Design and dynamic analysis of directional hydraulic sand jet perforation tool for horizontal wells
A directional hydraulic sand jet perforation tool was designed for horizontal wells based on hydraulic sand jet perfo-ration technique and gravity orientation principle.Dynamic analysis and surface experiments indicate that,when the axis of the spray gun is eccentric to the axis of the wellbore,the tool can be reliably oriented.A mechanical model was established for the directional deflection angle with the influence of spray gun deflection moment,interference fit resistance moment,seal resistance moment caused by liquid column pressure,bearing rotation resistance moment.The results show that the eccentric-ity and the gun weight are the key factors to improve the directional accuracy.Interference fit between seal and rotating shaft is the key factor to hinder orientation.At a certain design condition,the maximum resistance moment is accounted for 68.4%,and the deviation angle between the hole and the reference position is 2°-4° in the surface perforation experiment,which indicate that the directional function of the spray gun is satisfactory.When the position of perforation is changed,the gun can be automatically moved back to its original position whether by drag or rotation.The spray gun can still maintain good stability after pressure spray,and there is no phenomenon of disorderly rotation and oscillation.
hydraulic sand jet perforationdirectional perforationorientation by gravitymechanical model
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