河南省中-高煤阶构造变形煤甲烷吸附/解吸特征研究

煤体变质程度和变形结构不同,其对甲烷的吸附/解吸能力及特征也不同,通过对河南典型矿区5种中高煤阶构造变形煤的等温吸附/解吸试验研究,结果表明:中-高煤阶弱脆性构造变形煤的甲烷吸附能力随着煤变质程度的增加而增大;甲烷吸附量增量随着压力升高逐渐减小趋近于0,且甲烷吸附量增量随变质程度的增加而增大。单位压力段内甲烷解吸量随压力降低呈幂函数增大趋势,且变质程度越高,单位压力段内甲烷解吸量越大。不同类型构造变形煤单位压力段解吸量随压力降低呈单调递增的对数函数,且甲烷解吸量随着构造变形程度的增强而增大。

中-高煤阶构造变形煤纳米级孔隙结构及其对甲烷吸附能力的影响

通过镜质组反射率测试、显微组分测定、液氮吸附和等温吸附实验等,对河南中北部典型矿区6种中-高煤阶构造变形煤纳米级孔隙结构和吸附特征进行了研究。结果表明：中-高煤阶构造变形煤纳米级孔体积主要以过渡孔（10-100 nm）为主,而比表面积由微孔（1.5-10 nm）控制。纳米级孔体积、比表面积和过渡孔孔容从脆性变形碎裂煤、碎粒煤到韧性变形糜棱煤逐渐增大;中-高煤阶构造变形煤Langmuir体积与纳米级孔体积和比表面积之间呈线性正相关;过渡孔和微孔的分布关系对煤层气解吸特征产生重要影响,且过渡孔体积越大,甲烷解吸越容易。

不同变质变形煤微晶结构的XRD试验研究

煤的变质、变形作用不仅对煤的宏观特征具有重要影响,而且也影响着煤的微晶结构,煤微晶结构是影响煤储层物性的内在因素之一。为深入研究不同变质变形煤的微晶结构演化特征,本文采用X射线衍射(XRD)试验方法,综合前人的试验结果,对全煤级不同变质变形煤的微晶结构参数进行研究。结果表明:随着煤级的升高,面网间距d002逐渐减小、堆砌度Lc以及芳香层数Nc逐渐增大,呈现一定的阶段性,其数值最终趋于稳定;延展度La与最大反射率Ro,max呈线性关系,随着煤级的升高而逐渐增大。在变质作用的基础上,构造变形作用拉长了煤微晶参数的变化区间,使微晶结构得以提前演化;构造变形作用对堆砌度Lc、延展度La以及芳香层数Nc的增大有积极的影响;弱构造变形作用对d002最终稳定值影响较小,强构造变形煤d002的最终稳定值较原生煤的小;原生结构煤、弱构造变形煤以及强构造变形煤微晶参数随煤级变化时具有不同的特征,构造变形煤的微晶参数较原生结构煤变化空间更大。

宿东矿区脆性变形构造煤的渗透性特征

在综合分析宿东矿区的地质背景的基础上,通过对不同类型脆性变形构造煤的渗透性实验,并根据渗透性与有效应力之间的关系分析,研究了不同类型脆性变形构造煤渗透性之间的差异及其对煤层气开采的影响。结果表明脆性变形系列构造煤渗透率都比较大,随着有效应力的增大,构造煤的渗透率会减小。在相同压力点下碎斑煤的渗透率比较大,碎裂煤其次,然后是初碎裂煤,片状煤最小。

Mechanism of stepwise tectonic control on gas occurrence: A study in North China

To gain an understanding of gas occurrence, distribution is the fundamental basis for preventing gas disasters. Presently, how tectonic structures control gas occurrence remains problematic. This study proposes the theory and elucidates the mechanism of stepwise tectonic control on gas occurrence according to the characteristics of gas occurrence and the patterns of gas distribution in coal mines in North China. On the one hand, tectonic compression and shearing lead to stress concentration and thus deform the coal and reduce the coal seam permeability, further contributing to gas preservation. On the other hand, tectonic extension and rifting lead to stress release and thus improve the coal seam permeability, further contributing to gas emission. Therefore, the distribution zones of tectonic compression, ubiquitous coal deformation, and gas accumulation have been step-wisely revealed, and the coal-gas outburst proneness zones are finally identified. The proposed theory of step-wise tectonic control on gas occurrence is of practical significance for gas prediction and control.

Stability control of surrounding rocks for a coal roadway in a deep tectonic region

In order to effectively control the deformation and failure of surrounding rocks in a coal roadway in a deep tectonic region, the deformation and failure mechanism and stability control mechanism were studied. With such methods as numerical simulation and field testing, the distribution law of the displacement, stress and plastic zone in the surrounding rocks was analyzed. The deformation and failure mechanisms of coal roadways in deep tectonic areas were revealed: under high tectonic stress, two sides will slide along the roof or floor; while the plastic zone of the two sides will extend along the roof or floor,leading to more serious deformation and failure in the corner of two sides and the bolt supporting the corners is readily cut off by the shear force or tension force. Aimed at controlling the large slippage deformation of the two sides, serious deformation and failure in the corners of the two sides and massive bolt breakage, a ‘‘controlling and yielding coupling support'' control technology is proposed. Firstly, bolts which do not pass through the bedding plane should be used in the corners of the roadway, allowing the two sides to have some degree of sliding to achieve the purpose of ‘‘yielding'' support, and which avoid breakage of the bolts in the corner. After yielding support, bolts in the corner of the roadway and which pass through the bedding plane should be used to control the deformation and failure of the coal in the corner. ‘‘Controlling and yielding coupling support'' technology has been successfully applied in engineering practice, and the stability of deep coal roadway has been greatly improved.

FEATURES AND MINING GEOLOGY SIGNIFICANCES OF THE COAL SEAM SLIP FOLD STRUCTURE IN XU-HUAI DISTRICT

In the analysis of some in-seam slip fold structures in the area of Xuzhou and Huaibei Districta it is noted that there exist some in-seam roof and footwall rock layers extremely incompatible to the existence of coal seams. Some of them are tbe slip fold structures that are wedged into coal seam by folding, but all of them are passively generated by in-seam shearing forces. In this paper, a discussion is put forward of the damage to coal seams by slip folds and the coal mining significance resulted from the study of slip fold structures.

Controls on migration and aggregation for tectonically sensitive elements in tectonically deformed coal:An example from the Haizi mine, Huaibei coalfield, China

Tectonically deformed coal(TDC)develops because of the superimposed deformation and metamorphism of a coal seam by tectonic movements.The migration and accumulation of trace elements in TDC is largely in response to stress-strain conditions.To develop a law governing the migration and aggregation of sensitive elements and investigate the geological controls on TDC,coal samples from different deformation sequences were collected from the Haizi mine,in the Huaibei coalfield in Anhui Province,China,and the concentrations of 49 elements were determined by XRF and ICP-MS,and then microscopically analyzed.The results show that the distribution and morphology of minerals in coal is related to the deformation degree of TDC.The evolutionary process runs from orderly distribution of minerals in a weak brittle deformed coal to disordered distributions in ductile deformed coal.According to the elemental distribution characteristics in TDC,four types of element migration can be identified:stable,aggregate,declining,and undulate types,which are closely related to the deformation degree of TDC.Present data indicate that the overall distribution of rare earth elements(REE)does not change with metamorphism and deformation,but it shows obvious dynamic differentiation phenomena along with the deformation of TDC.Tectonic action after coal-formation,brittle or ductile deformation,and the metamorphic mechanism and its accompanying dynamic thermal effects are the main factors that influence the redistribution of elements in TDC.We conclude that tectonic movements provide the motivation and basis for the redistribution of elements and the paths and modes of element migration are controlled by brittle and ductile deformation metamorphic processes.The dynamic thermal effect has the most significant effect on coal metamorphism and tectonic-stress-accelerated element migration and accumulation.These factors then induce the tectonic-dynamic differentiation phenomenon of element migration.

Spectra response from macromolecular structure evolution of tectonically deformed coal of different deformation mechanisms

Coals with different deformation mechanisms(brittle deformation,brittle-ductile deformation,and ductile deformation) repre-sent different ways in macromolecular structure evolution based on the metamorphism.The evolution of coal structure could affect the occurrence condition of coalbed methane(CBM) because the nanopore structure affected by macromolecular struc-ture is the most important reservoir for CBM.This paper analyzes the evolutions and mechanisms of structure and functional group of tectonically deformed coals(TDCs) collected from Huainan-Huaibei coalfield using X-ray diffraction(XRD),Raman spectroscopy,and Fourier Transform Infrared(FTIR) spectroscopy methods.The results show that the macromolecular struc-ture evolutions of TDC are different from the primary structure coal as a result of the different metamorphic grade and defor-mation mechanisms.The different deformation mechanisms variously affect the process of functional group and polyconden-sation of macromolecular structure.Furthermore,the tectonic deformation leads to secondary structural defects and reduces the structure stability of TDC.The coupled evolution on stacking and extension caused by the changes of secondary structural de-fects results from different deformation mechanisms.We consider that the changes of chemical structure and secondary struc-tural defects are the primary reasons for the various structure evolutions of TDC compared with primary structure coal.