The Establishment Of Three-dimensional Finite Element Model And Stress Analysis Of Perforated Cement Ring

In the process of perforating completion of oil and gas wells,the jet generated by the shaped charge have perforated through the casing wall,cement ring and some strata of oil and gas wells.As a result,some perforating holes along the perforation spiral line will appear on the cement ring,which leads to the decrease of the structural stability of the cement ring.In the subsequent production process,the excessive load may cause the cement ring with perforated holes to be more prone to crushing or tensile fracture and other structural damage forms,thus endangering the structural integrity of the casing-cement-ring-formation complex.For this reason,this paper takes the cement-ring consolidation body with perforating holes as the research object,analyzes the physical interaction relationship of cement-ring consolidation in the perforating section under the action of load,and establishes the three-dimensional finite element model of casing,cement-ring and formation in the perforating section.The failure criterion of cement ring in perforating section is established by reasonably selecting the stress-strain curve of cement ring and taking the compressive strength,tensile strength,shear strength and yield strength of cement ring as evaluation indexes.Analyzed the different perforation parameters on the stress distribution law of cement loop hole,and the cement ring mechanics parameter,formation mechanics and concretion body geometry parameters on perforation cement ring the effects of stress,so as to evaluate the structural integrity of the cement gun perforation position loop ring mechanics parameter optimization problem,for reasonable security perforation cement ring structure integrity measures provides a method and means.The results show that after perforating the cement ring,there is an obvious stress concentration around the hole,and the maximum equivalent stress appears on the hole.The perforation density and the perforation phase angle have great influence on the circumferential stress of the cement ring,but the depth and diameter of the perforation have little influence on it.The elastic modulus of cement ring has a great influence on the stress of cement ring in perforating section.As the elastic modulus of cement ring increases,the Mises stress,tensile stress and shear stress are all gradually increase.On the premise of ensuring the structural stability of oil and gas wells,in order to further improve the oil and gas well production capacity,should choose 16 holes/m,90° phase angle of perforation,and elastic modulus of cement should not be too much.