Microwave-assisted synthesis of zinc oxide nanoflowers for improving the rheological and filtration performance of high-temperature water-based drilling fluids

Abstract

Zinc Oxide (ZnO) nanostructures have proved useful across a wide range of applications like medical technology, electronics, sulfur removal as well as microbial growth control. In the petroleum industry, ZnO nanostructures have been widely researched for application in Drilling Fluids. ZnO has been previously reported to work excellently in enhancing the electrical and thermal properties of water-based drilling fluids (WBDFs). However, the role of morphological features of the nanostructures in influencing the properties of bentonite-laden WBDFs is less understood. In this work, ZnO nanostructures were synthesized under microwave irradiation which resulted in different shapes like rods and flowers. The effect of microwave power and time was observed with Field Emission Scanning Electron Microscopy (FE-SEM) and Dynamic Light Scattering (DLS), and a suitable synthesis criterion was selected for achieving the smallest complex ZnO nanoflowers. These nanoflowers were further characterized for functional group and structural identification. Bentonite/Polymer Nanofluids were prepared and tested for properties like rheology, API, and HPHT filtration before and after thermal aging at 150 °C. The results show ZnO nanoflowers in WBDFs have excellent filtration control ability with ∼56% reduction in HPHT filtrate volume and can impart a flat-line rheological profile. Also, the breaking of nanoflowers into smaller nanorods and some further textural changes is predicted to enhance the stability of the WBDFs due to better dispersion and compact mud cake formation. The study shows that the morphological features of metal oxide nanostructures can be controlled with microwave irradiation and play an effective role in controlling the properties of bentonite/polymer WBDFs.