The Method and Practice of Constructing 3D Geological Model from Coalfield Exploration 2D Maps

3D geological modeling is an inevitable choice for coal exploration to adapt to the transformation of coal mining for green, fine, transparent and Intelligent mining. In the traditional Coalfield exploration geological reports, the spatial expression form for the coal seams and their surrounding rocks are 2D maps. These 2D maps are excellent data sources for constructing 3D geological models of coal field exploration areas. How to construct 3D models from these 2D maps has been studying in coal exploration industry for a long time, and still no breakthrough has been achieved so far. This paper discusses the principle, method and software design idea of constructing 3D geological model of an exploration area with 2D maps made by AutoCAD/MapGIS. At first, the paper analyzes 3D geological surface expression mode in 3D geological modeling software. It is pointed out that although contour method has unique advantages in coal field exploration, TIN (Triangular Irregular Network) is still the standard configuration of 3D modeling software for coal field. Then, the paper discusses the method of 2D line features obtaining elevation and upgrading 2D curve to 3D curve. Next, the method of semi-automatic partition is introduced to build the boundary ring of the surface patch, that is, the user clicks and selects the line feature to build the outer boundary ring of the surface patch. Then, Auto-process method for fault line inside of the outer boundary ring is discussed, it including construction of fault ring, determining fault ring being normal fault ring or reverse fault ring and an algorithm of dealing with normal fault ring. An algorithm of dealing with reverse fault ring is discussed detailly, the method of expanding reverse fault ring and dividing the duplicate area in reverse fault into two portions is introduced. The paper also discusses the method of extraction ridge line/valley line, the construction of fault plane, the construction of stratum and coal body. The above ideas and methods have been initially implemented in the “3D modeling platform for coal field exploration” software, and applied to the 3D modeling practice of data from several coal field exploration areas in Ningxia, Shanxi, Qinghai, etc.

Ramp facies in an intracratonic basin:A case study from the Upper Devonian and Lower Carboniferous in central Hunan,southern China

到在中央湖南的早含碳的碳酸盐岩石的迟了的泥盆纪上的详细研究，南部的中国导致了能被组织进的 25 岩相的识别：(1 ) 内部斜面 peritidal 站台，(2 ) 内部斜面器官的银行和墩，(3 ) 中间的斜面，(4 ) 外部斜面，并且(5 ) 架盆外形协会。peritidal 站台外形协会统治 Zimenqiao 形成(Namurian A 或迟了的 Datangian ) ，显示 peritidal 站台环境并且被石膏和包含 dolostone 序列描绘。另外的四个外形协会统治 Menggongao 形成(迟了的 Famennian ) ， Liujiatang 形成(Tournaisian 或 Yangruanian ) ， Shidengzi 形成(早 Visean 或早 Datangian ) 。五个浅向上的周期在这三形成被区分。在每形成开发的占优势的外形协会在迟了的泥盆纪表明一个全面 transgressionregression 周期到在中央湖南早含碳。全面 transgressive 顺序在 Shaodong， Menggongao，和 Liujiatang 形成被保存，并且全面回归的顺序在 Liujiatang， Shidengzi， Ceshui 和 Zimenqiao 形成被保存。

Subsidence control method by inversely-inclined slicing and upward mining for ultra-thick steep seams

Ultra-thick steep coal seam mining will inevitably lead to the increase of greater and violent ground subsidence and deformation.A subsidence control method by inversely-inclined slicing and upward mining is proposed in this paper.By this method,the sequence of collapse of overlying strata and the direction of propagation of strata movement are changed,the extent of roof-side deformation thereby is lessened,and boundary angle of roof-side subsidence is reduced by 5°-10°.The mechanism of this mining method for control of strata movement has been evidenced by numerical simulation and experiments with similarity materials.A subsidence prediction model based on the variation of mining influence propagation angle can be used to evaluate the surface movement and deformation of the mining method.The application of the method in No.3 Mine in Yaojie mining area has yielded the expected result.

Discovery of anomalous gallium enriched in stone coal: Significance, provenance and recommendations

Gallium(Ga)is a critical mineral that plays an irreplaceable role in consumer electronics,clean energy technologies and the aerospace industry.Nowadays competition for gallium resources at the national strategic level has begun to emerge,but gallium resources are unevenly distributed globally,and their presence is not guaranteed.New discoveries revealed an average gallium concentration of thirty-one samples from M_(1),M_(2),M_(3) and M_(4) stone coal-bearing seams of the Cambrian strata on South Qinling Orogenic Belt in central China is 157 mg/kg(9.98–747 mg/kg),which is 27.6-fold higher than the global hard coal average,as well as the existing association of Mo–V–U–Cd–Zn–Ba–Se–Mg–Ni–Cu enrichment.Ga average of these coal seams are 344 mg/kg(M_(3),44.5–747 mg/kg,n=11),270 mg/kg(M_(4),14.3–270 mg/kg,n=5),53.8 mg/kg(M_(2),22.6–75.4 mg/kg,n=8)and 19.8 mg/kg(M_(1),9.98–34.9 mg/kg,n=7)respectively,as well as the thickness of approximately 6,12,8,and 20 m,which be close to or exceed to the boundary grade standard(30 mg/kg)and minimum recoverable thickness(0.7 m)of gal-lium resources exploration.These findings indicate that the Cambrian stone coal deposits,especially in the middle and late Cambrian period,should be considered as promising alternative sources of gallium.The anomalous gallium-enriched sediments originated from a complex combination of hydrothermal flu-ids,original biomass and terrigenous materials.For the M_(1) stone coal-bearing seams,gallium most likely occurred in the mode of GaAs,Ga_(x)In_(1-x)As and GaO(OH),while modes of gallium in the M_(2) to M_(4) seams is interrelated with the organic affinity and clay minerals.The crude reserve estimate of gallium resources in central China is approximately 10.06?104 tons,corresponding to a super-large coal-hosted gallium ore deposit.The unique paleogeographic location and geological structure in central China resulted that this newly discovered deposit is a unique type of gallium-enriched deposit that has been discovered worldwide.These discoveries will provide the critical parameters when developing distinctive benefici-ation processes and appropriate extraction procedures,as well as guidance and effective for future prospecting regions of gallium resources around the globe,involving a combination consider the distri-bution of regional deep–large fault zones and the middle to late Cambrian black rock series deposits.

The evolution of coal, examining the transitions from anthracite to natural graphite: a spectroscopy and optical microscopy evaluation

Coal-derived natural graphite(CDNG)has multiple industrial applications.Here,ten metamorphic coals from anthracite to CDNG were obtained from Lutang and Xinhua in the Hunan Province and Panshi in the Jilin Province.Bulk characterization(proximate and ultimate analyses,X-Ray powder diffraction(XRD),and powder Raman spectroscopy),along with optical microscopy,scanning electron microscope(SEM)and micro-Raman spectroscopy were utilized to examine the transitions from anthracite to semi-graphite to CDNG.The XRD and Raman spectroscopy data indicate that from anthracite to highly ordered graphite the average crystal diameter(La)and height(Lc)increased from 6.1 and 4.6 nm to 34.8 and 27.5 nm,respectively.The crystalline parameters of the CDNG samples from Panshi and Lutang varied slightly when closer to the intrusive body.Optical microscopy and SEM indicated that in the anthracite samples there were thermoplastic vitrinite,devolatilized vitrinite,and some“normal”macerals.In the meta-anthracite,pyrolytic carbon,mosaic structure,and crystalline tar were present.In the CDNG there were flake graphite,crystalline aggregates,and matrix graphite.The crystalline aggregates show the highest structural ordering degree as determined from Raman spectral parameters(full-width at half maxima(G-FWHM)~20 cm^(−1),D1/(D1+D2+G)area ratio(R2)value<0.5).The flake graphite is less ordered with G-FWHM~28 cm^(−1) and 0.5<R2<1,but a larger grain size(up to 50μm).The mosaic structures were likely the precursors of the matrix graphite through in situ solid-state transformation.The pyrolytic carbon and crystalline tars are the transient phase of gas-state and liquid-state transformations.This study is beneficial to realize the rational utilization of CDNG.

Lithofacies palaeogeography of the Carboniferous and Permian in the Qinshui Basin, Shanxi Province, China

The Qinshui Basin in the southeastern Shanxi Province is an important area for coalbed methane(CBM) exploration and production in China, and recent exploration has revealed the presence of other unconventional types of gas such as shale gas and tight sandstone gas. The reservoirs for these unconventional types of gas in this basin are mainly the coals, mudstones, and sandstones of the Carboniferous and Permian; the reservoir thicknesses are controlled by the depositional environments and palaeogeography. This paper presents the results of sedimentological investigations based on data from outcrop and borehole sections, and basin-wide palaeogeographical maps of each formation were reconstructed on the basis of the contours of a variety of lithological parameters. The palaeogeographic units include the depositional environments of the fluvial channel, flood basin(lake), upper delta plain, lower delta plain, delta front, lagoon, tidal flat, barrier bar, and carbonate platform.The Benxi and Taiyuan Formations are composed mainly of limestones, bauxitic mudstones,siltstones, silty mudstones, sandstones, and economically exploitable coal seams, which were formed in delta, tidal flat, lagoon, and carbonate platform environments. The Shanxi Formation consists of sandstones, siltstones, mudstones, and coals; during the deposition of the formation, the northern part of the Qinshui Basin was occupied mainly by an upper delta plain environment, while the central and southern parts were mainly occupied by a lower delta plain environment and the southeastern part by a delta front environment. Thick coal zones occur in the central and southern parts, where the main depositional environment was a lower delta plain. The thick coal zones of the Taiyuan Formation evidently occur in the sandstone-rich belts, located mainly in the lower delta plain environment in the northern part of the basin and the barrier bar environments in the southeastern part of the basin. In contrast, the thick coal zones of the Shanxi Formation extend over the mudstone-rich belts, located in the areas of the lower delta plain environments of the central and southern parts of the Basin.The Xiashihezi, Shangshihezi, and Shiqianfeng Formations consist mainly of red mudstones with thick-interbedded sandstones. During the deposition of these formations, most areas of the basin were occupied by a fluvial channel, resulting in palaeogeographic units that include fluvial channel zones and flood basins. The fluvial channel deposits consist mainly of relatively-thick sandstones, which could have potential for exploration of tight sandstone gas.