The drilling solids content is an important consideration inCoiled Tubing Drilling (CTD) operations. This paper presentsan experimental investigation of the effects of drilling solidson frictional pressure losses in Coiled Tubing (CT) using asophisticated full-scale coiled tubing test facility for anindustry – university joint research project. The facilityconsists of seven reels of coiled tubing with diameters of 1”,1-1/2”, and 2-3/8”, fluid mixing and pumping equipment, anddata acquisition system. Fluids investigated include solid-freepolymer solutions at various concentrations, and real drillingfluids currently used in the drilling industry. The rheologicalproperties of test fluids were evaluated using Fann and Bohlinviscometers. Standard industry drilling solids (Rev Dust) wereadded to the drilling fluids to simulate the effect of drillingsolids on frictional pressure losses. Flow tests results indicatethat as solids concentration increases, the frictional pressurelosses increase significantly. The effect of lubricants onfriction reduction in coiled tubing was also investigated. It wasobserved that the lubricants investigated could effectivelyreduce the friction pressure loss in coiled tubing. The analysisof experimental data has been focused on the effect of solidsconcentration, lubricant concentration, coiled tubing geometryas well as drilling fluid rheology.
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