【作者】 吴群；

【导师】 蒲仁海；

【作者基本信息】 西北大学 ， 矿产普查与勘探， 2012， 博士

【摘要】 地应力是影响煤储层渗透性及煤层气井产能的重要因素。应用煤层气开发地质学、岩石(体)力学和渗流力学等多学科理论,针对鄂尔多斯盆地延川南区块实际,应用三维地震、钻井等勘探成果,通过实验分析、理论研究和数值模拟计算等方法,根据延川南区块断裂特征与构造格局,分析了含煤地层构造应力场分布及其演化规律,自中生代以来先后主要经历了2期构造应力场作用：第一期构造应力场在区内最发育,最大挤压应力方向为北西-南东向；第二期应力场最大挤压应力方向为北东—南西向。利用目前煤层气勘探开发井的测试资料,系统分析了现今地应力的大小、方向及其应力状态和煤储层压力及煤储层渗透性分布规律。1000m以浅煤储层地应力状态主要表现为σv>σhmax>σhmin,最小水平主应力小于16MPa,现今地应力处于拉伸应力状态；1000m以深煤储层地应力状态转化为σhmax≥σv≥σhmin,最小水平主应力大于16MPa,现今地应力转化为挤压应力状态。现今最大水平主应力方向主要以NEE-SWW方向为特征。通过应力敏感性试验分析,建立了煤储层渗透性与现今地应力和有效地应力之间的相关关系和模型,揭示了煤层气井排采过程中煤储层渗透性动态变化规律。煤储层渗透性受控于现今地应力的大小和所处的应力状态。当煤层深度小于1000米时,现今地应力状态处于伸张带,煤储层渗透性相对较好,煤储层试井渗透率平均大于O.1n-1.On×10-3μm2；当煤层深度大于1000米时,现今地应力状态转化为压缩带,煤储层试井渗透率平均为0.01n～0.1n×10-3μm2。煤层埋藏深度小于1000m区域,现今地应力状态处于伸张带,煤储层渗透性相对较好,是煤层气勘探开发的有利区(带)。煤储层渗透率随着有效压力的增加按负指数函数规律降低。在分析研究区现今地应力的基础上,跟踪研究区煤层气井试采动态资料,分析了煤储层应力对煤层气井产能影响的程度,煤储层的应力敏感性对煤层气井的产能有很大的影响,随着生产压差的增加,气井的产量增加幅度较小,并逐渐趋向稳定,放大生产压差并不能获得最大产量。更多还原

【Abstract】 The in-situ stress is a key factor affects permeability of coal reservoir and the production of coalbed methane (CBM) well. Coal bed methane development geology, rock mechanics, percolation mechanics and other multi-disciplinary theories were comprehensively used, according to the reality of Yanchuannan block in the Ordos Basin, through the methods of experimental analysis, theoretical study and numerical simulation, the fracture development features and its coupling relations and the distribution and evolution of tectonic stress field of coal reservoir at Yanchuannan block were analyzed. The structure in-situ stress field include two stages since Mesozoic. The frist is obvious and Maximum extrusion stress direction is NW-SE.The second stage Maximum extrusion stress direction is NE-SW.According to the test data of CBM exploration and development wells, the magnitude, direction and stress state of current in-situ stress and the distribution of coal reservoir pressure and permeability were systematically analyzed. Below1000m depth,the in-situ stress condition of coal reservoir is σv>σhmax>σh min and the minimum principal stress less than16MPa. Above1000m depth,the in-situ stress condition of coal reservoir is σhmax≥σhmax≥σhmin and the minimum principal stress more than16MPa.The correlations and their models between current in-situ stress and coal reservoir permeability were established according to analysis of stress sensitivity test, the dynamic variation of coal reservoir permeability in the process of CBM production was revealed. Coal reservoir permeability depend on the strength and condiction of in-situ stress.Permeability reduce with effective stress in terms of negative exponent.The exploration area is favorable which buried depth below1000m, tension in-situ stress condition.Based on the analysis of in-situ stress, combined with well test dynamic data, the influence degree of coal reservoir stress to CBM wells production was analyzed which provide scientific basis for Sinopec CBM exploration and development. The coal reservoir stress sensitivity have great influence with coalbed methane (CBM) well production. with the increase of drawdown pressure, gas well production increase amplitude is lesser, and gradually tend to be stable.更多还原