页岩储层渗吸特性的实验研究

Researching the Water Imbibition Characteristic of Shale by Experiment

页岩含有大量黏土矿物,遇水会导致页岩中黏土矿物水化、膨胀,为研究页岩吸水特性及探究页岩气井返排率的影响因素。开展了页岩动态渗吸及静态渗吸实验;并对实验结果进行了详细的分析。研究表明:页岩水化作用主要发生在页岩与水或水基溶液接触的表层附近,液体侵入深度十分有限;不同的液体介质下页岩的吸水能力各不相同;页岩吸水量由表面水化吸水量、渗透水化吸水量和毛管吸水量组成,而且水化吸水量基本无法排出,在一定程度上降低了页岩气井压裂液的返排率;相同的成藏条件下页岩的渗透水化吸水量及表面水化吸水量相同;页岩水化能力及压裂效果是影响返排率的主控因素。

Shale contains many clay minerals,so the clay will be hydration and swell when it comes across water. For researching the characteristic of shale water imbibition and the facturing fluid flowback,a series of dynamic imbibition experiments and static imbibition experiments and analyze the experiment data in detail were designed.The conclusions show that： the hydration of shale takes place on the surface of shale and the intruding depth is shallow; the water imbibition capacity of shale is different for different solutions; the water imbibition amount of shale consists of surface hydration,osmotic hydration and capillary suction,and the absorbed water cannot be discharged,which can lead to the low reverse rate; the water imbibition amount of osmotic hydration and the water imbibition amount of surface hydration is constant respectively in the same reservoir condition; the hydration capacity of shale are major factors which affect facturing fluid flowback.