New 9-7/8-in. HPHT Permanent Packer With New Back-up System Provides North Sea Operator with Effective Solution for Damaged or Worn Casing (SPE-130540)

摘要

A major operator in the North Sea had experienced a problem with damaged casing at the packer setting depth of an existing HPHT well, causing a leak into the production annulus. A workover was required, and a calliper survey conducted after retrieving the tubing showed two sizeable grooves along the longitudinal axis of the casing at 120 degrees to each other. This paper discusses the successful qualification and installation of an HPHT permanent packer for worn casing system. Permanent packers are qualified to ISO 14310 V0 in a test fixture to meet the API 5CT internal casing dimensions but do not account for any wear or damage in the casing. A test programme was developed to mimic the worn casing and HPHT well conditions and consisted of the following: 1. Install packer in 9-7/8-in casing and flow test to 3 bpm at 180aF to verify element circulation integrity 2. Test application using synthetic oil to mimic packer loading until failure, including setting, production, and hot/cold shut in.; apply 9000-psi annulus pressure to support the casing during testing. Max temperature was 423aF for over 200 hours. 3. Test modified ISO 14310 V0 at 450aF with 15000 psi differential pressure and 400,000 lbf tension and compression. The packer passed all tests with no extrusion of the three-piece multi-durometer Aflas element. The discussion will include packer design, HPHT test in worn casing, casing acceptance criteria, and lessons learned. This was the first packer test in worn casing that demonstrated compliant back-up system capability to support the entire element circumference at elevated temperatures. The packer was run and set in the HPHT well after over 3 months suspended in caesium formate.