Experimental studies on stability and viscoplastic modeling of colloidal gas aphron (CGA) based drilling fluids

• Effects of time and fluid's composition on size and stability of CGAs were studied.
• Eight flow models were used to make a description of rheological behavior of CGAs.
• A new viscosity model suitable for describing the CGAs flow behavior was developed.

This paper presents results of bubble size distribution, stabilization, and statistical evaluation of rheological behavior of drilling fluids containing CGAs. The stability analysis of CGAs is investigated using drainage rate measurement, monitoring bubble growth rate and shear stress/shear rate measurement over time. Eight rheological models are also employed to make a quantitative description of the shear flow behavior of CGA based drilling fluids. The applicability of each model is examined in detail. Finally, a new model to combine the effects of temperature and shear rate on the viscosity of CGA based drilling fluids is put forward. The results of this study can be helpful in selecting the appropriate procedure for utilizing the CGA based drilling fluids in oilfield drilling operation.