A COMPARATIVE STUDY OF DRILLING FLUIDS POWER DELIVERY OF WATER, AIR AND SC-CO2 IN COILED TUBING DRILLING

Recently, coiled tubing drilling becomes one of the most exciting technological
developments and a preferred technique in oilfield. Coiled tubing drilling has a wide
range of potential applications. However, it requires drilling fluids to supply sufficient
power for the down-hole drilling motor and to circulate cuttings out of wellbore.
Water, which is generally used as the drilling fluid, becomes a major problem when
drilling small deep holes in hard formation. Additionally water is incompressible fluid
and can only deliver hydraulic power. Hence, a comparative study of drilling fluids
power delivery in coiled tubing drilling by using water, air and supercritical carbon
dioxide (SC-CO2) as drilling fluids is proposed. Based on studies, both SC-CO2 and
air are compressible and low viscosity fluid. The water drilling fluid is then taken as
the benchmark. The properties of fluids are considered in order to enable achieving
sufficient energy delivery, prolong the coiled tubing lifetime as well as the associated
drilling components. Thus, in this project, calculation and comparison of water, air
and SC-CO2 will be carried out in terms of energy delivery in relation to inlet and
outlet pressure.