The Internal Flow Analysis Of Coiled Tubing Drilling

Coiled tubing (Coiled Tubing, referred to as CT) is also called flexible tubing, coiled pipe, from60s used in petroleum industry, coiled tubing drilling (Coiled Tubing Drilling, referred to as CTD) technology is a new development technology and research after90s. Coiled tubing drilling is mainly applicable to deepen old well, drill new wells, directional well, old well sidetracking horizontal well and underbalanced drilling. Fluid flow in the coiled tubing, accompany by a large frictional loss. Especially the flow of fluid through the coiled tubing spiral pipe, by the changing of centrifugal force, produce Secondary around flow, the resistance to the fluid is great. Therefore, clear flow characteristics in tube of the coiled tubing drilling process, for the design of continuous tubing pump power, calculation of bottom hole pressure, maximum wellhead pressure is very important. Combined with the national major science and technology projects (project36task6)2011ZX05036-006" The coiled tubing equipment and The application of technology " research task" continuous pipe sidetrack drilling and old well deepened technology research" Study the flow in the coiled tubing has the necessary significance.In this paper, on the basis of the former study, through the numerical analysis and Simulation ways analysis the coiled tubing internal flow. In the numerical analysis way, by using the boundary layer theory established the theoretical equation of friction coefficient calculation formula. Numerical simulation by FLUENT software separately for different velocity, diameter, geometry, fluid, flow and exit pressure were analyzed. Get relationship of the fluid friction coefficient and flow velocity, diameter, shape, outlet pressure. But for the fluid and flow combination analysis, the main focus in turbulent flow conditions, The Newtonian and non Newtonian fluid analysis. For a Newtonian fluid turbulent flow calculation formula of friction coefficient and the established mathematical model are coincides. Non Newtonian fluid respectively using the power law model and Bingham flow model is analyzed, with the foreign experimental study that the empirical formula for contrast detection, coiled tubing drilling frictional pressure drop and the numerical simulation results of Bingham flow model are consistent. As for established empirical formula for different Reynolds number stage adaptability are analyzed, and gives a certain range. The low Reynolds number interval of the Reynolds number and the critical Reynolds number ratio in the range of1-2.5(containing laminar flow and turbulent flow containing) have not an applicable calculation formula, based on the fitting correction for the experience formula of the friction coefficient, give a suitable for this kind of case calculation formula. For the experimental verification in this paper also do some jobs, get the experimental plan.