鄂尔多斯盆地陆相页岩孔隙演化特征——以长7油层组为例

发布时间：2018-04-04 22:35

本文选题：陆相页岩　切入点：页岩气　出处：《东北石油大学学报》2017年04期

【摘要】：以鄂尔多斯盆地三叠系延长组7段长7油层组陆相页岩为对象,基于X线衍射、场发射扫描电镜、等温吸附、物性测试及岩石热解等实验,研究陆相页岩孔隙演化特征。结果表明:研究区页岩孔隙直径和黏土矿物演化程度呈正相关关系,演化程度越高,黏土矿物平均孔径越大;随着矿物演化程度的增加,蒙脱石逐渐向伊利石转化,转化过程中,蒙脱石层间水分子的逐渐排出引起页岩储层孔隙度增加,且在层间形成微孔隙和微裂隙;伊/蒙混层从无序状态变为有序状态,大量脱出层间水,而层间水变为自由水进入页岩固有的孔隙空间,并在地层压实作用下使页岩孔隙体积增大。页岩有机质生烃对孔隙有保护作用,成岩后期压实作用使页岩孔隙减小,但随着地层温度和压力达到页岩生油窗,有机质生烃作用生成的部分油气进入之前的孔隙,增加孔隙内部压力,减缓压实作用下孔隙体积的降低。
[Abstract]:Based on X-ray diffraction, field emission scanning electron microscope, isothermal adsorption, physical property test and rock pyrolysis experiments, the pore evolution characteristics of continental shale in Chang 7 reservoir formation of member 7 of the Triassic Yanchang formation in Ordos Basin were studied.The results show that there is a positive correlation between the pore diameter of shale and the evolution degree of clay minerals, the higher the evolution degree, the larger the average pore size of clay minerals, and with the increase of mineral evolution degree, montmorillonite gradually transforms to Illite.During the process of transformation, the gradual discharge of water molecules between layers of montmorillonite resulted in the increase of porosity of shale reservoir, and the formation of micro-pores and micro-fractures in the interlayer, and the eosinite / montmorillonite layer changed from a disordered state to an orderly state and produced a large amount of interlayer water.The interlayer water becomes free water into the pore space of shale and increases the pore volume of shale under the action of stratigraphic compaction.Hydrocarbon generation of shale organic matter has protective effect on pore, compaction in late diagenesis makes shale pore decrease, but with formation temperature and pressure reaching shale oil generation window, some oil and gas generated by organic matter come into the pore before entering.Increase internal pore pressure and slow down the reduction of pore volume under compaction.
【作者单位】：成都理工大学能源学院;成都理工大学油气藏地质与开发工程国家重点实验室;四川省煤田地质局页岩气评价与开采四川省重点实验室;中国石化西南油气分公司广西采油厂;
【基金】：国家科技重大专项(2017ZX05036-004-006)
【分类号】：P618.13

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