页岩纹层结构分类与储集性能差异 ——以四川盆地龙马溪组页岩为例

纹层结构研究对页岩系统储层有效性评价具有重要意义。以四川盆地海相志留系龙马溪组页岩为例，综合利用成像测井、光学显微镜、场发射扫描电镜、孔隙度测定、氮气吸附及含气量测试等方法，明确了龙马溪组不同尺度纹层结构特征，评价了不同纹层结构储集性能的差异。龙马溪组发育水平等厚纹层结构—中粗纹层组合、水平—小型波状纹层结构—中粗纹层组合、水平不等厚纹层结构—薄纹层组合及块状无纹层组合；纹层成分主要为包括石英、碳酸盐、有机质与黏土矿物的三类组合，碳酸盐纹层的有机质孔隙和无机质孔隙相对发育；纹层状页岩与块状泥岩在孔隙类型、孔隙体积、有机质丰度及含气量等方面具有明显差异。总体来看，中粗纹层组合页岩储层性质优于薄纹层组合页岩优于块状泥岩，是龙马溪组优先勘探的目标。下一步研究应重点加强纹层结构形成的水动力学背景、对有机质富集及储层可改造性等方面的影响。相关认识可为深化四川盆地龙马溪组有利储层优选与评价提供重要的参考和技术支持。

Lamination Texture and Its Effect on Reservoir Properties: A Case Study of Longmaxi Shale,Sichuan Basin

Lamination texture is of great significance in shale reservoir effectiveness.This study of the marine Silurian Longmaxi Formation in the Sichuan Basin used image logging,optical microscopy,field emission scanning electron microscopy(FE-SEM),porosity measurement,nitrogen adsorption testing and gas content testing to clarify the structural characteristics of shale laminations at different scales.The relative reservoir properties of the different shales were evaluated.The Longmaxi Formation contains sedimentary rock combinations of horizontal equi-thickness medium coarse shale laminae and a combination of horizontal,slightly wavy to medium coarse laminae shale,and horizontal beds of unequal thickness,thin laminae combinations,and also combinations with massive mudstones.The laminations mainly include quartz,carbonate minerals,organic matter and clay minerals.The carbonate laminations exhibit large pores in organic matter and inorganic matter.The laminated shales and massive mudstones reveal obvious differences in pore types,pore volumes,organic matter enrichment and gas content.The data from this study indicates that the reservoir properties of the medium coarse laminae combinations are superior to those of thin laminae combinations,which in turn are better than those of the massive mudstone.The medium coarse laminae combination is the priority exploration target in the Longmaxi Formation.Future research should focus on the hydrodynamic background of laminae texture formation and its influence on organic matter enrichment and reservoir stimulation.Relevant knowledge can provide an important reference and technical support for increasing the optimization and evaluation of favorable reservoirs in the Longmaxi Formation,Sichuan Basin.