Next Generation Fluidic Oscillator

Abstract

Abstract This paper describes the development of a downhole cleaning device based on fluidic oscillation. This fluidic oscillator is used for removal of deposits from the near-wellbore area, perforations, and screens. The cleaning device creates pressure waves within the wellbore and formation fluids that (1) break up near-wellbore damage and (2) restore and enhance the permeability of the perforations and near-wellbore area. Fluidic oscillators have been used for various purposes in a wide range of industries for many years. They typically exhibit reliable oscillation over a wide range of flow rates and have no moving parts. The cleaning tools presented here are specifically designed for high-pressure, submerged operation and maximum pressure-pulse amplitude. The unique design has been carefully refined through theoretical and experimental methods. This paper discusses fluidic oscillator theory and presents a numerical analysis of a specific oscillator design, as well as an analysis of experimental test data at various flow rates. The provided case histories demonstrate the utility of fluidic oscillation as a wellbore-cleaning device. Introduction The industry has taken a quantum leap with the release and commercial application of the next generation of fluidic oscillator near-wellbore stimulation service. Over 50 successful field jobs have been performed with this new technology. In many cases, production increased over previous treatments that used an older type of fluidic oscillator. Several unique case histories resulting in production increase and job time reduction are discussed later in this paper. The new design is unique in its adaptation of the classical feedback loop oscillator design. One innovative design feature is the ability to tune the output frequency of this tool by scaling the oscillator pattern for optimum cleaning and stimulation efficiency as our knowledge and database of production results grows. Unlike other "use-as-is" fluidic oscillators this next generation fluidic oscillator design is "living" technology that can grow and adapt to field feedback. The fluidic oscillator is a downhole, cleaning device based on patented and patent-pending fluidic oscillator technology that generates alternating bursts of fluid. This tool is used for the removal of deposits from the near-wellbore area, perforations, and screens. The cleaning device creates pressure waves within the wellbore and formation fluids that can (1) break up near-wellbore damage and (2) restore and enhance the permeability of the perforations and near-wellbore area. This tool incorporates the proven, classical feedback loop theory for generation of the Coanda effect. Fluidic oscillators are available in sizes from 1.69 to 2.88-in. OD and are adaptable to both jointed pipe and coiled tubing applications. The tools operate at an optimal pressure drop of approximately 2,000 psi and oscillate at a frequency between 300 to 600 Hz. The tools are rated to 400°F and are suitable for sour gas service. Fluidic oscillators incorporate several design features that help improve reliability, function, and performance while reducing tool life-cycle costs. These features include:A patented, metal-to-metal, tapered seal---no moving parts or seals.Side jets that maximize cleaning energy by direct impingement on the casing or near wellbore.Multi-angular fluid impingement.Higher energy output over a narrower frequency range than conventional oscillators.Turbulence created by side and down jets that helps lift debris out of the hole.A down jet that clears debris, obstructions, or bridges while tripping into hole.Adaptability for running on either coiled tubing or jointed pipe.Customized inserts to maximize flow rate and pressures.Replaceable inserts manufactured using modern high-tech electrical discharge machining (EDM) process.