Failure and mitigation study of packer in the deepwater HTHP gas well considering the temperature-pressure effect during well completion test

Mechanical integrity of tubing string in high‐temperature and high‐pressure ultra‐deep gas wells based on uncertainty theory

“…The external pressure of the tubing string is related to the annulus pressure, density of the annulus protection fluid, and depth of the packer 25 : $$${F}_{1}={p}_{{\rm{t}}}+0.00981{\rho }_{{\rm{o}}}{h}_{{\rm{s}}},$$$where p t denotes the annulus pressure (MPa), ρ o denotes the density of the annulus protection fluid (kg/m 3 ), and h s denotes the packer depth (m).…”

“…The external pressure of the tubing string is related to the annulus pressure, density of the annulus protection fluid, and depth of the packer 25 :…”

“…When in service, the tubing string load can be classified as follows: (1) external pressure F 1 , (2) internal pressure F 2 , and (3) axial force F 3 . External pressureThe external pressure of the tubing string is related to the annulus pressure, density of the annulus protection fluid, and depth of the packer 25 : $$${F}_{1}={p}_{{\rm{t}}}+0.00981{\rho }_{{\rm{o}}}{h}_{{\rm{s}}},$$$where p t denotes the annulus pressure (MPa), ρ o denotes the density of the annulus protection fluid (kg/m 3 ), and h s denotes the packer depth (m). Internal pressureDuring the production process, the tubing string bears wellbore fluid pressure. Based on the acceleration pressure gradient, gravity pressure gradient, and friction pressure gradient of the wellbore fluid, the fluid pressure balance equation in the tubing string is obtained 26 as follows: $$${\rm{d}}{p}_{i}=-\frac{{\rm{d}}({\rho }_{i}{c}^{2})}{2}-{\rho }_{i}g{\rm{d}}z\,\cos \,\theta -f\frac{{\rho }_{i}{c}^{2}}{4{R}_{i}}{\rm{d}}h,$$$where p i denotes the fluid pressure in the tubing string (MPa), ρ i denotes the density of the fluid in the tubing string (kg/m 3 ), c denotes the velocity of the fluid in the tubing string (m/s), g denotes the gravitational acceleration (m/s 2 ), h denotes the length of tubing (m), θ denotes the well deviation angle (°), and f denotes the dimensionless friction coefficient.The gas density and fluid velocity in a tubing string can be calculated using the following formula: $$${\rho }_{i}=\frac{pM}{{Z}_{g}RT},$$$ $$$c=\frac{Q}{4\pi {R}_{i}^{2}},$$$where M denotes the molar mass of gas (kg), Z g denotes the gas compressibility factor (dimensionless), R denotes the general gas const...…”

The impact of thermal ageing on sealing performance of HNBR packing elements in downhole installations in oilfield wellhead applications

“…Different areas of the packers performance have been studied in the literature. For instance, Li et al [3] investigated the failure behaviour of the packing elements by modelling packers performance in high temperature and high-pressure environments. Their behaviour was linked to the size of the packers (dimensionless length), as well as gas output rate which both affect heat transfer throughout the length of the packer.…”

Investigation on the Depth of Slip Hanger Teeth Bite into Casing and the Mechanical Properties of Casing under Different Suspension Loads in Ultra-Deep Wells

“…Many efforts have been put in analysis of the force and structure of the slip hanger and casing. Li et al [4] and Tong et al [5] carried out the mechanical analysis of slips on the packer with statics principles and obtained the formula for calculating the normal stress on the slip insert during anchoring of the slips and. Tang et al [6] aim at the problem of damage caused by the casing pressure on the slip after setting, the pressure-bearing law of the slip teeth under the threetooth parameters was analysed.…”