Table of Content

20 August 2018, Volume 20 Issue 4

Previous Issue    Next Issue

CONDUCTIVITY CHANGING RULES OF LOW-RANK COAL RESERVOIR DURING METHANE ABSORPTION AND DESORPTION

 

MA Dongmin, CHEN Yue, YANG Fu, et al

2018, 20(4):  1-8.  DOI: 10.13776/j.cnki.resourcesindustries.20180730.002

Asbtract ( )   PDF (5782KB) ( )  

References | Related Articles | Metrics

To study the conductivity changing rules of low-rank coal reservoir during methane absorption and desorption, this paper, based on a case study on No.4 coal seam in Binchang coal mine, measures the resistivity of different coal samples during methane absorption and desorption, studies the conductivity changing rules and mechanism, and compares their variance of different coal rocks. Conductivity rises during the absorption process with an ascending pressure. Relation among resistivity, absorption quantity and equilibrium pressure can be described as a quadratic function. During pressure-descending-desorption process, conductivity rises slightly; it has linear relation with absorption quantity and equilibrium pressure. Heat-releasing and coal matrix swelling make a rise in conductivity during methane absorption, and vice versa. Methane absorption results in an irreversible change in coal structure; its resistivity cannot be recovered to its original level even after methane desorption. Durain, with high ash, even pore throat structure and less charged particles, is weaker than vitrain in conductivity, but stronger in absorption, leading to a greater and faster decrease in conductivity during methane absorption.

GAS CONTENT AND GAS GUSH MECHANISM OF LOW-RANK COAL SEAM 

WANG Wanhong

2018, 20(4):  9-12.  DOI: 10.13776/j.cnki.resourcesindustries.20180727.006

Asbtract ( )   PDF (2767KB) ( )  

References | Related Articles | Metrics

Coal seam gas content is one of key indicators in marking CBM reservoir features. To precisely obtain gas content of low-rank coal seam, this paper, based on a case study on Dafosi coal mine, Binchang district, uses Langmuir formula to calculate the gas content of No.4 coal seam through measuring the critical desorption pressure during extraction, with the results showing gas content 2.30-3.62 m^3/t, 2.87 m^3/t on average, 0.8 to 1.93 times test gas content, corresponding to the feature of low-rank coal, very close to the original gas content of No.4 coal seam. This paper also discusses the reason of gas gush during mining No.4 coal seam according to rock movement theory and flow theory. Release of stress produces new fissures as top and bottom transform, collapse and move in the process of coal mining, changing coal seam structures and permeability, leading to pressure-relief-permeability-rising and flow-increasing effects, which makes gas gush of Dafosi coal mine. 

FRACTURING EFFECT OF DEEP COAL RESERVOIR IN ZHENGZHUANG WELL FIELD, JINCHENG MINE DISTRICT 

ZHAO Xiaoshan, ZHANG Kun, LI Jiangbiao, et al

2018, 20(4):  13-17.  DOI: 10.13776/j.cnki.resourcesindustries.20180808.001

Asbtract ( )   PDF (3327KB) ( )  

References | Related Articles | Metrics

This paper uses Nolte-Smith net double logarithmic pressure-time curve, combined with in-situ operating curve changes, to establish 8 types of hydraulic-fracturing sanding curve, which are employed to study the fracturing curves in 230 beds in 120 wells in Zhengzhuang well field and the deep coal reservoir fracturing effect, aiming at offering references for fracturing design, adjusting operating parameters. Type NS-III-3 (interlayered end-desanding and halt-sanding-return-discharging process) and NS-IV-3 (object layer sub-layer pressure discharging process) are the premium fracturing curves of deep low-permeable coal reservoir in Zhengzhuang well field. Fracturing net pressure works on the original coal fissures, with fissures opened to connect coal sub-layers; then franc sand and fracturing liquid move to the interfaces of coal reservoir sub-layers along its original fissures. Medium-low permeable “sweet spot” areas exist in the deep coal reservoir, which may be considered as a supplement. 

INVESTMENT ASSESSMENT OF CBM PROJECTS BASED ON REAL OPTIONINVESTMENT ASSESSMENT OF CBM PROJECTS BASED ON REAL OPTION 

ZHAO Luzheng

2018, 20(4):  18-24.  DOI: 10.13776/j.cnki.resourcesindustries.20180727.013

Asbtract ( )   PDF (4325KB) ( )  

References | Related Articles | Metrics

Real option is a way to quantitative assessment of project active values during decision, which is an amendment to the traditional NPV economic assessment. This paper uses real option theory and way to analyze the real option in CBM project development stage and operation stage, determines that the gross value of this CBM project is the sum of cash flow NPV and active values. Binary tree option pricing is used to construct CBM project investment assessment and model based on real option. Combined with a case study on CBM to LNG project, NPV, delayed option based on real option, expansion option, and compound option are used to calculate the investment values of CBM project, with major parameters analyzing their sensibilities at the same time. Results show that the project value by real option is outstandingly higher than that by traditional ways, but the combined option can increase the project values. Subject asset values and option pricing largely impact the CBM option values. 

OPTIMIZATION OF FRACTURING LIQUID SYSTEM OF CBM: A CASE STUDY ON DAFOSI WELL FIELD, BINCHANG DISTRICT 

SUN Chenguang

2018, 20(4):  25-30.  DOI: 10.13776/j.cnki.resourcesindustries.20180730.001

Asbtract ( )   PDF (3837KB) ( )  

References | Related Articles | Metrics

This paper, based on a case study on No.4 coal seam of Dafosi well field, Binchang district, analyzes its reservoir physical properties, water sensibility, surface water quality and compatibility, anti\|swelling agent's features and harmfulness, and selects appropriate active hydraulic fracturing liquid system, aiming at providing references for Binchang district or similar regions to develop ground CBM. Results show that the No.4 coal seam bears less quantity of expansive clay minerals, and coal permeability is positive to fracturing water mineralization, with a strong water sensibility. Optimization of fracturing liquid formula indicates a good compatibility of ground water and coal reservoir water, good to be used as fracturing water. 1.5% KCl solution, less harmful to reservoir and less costly, may be used as anti-swelling agent. This final fracturing liquid formula is written as ground water+1.5% KCl anti-swelling agent + 0.3% DB-80 cleanup additive. 

WATER FEATURES AND TREATMENTS DURING CMB MINING 

FENG Huawei， LI Jia

2018, 20(4):  31-35.  DOI: 10.13776/j.cnki.resourcesindustries.20180727.002

Asbtract ( )   PDF (3393KB) ( )  

References | Related Articles | Metrics

Water pollution coming from mining CBM which is a major environmental issue can be classified as two types, fracturing return water and production discharge according to production time. Water volume and quality vary with location, generally showing a descending trend, with mineralization degree, COD, ammonia nitrogen, floats and fluorides as its chief indicators. In Chinas practice, water from CMB mining is discharged after settling down, but quality is much different from local standards, which shall be unified. Water shall be treated according to regional terrain, water quality and volume. This paper suggests applying natural evaporation, decentralized and centralized discharging based on allowable conditions. Besides removal of floats, ammonia nitrogen and COD, further processing needs to be done to treat fluorides, sulfides and iron ions. Treatments vary with mineralization degrees. Water after processed, if allowable, may be used for fracturing liquid, agricultural irrigation or sprinkling plants. 

COMPARISON OF FRACTURING TECHNOLOGIES IN COALBED METHANE WELLS 

ZHANG Yongcheng, BAI Yunyun, LIU Liangliang, et al

2018, 20(4):  36-41.  DOI: 10.13776/j.cnki.resourcesindustries.20180727.011

Asbtract ( )   PDF (4524KB) ( )  

References | Related Articles | Metrics

Poor connectivity and low permeability of coal fissure system need to be modified by using fracturing technology to increase the production. This paper, based on a case study of CBM wells fracturing technologies of Jincheng anthracite mining group, analyzes the pros and cons of hydraulic fracturing, nitrogen shock fracturing, high-energy gas fracturing and plasma pulse fracturing, compares their improved effects, aiming at offering references for selection of fracturing technologies and research direction. Active hydraulic fracturing is the chief means in raising the CBM production, but needs improvement in loose low-permeability and deep coal seams. Adaptability of gel and clean fracturing fluids to variable CBM reservoirs need further studies, and cost shall be lowered. Nitrogen shock fracturing is currently in tentative stage, which requires further research study in fracturing mechanism and technical adaptability. High-energy gas fracturing is not working well in deep coal seam and thin-bedded reservoirs, needing a technical milestone. Plasma pulse fracturing works well in old wells with excellent effect and should be used widely. 

DEVELOPMENT AND USE SITUATION AND OUTLOOK OF CBM IN YANGQUAN COAL MINE 

ZHANG Dongliang, JIANG Guilin

2018, 20(4):  42-46.  DOI: 10.13776/j.cnki.resourcesindustries.20180727.009

Asbtract ( )   PDF (3554KB) ( )  

References | Related Articles | Metrics

This paper, based on site investigation and data collection, discusses CBM resource distribution and occurrence in Yangquan coal mine, analyzes the development use situation of ground CBM, and points out the pros and cons in CBM mining. Yangquan coal mine possesses abundance of CBM resources and well-developed infrastructures, but is poor in geological research, low in CBM developing technology, and low yield in single well. CBM is developed at a large scale, but with low CBM concentration and recovery rate. In order to fasten Yangquans CBM industry, this paper suggests boosting exploration in CBM, improving technical research in CBM development and use, issuing governmental supportive policies and providing financial supports. 

CBM RESERVOIR DAMAGE AND REASONS OF DAFOSI WELL FIELD 

GAO Zhansheng, YANG Bo, LIU Jisheng

2018, 20(4):  47-51.  DOI: 10.13776/j.cnki.resourcesindustries.20180727.003

Asbtract ( )   PDF (3253KB) ( )  

References | Related Articles | Metrics

This paper, by means of XRD and TEM, conducts tests in velocity sensitivity, water sensibility and pressure sensibility of the major CBM reservoirs in Dafosi well field according to industrial code SY/T 5358-2010, aiming at reducing damages to reservoirs during CBM development and reaching an efficient development. A moderate damage to velocity sensibility comes from coal powder motion. A big damage to water sensibility is derived from kaolin, which disperses and migrates in the water, and blocks pore throats. Also there is a big damage to pressure sensibility by surrounding pressure; permeability is impossible to recover even if the surrounding pressure is restored. This paper suggests controlling liquid level reduction intensity and liquid quantity, reducing velocity sensibility, decreasing damage to pressure sensibility near wellbore zone, avoiding damage to water sensibility by using drilling liquid and fracturing liquid close to the original coal water mineralization degree. 

CBM OCCURRENCE FEATURES AND GROUND-PUMPING POTENTIALS OF YUXI WELL FIELD IN QINSHUI COALFIELD 

WU Jing

2018, 20(4):  52-55.  DOI: 10.13776/j.cnki.resourcesindustries.20180727.008

Asbtract ( )   PDF (2660KB) ( )  

References | Related Articles | Metrics

Qinshui coalfield as China's largest developed block of CBM resource has been extensively explored and developed, but receives less research in its Yuxi well field. This paper, based on its No.3 coal seam geology, studies its gas and CBM occurrence, and relation among gas content and coal metamorphism, coal thickness, buried thickness, coal bed top and bottom and structure, and applies simulation to forecast ground fractured vertical well gas production and recovery, assesses the ground pumping potential of No.3 coal seam. Results show that the structures are simple with less faults, thick coal seam, medium buried depth, high gas content, good permeability, strong absorbability, and favorable reservoir geology. The well field is a monocline with compact top and bottom, good for gas enrichment. Gas content rises as thickness, buried depth and coal metamorphism increase. It is predicted that the vertical fractured well would have an accumulative gas production up to 410.53×10^4 m^3 in 15 years at a recovery at 60%, and the working face gas content may be lowered below 8 m^3/t. This research offers references for CBM development and gas controls in Yuxi well field.  

GLOBAL COBALT RESOURCES DISTRIBUTION AND EXPLORATION POTENTIALS 

ZHANG Weibo, YE Jinhua, CHEN Xiufa, et al

2018, 20(4):  56-61.  DOI: 10.13776/j.cnki.resourcesindustries.20180727.010

Asbtract ( )   PDF (4195KB) ( )  

Related Articles | Metrics

Cobalt as a new energy material becomes a hot commodity in global exploration and investment as its demands are surging. Cobalt, rarely as an independent ore, coexists with copper, nickel and iron ore. Cobalt-bearing deposits can be classified as weathering laterite nickel\|cobalt deposit, sedimentary sand copper-cobalt deposit, magmatic copper-nickel-cobalt sulfides deposit and geothermal cobalt deposit. Cobalt resources are not even distributing globally; 80% of explored reserves are concentrating in Congo, Australia, Cuba, Zambia, Philippines, Canada and Russia. Much cobalt resources are hosted in the ocean floor. China is a big cobalt producer and consumer, but lacks cobalt resources with dependence upon exports. Central Africa, Oceania, northern Latin America, south-eastern Asia and North America are of big potential for cobalt exploration. China shall focus on such areas to acquire overseas high-quality cobalt resources so as to increase reserves and guarantee supplies. 

RELATION AMONG URBANIZATION, INDUSTRIAL STRUCTURE ADJUSTMENT AND URBAN\|RURAL GAIN INEQUALITY BASED ON YUNNAN 1986—2016 DATA 

ZHENG Xuhai, YANG Yishuang

2018, 20(4):  62-68.  DOI: 10.13776/j.cnki.resourcesindustries.20180727.014

Asbtract ( )   PDF (4566KB) ( )  

References | Related Articles | Metrics

This paper uses “learning by doing” model in endogenous economic growth theory to establish the social production function under urban-rural dual structure, which is applied to study the short- and long-term change among urbanization, industrial structure adjustment and urban-rural gain inequality, verified by Yunnans 1986—2016 data. This paper presents policy suggestions on mitigating urban-rural gain inequality, boosting urban-rural integration and coordinating industry and agriculture. Results show an upside-down U shape between urban-rural gain inequality and urbanization & industrial structure adjustment, rising then falling. Urban-rural gain inequality trends to diminish as urbanization rate reaches 28%, and starts to diminish when industrial structure adjustment reaches 4.28. Yunnan is currently in a key period in decreasing urban-rural gain inequality, positively driven by urbanization and industrial structure adjustment.  

COUPLING COORDINATION BETWEEN MINERAL RESOURCES DEVELOPMENT AND ECONOMIC GROWTH IN SICHUAN PROVINCE 

GAO Qing, HUANG Zhihua, CHEN Pengyu

2018, 20(4):  69-74.  DOI: 10.13776/j.cnki.resourcesindustries.20180727.001

Asbtract ( )   PDF (3536KB) ( )  

References | Related Articles | Metrics

To study their coupling coordination between mineral resources development and economic growth in Sichuan province, this paper uses investment intensity, industrial scale and economic development to mark mineral resource development level, and uses economic strength, local financing level and investment & consumption level to mark economic development level, and selects 14 indicators to establish a comprehensive system to evaluate the mineral resources development and economic development level. Entropy is used to give weight to each indicator, and TOPSIS is applied to score the mineral resource development level and economic development level from 2006 to 2015. Slope correlation model in the gray system is meant to determine their correlation degree. Coupling coordination model is employed to evaluate their coordinated development level. Results show a good correlation between the both, rising with fluctuation, from low level, to medium and to high level coupling stages, indicating a sound coupling coordination. It means a good achievement in mineral resources overall planning and economic structure transformation in Sichuan province.  

TEMPORAL-SPATIAL DISTRIBUTION AND DRIVING FACTORS OF MINING LOCALITIES IN DA-XIAO XING'ANLING AREA 

SONG Jincheng, ZHANG Zhi, SONG Guoce, et al

2018, 20(4):  75-81.  DOI: 10.13776/j.cnki.resourcesindustries.20180727.005

Asbtract ( )   PDF (5830KB) ( )  

References | Related Articles | Metrics

To better develop and use mineral resources and take mining activities, this paper, based on mining localities in Da-Xiao Xing'anling area from 2014—2017, uses kernal density estimation and nearest neighbor to study the temporal-spatial distribution and changes of mining intensity in this area, with results indicating that the distribution is not even, concentrating in the southern study area, and transferring to the western Hulun Buir and Chifeng as time goes on. Coal and iron ore mining localities trend to be centralized, with the latter moving to Xunke county of Heihe city, Horqin Right Wing Front Banner of Hinggan League, and Dong Ujimqin Banner of Xilin Gol League. Industrial minerals mining localities are concentrating in the southern study area, further moving southward as economic center shifts to the south. Regional geology and terrain determine the distribution of mining localities; infrastructures, markets and industrial development are the main driving forces; policies are the direct drive to confine and standardize mining activities.