Ultrasonic Measurement of Multiphase Flow Erosion Patterns in a Standard Elbow

Solid particle erosion is a mechanical process in which material is removed from a surface due to impacts of solid particles transported within a fluid. It is a common problem faced by the petroleum industry, as solid particles are also produced along with oil and gas. The erosion not only causes economic losses resulting from repairs and decreased production but also causes safety and environmental concerns. Therefore, the metal losses occurring in different multiphase flow regimes need to be studied and understood in order to develop protective guidelines for oil and gas production equipment. In the current study, a novel non-invasive ultrasonic (UT) device has been developed and implemented to measure the metal loss at 16 different locations inside an elbow. Initially, experiments were performed with a single-phase carrier fluid (gas-sand) moving in the pipeline, and the erosion magnitudes are compared with Computational Fluid Dynamics (CFD) results and found to be in good agreement. Next, experiments were extended to the multiphase slug flow regime. Influence of particle diameter and liquid viscosity were also studied. Two different particle sizes (150 and 300 micron sand) were used for performing tests. The shapes of the sand are also different with the 300 micron sand being sharper than the 150 micron sand. Three different liquid viscosities were used for the present study (1 cP, 10 cP and 40 cP). Carboxymethyl Cellulose (CMC) was used to increase the viscosity of the liquid without significantly altering the density of the liquid. While performing the UT experiments, simultaneous metal loss measurements were also made using an intrusive Electrical Resistance (ER) probe in a section of straight pipe. The probe in the straight pipe is an angle-head probe which protrudes into the flow with the face placed in the center of the pipe. The UT erosion measurements in a bend are also compared with experimental data obtained placing an intrusive flat head ER probe flush in a bend, and the results were found to be in good agreement. Finally, the non-invasive NanoUT permanent placement temperature compensated ultrasonic wall thickness device developed for this work has the capability of measuring metal loss at many locations and also identifying the maximum erosive location on the pipe bend.