Whole petroleum system in Jurassic coal measures of Taibei Sag in Tuha Basin,NW China

Based on the latest results of near-source exploration in the Middle and Lower Jurassic of the Tuha Basin,a new understanding of the source rocks,reservoir conditions,and source-reservoir-cap rock combinations of the Jurassic Shuixigou Group in the Taibei Sag is established using the concept of the whole petroleum system,and the coal-measure whole petroleum system is analyzed thoroughly.The results are obtained in three aspects.First,the coal-measure source rocks of the Badaowan Formation and Xishanyao Formation and the argillaceous source rocks of the Sangonghe Formation in the Shuixigou Group exhibit the characteristics of long-term hydrocarbon generation,multiple hydrocarbon generation peaks,and simultaneous oil and gas generation,providing sufficient oil and gas sources for the whole petroleum system in the Jurassic coal-bearing basin.Second,multi-phase shallow braided river delta–shallow lacustrine deposits contribute multiple types of reservoirs,e.g.sandstone,tight sandstone,shale and coal rock,in slope and depression areas,providing effective storage space for the petroleum reservoir formation in coal-measure strata.Third,three phases of hydrocarbon charging and structural evolution,as well as effective configuration of multiple types of reservoirs,result in the sequential accumulation of conventional-unconventional hydrocarbons.From high structural positions to depression,there are conventional structural and structural-lithological reservoirs far from the source,low-saturation structural-lithological reservoirs near the source,and tight sandstone gas,coal rock gas and shale oil accumulations within the source.Typically,the tight sandstone gas and coal rock gas are the key options for further exploration,and the shale oil and gas in the depression area is worth of more attention.The new understanding of the whole petroleum system in the coal measures could further enrich and improve the geological theory of the whole petroleum system,and provide new ideas for the overall exploration of oil and gas resources in the Tuha Basin.

Fuzzy inference system using genetic algorithm and pattern search for predicting roof fall rate in underground coal mines

One of the most dangerous safety hazard in underground coal mines is roof falls during retreat mining.Roof falls may cause life-threatening and non-fatal injuries to miners and impede mining and transportation operations.As a result,a reliable roof fall prediction model is essential to tackle such challenges.Different parameters that substantially impact roof falls are ill-defined and intangible,making this an uncertain and challenging research issue.The National Institute for Occupational Safety and Health assembled a national database of roof performance from 37 coal mines to explore the factors contributing to roof falls.Data acquired for 37 mines is limited due to several restrictions,which increased the likelihood of incompleteness.Fuzzy logic is a technique for coping with ambiguity,incompleteness,and uncertainty.Therefore,In this paper,the fuzzy inference method is presented,which employs a genetic algorithm to create fuzzy rules based on 109 records of roof fall data and pattern search to refine the membership functions of parameters.The performance of the deployed model is evaluated using statistical measures such as the Root-Mean-Square Error,Mean-Absolute-Error,and coefficient of determination(R_(2)).Based on these criteria,the suggested model outperforms the existing models to precisely predict roof fall rates using fewer fuzzy rules.

Synergistic CO_(2) mineralization using coal fly ash and red mud as a composite system

CO_(2) mineralization plays a critical role in the storage and utilization of CO_(2).Coal fly ash(CFA)and red mud(RM)are widely utilized as CO_(2) mineralizers.However,the inert calcium species in CFA limit its carbonation capacity,meanwhile the substantial Ca^(2+)releasing of RM is hindered by a covering layer of calcium carbonate.In this study,CO_(2) mineralization in a composite system of CFA and RM was investigated to enhance the carbonation capacity.Multiple analyzers were employed to characterize the raw materials and resulting mineralization products.The results demonstrated that a synergistic effect existed in the composite system of CFA and RM,resulting in improving CO_(2) mineralization rate and efficiency.The produced calcium carbonate was ectopically attached the surface of CFA in the composite system,thus slowing down its coverage on the surface of RM.This phenomenon facilitated further releasing Ca^(2+)from the internal RM,thereby enhancing CO_(2) mineralization efficiency.Meanwhile,the inclusion of RM significantly improved the alkalinity of the composite system,which not only promoted the dissolution of Ca^(2+)of the inert CaSO_(4)(H_(2)O)_(2) in CFA,but also accelerated CO_(2) mineralization rate.The investigation would be beneficial to CO_(2) mineralization using industrial solid wastes.

Technical evaluation system of co-extraction of coal and gas

Coal and gas are two important resources in China,and it is an effective way to recycle them with the method of co-extraction of coal and gas.In view of actual situation of China's co-extraction of coal and gas,this research adopts the science evaluation of gas extraction of coal by the method of quantitative evaluation,and preliminarily establishes the technical evaluation system of co-extraction of coal and gas.Technical evaluation system of co-extraction of coal and gas includes safety evaluation,economic evaluation and resource recovery evaluation in the process of mining coal and gas.In addition,this paper results in the selected evaluation parameters and target functions that are used in the three evaluation methods.The establishment of evaluation system for co-extraction of coal and gas plays an important theoretical significance and guiding role in co-extraction of coal and gas for China's coal enterprises.

The Role of Diatomite Particles in the Activated Sludge System for Treating Coal Gasification Wastewater

Diatomite is a kind of natural low-cost mineral material. It has a number of unique physical properties and has been widely used as an adsorbent in wastewater treatment. This study was conducted to investigate the aerobic biodegradation of coal gasification wastewater with and without diatomite addition. Experimental results indicated that diatomite added in the activated sludge system could promote the biomass and also enhance the performance of the sludge settling. The average mixed-liquor volatile suspended solids （MLVSS） is increased from 4055 mg.L^-1 to 4518 mg.L^-1 and the average settling volume （SV） are changed only from 45.9% to 47.1%. Diatomite additive could enhance the efficiency of chemical oxygen demand （COD） and total phenols removal from the wastewater. The COD removal increased from 73.3% to near 80% and the total phenols removal increased from 81.4% to 85.8%. The mechanisms of the increase of biomass and pollutants removal may correlates to the improvement of bioavailability and sludge settlement characteristics by diatomite added. Micrograph of the sludge in the diatomite-activated sludge system indicated that the diatomite added could be the carrier of the microbe and also affect the biomass and pollutant removal.

Research and practice of intelligent coal mine technology systems in China

This study considered the role of coal as China’s basic energy source and examines the development of the coal industry.We focused on the intelligent development of coal mines,and introduced the“Chinese mode”of intelligent mining in underground coal mines,which uses complete sets of technical equipment to propose classifcation and grading standards.In view of the basic characteristics and technical requirements of intelligent coal mine systems,we established a digital logic model and propose an information entity and knowledge map construction method.This involves an active information push strategy based on a knowledge demand model and an intelligent portfolio modeling and distribution method for collaborative control of coal mines.The top-level architecture of 5G+intelligent coal mine systems combines intelligent applications such as autonomous intelligent mining,human–machine collaborative rapid tunneling,unmanned auxiliary transportation,closed-loop safety control,lean collaborative operation,and intelligent ecology.Progress in intelligent mining technology was described in terms of a dynamic modifed geological model,underground 5G network and positioning technology,intelligent control of the mining height and straightness of the longwall working face,and intelligent mining equipment.The development of intelligent coal mines was analyzed in terms of its imbalances,bottlenecks,and the compatibility of large-scale systems.Implementation ideas for promoting the development of intelligent coal mines were proposed,such as establishing construction standards and technical specifcations,implementing classifcation and grading standards according to mining policy,accelerating key technology research,and building a new management and control model.

Control mechanism of a cable truss system for stability of roadways within thick coal seams

Cable truss systems have been widely applied in roadways with complicated conditions, such as the large cross-sections of deep wells, and high tectonic stress. However, they are rarely applied to roadways with extremely thick coal seams because the control mechanism of the system for the deformation of the roof and the separation between coal rock segments is not completely understood. By using the relationship between the support system and the roof strata, a mechanical model was established to calculate the deformation of the roof in a thick coal seam with bedding separation under different support conditions: with an anchor truss support and without support. On this basis, the research was used to deduce a method for computing the minimum pre-tightening forces in the anchor truss, the maximum amounts of subsidence and separation with, and without, anchor truss support under the roof, and the maximum subsidence and the decreasing amounts of the separation before and after adopting the anchor truss. Additionally, mechanical relationships between the minimum pre-tightening force and the anchoring force in the anchor were analyzed. By taking a typical roadway with thick coal roof as an example, the theoretical results mentioned above were applied in the analysis and testing of a roof supporting project in a roadway field to verify the accuracy of the theory: favorable experimental results were achieved. In addition, the relationships among other parameters were analyzed, including the minimum pre-tightening forces applied by the anchor truss, the angle of inclination of the anchor cable, and the array pitch. Meanwhile, the changing characteristics of the amounts of roof separation and subsidence with key parameters of the support system(such as array pitch, pre-tightening force, and inclination angle) were also analyzed. The research results revealed the acting mechanism of the anchor truss in control of roadway stability with a thick coal seam, providing a theoretical basis of its application in coal mining.

Research on coal staged conversion poly-generation system based on fluidized bed

A new coal staged conversion poly-generation system combined coal combustion and pyrolysis has been developed for clean and high efficient utilization of coal.Coal is the first pyrolysed in a fluidized pyrolyzer.The pyrolysis gas is then purified and used for chemical product or liquid fuel production.Tar is collected during purification and can be processed to extract high value product and to make liquid fuels by hydro-refining.Semi-coke from the pyrolysis reactor is burned in a circulating fluidized bed(CFB)combustor for heat or power generation.The system can realize coal multiproduct generation and has a great potential to increase coal utilization value.A 1 MW poly-generation system pilot plant and a 12 MW CFB gas,tar,heat and power poly-generation system was erected.The experimental study focused on the two fluidized bed operation and characterization of gas,tar and char yields and compositions.The results showed that the system could operate stable,and produce about 0.12 m^(3)/kg gas with 22 MJ/m^(3)heating value and about 10 wt%tar when using Huainan bituminous coal under pyrolysis temperature between 500 and 600℃.The produced gases were mainly H_(2),CH_(4),CO,CO_(2),C_(2)H_(4),C_(2)H_(6),C_(3)H_(6)and C_(3)H_(8).The CFB combustor can burn semi-coke steadily.The application prospect of the new system was discussed.

Experimental and theoretical investigation on mechanisms performance of the rock-coal-bolt(RCB)composite system

For coal mines,rock,coal,and rock bolt are the critical constituent materials for surrounding rock in the underground engineering.The stability of the“rock-coal-bolt”(RCB)composite system is affected by the structure and fracture of the coal-rock mass.More rock bolts installed on the rock,more complex condition of the engineering stress environment will be(tensile-shear composite stress is principal).In this paper,experimental analysis and theoretical verification were performed on the RCB composite system with different angles.The results revealed that the failure of the rock-coal(RC)composite specimen was caused by tensile and shear cracks.After anchoring,the reinforcement body formed inside the composite system limits the area where the crack could occur in the specimen.Specifically,shearing damage occurred only around the bolt,and the stress-strain curve presented a better post-peak mechanical property.The mechanical mechanism of the bolt under the combined action of tension and shear stress was analyzed.Additionally,a rock-coal-bolt tensile-shear mechanical(RCBTSM)model was established.The relationship(similar to the exponential function)between the bolt tensile-shear stress and the angle was obtained.Moreover,the influences of the dilatancy angle and bolt diameter of the RCB composite system were also considered and analyzed.Most of the bolts are subjected to the tensile-shearing action in the post-peak stage.The implications of these results for engineering practice indicated that the bolts of the RCB composite system should be prevented from entering the limit shearing state early.

Presenting an engineering classification system for coal spontaneous combustion potential

The phenomenon of coal spontaneous combustion is one of the common hazards in coal mines and also one of the important reasons for the loss of coal in piles and mines. Based on previous researches, different types of coals have different spontaneous combustion characteristics. For coal loss prevention, a measure is necessary for prediction of coal spontaneous combustion. In this study, a new engineering classification system called ＂Coal Spontaneous Combustion Potential Index （CSCPI）＂ is presented based on the Fuzzy Delphi Analytic Hierarchy Process （FDAHP） approach. CSCPI classifies coals based on their spontaneous combustion capability. After recognition of the roles of the effective parameters influencing the initiation of a spontaneous combustion, a series of intrinsic, geological, and mining characteristics of coal seams are investigated. Then, the main stages of the implementation of the FDAHP method are studied and the weight of each parameter involved is calculated. A classification list of each parameter is formed, the CSCPI system is described, and the engineering classifying system is subsequently presented. In the CSCPI system, each coal seam can be rated by a number from 0 to 100; a higher number implies a greater ease for the coal spontaneous combustion capability. Based on the CSCPI system, the propensity of spontaneous combustion of coal can be classified into three potential levels： low, medium, and high. Finally, using the events of coal spontaneous combustion occurring in one of the Iranian coal mines, Eastern Alborz Coal Mines, an initial validation of the mentioned systematic approach is conducted. Comparison of the results obtained in this study illustrate a relatively good agreement.

Coal and gas outburst dynamic system

Coal and gas outburst is an extremely complex dynamic disaster in coal mine production process which will damage casualties and equipment facilities, and disorder the ventilation system by suddenly ejecting a great amount of coal and gas into roadway or working face. This paper analyzed the interaction among the three essential elements of coal and gas outburst dynamic system. A stress-seepage-damage coupling model was established which can be used to simulate the evolution of the dynamical system, and then the size scale of coal and gas outburst dynamical system was investigated. Results show that the dynam- ical system is consisted of three essential elements, coal-gas medium （material basis）, geology dynamic environment （internal motivation） and mining disturbance （external motivation）. On the case of CI 3 coal seam in Panyi Mine, the dynamical system exists in the range of 8-12 m in front of advancing face. The size scale will be larger where there are large geologic structures. This research plays an important guid- ing role for developing measures of coal and gas outburst prediction and prevention.

A semi-quantitative coal burst risk classification system

Safety is the highest priority in the mining industry as underground mining in particular poses high safety risks to its workers. In underground coal mines, coal bursts are one of the most catastrophic hazards, which involves sudden and violent dynamic coal mass failure with rapid ejection of the broken material into the mine workings. Despite decades of research, the contributing mechanisms of coal bursts are still not completely understood. Hence, it remains challenging to forecast coal bursts and quantify their likelihood of occurrence. However, a range of geological and geotechnical factors are associated with coal bursts and can increase the coal burst proneness. This paper introduces a semi-quantitative coal burst risk classification system, namely, BurstRisk. Based on back-analysis of case histories from Australia, China and the United States, BurstRisk classifies the coal burst risk into three categories:low, medium and high risk. In addition, it allows mining engineers to modify the weighting of the selected factors based on specific conditions. The risk classification charts introduced are for both longwall retreat and development sections of long-wall mining operations. This paper also provides a set of risk management strategies and control measures for effective coal burst mitigation.

Upper Paleozoic coal measures and unconventional natural gas systems of the Ordos Basin,China

Upper Paleozoic coal measures in the Ordos Basin consist of dark mudstone and coal beds and are important source rocks for gas generation. Gas accumulations include coal-bed methane （CBM）, tight gas and conventional gas in different structural areas. CBM accumulations are mainly distributed in the marginal area of the Ordos Basin, and are estimated at 3.5 × 1012 m3. Tight gas accumulations exist in the middle part of the Yishan Slope area, previously regarded as the basin-centered gas system and now considered as stratigraphic lithologic gas reservoirs. This paper reviews the characteristics of tight gas accumulations： poor physical properties （porosity 〈 8%, permeability 〈 0.85 × 10 3 μm2）, abnormal pressure and the absence of well-defined gas water contacts. CBM is a self-generation and self- reservoir, while gas derived from coal measures migrates only for a short distance to accumulate in a tight reservoir and is termed near-generation and near-reservoir. Both CBM and tight gas systems require source rocks with a strong gas generation ability that extends together over wide area. However, the producing area of the two systems may be significantly different.

Hydrogeochemical Characteristics and Groundwater Inrush Source Identification for a Multi-aquifer System in a Coal Mine

Correct identification of water inrush sources is particularly important to prevent and control mine water disasters.Hydrochemical analysis,Fisher discriminant analysis,and geothermal verification analysis were used to identify and verify the water sources of the multi-aquifer groundwater system in Gubei coal mine,Anhui Province,North China.Results show that hydrochemical water types of the Cenozoic top aquifer included HCO3-Na+K-Ca,HCO3-Na+K-Mg and HCO3-Na+K,and this aquifer was easily distinguishable from other aquifers because of its low concentration of Na++K+and Cl-.The Cenozoic middle and bottom aquifers,the Permian fissure aquifer,and the Taiyuan and Ordovician limestone aquifers were mainly characterized by the Cl-Na+K and SO4-Cl-Na+K or HCO3-Cl-Na+K water types,and their hydrogeochemistries were similar.Therefore,water sources could not be identified via hydrochemical analysis.Fisher model was established based on the hydrogeochemical characteristics,and its discrimination rate was 89.19%.Fisher discrimination results were improved by combining them with the geothermal analysis results,and this combination increased the identification rate to 97.3%and reasonably explained the reasons behind two water samples misjudgments.The methods described herein are also applicable to other mines with similar geological and hydrogeological conditions in North China.

Systematic principles of surrounding rock control in longwall mining within thick coal seams

Effective surrounding rock control is a prerequisite for realizing safe mining in underground coal mines.In the past three decades, longwall top-coal caving mining(LTCC) and single pass large height longwall mining(SPLL) found expanded usage in extracting thick coal seams in China. The two mining methods lead to large void space left behind the working face, which increases the difficulty in ground control.Longwall face failure is a common problem in both LTCC and SPLL mining. Such failure is conventionally attributed to low strength and high fracture intensity of the coal seam. However, the stiffness of main components included in the surrounding rock system also greatly influences longwall face stability.Correspondingly, surrounding rock system is developed for LTCC and SPLL faces in this paper. The conditions for simultaneous balance of roof structure and longwall face are put forward by taking the stiffness of coal seam, roof strata and hydraulic support into account. The safety factor of the longwall face is defined as the ratio between the ultimate bearing capacity and actual load imposed on the coal wall.The influences provided by coal strength, coal stiffness, roof stiffness, and hydraulic support stiffness,as well as the movement of roof structure are analyzed. Finally, the key elements dominating longwall face stability are identified for improving surrounding rock control effectiveness in LTCC and SPLL faces.

The pore-fracture system properties of coalbed methane reservoirs in the Panguan Syncline,Guizhou,China

The Panguan Syncline contains abundant coal resources, which may be a potential source of coalbed methane. In order to evaluate the coalbed methane production potential in this area, we investi- gated the pore-fracture system of coalbed methane reservoirs, and analyzed the gas sorption and seepage capacities by using various analytical methods, including scanning electron microscopy （SEM）, optical microscopy, mercury-injection test, low-temperature N2 isotherm adsorption/desorption analyses, low- field nuclear magnetic resonance and methane isothermal adsorption measurements. The results show that the samples of the coal reservoirs in the Panguan Syncline have moderate gas sorption capacity. However, the coals in the study area have favorable seepage capacities, and are conductive for the coalbed methane production. The physical properties of the coalbed methane reservoirs in the Panguan Syncline are gener- ally controlled by coal metamorphism： the low rank coal usually has low methane sorption capacity and its pore and microfractures are poorly developed; while the medium rank coal has better methane sorption capacity, and its seepage pores and microfractures are well developed, which are sufficient for the coalbed methane＇s gathering and exploration. Therefore, the medium rank coals in the Panguan Syncline are the most prospective targets for the coalbed methane exploration and production.

A dynamic optimization model of an integrated coal supply chain system and its application

Various nodes,logistics,capital flows,and information flows are required to make systematic decisions concerning the operation of an integrated coal supply system. We describe a quantitative analysis of such a system. A dynamic optimization model of the supply chain is developed. It has achieved optimal system profit under conditions guaranteeing a certain level of customer satisfaction. Applying this model to coal production of the Xuzhou coal mines allows recommendations for a more systematic use of washing and processing,transportation and sale resources for commercial coal production to be made. The results show that this model,which is scientific and effective,has an important value for making reasonable decisions related to complex coal enterprises.

Research on effectiveness of coal mine safety supervision system reform on three types of collieries in China

Coal mine safety supervision system plays an important role in the coal mine safety management in China.However,the current supervision system is established on the basis of learning the advanced experience from other developed countries.It needs to be further improved according to national conditions.Therefore,the effectiveness of coal mine safety supervision system reform on three types of collieries are assessed by using time series analysis method based on comparative analysis of the supervision system before and after the reform in this paper.The regression results show that the structural reform is not conductive to the improvement of coal mine safety situation in the short term,but conductive significantly in the long term.Specifically,the effects in township coal mines are more significant than stateowned key coal mines in the long run,but negative effects also exist in the short term.The negative effects in state-owned key coal mines are non-significant compared with township coal mines.Moreover,the regression results are analyzed from the aspects of the closure policy of illegal small township coal mines at the end of 1998 and shortage of the new supervision system.Finally,the suggestions on improving the new supervision system are put forward based on the above analysis.

Coal Gasification Wastewater Pretreatment with Coagulation and N_2 Flotation Combined System

A N 2 flotation tank combined with coagulation was developed as a pretreatment equipment of biological process to remove oil and other pollutants in coal gasification wastewater( CGW). With optimal PAC dosage of 20 mg / L,the sole coagulation process achieves removal efficiencies of 29. 34% and 26. 83% for oil and COD,respectively. For the sole N 2 floatation process,the optimal N 2 flux and HRT are 20 m3/ h and 20 min. Meanwhile,the oil and COD removal efficiencies are 35. 41% and 14. 26%,respectively. For the combined system of coagulation and N 2 floatation,the optimal parameter values are the same as the ones of separate processes. Correspondingly,the removal efficiencies are 46. 28% and 31. 89% for oil and COD, respectively. Besides,BOD 5 / COD of the effluent is improved. In contrast with conventional dissolved air floatation,the inert gas- N 2 prevents the formation of cyclopentenone, pyridine derivatives, and other heterocyclic aromatic hydrocarbons,thus improving the biodegradability of influent for the subsequent biological processes.

A Systematic Analysis of Coal Accumulation Process

Formation of coal seam and coal-rich zone is an integrated result of a series of factors in coal accumulation process. The coal accumulation system is an architectural aggregation of coal accumulation factors. It can be classified into 4 levels： the global coal accumulation super-system, the coal accumulation domain mega-system, the coal accumulation basin system, and the coal seam or coal seam set sub-system. The coal accumulation process is an open, dynamic, and grey system, and is meanwhile a system with such natures as aggregation, relevance, entirety, purpose-orientated, hierarchy, and environment adaptability. In this paper, we take coal accumulation process as a system to study origin of coal seam and coal-rich zone; and we will discuss a methodology of the systematic analysis of coal accumulation process. As an example, the Ordos coal basin was investigated to elucidate the application of the method of the coal accumulation system analysis.