Browsing by Author "Mugisa, John"

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    Effect of Wettability on Oil Recovery and breakthrough Time for Immiscible Gas Flooding
    (Petroleum Science and Technology, 2016) Sagala, Farad; Mugisa, John; Alahdal, Hussein A.; Kisiki, Nsamba Hussein; Kabenge, Isa
    The effect of wettability on oil recovery at higher water saturation is still not fully understood, especially in the case of mixed wettability. This study was conducted to examine the effects of wettability on oil recovery and breakthrough time through experiments for two wettability conditions (water-wet and mixed-wet) and three water saturations (20%, 40%, and 60%). Clashach sandstone core with a porosity of 12.8% and a permeability of 75 md was utilized as the porous media. Immiscible gas flooding was performed by injecting nitrogen gas into the core at room temperature and pressure. The results showed 54.3% and 48.8% of the initial oil in place (IOIP) as the ultimate oil recovery at 40% water saturation from mixed-wet core and water-wet core respectively. In contrast, the water-wet core displayed better results (32.6% of the IOIP) in terms of breakthrough time compared to the results of water-wet core (10.6% of the IOIP) at the same water saturation. In conclusion, oil recovery was found highly dependent on water saturation while breakthrough time was mainly affected by the wettability of the cores.
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    Experimental Investigation of Cuttings Lifting Efficiency Using Low and High Density Polyethylene Beads in Different Hole Angles
    (J Mater Sci Appl, 2017) Tan, Tin Yi; Katende, Allan; Sagala, Farad; Mugisa, John
    This study investigates the impact of low and high density polyethylene beads on wellbore cleaning using water-based mud at different hole angles of 0°, 60°, and 90°. The polyethylene beads concertation is varied from 1 to 5% by volume. Experimental investigations were accomplished using 11ft long acrylic concentric annulus flow test section with a 1.80in casing inner diameter equipped with a fixed inner pipe of 0.85in as the outer diameter. A total of 66 runs were completed using sand of size ranging from 1.18 – 2.00mm and density of 2.65 g/cc. Mud density and viscosity were maintained at 10 ppg and 7cp respectively, in a flow velocity of 0.80m/s. The densities of low and high density polyethylene beads were 0.92 g/cc and 0.96 g/cc respectively while their size was 3mm in spherical shape. The introduction of polyethylene beads were found to be more efficient in the vertical hole in which the incremental cuttings transport ratio was more than 15% being registered. This was due to sufficient buoyancy force provided by the low density polyethylene beads to counteract the gravity force and reduce the slip velocity of cuttings due to their low densities. In addition, the impulsive force due to collision between beads and sand enabled the cuttings to be lifted more efficiently.