Structure optimization of completion packer slips for offshore thermal recovery wells

In Bohai oilfield, the production casing of high steel grades is commonly used in wells of heavy oil recovery to meet the technical requirements of thermal recovery. However, positioning failure of completion packers after setting often occurs in practice, due to insufficient suspension force. Given this, a novel packer slip was developed via the structural optimization in accordance with the structural features of the split wedge slip of the packer and the design requirement for full contact between the slip tooth face and inside wall surface of the casing. A theoretical model was developed via the force analysis to calculate the penetration depth of the packer slip into casing, and moreover, the calculation model of the shear strength of the presented packer slip was constructed with respect to the penetration depth of slip teeth and slip structure. The slip design was optimized via both the theoretical analysis and finite element method, and the effects of the slip outside diameter, setting force and casing steel grade on the limit suspension load of the slip were investigated. The calculation showed that the slip outside diameter is the major factor affecting the slip suspension capacity, and the eccentric full-contact wedge slip greatly improves the suspension capacity. Laboratory testing demonstrated that the presented packer slip can effectively anchor casing of the TP 125H steel grade, with a setting force of 350 kN, which meets the operation requirements. The presented packer slip is promising for solving field technical difficulties.