Specialized High Tensile Strength and Quick Disconnect Tool Used to Achieve 6,500-ft Plug Length Saves 9 Days of Rig Time

Abstract Ensuring long-term integrity of the pilot hole through permanent plug and abandonment (P&A) presents challenges related to the maximum length of the plug, type of formation to be isolated, and the type of cement slurry used. The technology used to abandon an appraisal well with 6,463 ft of tubing in one operation is discussed. It highlights the use of specialized, high-tensile-strength, quick-disconnect tool in highly deviated and deep well conditions. The operation was successfully completed and saved the operator nine days of rig time. The main challenge of the given appraisal well was to isolate a 6-in. pilot hole with 20,000 ft TD and 88° inclination. A specialized, high-tensile-strength, quick-disconnect tool with sacrificial 3.5-in. tubing was run in hole (RIH) and, after placement of cement across and inside the tubing, was successfully disconnected to leave 6,463 ft of the tubing in the hole. Because the job principle was close to the primary casing operation, centralizers were used with consideration to standoff calculations to determine eccentricity of the tubing with such inclination. To help ensure long-term isolation and minimize channeling, slurry with enhanced mechanical properties was used for cementation. The primary purpose for the specialized, high-tensile strength quick-disconnect tool was to place a competent cement plug for P&A. Placement of the release mechanism near the top of cement (TOC) minimized contamination by avoiding swabbing of the cement plug while the work string was pulled out of the hole (POOH). The tailpipe remained in the cement plug to prevent cement contamination as the work string was POOH. The disconnect mechanism of the tool is simple and all risks were evaluated and considered during operational planning. Conventional abandonment methods consume significant rig time, including placement time, POOH time, WOC, and RIH to verify the plug to place the next one. Typical industry recommended plug length is usually no more than 1,000 ft, as considerable risk of stuck drillpipe and contamination were potential outcomes of this operation. The successful application of the tool technology combined with the appropriate slurry design are discussed. Use of the proposed technology can help reduce well abandonment time and costs to operators as well as reduce the overall authorization for expenditure (AFE).