Sustainability Commons^™

Droughtscape, Summer 2019, Cory Matteson

DroughtScape: Quarterly Newsletter of the National Drought Mitigation Center (2007–2023)

Contents

From the Director

Quarterly drought summary

Quarterly drought impacts

NDMC welcomes African visitors

Ready for Drought game debuts

U.S. Virgin Islands added to USDM

Australian programmer visits NDMC

Upcoming events

Partnerships with NDMC extended

Reasonable Length Of Working Face 11-101 During Mining Above Confined Aquifer In Tuanbai Mine, Li Gang, Zhang Kai, Su Junhui, Wang Jinbo

Coal Geology & Exploration

The working face 11-101 of Tuanbai coal mine in Huozhou, Shanxi Province is exploited above aquifer. In order to prevent floor water inrush accidents during mining, research combination of elasto-plastic theory, on-site measurement and numerical simulation was carried out to analyze the development rule of failure depth of the floor, then the reasonable length of the mining face under this condition was determined. The result shows that with the advancement of working face, the bottom plate of lagging working face is stretched and destroyed at about 6 m behind the lagging working face, and the bottom plate has a wedge …

Development Of Data Acquisition And Control Software For Seismic Monitoring With Mining, Duan Jianhua, Wang Yunhong, Wang Baoli

Coal Geology & Exploration

Seismic monitoring with mining can continuously detect and real-time predict geological anomalies in front of work, it has become a research hotspot in recent years, but at present, there is no equipment that can carry out seismic monitoring with mining in coal mine.Therefore, the development of seismic monitoring equipment with mining has become a top priority. In order to solve this problem, based on the MFC development framework, a set of seismic monitoring data acquisition software is developed. A three-month joint survey was carried out indoors and outdoors, and a three-month comprehensive trial operation was carried out in Yanjiao Coal …

Experiment On Methane Displacement In Coalbed By Supercritical Carbon Dioxide, Wu Di, Liu Xueying, Sun Keming, Xin Liwei, Miao Feng

Coal Geology & Exploration

Using self-made experimental system, experiments were performed on coal samples to study supercritical CO₂ seepage, adsorption and CH₄ displacement by supercritical CO₂. Experimental results show that permeability and adsorption of supercritical CO₂ in coal increase with CO₂ pressures. Pressures and temperatures of CO₂ influence the values of displaced CH₄. Values of displaced CH₄ increase by average 0.076 cm³/g and sweep efficiency rises by 17%-23% with the CO₂ pressure increasing from 8 MPa to 12 MPa, while displacement volume decreases linearly. With the temperature rising by 10℃, sweep …

The Matching Of Gas Production Curve Characteristic And Reservoir Conditions In Vertical Coalbed Methane Wells, Han Wenlong, Wang Yanbin, Liu Du, Chang Hong, Ding Tao

Coal Geology & Exploration

The matching of coalbed methane(CBM) production curve type and geological conditions directly affects the gas production. Based on dividing gas production curves types of vertical CBM wells in the southern block of Shizhuang in Qinshui basin over 4 years, the characteristics of gas production curve were analyzed. The matching of gas production curve with reservoir parameters was further analyzed. The paper discovered and divided the gas production curve into four types:type of fast rising of single peak, type of stable rising of single peak, bimodal type of being low later and bimodal type of being high later. The original permeability, …

The Seepage Characteristics Of A Single Well Dewatering From An Unconfined Aquifer Bottom, Li Yang, Wang Wenxue, Xiao Hang, Sun Yi, Wang Yun, Di Mengna

Coal Geology & Exploration

Dewatering from an aquifer bottom for drain and depressurization is one common method to ensure safety mining. This method is significantly different from pumping from the ground. In order to study the seepage characteristics of the dewatering hole(well), the seepage characteristics of a single well dewatering from an unconfined aquifer bottom was taken as an example and studied using numerical simulation method. The results show that when l_w<l_c, the pore water pressure above the dewatering well is greater than zero, which presents the rule of increasing first then decreasing from bottom to top, and the seepage …

Quantitative Quality Evaluation Of Seismic-While-Mining Data, Qin Si, Cui Weixiong, Wang Wei

Coal Geology & Exploration

A seismic-while-mining(SWM) monitoring system laid in a working face of an underground coalmine will continuously generate tremendous amount of SWM data. When a coalmine cutting machine cuts coal seam actively, the SWM data will be of high correlation, and when it is not, the SWM data will be of low correlation or even no correlation at all. Based on this characteristic, a method for automatically and quantitatively evaluating the quality of SWM data was proposed. Using this method to process SWM data from a coal mine in Inner Mongolia, the result showed that this method can recognize the correlation peak …

Study On Noise Attenuation Of Seismic While Mining, Liu Qiang

Coal Geology & Exploration

In view of the closure of the environments and the high requirements of safe production of underground coal mine, the explosive source has many limitations in the operation of seismic exploration of coal mine, and the coal shearer as the source can avoid many inherent shortcomings of the source of explosives, has the advantage of real-time detection of the internal structure and the stress of the working face without affecting the normal operation of the mining face. However, as the energy generated by the shearer is much smaller than that of the explosive source, the quality of the collected signal …

Development And Application Of Software In Seismic While Mining Data Processing, Wang Baoli

Coal Geology & Exploration

The seismic while mining detection technology with coal cutter as seismic source in coal face is the key to accurately know the geological conditions of mining, improve the detection accuracy of geological anomaly structure in coal face, and realize unmanned intelligent mining or with few people. It has broad application prospects.The conventional seismic data processing software can not meet the requirements of real-time, continuous and large data volume for seismic while mining data. By analyzing the requirement of seismic while mining detection technology for data processing software(SWM), a framework of hierarchical and multi-task data processing software is proposed. The components …

Auxiliary Outburst Prevention Techniques By Surface Pre-Drainage For Coalbed Exposed In Tunnel And Mine Shaft, Zhang Dongliang

Coal Geology & Exploration

How to expose an outburst-prone coal seam safely and efficiently in tunnel and mine shaft is always a subject to study continuously in outburst prevention, surface coalbed gas pre-drainage is an effective approaches for outburst prevention. Based on the analysis of outburst mechanism in tunnel and mine shaft and the core task of outburst prevention, the characteristics and adaptability of the outburst prevention techniques by surface pre-drainage are studied. Practical engineering application shows that the gas content and pressure in coal exposure area can be effectively reduced using surface pre-drainage well by cavern completion or hydraulic fracturing, the stress or …

Study On Sediment Environment And Rock Mechanics Characteristics Of The Delta Plain Of Jurassic Coalfield In Northern Shaanxi, Wang Haijun, Ma Liang

Coal Geology & Exploration

Delta plain sedimentary environment is one of the coal-forming environments of the coal resources of Jurassic coalfield in northern Shaanxi. In order to get the rock mechanics parameters and characteristics of coal seam roof in different environments and to further investigate the relationship between the sedimentary environments and the rock mechanics characteristics, firstly from the analysis of the regional sedimentary environments, then by using techniques such as accurate core description, sedimentary structural analysis, facies analysis of geophysical logging, the microfacies were recognized, the sedimentary microfacies types of roof and their combination characteristics were classified. Later, rock samples of different lithology …

Application Of Sec Dynamic Reserves Evaluation Method In Coalbed Methane Field: A Case From Hancheng Block In Ordos Basin, Yi Wei, Xiong Xianyue, Cao Yimin, Ding Rong

Coal Geology & Exploration

At present, all the SEC reserves evaluation of coalbed methane fields uses dynamic assessment methods. In the process of evaluation, the parameters and calculation results are various. In order to solve this problem, this paper takes the Hancheng block in Ordos basin as an example, a series of evaluation methods adapted to the production characteristics of coalbed methane have been comprehensively applied, optimizing various parameters, and summarizing the law of decline. The results show that geological units are divided according to tectonic conditions, and on this basis, evaluation units are divided according to development effect, which can objectively and reasonably …

Diffusion Ability Of Contaminants Of Coal Gangue Leachate In Geosynthetic Clay Liners, Dong Xingling, Dong Shuning, Zhou Zhenfang, Wang Qiangmin, Liu Ji

Coal Geology & Exploration

To verify the feasibility of geosynthetic clay liners(GCL) as liners material for coal gangue impoundment, diffusion tests were conducted with vertical double reservoir method to determine the diffusion ability of heavy metals(Zn²⁺、Mn²⁺) and sulfate from coal gangue leachate in GCL-S(Sodium-activated bentonite), and POLLUTE V7 based on finite layer method was used to draw the fitting curve of pollutant changing with time in the diffusion device, which calculated the diffusion coefficient of contaminants in GCL. The data show that the diffusion coefficient in GCL was lower than that in compacted clay liners, so GCL could control the …

Occurrence Regularity Of Uppermost Minable Coal Seams And Their Harmful Level Of Mining In Yushen Mining Area, Li Zhixue, Shen Xiaolong, Li Mingpei, Wang Hongsheng

Coal Geology & Exploration

In order to study the occurrence regularity of uppermost mining coal seams and the damage degree of Salawusu Formation aquifer caused by mining in Yushen mining area, occurrence characteristics of the uppermost mining coal seams was analyzed, and spatial distribution law and combination of the uppermost mining coal seams overlying strata, the development law of the water flowing fractured zone based on the ratio of rock and loading thickness and mining height, and the damage degree of the Salawusu Formation aquifer caused by coal seam mining. The damage degree of the Salawusu Formation aquifer was divided into four kinds of …

Detection Electric Field Control Strategy For Advanced Scanning Detection Of Focusing Multipoint Current Sources In Coal Mine Roadway, Liu Zhimin, Meng Cairu, Li Bing, Han Lei, Pan Yue

Coal Geology & Exploration

In order to realize the effective detection of electric field focusing depth and deflection angle scanning of focusing multipoint current sources in coal mine roadway, and accurately grasp its variation, according to the advanced scanning detection mechanism, Gauss theorem and two different methods were used to solve the integration process and derive the electric field line equation of a uniformly charged linear electrode with finite length. The electric field line equation of coplanar multi-electrode layout is induced and deduced through using its spatial distribution symmetry. By changing focusing shielding current ratio coefficient, this paper calculates the boundary line equation of …

Development Of High Temperature Borehole Inclinometer, Qu Zhaogui, Gong Mingmao, Zhou Ce, Wang Guangzhai

Coal Geology & Exploration

In the detection of high-temperature and high-pressure dry heat rock drilling location trajectory, the instrument has some problems, such as poor performance, poor stability, low measurement accuracy and large energy consumption. A set of high temperature borehole inclining device is designed to solve the problem of high temperature and high pressure measurement deviation and temperature measurement. Adopt high temperature resistant components, design control and measurement circuit. Automatic intermittent power supply is adopted to reduce heat dissipation and power consumption. The design of heat preservation pipe and pressure detection pipe is carried out by using ANSYS finite element software to conduct …

Application Of Wire Line Coring Technique In Overburden Drilling, Li Baijun, Zou Run, Guo Chao

Coal Geology & Exploration

In order to improve the drilling efficiency of two oil and gas geological survey wells "Jitaodi 1" and "Ji Bai Di 1" in Baicheng area of Jilin Province, wireline coring technique was applied in overburden drilling. Based on the lithological characteristics of the drilled strata, combined with the technological characteristics of core extraction by lifting the drill pipe and wireline core extraction, by designing the bit, drilling flushing fluid and by improving drilling procedure parameters, drilling tool nozzle flow channel, the wireline coring drilling method has been successfully applied in drilling overburden strata(about 1 100 m thick). Compare with the …

Table Of Contents, The Editors

Coal Geology & Exploration

No abstract provided.

The Development Of Seismic-While-Mining Detection Technology In Underground Coal Mines, Cheng Jianyuan, Qin Si, Lu Bin, Wang Baoli, Wang Ji

Coal Geology & Exploration

The explosive source of underground seismic exploration in coal mines is greatly affected by the control of pyrotechnics and cannot realize the monitoring and early warning of dynamic geological disasters in coal mining. Seismic-while-mining(SWM) is a new technique based on shearer as a seismic source underground. The paper reviewed the research status of SWM technique at home and abroad, introduced the SWM's principle and its unique advantages. According to some pilot experiments of SWM, the results show that the shearer can be used as a seismic source because it has the character of strong excitation energy, wide frequency band, safety, …

Method Of Transparent Working Face Based On Dynamic Detection Of Cross Hole Seismic Subdivision, Lu Bin

Coal Geology & Exploration

Transparent working surface is an important part of intelligent coal mining. It provides detailed geological structure information of working face for intelligent coal mining. This paper proposes a working surface exploration method based on segmented and dynamic cross-hole seismic, which can realize progressive fine detection of coal working face. The method is a new development with seismic while mining, which is using the coal cutter as seismic source. The main idea is to image the working face segmented by deploying some detectors in a series of horizontal holes parallel to the long wall. The method performs fine imaging on the …