Development a new type of oil based drilling fluid with good temperature resistant

The complexity of reservoir conditions puts forward higher requirements for drilling fluid performance. The existing water-based drilling fluids (WBFDs) are difficult to meet the requirements at high temperature reservoirs. Oil-based drilling fluids (OBDFs) are suitable for deep and ultra-deep wells because of its good temperature resistant. In this paper, the plastic viscosity (PV), apparent viscosity (AV), yield point (YP), dynamic shear ratio, filtration loss (FL) and other properties are measured to investigate the type and concentration of bentonite, emulsifier, filtration reducer, wetting agent, and barite in the OBDF. The final formula of the OBDF is: No. 5 white oil + 4% sodium dodecyl-benzenesulfonate (SDBS) + 5% bentonite + 4% 180°C oxidized asphalt powder + 10% Tween-80 + 1.5% BaSO4. The PV, AV, and YP of No. 5 white OBDF increase by 22.4%, 17.0%, and 12.8% respectively, also the demulsification voltage can keep above 2000 V after aging at 220°C for 24 h. Compared with the drilling fluid used in Shanxi Oilfield, the properties of the No. 5 white OBDF have greatly improved the properties. The No. 5 white OBDF preparation provides new ideas for the development of OBDFs with good temperature resistant and environmental feasibility.