Study on the preparation and mechanism of two-dimensional nanomaterials as plugging agents for oil-based drilling fluids

Abstract

During the drilling of shale formations using oil-based drilling fluids (OBDFs), the infiltration of filtrate into formation micro-fractures is one of the primary causes of wellbore instability. Wellbore instability not only increases non-productive time during the drilling process but also significantly raises development costs. The key to addressing this issue is the development of nano plugging agents capable of effectively sealing formation micro-cracks. However, existing nano plugging agents suffer from poor dispersibility and mismatch with the scale of rock fractures under formation conditions. In this study, two-dimensional nano graphene oxide was synthesized via a redox method. XRD and Raman analyses confirmed the production of high-quality, few-layer two-dimensional graphene sheets. TEM analysis revealed that the synthesized high-reduction graphene oxide (R-GO) had an average lateral size of 2.16 μm, making it suitable for sealing formation micro-cracks. Performance tests demonstrated that R-GO maintained its non-aggregating and highly dispersible properties under formation conditions. Additionally, permeability reduction experiments showed that adding 0.25 %, 0.50 %, and 0.75 % R-GO resulted in permeability reduction rates of 29.12 %, 31.86 %, and 49.16 %, respectively. The conclusion is that R-GO, as a nano plugging agent for OBDFs, can form a dense sealing layer on the surfaces of shale nano-micro pores and fractures, thereby enhancing the stability of shale formations.