Laboratory investigation of the effect of GO-ZnO nanocomposite on drilling fluid properties and its potential on H2S removal in oil reservoirs

Drilling fluid loss is one of the basic problems in the drilling industry, which includes 10 to 20 percent of the cost of a drilling operation. It can cause some complications, such as creation of the water in oil emulsion. Furthermore, the presence of toxic hydrogen sulfide (H2S) gas in the excavation formations and the risk of its transfer to the surface, is a hazard to the health of employees on drilling rigs and causes corrosion of surface and subsurface equipment. In this study, the effect of adding Graphene Oxide-Zinc Oxide (GO-ZnO) nanocomposite on the drilling fluid properties and H2S removal were investigated. First, the GO-ZnO nanocomposite was synthesized. After XRD, SEM and EDS characterization tests and assuring the formation of the nanocomposite, drilling fluid samples were prepared by adding different concentrations of GO-ZnO nanocomposite to the base fluid (used in a real reservoir). Then the rheology, filtration, and gas chromatography tests were performed on various fluid samples. The results indicated desirable increases in the rheological properties such as plastic viscosity (5%-28%), yield point (25%-42%) and gel strength (25%-33%) and a significant decrease in the filtration rate. Besides, the results of the chromatographic tests indicated the ability of GO-ZnO nanocomposite to entirely remove the H2S in 15 min.