页岩储层纳米孔隙结构特征及其含气因素实验研究

Experimental study on the characteristics of nanoscale pore structure and its gas content factors in shale reservoirs

针对页岩气储层的特点,通过运用页岩气解吸仪、场发射扫描电子显微镜、比表面积及孔径分析仪及X射线衍射仪对临兴地区泥页岩储层进行岩石组分、孔隙结构及页岩含气性特征分析,从而确定该区的页岩气勘探潜力。结果显示,临兴地区泥页岩具有复杂和非均质的孔隙分布特征,孔隙发育较差。有机质孔相对丰富,尤其是在机质较为富集的样品中,有机质孔对纳米级孔隙的发育起很大的控制作用。矿物组成和页岩气解吸分析显示出有机质对储层甲烷吸附量的巨大贡献,有机质发育的深灰色泥页岩甲烷解吸量(2.3~9.35mL/g)明显高于相同条件下的低有机质泥页岩(0.13~0.89mL/g)。此外,储层黏土矿物(18~94%)中的高岭石与页岩气含量之间呈较好的正相关性,对页岩气的赋集有利,碎屑矿物不利于储层储集能力的提高。

In view of the characteristics of shale gas reservoirs,through the use of shale gas desorption instrument,field emission scanning electron microscopy,surface area and pore size analyzer and X ray diffraction analysis of the rock components,pore structure and shale gas content characteristics of Lingxing area shale reservoir,thus in order to determine the shale gas exploration potential in this area.The results show that the mudstone shale in Linxing area has complex and heterogeneous pore distribution characteristics and poor pore development.The pore of organic matter is relatively abundant,especially in the samples with abundant organic matter,the pore of organic matter plays a great role in controlling the development of nano-pore.Mineral composition and shale gas desorption analysis show that organic matter contributes greatly to methane adsorption capacity of reservoir.The methane desorption capacity of dark gray shale(2.3-9.35ml/g)developed by organic matter is obviously higher than that of low organic shale(0.13-0.89ml/g)under the same conditions.In addition,there is a good positive correlation between the content of kaolinite and shale gas in the clay minerals(18-94%)of the reservoir,which is beneficial to the accumulation of shale gas,and clastic minerals are not conducive to the improvement of reservoir capacity.