Mechanical Analysis And Safe Evaluation For Testing Packer In Hostile Well

In the process of ultra deep high pressure gas well testing and reservoir reconstruction,width of pressure range was very large, well startup and shut in frequently, down-holeaccidents was easily caused such as packer loss of seal, creeping, central tube fracture, rubberdamage, hydraulic anchor failure and rise of casing pressure. Therefore, to find runningregularity, mechanical properties and working mechanism of testing packer, RTTS packer wastaken on as research object this paper, strength safety and construction parameters controltechnology of RTTS packer in ultra deep high pressure gas well was analyzed by elasticmechanics, material mechanics and tubular mechanics.Firstly, stress field, strain field and displacement field of rubber were derived by polarcoordinate method and inverse method in free deformation and restrained deformation stage.Contact stress and extreme differential pressure were calculated between casing and rubber inthe production process. Shear stress relaxation and creep prediction equation of packer rubberwere established based on rheological mechanical theory. The factors that effect on sealingrubber were analyzed by using mechanical analysis software of packer for optimizing rubbermaterials, hardness, setting and construction parameters.Secondly, stress distribution and stress concentration of slip root was analyzed by elasticmechanics, its strength was checked, the method to calculate true axial setting load of slip wasderived. The equation of calculating bitten depth，extrusion stress equation，shear stress andtouch area of hydraulic anchor which bites into casing was derived through energy method.Stress distribution of slip and mechanical properties of hydraulic anchor was analyzed indifferent casing for optimization structure parameters of slip and hydraulic anchor.Finally, overall force equation of RTTS packer was established, engineering exampleswas analyzed. Integrity control technical points and safe evaluation recommended practice oftesting packer were put forward.