Experimental study of rheological properties of aphron based drilling Fluids and their eff ects on formation damage

Drilling Fluid is one of the most important and expensive aspects of any drilling process. Colloidal Gas Aphron (CGA) has been found e ective in controlling the ltration rate by bridging the pores of the reservoir rock; hence, reducing the formation damage. This work aims to synthesize the CGA in water based drilling Fluids to study the stability, rheology, ltration loss characteristics and formation damage properties of the resulting Fluid. Besides, an investigation on type of polymer, surfactant, and their concentration eff ects on the characteristics of the Fluid, as well as optimum ratios of polymers in drilling Fluid was performed. Experimental results showed that Xanthan Gum (XG) provides more acceptable rheological properties (especially viscosity) in comparison to Guar Gum (GG) for preparing the base Fluid. Moreover, the Sodium Dodecyl Sulfate (SDS) produces more stable micro-bubbles than Hexadecyl Trimethyl Ammonium Bromide (HTAB) as a surfactant. Bubble size measurement to observe the e ffect of polymer, surfactant type and concentration was performed. Through the experiments, the pH of the drilling Fluid was monitored which proved the CGA introduced the best performance around a pH of 9. Furthermore, a XG/GG ratio of 3:1 is suggested to reduce the cost while maintaining the Fluid properties.