沁水盆地南部煤中矿物赋存特征及其对煤储层物性的影响

煤中矿物可以影响煤储层物性，进而影响煤层气的开发。运用光学显微镜和扫描电镜研究沁水盆地南部煤中矿物的种类、含量和赋存特征。基于煤储层的平衡水等温吸附实验和压汞实验，研究了沁南地区煤中矿物对煤储层吸附性能和孔渗性能的影响。结果表明，柿庄北区块3号和15号煤平均矿物含量分别为10.68%和12.81%，且15号煤硫化物含量较高。扫描电镜下可观察到充填煤储层胞腔孔、粒间孔隙和微裂隙的方解石、黄铁矿、高岭石和石英。孔隙度和渗透率以及兰氏体积和煤中大中孔比例均随灰分产率的增加而减小，表明煤中矿物的存在会降低煤储层的吸附性能和孔渗性能，煤储层中矿物充填主要影响煤的大中孔和裂隙，影响煤层气在割理和裂隙中的渗流，导致孔隙度和渗透率下降，而少量粘土矿物充填微孔可导致煤的吸附性能下降。

Occurrence Characteristics of Minerals and Their Influences on Physical Properties of Coal Reservoirs in Southern Qinshui Basin

Minerals in coal can influence coal reservoir physical properties and the development of coalbed methane. Mineral species, content and occurrence characteristics in coal of southern Qinshui Basin were studied by using optical microscope and scanning electron microscope (SEM). Based on the test of isothermal adsorption experiment and mercury-injection method, the effects of minerals on adsorption capacity, porosity and permeability of coal reservoir were analyzed. The results show that the mineral content of No.3 and No.15 coal seams of Shizhuang block are 10.68% and 12.81%, respectively, and the content of sulfide minerals in No.15 coal seam is higher than that in No.3 coal seam. Calcite, pyrite, kaolinite and quartz filling in cell pores, intergranular pores and microfractures can be identified under SEM. The values of langmuir volume, proportion of macropores and mesopores, porosity and permeability decrease with the increasing of ash content, indicating that minerals in coal can decrease the adsorption capacity, porosity and permeability of coal reservoirs. Minerals in coal mainly fill in macropores, mesopores and microfractures of coal and they can influence the diffusion of coalbed methane in cleats and fractures, causing the decrease of porosity and permeability. However, a small part of clay minerals which fill in micropores of coal reservoir can lead to the decrease of adsorption capacity.