Advanced Materials Research Vols. 734-737

Abstract: The precise mechanism of the coal and gas outburst is still unresolved, but productive practices in Qidong mine have testified that the coal and gas outburst accidents are predominantly associated with the belt of geological structure, the zone of tectonic coal occurrence and the area of the stress concentration. So it is very important to study characteristics of coal bed gas geology for coal bed gas prediction and prevention. Using gas-geology theory and method, the research focused on the factors of coal and gas outburst, such as coal bed gas occurrence, stress distribution, tectonic coal occurrence and magmatic rock presence within Qidong mine. The result shows that: Qidong mine district could be divided into 4 geological units by 3 faults as the boundary, the faults of Weimiao fault, F₂, and F₅; there are different conditions and main controlling factors of coal bed gas occurrence within four geological units. The unit I of geology: coal bed gas occurrence conditions are simpler, mainly contacted with the coal burial depth; the unit II: the conditions are more complex, predominantly associated with fault structures; the unit III: as a result of the presence of igneous intrusions, coal bed gas content in unit III is the highest within the whole mine; the unit IV: major factor of the conditions is the fold caused by strata uplift, which also leads to a large number of gas emissions. 25 coal and gas outburst accidents all occurred within the unit II of geology.

Abstract: The lead and zinc polymetallic deposit in LuziYuan is an ultra-large type skarn deposit. The ore body originated from the interlayer crushed zone between the second and thrid section of stratum marble and slate (schist) interbedding of upper Cambrian series Shahechang group, the wall rock alteration is intensice in the diggings, and the alteration zoning is obvious. Through field geological investigation and data analysis, based on the petrography of alterated rocks and combined with catalog information of drilling, the wall rock alteration in the diggings of LuziYuan is divided into four alteration zones,which are in sequence: carbonate-quartz-chloritization zone; carbonate-quartz-skarn lithification zone; skarn-lead zinc ore mineralization zone; and skarn-pyritization zone. The forming of ore body is related to alterations such as skarn lithification, silicification, marmarization, magnetite, etc.

Abstract: This paper focuses on the research of the vertical and regional distributions of stress characteristics in the Shizhuangnan coalbed methane field, southeastern Ordos basin. The minimum and maximum horizontal stresses were firstly calculated by the breakdown pressure, closure pressure and tensile strength of the fracturing data of key wells. Then the calculated results are compared with the results calculated from the natural gamma-ray, density and acoustic logging data and Anderson’s Model. Based on the comparison, the residual stress in the Anderson’s Model is corrected. By adding the residual stress data in the Anderson’s Model, the modified model can be well used for evaluating the stress characteristics in the area with complex structure types. Finally, the distribution of stress characteristics in the Shizhuangnan coalbed methane field were evaluated by using the modified Anderson model.

Abstract: The Qinling orogenic belt (QOB) located between the North China Craton (NCC) and the South China Craton (SCC) is composed of the Northern Qinling Belt (NQB) and the Southern Qinling Belt (SQB). This study presents new geochemical data, zircon U-Pb ages and Hf isotopes from two rocks from the Qinling complex in the NQB. LA-ICP-MS zircon U-Pb dating results suggest that the Qinling complex was formed in early Neoproterozoic and experienced the early Paleozoic metamorphism. High ε_Hf(t) values of 9.0-12.0 for the early Paleozoic zircons indicated that there is mantle-derived magma intruding into the Qinling complex in the early Paleozoic.

Abstract: Well data, cores, logging, connecting with the characteristic of structure evolution are used to establish the sequence stratigraphic framework of the coal-bearing formation of Yimin Depression in Early Cretaceous. The coal-bearing formation can be divided into two three-order sequences and Yimin Formation, as one of the three-order sequences,is the most important object of study. Through cores description, research of Spontaneous Potential and Resistivity curve shape and analysis of sedimentary Cumulative Probability Size Curve, four facies including fan delta, braid river delta, sublacustrine fan and lake,and some subfacies are identified in Yimin Formation in the sequence stratigraphic framework. Coal-rich belts develop in the southwest delta plain and northwest interdeltaic bay in Yimin Depression. According to the characteristic of the development of coal and sedimentary system, two kinds of coal accumulation models, shallow lake and flood plain in delta front and interdelta, are concluded in Yimin Depression.

Abstract: The Huyanshan alkaline complex outcrops in the middle part of the eastern wing of the Lvliang Mountain in Shanxi Province. Due to its typical alkaline rock type, the Huyanshan alkaline complex has attracted much attention from the geological field all the time. This paper describes the characteristic of trace elements of the Huyanshan alkaline complex and discussed the scientific problems such as magma sources and substance composition. The primitive mantle-normalized trace element spider diagram shows that the Huyanshan alkaline complex are enriched in Pb, Hf, Sr, Ba, Cs, Th, U and depleted in Cr, Ni and Co. The data presented indicates that the complex has deep source characteristic and derives from enriched mantle controlled by spinel peridotite partial melting process.

Abstract: 16 samples included coals, roofs, floors and tonstein of Late Permian collected from Yantang mine, Xuanwei were characterized through a petrographic and geochemical investigation. The results showed that, Yantang coals are medium degree of coalification bituminous coals; between gas coal and rich coal; have middle to high ash yields; extraordinarily low sulphur except B2-4, and dominanted by pyritic sulphur. Yantang coals are mainly composed of vitrinite and inertinite. The major minerals are clay minerals and quartz, followed with calcite, pyrite, illite and so on. The contents of Cu, W, Zr and V in Yantang mine were higher than the coals of national and Permian of southern China. Pearson correlation analysis results show that Be, Ni, Tl, Th, Li, Ga, Cs, Zr and Hf and ash yields significantly related at the 90% confidence level (r=0.51-0.79), and it indicate the nine elements are combined in minerals in the coal or related with minerals closely.

Abstract: The organosulfur compounds in the extract of the unusually organic sulfur rich of Hedong coal mine had been identified by gas chromatography and mass spectrometry. There are two series organosulfur compounds (OSC) were detected in the extract, they are benzonaphthothiophen and dibenzothiophene and the content of methylbiphenyl is overwhelming advantages in the biphenyl series. It demonstrates that the coal was formed in alkaline environment. The coal was formed in a reduction environment generally but there are exceptions, the samples HD9-2 and HD10-13 which have the value of Pr/Ph was 3.52 and 4.05 and So/St in sample HD9-2 was 78.82%, 73.08% in sample HD10-13 respectively . It show that the coal suffer strong oxidation and there are no good correlation between the content of organic sulfur and the oxidation environment.

Abstract: The geoelectrochemical-extraction measurement is a ore prospecting method of deep-penetrating geochemistry, by using the element receptors to extract the mobile metal ions from the soil under the artificial electric field to look for the hidden ore deposit. The study of using the geoelectrochemical-extraction measurement method to look for blind lead-zinc ore deposit has been carried out in the Fuzichong lead-zinc polymetallic ore deposit and Panlong lead-zinc ore deposit of Guangxi, which resulted in the clearly geoelectrochemical anormaly above the known ore bodies. And the ore prospecting forecast conducted in the unknown ore regions shows that it is feasible to use the geoelectrochemical-extraction measurement method to expore the deep hidden lead-zinc ore deposits.

Abstract: According to geological characteristics and the occurrence of heavy oil properties in the northern Tibetan plateau, the development feasibility studies and risk analysis were carried out . A detailed examination of the effects of diagenesis were conducted in terms of microcopic observation , stratigraphic facies and other low permeability reservoir aspects. The main factor affecting reservoir properties was theorized. Finally, the reservoir development risk is illustrated. Measures of the reservoir protection and efficient exploitation were presented. The results show that diagenetic compaction and cementation makes greate impact on the reservoir properties distribution .And it is recommended to use the steam stimulation method test mining , the method is less investment , the technology is simple , fast yield , good economic returns .