CFD simulation of downhole thruster performance evaluation

Mohamed, Bashir (2018) CFD simulation of downhole thruster performance evaluation. Masters thesis, Memorial University of Newfoundland.

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Abstract

The present study investigates the rule that the downhole Thruster could contribute towards enhancing drilling performance of oil and gas wells. The core study was numerical simulation implemented ANSYS Software using different fluids of various viscosities. As a main part of the numerical study, an evaluation of the variation of fluid velocities and their resultant pressures at several planes within the Thruster geometry was included. The evaluation methodology included a comparative study of “With-Thruster” versus “Without-Thruster”, which represent two drilling modes involving drilling with axially induced oscillations and drilling without axially induced oscillations; respectively. This was performed to simulate different drilling modes of unconventional (i.e. with controlled and desirable axial oscillations) and conventional (i.e. rigid drilling system); respectively. By implementing the downhole Thruster, the conventional drilling can be shifted to the unconventional drilling mode that produces controlled axial vibrations empowered hydraulically through generating pressure pulses. At first, the drilling performance was simulated by implementing Maurer model, which showed significant increase in the rate of penetration (ROP) when using the Thruster for all fluid velocities. The improvement in ROP was noticed to increase from quarter unit to a one unit induced by a generated force of at as low as 6000 (N) to as high as 10000 (N); respectively. The clear increase in ROP in the simulation work was then carried out for further simulation of the Thruster for comprehensive evaluation under various conditions, including applying back pressures as well as using various fluid viscosities, which also showed improvement in ROP with Thruster implementation.

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