Analysis Of Residual Strength Of Inclined Angle Perforated Casing

In order to improve the perforation depth and facilitate fracturing and fracture making,the casing needs to be perforated along the direction of parallel formation.Because of formation inclination and borehole deviation,it needs to be perforated at an inclined angle.However,at present,there is little research on the perforated casing at an inclined angle at home and abroad.In this paper,mechanical,finite element and experimental methods are used to analyze the residual strength of the inclined angle perforated casing.Focusing on the analysis of the remaining strength of the perforated casing at an oblique angle,the domestic and foreign literature research and review work on perforated casing strength,orifice plate theory,etc.were conducted.Based on the perforated plate theory and the mechanical formula of the residual anti-extrusion strength of the vertical perforated casing,the mechanical equation of the residual antiextrusion strength of the oblique angle perforated casing is derived.Taking Ф139.7mm× 7.72 mm P110 casing and Ф139.7mm × 9.17 mm N80 casing as examples,the perforation is considered.Variations of perforation parameters such as inclination angle,phase angle,aperture,and hole density were analyzed by multiple sets of examples.The ANSYS finite element software was used to analyze the three-dimensional modeling of the inclined angle perforated casing.The numerical solution and the analytical value obtained from the mechanical formula were compared and analyzed.According to the inclined angle perforated casing test specimens used in an oil field project,mechanical analysis,finite element analysis,and diameter crushing test analysis are performed.The results obtained by the three methods are compared and analyzed to verify the remaining resistance of the inclined angle perforated casing to external extrusion.Correctness of strength mechanics formula.The results show that the remaining anti-extrusion strength of the perforating sleeve decreases with the increase of the perforation inclination angle.Compared with the vertical perforating sleeve,the reduction range is within 15%;changing the perforation parameters such as phase angle,aperture,and hole density,the residual strength reduction of the oblique angle perforating sleeve is 5%,17.62% and 10.48%,respectively.The error between the analytical value calculated by the mechanical formula and the numerical solution calculated by the finite element method is not more than 10%;the analytical value obtained by using the mechanical formula of the residual anti-extrusion strength of the perforated casing at an oblique angle is limited by using the three-dimensional modeling Comparing and analyzing the numerical solution obtained from the meta-simulation calculation and the experimental value obtained from the experiment,the maximum error of the three sets of data is not more than 6%.