Research On Regularity Of Sand Particle Migration In Horizontal And Sand Cleaning Tools

In the process of oil and gas extraction,horizontal well extraction technology is widely used in current oil and gas well development due to its efficient recovery factor.Especially in loose sandstone oil and gas reservoirs,sand production problems often occur in oil wells,and the flow of sand particles in the horizontal wellbore is perpendicular to the direction of fluid flow due to gravity,which is easy to cause sand particles to form sand beds in the wellbore.If the sand bed deposited in the wellbore is not cleaned in time,it is easy to cause blockage of the borehole and accelerate the wear of downhole equipment,affecting the normal production of the oil well.In serious cases,it will cause safety accidents and cause the borehole to be scrapped.Therefore,in addition to taking sand control measures on the wellbore before oil well production,it is also necessary to clean up the wellbore sedimentation in time during the production process.Aiming at this problem,this article mainly carries out the following aspects of research.Firstly,this thesis analyzes the sand migration mechanism in the annulus of the horizontal well segment,establishes a sand stress model,and uses CFD simulation to analyze the annulus gap,pipe eccentricity,sand-carrying fluid flow rate,viscosity,and sand particle size to the horizontal well.The influence of annulus flow field flow law.It is found that the smaller the annulus gap,the greater the influence of the sand particles in the annulus flow channel area,and the easier it is to form a sand bed;the eccentricity of the pipe string causes the unevenness of the sand particles flowing in the annulus watershed,and the sand particles are easy to deposit to form a sand bed;The inlet flow rate of the sand-carrying fluid is positively related to the axial velocity of the sand particles,which can slow down the formation of the sand bed;the high viscosity of the sand-carrying fluid increases the fluid flow resistance,which may cause some sand particles to undergo secondary deposition due to insufficient power,and it is easy to form the sand bed.Then,based on the two-phase flow analysis model of the sand-carrying fluid and sand particles in the annulus flow field,the influence of the parameters of the sand-carrying fluid flow rate,viscosity and sand particle size on the sand sedimentation law in the annulus flow field was studied.The analysis results show that: increasing fluid flow is conducive to the suspension of sand particles and reducing the thickness of the sand bed;the increase in the viscosity of the sand-carrying fluid is not conducive to the suspension of the sand particles.The thickness of the sand bed is also the largest;theincrease in the particle size of the sand particles makes it easier for the sand particles to settle down to form a sand bed during the flow in the annulus flow field.Finally,based on the sand particle transport mechanism,a new type of sand cleaning tool was designed.The sand cleaning tool was equipped with a forward cleaning nozzle,a backward nozzle and a reversing mechanism.The sand cleaning tool realizes the forward flushing of the cemented bottom sand and the reverse flushing suspended secondary sedimentation sand bed through the reversing mechanism.Based on the influence of the eccentricity of the pipe string,the flow rate of the sand-carrying fluid,the viscosity and the particle size of the sand particles on the flow law of the annulus flow field of the horizontal well and the settlement law of the sand particles in the annulus flow field,the structural parameters of the nozzle are mainly optimized When the diameter of the nozzle and the angle of inclination of the nozzle are 4mm and55 ° respectively,the positive cleaning effect is best under this condition;when the diameter of the nozzle and the angle of inclination of the nozzle are 4mm and 45 °respectively,under this working condition Reverse flushing,the sand particles get the maximum return speed,the best cleaning effect.In this thesis,combined with on-site data and simulation analysis,the optimal design parameters of sand cleaning tools provide theory and design basis for sand cleaning tool design and field operations.