煤的孔隙度、渗透率、裂缝和煤体结构等物性参数发育特征受控于构造及其演化特征。以沁水盆地南部柿庄地区为研究对象，基于野外节理和测井天然裂缝产状统计，利用节理（裂缝）的分期和配套、波叠加原理，对燕山期和喜山期构造应力场、构造形迹进行反演；通过地史最大构造曲率r表征了煤层在地质历史时期的变形程度，进而探讨了多期构造作用对煤储层物性的影响特征。研究结果表明：柿庄地区节理（裂缝）走向发育具有五个优势方向，分别为NNE向（10°～25°）、NEE向（45°～85°）、NWW向（85°～110°）、NW向（135°～145°）、NNW向（160°～175°）；倾角较大，主要分布在50°～90°，且大于70°的高达76%。自晚古生代以来的燕山期NWW—SEE向挤压和喜山早期NWW—SEE向拉伸运动造成煤层底板形态复杂，煤层物性差异较大。地史最大变形程度控制着煤体真实的损伤程度，随着地史最大变形程度的增加，裂隙发育增多，煤体破碎程度增加，当r<48×10^-6 m^-1时，发育原生结构煤;当48×10^-6 m^-1 <r<150×10^-6 m^-1时，发育碎裂结构煤;当r>150×10^-6 m^-1时，发育碎粒结构煤；糜棱结构煤基本不发育。在一定范围内，随地史最大变形程度的增加，煤储层渗透率呈现出先增大后减小的趋势，其界线值在r≈110×10^-6 m^-1处；煤层的孔隙度多受埋深和应力特征控制，地史最大变形程度对其影响不明显。为多期构造活动对煤储层物理性质影响的研究提供了一种新方法，可望应用于柿庄区块及其他煤层气区块的储层物性评价及预测。

The physical properties of coal reservoirs,i.e.,porosity,permeability,fractures,and coal structures,restrict the exploration and development of coalbed methane. The developmental characteristics of physical properties are controlled by the tectonic evolution process. Based on the occurrence statistics of field joints and natural fractures from loggings,using staging and matching of joints (cracks) and wave superposition principle,the tectonic stress field and structural features of Yanshanian period and Himalayan period are inversed in the Shizhuang area of southern Qinshui Basin. The deformation degree of the coal seam in geological history period was characterized through the largest tectonic curvature (r),and the influence on coal reservoir physical properties of multi period tectonic activities was discussed. Research has shown that the joint (fracture) trend has five advantageous directions,which are NNE (10～25 degrees),NEE (45～85 degrees),NWW (85°～110°),and NW (135°～145°),NNW direction (160°～175°).The inclination angle is large,mainly distributed between 50～90 degrees,and it is 76% greater than 70 degrees. Since the late Paleozoic,the NWW-SEE trend in the Yanshanian and NWW-SEE-direction tensile stress in the early Xishantectonic movement has caused the complex shape of the coal seam floor. The physical properties of the coal seam were quite different. The maximum deformation degree of the earth's history controls the actual damage degree of the coal body. With the increase of history's largest deformation degree,fractures and the broken degree of coal increased. When r<48×10^-6 m^-1,primary structural coals were developed; when 48×10^-6 m^-1<r<150×10^-6 m^-1,cataclastic coals were developed; when r>150×10^-6 m^-1,granulated coals were developed; mylonite coals were barely developed. With the increase of the historical maximum deformation degree in a certain range,coal reservoir permeability shows a trend of increasing first and then decreasing. Its boundary value is at 110×10^-6 m^-1.The porosity of coal seams is mostly controlled by burial depth and stress characteristics,so the influence of deformation degree of the coal on the porosity was not obvious. This presents an applicable method for evaluating the influence of tectonic movement on the physical properties of coal during different times and would benefit the evaluation of coalbed methane reservoirs in Shizhuang area as well as other coal basins in the world.

0 引言

1 地质概况

2 构造应力场及古构造形迹恢复

   2.1 节理（裂缝）观测

   2.2 古构造应力场恢复

   2.3 古构造形迹恢复

3 多期构造作用对煤储层物性的影响

   3.1 不同时期构造作用后的煤岩变形程度表征

   3.2 多期构造作用对煤体结构的影响

   3.3 多期构造作用对煤储层孔渗的影响

4 结论