Shell has operations in Pinedale Anticline, Wyoming. Most wells in this region are approximately 14,000 ft deep and take an average of 30 - 40 days to drill. Drilling within their 4 1/2" production tubing strings will allow deeper penetration into the production zone resulting in increased production. To reduce well cost, Shell requested Grant Prideco to qualify the 4 1/2", 13.50ppf, P110 DWC/C-SR to utilize for its production string. This paper details the specific test plan.
DWC/C-SR is a thread seal connection which has been integrated with a resilient seal. Both fatigue and seal ability performances were to be verified because the connection will be used for drilling applications. Fatigue testing followed API RP7 guidelines. Seal ability testing was based on ISO 13679 qualification requirements.
Finite element analysis (FEA) was performed on different ISO configurations to determine the worst-case fatigue configuration based on linearized Stress Amplification Factor (SAF) analysis. In addition, FEA was used to determine the worst-case galling configuration. Three specimens were tested at targeted stress levels to determine the connector fatigue life. Next, four specimens were fatigued to a pre-determined number of cycles at a target stress level. This was followed with ISO series B tests. In order to evaluate high temperature performance, one of the ISO Series B test was conducted at 300°F. Additionally, make/break specimens were tested to verify galling resistance.
Casing drilling technology is quickly expanding into more stringent applications. However, connection performance under these severe fatigue and combined load applications is uncertain. Previously, casing drilling connection design focused on providing high torsion capacity and fatigue resistance; however, sealability characteristics should be seriously evaluated. The test program detailed in this paper evaluates connection performance for both fatigue and sealability. This information will assist in facilitating a broader application of casing drilling connections.