Research On The Anti-erosion Performance Of A New Type Of Hydraulic Impactor

With the number of deep well,ultra-deep well and highly-deviated well increases,chances are raised in drilling with hard and complex layer.Rotary percussion drilling with hydraulic impactor as core assembly has been developed in oil and gas industry,whose operating principle combines single shock of rock breaking and rotary of continuous rock breaking to improve flow field situation in downhole,deliver weight on bit(WOB)effectively and enhance the productivity of rock breaking.Whereas some drawbacks are discovered currently such as short lifetime,small impact energy and water-only medium.Short lifetime result from serious mud erosion of hydraulic impactor failed to be industrialized in mud drilling process.Therefore massive study gap needs to be done in mud erosion field of hydraulic impactor.Aiming at the engineering problem mentioned above,theoretical derivation and numerical simulation are combined to analyze the whole and the part of neo-type hydraulic impactor,the following researches are completed:(1)Transient analysis technology with dynamic mesh is introduced to simulate normal working process of hydraulic impactor.Dynamic analysis of impactor is obtained to find the particular moment which has a drastic change of parameter velocity,pressure and turbulent kinetic energy.Based on liquid-solid two-phase flow dynamics,erosion theory and standard k-? turbulent model,hydraulic impactor erosion model is established to predict the distribution of erosion area at that moment.Lagrange Tracing are applied to calculate the movement trajectory of solid particles.Serious erosion areas inside hydraulic impactor are appeared on the bottom area,corner and inlet of flow channel hole in piston upper chamber,inlet of spiracle and upper wall in up-sleeve.(2)Single-factor and multi-factor analysis are used to explore the influence between erosion and velocity,angle,diameter,shape of particle and viscosity of drilling fluid.After mathematical statistical analyzing,regular patterns of influential factors to piston and up-sleeve are summarized.Influential significance rankings among factors are presented considering with interaction effect.(3)Fluid structure interaction(FSI)model is built to investigate the distribution and law of von misses stress,maximum principle stress,maximum shear stress,deformation on the basis of erosion simulation results.According to numerical simulation result,Stress is concentrated on the inner wall in piston upper chamber,outer wall in upside part of piston,outer wall in piston bottom chamber,wall in upside part of up-sleeve.Maximum deformation areas are presented on middle part in piston and bottom side in downside part of up-sleeve.Serious erosion areas can be protected in industrial application of hydraulic impactor.Erosion phenomenon can be mitigated to adjust influential factors properly in practice based on erosion law.Stress concentration area and deformation situation can be acquired shortly after FSI simulation analysis to provide valuable reference of anti-erosion designing of hydraulic impactor.