Modeling of micro-bubble surfactant multi-layer drilling fluid stability based on single bubble behavior under pressure and temperature in a deviated gas well

Micro-bubble surfactant multi-layer (MBSML) drilling fluids are included in the drilling operation of low pressure reservoirs. These fluids contain tiny dispersed micro-bubbles coated with two surfactant layers. For the stability evaluation of these fluids in operational conditions, surfactant type, concentration, pressure and temperature effects on the size of micro-bubble fluid, should be scrutinized. For investigating these variables, a diffusion model for solute transport in micro-bubble fluids was proposed with the mass transfer concept. The model included mass transfer resistance of fluid phases and interfaces. It was observed that the bubble sizes decrease as a result of adding surfactant to the fluid. However, there were pressure, temperature and surfactant concentration thresholds for the bubble stability.