氧化石墨烯的制备及其封堵龙马溪组泥页岩机理研究

Preparation of graphene oxide and study on mechanism of blocking mud shale in Longmaxi formation

摘要:

孔隙压力传递是泥页岩井壁失稳的重要机理之一，纳微米尺度氧化石墨烯的研究为泥页岩孔隙封堵提供了新的途径。针对四川龙马溪组泥页岩，基于扫描电镜（SEM）、氮气吸附等方法表征了其孔隙结构；以改性Hummers法制备了厚度约为1.2 nm，平均片层尺寸分布范围为197 nm - 969.9 nm的氧化石墨烯（GO），并通过压力传递实验评价了其封堵性能；基于封堵后泥页岩的 SEM 及 X 射线能量色散谱（EDS）测试，探讨了GO封堵泥页岩岩心的主要机理。结果表明，片层尺寸为969.9 nm、质量分数为0.1%的GO阻缓压力传递效果最明显，其1 MPa压差传递时间为1000 s，而蒸馏水传递时间为30 s；GO呈半透明絮状膜堆叠、覆盖在岩心表面，对岩心纳微米孔隙进行了充填与封堵。

Abstract:

Pore pressure transmission is one of the important mechanisms for the instability of mud shale wellbore, and nano-micron scale graphene oxide research provides a new way for pore shale plugging. The pore structure of Longmaxi formation mud shale in Sichuan was characterized by scanning electron microscopy (SEM) and nitrogen adsorption; Graphene oxide (GO) with thickness of 1.2 nm and average slice size range from 197 nm to 969.9 nm was prepared by modified Hummers method, and its plugging performance was evaluated by pressure transmission experiments; Based on SEM and X-ray energy dispersive spectroscopy(EDS) tests of shale after plugging, the main mechanism of GO plugging shale core was discussed. The results show that GO with size of 969.9nm and mass fraction of 0.1% has the most obvious effect of resisting pressure transmission; The transmission time of 1MPa differential pressure is 1000s, while the transmission time of distilled water is 30s; GO which is a semi-transparent flocculent film stacked on the surface of the core filled and sealed core nano-micron pores.