| The use of drilling foams is increasing because foams exhibit properties that are desirable in many drilling operations. A good knowledge of foam hydraulics and cuttings transport mechanism is essential for safe and economical foam drilling. This work focuses on the study of foam rheology and cuttings transport with foam in a horizontal annulus under simulated downhole conditions.; Foam rheology was determined with both Foam Generator and Viscometer (FGV), and Advanced Cuttings Transport Facility (ACTF). Cuttings transport with foam experiments were conducted using the ACTF.; Foams with three different concentrations (0, 0.25%, and 0.5%) of hydroxylethyl cellulose (HEC) and 1% commercial surfactant (KLEAN-FOAM) were investigated, and three foam qualities (70%, 80% and 90%) were tested. A set of rheological parameters were obtained for foams with different qualities and polymer concentrations. Significant rheological variations were observed between aqueous foams containing no polymers and polymer-thickened foams.; Cuttings transport with foam experiments were conducted to determine the effects of polymer additives, foam quality, flow velocity, temperature and pressure on cuttings transport. Experiments were carried out at elevated pressure (100 psi to 400 psi) and temperature (80°F to 170°F) conditions in a 73-ft long horizontal test section (5.76" x 3.5" concentric annulus).; Two flow patterns, stationary cuttings bed and fully suspended flow, were observed during the cuttings transport tests. The results show that foam flow velocity, foam quality and polymer concentration all have pronounced effects on cuttings transport and frictional pressure loss. Pressure and temperature do affect cuttings transport efficiency, but the effects are fairly limited.; In the mathematical modeling part, a model for calculating foam flow hydraulics in wellbore has been developed. This model incorporates frictional, gravitational and acceleration pressure losses in a wellbore, and it can be used to calculate hydraulics along a three-segment wellbore (vertical-inclined-horizontal).; A mechanistic model for cuttings transport, which combines foam flow hydraulic equations and particle transport mechanism, was developed. It can be used to predict cuttings volumetric concentration in the annulus. The predictions are compared with experimental results, and the model predictions are in agreement with measured data. |
