Using differential pressure and image processing for cuttings transportation measurements

Abstract

Dynamic aspects of liquid-particle flow were investigated through frequency analysis of pressure gradients and image processing of particle flow patterns. Experiments were conducted in a medium-scale flow loop with a horizontal and an inclined test section. The inclined section contained a drill string, capable of rotating, to simulate annular flow. Experiments were run on single-phase liquid and two-phase liquid-particle flow. The liquid used in the experiments was water and the particles were glass pellets. The pressure gradients for both test sections were recorded at different superficial liquid velocities for both single and two-phase flows. In addition to the pressure gradient, images of the liquid-particle flow were recorded, using high-speed cameras. The pressure gradients were converted from the time domain into the frequency domain, by applying Fast Fourier Transform on the time series of the data. An algorithm was developed to post-process the images and was written as a graphical user interface (GUI) in Matlab. The GUI was able to calculate the dune front velocity, the particle concentration in the static and moving layer as well as the changes in the bed height. The GUI was only applicable to the horizontal section, as the drill string in the inclined section caused problems with the processing. The dune front velocity calculated from a cross-correlation of the images matched up well with the amplitude peaks in the frequency spectrum.