大黄山一号井地质构造特征及其对煤层瓦斯赋存的影响

Geological Structure Characteristics of No.1 Well in Dahuangshan and Its Influence on Coal Seam Gas Storage

为了分析地质构造及其演化对新疆大黄山一号井煤层瓦斯赋存的影响,对井田地质构造及演化特征、含煤地层埋藏-抬升史、煤层变质作用、瓦斯生成与赋存特征等开展研究,为大黄山一号井瓦斯灾害防治提供理论指导。研究表明:井田地处博格达山北缘逆冲推覆构造带之山前弧形逆冲断褶带,受高角度叠瓦状逆冲断层及南北向构造挤压应力控制,井田主体构造表现为一南北翼被NE、NW向共轭走滑平移断层切割的轴面南倾的弧形紧闭倒转向斜。井田含煤地层沉积后主要经历了两个阶段:第Ⅰ阶段为快速沉降,并于晚侏罗世至最大埋深4 000m左右,煤层达到气煤变质阶段,煤层瓦斯大量生成;第Ⅱ阶段为持续挤压抬升形变,煤层瓦斯大量逸散。受切向应变主动褶皱作用控制,井田向斜南北两翼向核部,煤层所受挤压应力越来越大,导致煤层孔隙率、透气性系数愈来愈小,煤层瓦斯含量及瓦斯压力愈来愈高。受东西差异性挤压弧形构造背景控制,北翼西部煤层瓦斯含量及瓦斯压力普遍高于东部,且表现出由西向东逐步降低的趋势。受走滑斜移断层控制,断层附近煤层瓦斯含量及瓦斯压力出现局部高值。

In order to anlysis the influence of geological structure and its evolution on the gas occurrence in the coal seam of Dahuangshan No.1 Well in Xinjiang,this paper study the geological strueture and evolution characteristics of the mine field,burial uplift history of coal bearing strata,metamorphism of coal seams,and gas generation and occurrence characteristics,so as to provide theoretical guidance for the prevention and control of gas disasters in Dahuangshan No.1 Well.The research shows that the mine field is located in the piedmont arcuate thrust fold belt of the thrust nappe structural belt on the northerm edge of Bogeda mountain,controlled by high angle imbricate thrust fault and north-south structural compression stress,and the main structure of the mine field is shown as an arc-shaped closed reverse steering slope with southward dipping axial plane cut by NE and NW conjugate strike slip translational faults on the north and south wings.The coal bearing strata in the mine field have undergone two main stages since sedimentation.The first stage is the rapid subsidence and the maximum burial depth of about 4000m in the Late Jurassic.The deep thermal metamorphism caused the coal seams to reach the gas coal metamorphic stage and the peak of thermal gas and gas appeared;The second stage is the continuous compression and uplift deformation of the coal bearing strata,resulting in a large amount of coal seam gas escape.Controlled by the active folding effect of tangential strain,the compression stress on the coal seams in the north and south wings of the rmine field syncline towards the core is increasing,resulting in smaller porosity and permeability coefficients of the coal seams,and higher gas content and pressure in the coal seams.Controlled by the background of the east-west differential compression are structure,the gas content and pressure in the westem coal seam of the northerm wing are generally higher than those in the eastern part,and show a gradually decreasing trend from west to east.Controlled by strike slip and displacement faults,local high values of gas content and pressure in coal seams near the faults occur.