Full-Scale Pore and Microfracture Characterization of Deep Coal Reservoirs: A Case Study of the Benxi Formation Coal in the Daning–Jixian Block, China

International Journal of Energy Research, Journal Year: 2024, Volume and Issue: 2024, P. 1 - 21

Published: April 23, 2024

The pore-fracture structure of deep coal reservoirs is highly important for evaluating, exploring, and developing coalbed methane (CBM) resources. This study considers three samples from the DJ57 well in Benxi Formation Daning–Jixian block on eastern margin Ordos Basin as research object. Based quality parameters samples, field emission scanning electron microscopy (FE-SEM), gas adsorption experiments, high-pressure mercury intrusion porosimetry (MIP), microcomputed tomography (micro-CT) were used to quantitatively characterize nanoscale pores microscale fractures evaluate at different scales. results reveal that pore types are diverse include mainly organic matter (OM) pores, inorganic (intraparticle interparticle pores), microfractures. shape exhibit round, oval, wedge shapes, while microfractures slender stripes or serrated curves. multiscale quantitative characterization reservoir based a variety methods, fracture volume distributions U-shaped, revealing coexistence micropores volumes (0.3–2 nm), mesopores (2–50 macropores (50 nm 10 μm), (>10 μm) account 78.00%, 6.78%, 2.08%, 13.14%, respectively, total (PV). full-scale splicing calculation, permeability ranges 5.77 28.22 mD. observation indicate connected each other, forming network with strong connectivity. associated diameters>100 μm, accounting approximately 95% permeability. Moreover, provide large space CBM adsorption, enhance seepage capacity CBM.

Language: Английский

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Dynamic Production Characteristics of Deep Coalbed Methane: A Case Study of Daning-Jixian Block

Energy & Fuels, Journal Year: 2024, Volume and Issue: 38(10), P. 8700 - 8711

Published: April 30, 2024

The Daning-Jixian block, located in the eastern margin of Ordos Basin, is abundant deep coalbed methane (CBM) resources and serves as a pilot test block for CBM development China. Currently, exploration are early stages. production characteristics laws across different stages not fully elucidated, leading to uncertainties discharge control measures well optimization system. This study addresses these challenges by analyzing actual data from wells. It establishes classification standard wells stage model diagram. Based on this, it compares analyzes with middle shallow variations among types findings reveal following key points: (1) gas categorized low-, medium- high-production based average daily 1500 3000 m3/d, respectively; (2) delineated into four stages: rise, decline, stable production, depletion; (3) contrast wells, predominantly produce free stage, characterized rapid high production; (4) capacity mainly influenced reservoir stress characteristics, effectiveness fracturing, continuity production. provides valuable reference formulation drainage systems strategies.

Language: Английский

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Challenges and development direction of deep fragmented soft coalbed methane in China

Earth energy science., Journal Year: 2024, Volume and Issue: unknown

Published: Sept. 1, 2024

Developing deep fragmented soft coalbed methane (CBM) can significantly enhance domestic natural gas supplies, reduce reliance on imported energy, and bolster national energy security. This manuscript provides a comprehensive review of commonly employed extraction technologies. It then delves into several critical issues in the current stage CBM exploration development China, including compatibility existing technologies with reservoirs, characteristics occurrence states desorption pressure, generation mechanisms. Our research indicates that China have reached an internationally advanced level, yet industry is facing unprecedented challenges. Despite progress low-permeability, high-value coal seams, significant breakthroughs not been achieved exploring other types seams. For different integrated developed, such as surface pre-depressurisation segmented hydraulic fracturing seam roof strata. Additionally, techniques like large-scale volume horizontal wells established, enhancing reservoir stimulation effects recovery rates. However, all these are fundamentally based permeation. These lack direct methods aimed at diffusion rate CBM, thereby failing to fully reflect unique CBM. Current theories universally applicable They do adequately account for predominantly adsorbed state complex variable mechanisms further constrain China. Finally, continuous new necessary. Integrating more effective essential technical adaptability concerning characteristics, states, mechanisms, ultimately achieving efficient development. We conclude while possesses substantial foundation fractured resources, constrained requires utilize resources effectively.

Language: Английский

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Pore Size Distribution and Fractal Characteristics of Deep Coal in the Daning–Jixian Block on the Eastern Margin of the Ordos Basin

ACS Omega, Journal Year: 2024, Volume and Issue: unknown

Published: July 20, 2024

Important breakthroughs have recently been achieved in deep coalbed methane (CBM) exploration and development regions such as the eastern margin of Ordos Basin, China. Investigating characteristics various-scale pores coalbeds is great significance for resource assessment selection favorable zones CBM exploration. Herein, six coal samples were selected from Shanxi Taiyuan Formations Daning-Jixian block on Basin. Low-pressure CO

Language: Английский

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Genetic Types and Gas Source Analysis of Jurassic Deep Coalbed Methane in Baijiahai Uplift, Junggar Basin

ACS Omega, Journal Year: 2025, Volume and Issue: 10(9), P. 9321 - 9336

Published: Feb. 27, 2025

Multiple sets of source rocks are developed in the Baijiahai Uplift Junggar Basin. The gas genetic types and sources deep coalbed methane (CBM) Jurassic period inconclusive. Based on analysis geochemical characteristics, maturity, natural composition, carbon isotope rocks, combined with plate verification seismic interpretation, CBM were identified, migration path revealed. results show that three Carboniferous, Permian, have good hydrocarbon potential. organic matter mainly II2 III, evolution is low-maturity stage. atoms a mixed containing exogenous input gas. coal-type derived from humic kerogens, an average proportion 54.47%. oil-type Permian sapropelic 45.43%. In plane, closer to fault, greater clarified this study area. research helpful deepen understanding enrichment law provide references for optimization favorable exploration areas.

Language: Английский

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Evaluation of Pore-Fracture Structures and Gas Content in Deep Coal Reservoir of Yan’an Gas Field, Ordos Basin

Processes, Journal Year: 2025, Volume and Issue: 13(4), P. 1177 - 1177

Published: April 13, 2025

Research has delved into the main controlling factors for evolution of pore-fracture structure in deep coal samples. The gas content is influenced by multiple factors, among which samples stands as one key determinants. To ascertain and Yan’an Gas Field, 16 were collected from Field Ordos Basin this study. A series laboratory tests analyses then carried out. According to test results, major analyzed accordance with proximate analysis components, maceral mineral composition samples, Ro,max, conjunction pore volume specific surface area nanopores. Meanwhile, based on situ desorption experiment, explored. First, SEM hand specimen identification, relatively well developed. Calcite filling fractures can be seen specimens This indicates that a very important influence Secondly, study primarily ash fixed carbon. As increased, mesopore rose across all sample types, Type C showing highest increase (78.1% 12.4% compared A). Conversely, micropore characteristics declined, exhibiting 4.8% drop 4.7% reduction volume. Ro,max generally higher than 2.8%, multifaceted impact evolution. Finally, mainly controlled nanopores, industrial components compositions minimal direct influence. suggests results combined effects material Inorganic minerals like quartz calcite indirectly affect influencing development—occupying spaces while also creating new pores, especially through dissolution. clay hinder development limited fracture-forming capacity. purpose evaluate Yan‘an Field. There are few studies previous scholars.

Language: Английский

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Study on Evaluation of the Virtual Saturated Vapor Pressure Model and Prediction of Adsorbed Gas Content in Deep Coalbed Methane

Processes, Journal Year: 2024, Volume and Issue: 12(9), P. 1837 - 1837

Published: Aug. 29, 2024

Accurately predicting the adsorbed gas content in coal reservoirs is crucial for evaluating deep seams. However, due to significant variations temperature and pressure conditions across different reservoirs, accurately assessing quantity presents challenges. Based on adsorption potential theory, this paper proposes a prediction model of that applicable under various conditions. The results indicate influenced by combination temperature, pressure, rank. increase rank enhances inhibitory effect methane adsorption. Meanwhile, there are differences obtained from virtual saturated vapor models. Among them, Amankwah theoretically satisfies uniqueness characteristic curve, with optimal k values samples ranging between 2 9. In terms gas, performance models ranked as follows: > Antonie Astakhov Dubinin Reid model. exhibits smallest average relative error root mean square error. addition, burial depth increases, influence decreases, while significance critical located around 1600 m. At depths shallower than depth, tends preferentially accumulate form which generally have lower commercial value. deeper free has reservoirs. stage, dominated start transitioning those containing gas. These findings expected deepen understanding coalbed provide scientific basis exploration development study area.

Language: Английский

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Study of the Methane Adsorption Characteristics in a Deep Coal Reservoir Using Adsorption Potential Theory

Applied Sciences, Journal Year: 2024, Volume and Issue: 14(8), P. 3478 - 3478

Published: April 20, 2024

The gas adsorption characteristics in deep coal reservoirs are the focus of coalbed methane geology research. In order to reveal and quantitatively characterize amount adsorbed seams, four coals were collected from Permian Longtan Formation southern Sichuan Province. Methane isothermal tests carried out on samples at 30 °C. characteristic curve was established based data adsorption. potential theory used predict curves under different temperatures evolutionary relationship between capacity seam burial depth C17 C25 seams Province, China. results showed that °C belonged Type I isotherm curve. for various 45 °C, 60 75 predicted uniqueness comprehensively controlled by pressure temperature. a positive effect adsorbed, while temperature negative methane. became more significant with increase pressure. study beneficial further promoting exploration development Province

Language: Английский

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Physical Properties of High-Rank Coal Reservoirs and the Impact on Coalbed Methane Production

Processes, Journal Year: 2024, Volume and Issue: 12(8), P. 1754 - 1754

Published: Aug. 20, 2024

The physical characteristics of coal reservoirs are important factors affecting the occurrence status coalbed methane, as well key restricting production capacity. Therefore, taking 3# in Qinnan region China research object, based on actual data 200 methane wells area, experimental testing combined with simulation analysis was used to explore properties medium and high-order their impact methane. reservoir formation capacity changes area were revealed, calculated using gray correlation method. results indicate that micropores study well-developed, while macropores mesopores (exogenous fractures) underdeveloped, surface is complex, connectivity poor, resulting high gas adsorption low permeability. fractal pores fractures can reflect permeability reservoirs. Permeability positively correlated mesopores, negatively micropores. There a positive between productivity, has stress-sensitive boundary. main productivity under complex pore fracture system high-rank identified, relational method evaluate development effect area. This provides guidance for

Language: Английский

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Oolitic Sedimentary Characteristics of the Upper Paleozoic Bauxite Series in the Eastern Ordos Basin and Its Significance for Oil and Gas Reservoirs

Processes, Journal Year: 2024, Volume and Issue: 12(10), P. 2123 - 2123

Published: Sept. 29, 2024

In recent years, great breakthroughs have been made in gas explorations of the Upper Paleozoic bauxite series Longdong area Ordos Basin, challenging understanding that is not an effective reservoir. Moreover, studying reservoir characteristics crucial for oil and exploration. Taking as example, this study systematically collects data from previous publications analyzes petrology, mineralogy, oolitic micro-morphology, chemical composition, other sedimentary using field outcrops, core observations, rock slices, cast X-ray diffraction analysis, scanning electron microscopy energy spectra, so on. study, microscopic significance reservoirs are described. The results show main minerals boehmite clay composed 73.5–96.5% boehmite, with average 90.82%. rocks mainly bauxitic mudstone bauxite. A large number oolites observable series, corrosion pores intercrystalline about 8–20 μm size generally developed. These important storage spaces brittleness index was found to be high 99.3%, which conducive subsequent mining fracturing. source coal measure Paleozoic. obvious content, but continuity planar distribution poor, providing a scientific basis improving exploratory effects reservoirs.

Language: Английский

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