黔西比德——三塘盆地多层叠置独立含煤层气系统发育规律与控制机理  

Development features and mechanism of multi-layer superimposed independent CBM systems in Bide-Santang Basin,western Guizhou,South China

作　　者：郭晨[1] 夏玉成[1] 卢玲玲[1] 任亚平[1] Guo Chen Xia Yu-cheng Lu Ling-ling Ren Ya-ping(College of Geology and Environment ,Xi ＇ an University of Science and Technology ,Xi ＇an 710054 ,China)

机构地区：[1]西安科技大学地质与环境学院,陕西西安710054

出　　处：《天然气地球科学》2017年第4期622-632,共11页Natural Gas Geoscience

基　　金：国家科技重大专项项目(编号:2011ZX05034);西安科技大学博士启动基金项目(编号:2016QDJ028);西安科技大学科研培育基金项目(编号:201718)联合资助

摘　　要：在多煤层含煤地层中,往往形成垂向上叠置发育的多个独立含煤层气系统,严重影响了多煤层合排效果。以黔西比德—三塘盆地为对象,运用含气量梯度和压力系数的变异系数定量表征独立含气系统的发育程度,揭示其平面分布规律,并从构造、沉积、水文等3个方面综合分析其地质控制因素。研究认为:研究区周缘主干断裂以及由此形成的三角形构造控制了区内应力应变特点和聚煤作用,由西缘断裂带向盆地内部应力应变逐渐减弱,煤层厚度和稳定性逐渐增加,泥岩顶板渐趋发育;沉积相带呈NE向展布,并随着海水作用的增强,由西向东沉积特征发生规律性变化,砂泥比降低,沉积旋回渐趋发育,并易于形成黄铁矿、高岭石等成岩矿物充填孔隙;地下水总体由NW向SE方向径流,流动过程中渗流阻力增大,滞留程度增加。在构造、沉积、水文的耦合控制之下,独立含气系统由盆地NW向SE方向渐趋发育。依此进行了叠置含气系统发育程度分区,勘探开发实践在一定程度上佐证了分区的客观性。A number of independent coalbed methane（CBM） systems are often superimposed in coal-bearing strata with multiple coal seams,and severely impede the multi-layer commingled CBM production rate.So we take Bide-Santang Basin,western Guizhou as examples,variable coefficient of gas content gradient and water head pressure coefficient are used to represent development degree of independent CBM systems quantitatively,and the geological controlling factors and mechanism are analyzed from perspectives of structure,sedimentary and hydrogeology,respectively.Following conclusions are obtained：the marginal faults and the resulted triangle structure framework control the stress-strain characteristics and coal accumulation of the study area.From western marginal fault zone to basin internal part,the ground stress and strain weaken,coal thickness and stability increase and mudstone roof is more developed.Sedimentary facies distribute in NE direction,with the sea influence increasingly enhanced,the deposited characteristics of coal-bearing strata change regularly from west to east in the basin：The sand/mud ratio reduces,sedimentary cycles occur at higher frequency,and authigenic minerals,such as pyrite and kaolinite,tend to be more developed and fill the pores.Groundwater flows from NW to SE,with the increasing flowing resistance,resulting in weak hydrodynamic conditions and groundwater stagnation in the SE direction.Under the coupling controls of structure,sedimentary and hydrogeology conditions,the independent CBM systems are increasingly developed from NW to SE in the basin.The study area is partitioned into four subareas with different development degrees of superposed CBM systems,which are verified by the CBM exploration and development practice,to a certain extent.

关 键 词：黔西 多层叠置独立含煤层气系统 构造 沉积 水文地质 

分 类 号：TE122[石油与天然气工程—油气勘探]