A Simulating Study for Back Pressure Impacts on Selected Foam Rheological Properties in Vertical Wells

Abstract

In this paper, the emphasis is put on the effect of the surface back pressure on selected foam rheological properties. A hydraulic model for foam drilling in vertical well has been developed using Visual Basic program to thoroughly analyze foam hydrodynamics and to study the effect of the back pressure on these selected rheological properties such annular pressure, foam quality, density, effective viscosity, power and consistency indices and cuttings concentration along the entire annular section. The model intends to simulate and predict foam rheology and characteristic parameters for foam drilling in vertical wells. The model was evaluated and validated by running its program on two foam-drilled wells in the Middle East. The developed model was also compared with two other models: Valco-Economides’ model; and Sporker’s model. The average errors of the developed model accuracy were 2.59% and 10.85% for the first and second wells, respectively. The model accuracy was slightly better than that of Valco-Economides’ one, but less than that of the Sporker’s one.