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Resistivity response of coal under hydraulic fracturing with different injection rates:A laboratory study

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International Journal of Mining Science and Technology 2022年第4期32卷 807-819页

作者： Mingyang Song quangui li Qianting Hu Yanqing Wu Guanhua Ni Yangcheng Xu Yuebing Zhang liangping Hu Jialin Shi Jichuan liu Yize Deng State Key Laboratory of Coal Mine Disaster Dynamics and Control Chongqing UniversityChongqing 400044China School of Resources and Safety Engineering Chongqing UniversityChongqing 400044China College of Safety and Environmental Engineering Shandong University of Science and TechnologyQingdao 266510China

Resistivity will have different response characteristics to the hydraulic fracture propagation process. In this work, a resistivity testing system for hydraulic fracturing specimens was established. Resistivity and acoustic emission(AE) information were jointly analysed to determine the dynamic response characteristics of resistivity during hydraulic fracture propagation. The results show that the water and fracture exert a competitive influence on the connection structure of the circuit, and there are two significant peak resistivity points in the curve, presenting a double peak therein. The peak resistivity data of the specimen with a larger fracture area are much different from the initial value. With the increase of the rate of injection, the range of variation of the highest value that can be reached with the specimen resistivity decreases. High resistivity rates or high resistivity fluctuations exhibit rapid a release of fracture energy. The fracture failure mode dominated by shear fractures makes the formation produce a “series+parallel” electrical connection structure;a calculation model of formation resistivity based on shear and tensile failure was proposed to characterize the proportion of different types of hydraulic fractures and elucidate the control effect of matrix resistivity on the electrical performance of the overall circuit structure.

关键词： Resistivity Hydraulic fracturing Injection rate Fracture extension Acoustic emission

Extraction and identifcation of spectrum characteristics of coal and rock hydraulic fracturing and uniaxial compression signals

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International Journal of Coal Science & Technology 2023年第4期10卷 1-16页

作者： Ya′nan Qian quangui li Qianting Hu Zhizhong Jiang Ronghui liu Jie li Wenxi li Changjun Yu State Key Laboratory of Coal Mine Disaster Dynamics and Control Chongqing UniversityChongqing 400044China School of Resources and Safety Engineering Chongqing UniversityChongqing 400044China State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mines(Anhui University of Science and Technology) Huainan 232001China Mining College of Guizhou University Guiyang 550025GuizhouChina China Coal Technology and Engineering Group Shenyang Research Institute Fushun 113122China

Microseismic(MS)events generated during coal and rock hydraulic fracturing(HF)include wet events caused by fracturing fuid injection,in addition to dry events caused by stress perturbations.The mixture of these two events makes efective fracturing MS events pickup difcult.This study is based on physical experiments of diferent coal and rock HF and uniaxial compression.The diferences of waveform characteristic parameters of various coal and rock ruptures were analyzed using the Hilbert–Huang transform,leading to some useful conclusions.The phase characteristics of the acoustic emission(AE)energy difered signifcantly and responded well to the pumping pressure curve.The AE waveforms of HF exhibit similar energy and frequency distribution characteristics after Empirical mode decomposition.The main frequency bands for coal,sandstone,and shale samples are 100–300 kHz,while the mudstone sample is in the range of 50–150 kHz.The decay ratios for coal,sandstone,shale and mudstone samples are 0.78,0.83,0.67 and 0.85,respectively.When compared to the uniaxial compression test,the main frequency bands of HF were reduced for coal,sandstone and mudstone samples,whereas shale remained essentially unchanged.The duration,instantaneous energy,and total energy of the HF waveform are smaller than those of uniaxial compression,while the decay ratio is greater,especially for the mudstone samples.The waveform characteristic parameters,trained using the multilayer perceptron neural network,can efectively identify HF and uniaxial compression events with an accuracy of 96%.

关键词： Hydraulic fracturing Uniaxial compression Hilbert-Huang transform Acoustic emission Microseismic

天然气分布式能源项目开发要点分析——以江苏省为例

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中国资源综合利用 2024年第2期42卷 73-75页

作者：吴亮李全贵李伟中海石油气电集团有限责任公司江苏分公司南京210019

天然气分布式能源作为一种清洁高效的供能方式,在节能减排、削峰填谷、平衡能源供给等方面具有独特优势,是能源结构转型阶段的有力补充。本文以江苏省为例,分析其发展天然气分布式能源的资源条件,指出天然气分布式能源项目开发难点,然... 详细信息

天然气分布式能源作为一种清洁高效的供能方式,在节能减排、削峰填谷、平衡能源供给等方面具有独特优势,是能源结构转型阶段的有力补充。本文以江苏省为例,分析其发展天然气分布式能源的资源条件,指出天然气分布式能源项目开发难点,然后结合南京禄口国际机场分布式能源项目,开展运行实例分析并提出建议,以促进江苏省天然气分布式能源的发展。

关键词：天然气分布式能源梯级利用产业政策发展建议

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Kinetic characteristics of coal gas desorption based on the pulsating injection

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International Journal of Mining Science and Technology 2014年第5期24卷 631-636页

作者： Ni Guanhua lin Baiquan Zhai Cheng li quangui Peng Shen li Xianzhong School of Safety Engineering China University of Mining & Technology State Key Laboratory of Coal Resources and Mine Safety School of Energy Science and Engineering Henan Polytechnic University

In order to understand the kinetic characteristics of coal gas desorption based on the pulsating injection(PI), the research experimentally studied the kinetic process of methane desorption in terms of the PI and hydrostatic injection(HI). The results show that the kinetic curves of methane desorption based on PI and HI are consistent with each other, and the diffusion model can best describe the characteristics of methane desorption. Initial velocity, diffusion capacity and ultimate desorption amount of methane desorption after PI are greater than those after HI, and the ultimate desorption amount increases by 16.7–39.7%.Methane decay rate over the time is less than that of the HI. The PI influences the diffusion model parameters, and it makes the mass transfer Biot number B0 idecrease and the mass transfer Fourier series F00 increase. As a result, PI makes the methane diffusion resistance in the coal smaller, methane diffusion rate greater, mass transfer velocity faster and the disturbance range of methane concentration wider than HI.Therefore, the effect of methane desorption based on PI is better than that of HI.

关键词：瓦斯解吸动力学特性煤气脉动扩散模型传质速度动力学特征动力学过程

Guiding-controlling technology of coal seam hydraulic fracturing fractures extension

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International Journal of Mining Science and Technology 2012年第6期22卷 822-827页

作者： Zhai Cheng li Min Sun Chen Zhang Jianguo Yang Wei li quangui State Key Laboratory of Coal Resources and Mine Safety China University of Mining & Technology School of Safety Engineering China University of Mining & Technology Zhongping Energy Chemical Group

Aiming at the uncontrollable problem of extension direction of coal seam hydraulic fracturing,this study analyzed the course of fractures variation around the boreholes in process of hydraulic fracturing,and carried out the numerical simulations to investigate the effect of artificial predetermined fractures on stress distribution around fractured holes.The simulation results show that partial coal mass occurs relatively strong shear failure and forms weak surfaces,and then fractures extended along the desired direction while predetermined fractures changed stress distribution.Directional fracturing makes the fractures link up and the pressure on coal mass is relieved within fractured regions.Combining deep hole controlling blasting with hydraulic fracturing was proposed to realize the extension guiding-controlling technology of coal seam fractures.Industrial experiments prove that this technology can avoid local stress concentration and dramatically widen the pressure relief scope of deep hole controlling blasting.The permeability of fractured coal seam increased significantly,and gas extraction was greatly improved.Besides,regional pressure relief and permeability increase was achieved in this study.

关键词： Hydraulic fracturing Gas extraction Fractures Pressure relief and permeability increase

Variable frequency of pulse hydraulic fracturing for improving permeability in coal seam

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International Journal of Mining Science and Technology 2013年第6期23卷 847-853页

作者： li quangui lin Baiquan Zhai Cheng Ni Guanhua Peng Shen Sun Chen Cheng Yanying School of Safety Engineering China University of Mining&Technology

Variable frequency,a new pattern of pulse hydraulic fracturing,is presented for improving permeability in coal seam.A variable frequency pulse hydraulic fracturing testing system was built,the mould with triaxial loading was developed.Based on the monitor methods of pressure sensor and acoustic emission,the trials of two patterns of pulse hydraulic fracturing of single frequency and variable frequency were carried out,and at last fracturing mechanism was analyzed.The results show that the effect of variable frequency on fracture extension is better than that of single frequency based on the analysis of macroscopic figures and AE.And the shortage of single frequency is somewhat remedied when the frequency is variable.Under variable frequency,the pressure process can be divided into three stages:low frequency band,pressure stability band and high frequency band,and rupture pressure of the sample is smaller than that of the condition of single frequency.Based on the Miner fatigue theory,the effect of different loading sequences on sample rupture is discussed and the results show that it is better to select the sequence of low frequency at first and then high frequency.Our achievements can give a basis for the improvement and optimization of the pulse hydraulic fracturing technology.

关键词： Variable frequency Pulse hydraulic fracturing Fracture AE Fatigue

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耦合用户公共特征的单类协同过滤推荐算法

计算机科学与探索 2022年第3期16卷 637-648页

作者：张全贵胡嘉燕王丽辽宁工程技术大学电子与信息工程学院辽宁葫芦岛125105

将显式特征与隐式反馈相结合是提高单类协同过滤(OCCF)推荐准确性的常用方法。但目前的研究一般是直接将原始显式特征或交叉特征集成到OCCF模型中,因其难以判断哪些显式特征是真正重要的,故很难获得显著的性能改进。基于此,提出了一种... 详细信息

将显式特征与隐式反馈相结合是提高单类协同过滤(OCCF)推荐准确性的常用方法。但目前的研究一般是直接将原始显式特征或交叉特征集成到OCCF模型中,因其难以判断哪些显式特征是真正重要的,故很难获得显著的性能改进。基于此,提出了一种耦合用户公共特征的单类协同过滤推荐算法(UCC-OCCF)。首先,建立基于邻居的共同偏好表示网络(NB-CPR),学习与当前用户具有相似显式特征的邻居用户和某一类项目之间的交互关系,间接利用显式特征以获得共同偏好;然后,建立个人深度潜在因素表示网络(DLFR),使用深度神经网络学习用户-项目之间的潜在因素,从而得到当前用户与项目之间的交互概率;最后,基于邻居的共同偏好表示网络与个人深度潜在因素表示网络进行联合训练,从而将用户公共特征耦合到单类协同过滤推荐模型中,以提高推荐准确度。在公共数据集MovieLens 100K、MovieLens 1M和MyAnimelist上的实验结果表明,UCC-OCCF可以显著提高OCCF的推荐准确性。

关键词：单类协同过滤(OCCF) 深度学习共同偏好隐式反馈显式特征

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我国煤与瓦斯突出预测与预警研究现状

煤炭学报 2023年第8期48卷 2976-2994页

作者：梁运培郑梦浩李全贵毛树人栗小雨李建波周俊江重庆大学煤矿灾害动力学与控制国家重点实验室重庆400044 重庆大学资源与安全学院重庆400044

煤与瓦斯突出是制约煤矿安全生产的重大灾害之一。我国煤层赋存环境复杂多变。针对时有发生的突出灾害事故,为了进一步提高突出预测和预警的准确率。梳理了突出发生机理的研究进展,指出地应力、瓦斯、煤体物理力学性质仍是防治突出的关... 详细信息

煤与瓦斯突出是制约煤矿安全生产的重大灾害之一。我国煤层赋存环境复杂多变。针对时有发生的突出灾害事故,为了进一步提高突出预测和预警的准确率。梳理了突出发生机理的研究进展,指出地应力、瓦斯、煤体物理力学性质仍是防治突出的关键三要素,预测和预警的指标仍以此为基础;总结了突出预测的发展现状,指出预测的方法主要有单指标法、综合指标法和多属性指标法。主要存在预测位置局部、预测时间不连续、适应性差等不足;分析了突出预警的关键进展,指出基于突出孕育过程中的地应力、瓦斯、煤体演化机理,主要有声发射监测、电磁辐射监测、微震监测、瓦斯浓度时序监测,以及声电瓦斯综合监测预警方法。由于监测数据精度低、预警结果准确率低等不足而影响现场应用效果。基于当前突出预测和预警现状,以及煤矿安全智能化的需求,提出未来研究展望:突出预测应在启动判据与强度预测上,同时发展精细化、可量化指标;突出预警应跟踪指标的非线性变化,发展基于理论指标的趋势预警,基于事故经验的匹配预警,以及基于监控数据挖掘的前兆预警。通过组合预警模型,将定性与定量预警相结合,形成基于理论-经验-数据多重驱动组合预警模型,进一步提高预警准确率。同时发展矿山数字孪生建设,形成整体、连续、准确的煤矿突出灾害可视化智能预警。

关键词：煤与瓦斯突出突出机理突出预测突出预警煤体物理力学性质

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煤系地层弹性波阶段性衰减特性分析

中国矿业大学学报 2023年第3期52卷 466-477页

作者：李全贵凌发平胡千庭李楠姜志忠钱亚楠刘荣辉李文禧重庆大学煤矿灾害动力学与控制国家重点实验室重庆400044 重庆大学资源与安全学院重庆400044 中国矿业大学煤炭资源与安全开采国家重点实验室江苏徐州221116 贵州大学矿业学院贵州贵阳550025

微震监测技术在矿山动力灾害预警、水力压裂增透效果评价等方面发挥着显著作用.煤系地层是典型的层状介质,介质各向异性和层间界面是弹性波在煤系地层中传播和衰减的重要影响因素.结合弹性波传播理论,采用有限元数值模拟为手段,研究了... 详细信息

微震监测技术在矿山动力灾害预警、水力压裂增透效果评价等方面发挥着显著作用.煤系地层是典型的层状介质,介质各向异性和层间界面是弹性波在煤系地层中传播和衰减的重要影响因素.结合弹性波传播理论,采用有限元数值模拟为手段,研究了层状介质中弹性波传播的阶段性衰减特征.研究结果表明:相同试验条件下,层状介质中弹性波传播的信号幅值随着传播距离的增加呈指数衰减.由于层间界面的反射和透射作用,雷克子波速度幅值在100~400 Hz频带内显著衰减,在低频段(100~200 Hz)内的垂直衰减系数约为水平衰减系数的1.5倍,测点有效监测范围为8~12 m.雷克子波作用1个周期内,穿层方向的垂直应力场在近震测点(距离≤13 m)范围内具有相同的波动规律,应力响应表现出传递特性;随震源作用时间和传播距离增加,层间不连续界面阻断弹性波应力传递过程,弹性波幅值在主应力方向表示出阶段性衰减规律,应力状态呈现“正—负—正”交替变化特征.通过数据拟合分析发现,层状介质中的衰减系数介于单层介质吸收衰减系数的最小值与最大值之间.

关键词：弹性波传播阶段性衰减层状介质微震数值模拟