Design of a Cyclonic-Jetting and Slurry-Transport System for Separators

Abstract

Summary Sand and solids are removed from production separators either off line (shut down for physical removal) or on line by use of jetting systems. Traditional jetting designs use spray nozzles to fluidize and push the sand toward a covered outlet to evacuate the solids from the vessel. Cyclonic-jetting technology combines the fluidization and evacuation functions into a single, compact device. On the basis of a hydrocyclonic platform, this technology converts jetting spray water into shielded vortex flow that fluidizes sand in a circular zone without disturbing the oil/water interface. Total solids removal is primarily a function of set height, spray flow, and spacing. A single unit was optimized at a set height of 10 cm (4 in.) with spray pressure of 0.7 barg (11 psig) to provide an area of influence of 1.1 m² (12.0 ft²) with 28 cm (11 in.) of sandbed depth. Placing two units in parallel with overlap of their affected zones reduces the “egg-carton” effect associated with this technology; however, optimum operation, in terms of total sand removed, occurs when the units do not overlap. Slurry at up to 60 wt% solids is transported from the jetting system to the handling equipment. The boundary design conditions for slurry transport are erosion velocity (upper limit) and particle-transport velocity (lower limit). By use of published models, the piping design for a fourunit cluster of cyclonic-jetting devices was validated at 5.0-cm (2in.) nominal size. Integration and operation of a jetting system with transport, dewatering, and disposal stages of facilities sand management are presented as guidelines for system design.