members, namely Upper Bakken, Middle Bakken, and Lower Bakken. Subsequently, we conducted a series of measurements of ultrasonic compressional and shear wave velocities, as well as pulse decay permeabilities using nitrogen, under various confining pressures employing the Autolab-1500 apparatus. Our experimental observations revealed that the ultrasonic wave velocities and permeability display a significant sensitivity to stress changes. We investigated existing empirical relationships on velocity-effective stress, compressional-shear wave velocities, and permeability-effective stress, and proposed the best models and associated fitting parameters applicable to the current datasets. In conjunction with the acquired datasets, these models have considerable potential for use in time-lapse seismic monitoring and the study of production decline behavior. The best fitting models can be used to forecast the petrophysical and geomechanical property changes as the reservoir pore pressure is depleted due to the production, which is critical to the production forecast for unconventional reservoirs.

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Experimental study on stress-dependent permeability of coal samples with different salinities of water in coal

Cited by 5 publications

References 34 publications

Construction and Evaluation of a Degradable Drilling Fluid for Underground Coalbed Methane Extraction Boreholes

Construction and Evaluation of a Degradable Drilling Fluid for Underground Coalbed Methane Extraction Boreholes

Coal Wettability: A Holistic Overview of the Data Sets, Influencing Factors, and Knowledge Gaps

Stress-Dependent Petrophysical Properties of the Bakken Unconventional Petroleum System: Insights from Elastic Wave Velocities and Permeability Measurements

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