Influence of Pitting Casing Damage on the Sealing Performance of Packers
In downhole plugging operations,the pitting casing damage may affect the sealing performance of the packer,thus threatening the field operations and even leading to serious accidents.However,the impact of pit-ting casing damage on the sealing performance of packer is unclear.In this paper,the damage characteristics of the casing were analyzed.Different pitting casing damage models were built based on the finite element method to iden-tify the influences of the width and depth of the pitting damage on the casing surface and the position of the pitting damage relative to the rubber packer on the sealing performance of the packer.The results show that the pitting damage on the casing surface can alter the magnitude and distribution of contact pressure of the sealing face,and reduce the sealing performance of the packer to varying degrees.Compared with the undamaged casing,the casing with pitting damage exhibits an"M"shaped contact pressure curve of the rubber packer,with an increase in con-tact pressure on both sides of the pit and a decrease in other areas.When the width of the pit is 4 mm,as the depth increases,the sealing coefficient of the packer hardly changes,and the sealing performance decreases by about 14%.When the width of the pit is greater than 4 mm,as the depth increases,the sealing coefficient of the packer significantly decreases,the sealing performance largely drops(18%-52%),and the risk of failure intensifies.The relative position between the pit and the rubber packer has an obvious influence on the sealing performance of the packer.The pit located in the middle of the rubber packer destroys the integrity of the sealing contact pressure curve,which further reduces the sealing performance of the packer.The study results provide reference for the seal-ing operation of packers and have practical engineering significance.
万方数据
维普
