Gas emission prediction and recovery in underground coal mines

Strata gas can be released and captured from non-active and active gas resources either from virgin or relaxed strata, both prior to and when mining activities take place. The high and irregular gas emissions associated with high production longwall mining have provided a need to optimise the methods used to predict these gas levels and the ventilation requirements for gas dilution. A forecast of gas emissions during development drivage and longwall mining indicated possible gas and ventilation problems requiring the introduction of various gas drainage techniques and in maintaining the necessary air quantities in ventilation systems to satisfy the statutory gas limitations for various coal production rates. Although there are sound principles used in world-recognised methods of gas emission prediction, a new approach developed from long-term practical experience in underground gassy coal mine practices and gas-rock mechanics studies appear most suitable for local conditions and mining systems in use. The Lunagas ‘Floorgas' and ‘Roofgas' geomechanical and gas emission models offer an effective solution to these problems. Both programs are the most advanced engineering, numerical tools available to calculate gas source contributions to total gassiness and improve the accuracy and quality of gas control, gas capture technologies and ventilation system design.     

川西坳陷中段新场地区天然气研究及气源对比

经过大量学者多年的研究总结,川西坳陷中段新场地区具备良好的生、储、盖等成藏组合。结合地质背景及碳同位素、轻烃的研究,认为新场地区天然气主要是Ⅲ型干酪根的煤型气,气藏主要分布在上三叠系的须二段和须四段,以及中侏罗系、上侏罗系地层中。     

Evidence for Chemical Heterogeneity in the Nucleus of C/1995 O1 (Hale–Bopp)

We present an analysis of OH, CN, and C₂ jets observed in thecoma of Comet Hale–Bopp on UT April 22, 23, and 25, 1997. Monte Carlomodels designed to simulate the gas jets were employed to analyze thenuclear active areas responsible for the observed coma gas jets. Ourresults indicate that four active areas are necessary to reproduce theCN and C₂ jets while five active areas are required to simulatethe OH jets. The additional OH active area must produce significantlevels of OH, but cannot emit measurable quantities of either carbonradical. This difference suggests that the nucleus of Comet Hale–Boppis chemically heterogeneous.     

A unified theory of the formation of galactic bars

We give arguments for a basically unified formation mechanism of slow (Lynden-Bell) and fast (common) galactic bars. This mechanism is based on an instability that is akin to the well-known instability of radial orbits and is produced by the mutual attraction and alignment of precessing stellar orbits (so far, only the formation of slow bars has been explained in this way). We present a general theory of the low-frequency modes in a disk that consists of orbits precessing at different angular velocities. The problem of determining these modes is reduced to integral equations of moderately complex structure. The characteristic pattern angular velocities Ω_p of the low-frequency modes are of the order of the mean orbital precession angular velocity \(\bar \Omega _{pr}\). Bar modes are also among the low-frequency modes; while \(\Omega _p \approx \bar \Omega _{pr}\) for slow bars, Ω_p for fast bars can appreciably exceed even the maximum orbital precession angular velocity in the disk Ω _pr ^max (however, it remains of the order of these precession angular velocities). The possibility of such an excess of Ω_p over Ω _pr ^max is associated with the effect of “repelling” orbits. The latter tend to move in a direction opposite to the direction in which they are pushed. We analyze the pattern of orbital precession in potentials typical of galactic disks. We note that the maximum radius of an “attracting” circular orbit r_c can serve as a reasonable estimate of the bar length l_b. Such an estimate is in good agreement with the available results of N-body simulations.     

H<Emphasis Type="Italic">α</Emphasis> survey of the local volume: Isolated southern galaxies

We present our Hα observations of 11 isolated southern galaxies: SDIG, PGC 51659, E 222-010, E 272-025, E 137-018, IC 4662, Sag DIG, IC 5052, IC 5152, UGCA 438, and E 149-003, with distances from 1 to 7 Mpc. We have determined the total Hα fluxes from these galaxies. The star formation rates in these galaxies range from 10^?1 (IC 4662) to 10^?4 M _⊙ yr^?1 (SDIG) and the gas depletion time at the observed star formation rates lies within the range from 1/6 to 24 Hubble times H ₀ ^?1 .     

“十三五”期间中国探矿权及地质勘查投资时空演变

基于详细的统计数据,从时间、空间、结构等多个纬度,对中国探矿权及地质勘查投资情况进行了时间序列、因素相关性等对比分析和综合研究,为政府管理部门制定政策和规划提供参考依据。通过研究,揭示了影响探矿权及地质勘查投资的主要因素、底层逻辑和发展规律,并认为受国内外宏观经济增速放缓、地缘政治等因素影响,特别是国内相关产业政策、生态和环境保护压力,“十三五”期间中国探矿权数、地质勘查投入和新发现矿产地持续大幅度减少。“十三五”期间,新立探矿权同比减少52.1%,注销探矿权数是“十二五”期间的3.7倍多。油气矿产的探矿权登记面积和地质勘查投资分别占全国的96%和77.6%;非油气矿产探矿权数占全国的90%以上,有近60%的非油气探矿权在西部地区;非油气地质勘查投资中,水工环及科技等投资额占居半壁江山。预计中国在能源矿产、战略性矿产等勘查领域将增加勘查投入,地质勘查投资将于2024年后逐渐走出低谷。     

中国煤层气资源控制程度及可靠性分析

准确认识深部条件下气体和水分的赋存状态、相对含量及分布特征,对煤层气高效勘探开发具有重要指导意义。基于理论模型、分子模拟和气水演变分析,明确了煤层中气、水的赋存状态,揭示了气、水动态运聚界限和动态演化过程。考虑煤−水界面作用、水的可动性及赋存状态,煤中水可分为可动水(重力水和毛细水)、束缚水(吸附水、沸石水、结晶水和层间水)、结构水,其中毛细水、重力水和吸附水由孔隙主导,沸石水、结构水、结晶水和层间水由矿物主导。分子模拟结果显示,水分子在0.7 nm孔隙中可以饱和充填,吸附和解吸路径一致,在更大孔隙中出现弱吸附层和自由态。水分子吸附过程表现为单分子含氧基团吸附、单层强吸附、多层弱吸附、水团簇形成和充填孔隙等阶段。甲烷分子在1.5 nm孔隙可存在3层稳定充填吸附,在较大孔隙中(>1.5 nm)即以单层吸附和游离态共存,游离态在介孔及更大孔隙中普遍存在。结合上述吸附−游离气存在界限,改进了游离气和吸附气理论计算公式,为含气量计算提供新思路。深部热成因煤层气是煤大规模生排烃之后的残余气,在排烃过程中发生气驱水和水分蒸发扩散,残余水分为束缚水和结构水,后期无法改变。假定静水压力20 MPa,在0、5、10、15和20 MPa储层压力下,外来水分可入侵最大孔径为7、9、13、27 nm和不侵入。受差异保存条件控制,煤成气除了形成超压和欠压等差异含气系统外,还可能在煤系形成多类型含气模式。上述研究明确了煤层气、水微观赋存机制及形成演化模式,对深部煤层气富集特征及高效开发设计具有指导意义。

     

Characteristics of China’s oil and gas pool formation in latest geological history

The structural activities took place extensively in the Asia continent during the Cenozoic era owing to the strong continent-to-continent collision and continuous compression between the India Plate and the Eurasia Plate. Huang Jiqing called such structural activities Himalayan movement. China’s sedimentary basins developed and took shape mainly during the Himalayan movement period. It is also the main period for formation and development of the oil and gas reservoirs. Of 366 large and medium-sized oil and gas fields currently found in China, 212 reservoirs were formed in the Neogene-Quaternary period. The proportion is as high as 68.2%. The oil and gas migration and accumulation in the latest geological period, which were controlled by the times, properties, styles and strength of the Himalayan movement, took place mainly in eight regions, such as the low uplift area of Bohai Sea, the onshore faulted sag area of Bohai Bay, anticlinorium zone in Daqing, the foreland fold-and-thrust belt in West China, the tilted structural zone in West China, the cratonic palaeohigh in the Tarim Basin, the zone of fault and fold belt in the East Sichuan Basin, and the biological gas zone in the East Qaidam Basin. The oil and gas pool formations in those regions have their own characteristics. With the great potential and broad prospect, those regions are the main exploration areas in China in the future.     

西气东输三线输气管道工程线路区域地震地质环境与地质灾害

我国国民经济发展迅速, 国内中南和沿海地区能源需求持续递增。中亚地区有丰富的天然气资源, 需要新建管道输送新增气量, 国家适时启动了西气东输三线工程。西气东输三线工程管道线路自西北向东南斜贯我国西部、中部和东南, 干线总长度达5220km, 沿线各类地貌发育, 线路区域地震地质环境复杂, 地质灾害类型多样, 做好该项目的前期研究论证, 查明沿线地震地质构造与活动断裂和各类地质灾害, 对确保西三线管道工程的设计、施工与安全运营十分重要。     

泥石流源地松散体起动人工降雨模拟及放水冲刷实验

以神府－东胜矿区人为泥石流及云南东川蒋家沟自然泥石流为研究对象,采用人工降雨及放水冲刷模拟实验方法,分析了不同类型,不同地区泥石流源地松散体起动条件及泥石流过程,得出一些有意义的结论。