Cuttings transport with aerated mud in horizontal annulus under elevated pressure and temperature conditions

Aerated mud experiments were conducted at EPET in ACTF flow loop. A view port was installed to observe flow patterns in the test section. Two gamma-ray nuclear densitometers were used to measure steady state mean mixture density. During test runs, the water and air flow rates were in the range of 50--250 gal/min and 50--150 scf/min, respectively. For all the tests, measurements of pressure drop and mixture density over the entire annular section were carried out. Stratified and slug flow were the two flow patterns observed over the range of the chosen test matrix. The experimental results indicated that the two phase flow patterns and frictional pressure losses were affected by elevated temperature.; Cuttings transport experiments were carried out in a unique full-scale flow loop which included a 73-ft (22.25m) long annular section of 6-inch (152mm) casing and 3.5-inch (89mm) concentric drillpipe at elevated pressures and elevated temperatures (EPET) ranging from 100 to 500 psi, and 80 to 175°F respectively. The in-situ cuttings volumetric concentration was determined by using a special designed multiphase measurement system. The following data was collected: cuttings weight in the annulus (the volumetric cuttings concentration), mixture density and pressure losses. The results clearly show that: in addition to liquid flow rate and gas liquid ratio (GLR), temperature essentially affects the cuttings transport efficiency. The volume of cuttings which accumulated in the annulus was very sensitive to the liquid flow rate. Predominately, elevated temperature was found to cause a significant increase in the cuttings volumetric concentration at a given flow conditions. The injection of gas has both negative and positive effects on the cuttings transportation depending on other flow parameters. The effect of pressure on cuttings concentration and frictional pressure loss is insignificant.; The mechanistic model for aerated mud hydraulics and cuttings transport, that was developed by combining two-phase hydraulic equations, turbulent boundary layer theory and particle transport mechanism, can be useful for predicting the cuttings volumetric concentration in the annulus and critical pressure gradient for preventing cuttings from deposition. The predictions of the mechanistic model are in agreement with measured data.