Stress Redistribution Analysis in Multiple Eccentric Packers During Completion Operations

Abstract

Abstract Advancement in multiple zone completion has been quite rapid in recent years but it poses numerous operational challenges that adversely affect the efficiency of the completion process. In addition to increasing the number of activities involved in horizontal drilling, a lot of packers are used during completion which results in various problems during pulling out and running in. These problems include increased torque and drag and buckling. The increasing complexities of wellbore geometry imply an increasing potential for damage when running packers for completion operations. In addition, hole diameters vary frequently during the drilling process. When the diameter of the casing changes, even though the production tubing size remains the same, the packer usually becomes eccentric. Current methods are not modeled properly and severely underestimate stress values and pick-up loads when completion strings are run in. Normally, a packer is designed for central symmetry. When a packer is in an eccentric position, the stress in the packer gets redistributed to suit the eccentric condition. In addition, the pressure limitation is also changed. This study describes a new analytical model for estimating the stress distribution in eccentric packers by assuming that the packer material is elastic. This study concludes that when the packer is run into an eccentric wellbore, the stress distribution in the packer changes and the pressure limitation of the packer decreases. A methodology and a mathematical model have been developed to calculate the stress and the pressure limitation of a packer with an eccentric profile.