Sand Detection Using Acoustic Sand Monitors for Liquid-Dominated Multiphase Flow Production

Abstract

Abstract Solid particle erosion in the oil and natural gas industry can be damaging to pipes fittings and equipment, which can lead to maintenance or in the worst case a production shutdown. In both cases, this represents a huge economic loss for the industry. Acoustic sand monitoring is one of the most widely used practices to estimate the amount of sand in the flow. In addition to being commercially available, they can be easily clamped to the outside of a pipe wall, measuring the acoustic energy generated by sand grain impacts on the inner side of a pipe wall. In this work, a broad range of multiphase operating conditions has been experimentally investigated with acoustic sand monitors in large-scale flow loop facilities to determine the effectiveness of sand monitoring in liquid-dominated multiphase flow. The main objective is to use acoustic sand monitors to determine the Threshold Sand Rate (TSR). This is the minimum sand rate necessary to achieve monitor output higher than the background noise level. Acoustic monitors were placed upstream and downstream of standard (r/D = 1.5) elbows while varying superficial gas and liquid velocities, sand size (25, 75, 150, 300 and 600 micron), pipe diameter (2-inch and 3-inch) in vertical orientation. The experimental conditions were selected to cover slug-churn, dispersed-bubble flow and liquid-sand flow conditions. These results are compared to the previously obtained test results on 50.8 mm (2-inch) ID test loops. The TSR results for liquid-dominated multiphase flow regimes are determined experimentally. The effects of sand size and flow regimes on TSR had been obtained. In 50.8 mm (2-inch) threshold limits were observed for dispersed-bubble flows regimes and liquid-sandas compared to gas-dominated flow conditions. While TSR is highest in dispersed-bubble flows regimes. The present data was compared to previous results obtained for annular, slug and stratified flow patterns in vertical flow. It was observed that the annular flow regime has the lowest TSR values showing an increase in TSR when the liquid rate increased. The results from this work can help operators understand how acoustic monitors can detect and distinguish sand impact noise from the background flow noise in liquid-dominated multiphase flow in production facilities. In this way, greater assurance is provided to operators for optimizing oil and gas production rates, especially in wells that tend to produce solids.