High-speed Fluid Erosion of Downhole Stratification Control Tool for Combined Production of Three-phase Gas
During the extraction process of three-phase natural gas hydrates,downhole layer control tools are prone to erosion from solid particles like sludge and rock fragments carried by high-speed and high-pressure gas. To enhance the lifespan of these tools and reduce erosion,it is crucial to analyze susceptible areas for erosion and improve their structural design. The computational fluid dynamics was employed to establish a three-dimensional erosion model of downhole layer control tools and a discrete phase model was adopted to depict the trajectories of solid particles. Numerical simulations were conducted to investigate the primary erosion-wear zones in these tools,including the bottom section of the casing,orifice holes and their inner walls,the transition section between the casing segment and the fixed oil nozzle,the inlet of the fixed oil nozzle,and its internal wall. Moreover,the effects of various structural parameters (such as inlet structure of the fixed oil nozzle,different bottom radii of the casing,and valve core opening) and production parameters (particle size,mass flow rate of solid particles) on the erosion rate of downhole layer control tools were studied. The study findings indicated that as the inlet angle of the fixed oil nozzle increased,the maximum erosion rate on the internal wall surface remained relatively stable,while the maximum erosion rate at the transition section and the inlet end of the nozzle firstly increased,then decreased,and subsequently increased again. Analysis suggested that an inlet angle of 35° yielded optimal results. With an increase in the bottom radius of the casing,the maximum erosion rate at the bottom section of the casing remained relatively low,but the erosion rate at the orifice holes and their inner walls gradually increased,resulting in a higher erosion rate at the bottom section of the casing. Analysis suggested that a casing bottom radius between 25 mm and 30 mm provided increased erosion resistance for downhole layer control tools. As the valve core opening increased,the maximum erosion rate at the orifice holes and their inner walls remained relatively low and exhibited no significant variation. However,the maximum erosion rate at the transition section and the inlet end of the nozzle reached its peak when the valve core opening reaches 60％. Analysis suggested that erosion wear levels were lower when the valve core opening was below 50％ or above 70％. Additionally,an increase in particle size and mass flow rate led to an upward trend in the maximum erosion rate at the orifice holes and inner wall surfaces,the transition section,and the inlet of the fixed oil nozzle. However,the maximum erosion rate at the casing bottom and the internal wall surface of the fixed oil nozzle remained relatively low with no significant change. Hence,it is suggested that gas wells with higher sand content require sand control devices to mitigate erosion during the production process. The predicted primary erosion zones are validated through erosion tests on the nozzle and casing valve core,affirming the accuracy of the numerical analysis. For similar downhole tool designs,selecting an inlet angle of 25° to 30° for the fixed oil nozzle,a casing bottom radius between 25 mm and 30 mm,and a valve core opening below 50％ or above 70％ can effectively reduce erosion and enhance tool service life. Additionally,in the context of three-phase gas extraction layer control processes,process designers can optimize the process by considering factors like particle size and particle mass flow rate and their effect on the maximum erosion rate,thereby offering guidance for optimizing structural parameters and predicting erosion wear for similar downhole tools.
combined production of three-phase gasdownhole layering control toolerosion failure mechanismnumerical analysiscomputational fluid dynamicsnatural gas hydrates
万方数据
维普
