Sand Fines Erosion and Asset Integrity Management of Deepwater Gas Facilities: Effect of Liquid Loading

AbstractIn spite of the sand control/management techniques implemented down-hole, fine sand (< 50-75 microns) often may find its way into the piping components of onshore, offshore, and subsea facilities causing erosion/wear and subsequent pipeline integrity issues. Existing erosion models (both CFD-based and correlations) widely used in the industry have been reasonably benchmarked with erosion due to sand particles that are greater than 100-150 microns and the predictions are within ±100% of observations even in single-phase carrier (liquid or gas) flows. Although there is only a limited set of the fines erosion data (both lab and field), there is a considerable mismatch between the data and what the models predict even when the fines (< 50 microns) are carried in single-phase (let alone multiphase) fluid flow. Also, current industry practice is to assume that the low liquid content of gas stream reduces fines erosion by forming a protective film on the pipe wall although there is no clear understanding on what fraction of the liquid content (a) gets atomized into droplets (that may or may not wet the fine particles) in the gas stream and (b) wets the pipe wall. Even the development and validation efforts of the correlations for fine particle-pipe wall interaction leading to a single erosion event (let alone CFD-based erosion simulation) are still at their infancy. Several renowned erosion research groups around the world have been working on addressing the afore-said gaps. New fines erosion experiments were conducted in a 4" flow facility that consists of several piping components (orifice plates, elbows, and tees) that were connected in series and pipe wall thickness loss due to erosion was measured using a standard ultrasonic method. This paper elucidates the effect of (a) interaction of piping components connected in series (in-plane and out-of-plane) and (b) effect of low liquid loading in gas on fines erosion, scaleup to field conditions, and provides some directions for future efforts needed on this topic that are critical to the safe and efficient operation of oil-gas producing/processing facilities.