Poly(Vinyl Alcohol)-Doped Surface-Modified Graphene Oxide/Cellulose Porous Aerogel for Oil-Based Drilling Fluid Plugging.

To counter the threat to wellbore stability in shale formations posed by filtrate invasion and pressure transmission of oil-based drilling fluids (OBDFs), it is critical to develop a material that can effectively seal micron-scale fractures. Graphene oxide was surface-modified and a cross-linking entanglement strategy was used to prepare tough carbon aerogels (HPGA2) with a porous structure, and HPGA2 were characterized by Fourier transform infrared, Raman, thermogravimetric analysis, X-ray photoelectron spectroscopy, and X-ray diffraction. Scanning electron microscopy, SDM, and Brunauer-Emmett-Teller confirmed that the pores of HPGA2 are mainly micro- and mesopores less than 10 nm in size, which results in swift absorption of oil by HPGA2. SLS was found to have 90% of HPGA2 particles below 35 μm, which is suitable for plugging microcracks in the formation. The impact of HPGA2 on the rheological characteristics and stability of drilling fluids were assessed through a rheological performance test and an emulsion breaking voltage test, respectively. The plugging performance was evaluated via a medium-pressure filtration test, a high-temperature and high-pressure filtration test, and a simulated microfracture plugging experiment. The experimental results show that the inclusion of HPGA2 has minimal impact on the rheological characteristics and stability of OBDFs; when HPGA2 is added at a level of 2%, it demonstrates outstanding compatibility with OBDFs and can substantially cut down on filtrate loss in both standard and high-temperature, high-pressure environments; in the simulated experiment of microcrack plugging, the pressure-bearing capacity of the drilling fluid with 2 wt % HPGA2 was about 10 times higher than that of the original drilling fluid, while the permeability decreased from 92 to 9%. This paper introduces a technique for fabricating a composite material that exhibits superior sealing capabilities, providing a way to solve the instability of the wellbore caused by OBDFs during drilling.