Development and Working Mechanism of Flow Pattern Enhancer for Synthetic Base Drilling Fluids

A flow pattern enhancer has been developed to deal with the rheology problem of synthetic base drilling fluids at low temperatures. In laboratory experiment, the effects of the flow pattern enhancer on the rheology of water-in-oil emulsion were measured, the IR and XRD characteristics of the flow pattern enhancer and organophilic clays were compared and analyzed. Using Cryo-SEM and TEM, the effects of the flow pattern enhancer on the micro-structure of the emulsion were observed and the working mechanisms of the flow pattern enhancer analyzed. The laboratory experimental results were then used to evaluate the applicability of the flow pattern enhancer in high density synthetic base drilling fluids. It was found that the flow pattern enhancer was able to remarkably improve the low-temperature rheology of synthetic base drilling fluids and was beneficial to the stability of emulsion. The molecules of the flow pattern enhancer are adsorbed on the interface of oil and water in the emulsion, thereby reducing the structural force between the drops of the emulsion and the particles of the organophilic clay, and improving the interaction between the clay particles and emulsion drops. All these are helpful to the stability of the gel strength of the water-in-oil emulsion. Compared with conventional synthetic base drilling fluids, the constant-rheology synthetic base drilling fluids have more stable low-temperature rheology which is critical to the safety of downhole operation.