Lessons Learned from Perforated Liner Stuck in N. Azadegan Field

Abstract

Abstract N.Azadegan oilfield is a laminar characteristic of bottom water limestone reservoir with about 50m thickness from hole toe to oil-water interface, so a water cone may exist. When water breaks through to the wellbore and reaches 10% in the field, the production well will be closed in accordance with Buy-back development contract. So all of 21 highly deviated wells and some horizontal wells are planned to use enough open-hole swell packers for preventing and managing water cut. But there is the few report about stuck perforated liner with swell packer in the high angle hole. This paper discusses expandable experiments of swell packer in the lab and well completion string design such as packer’ setting placement, then give some risks analysis of running 4-1/2" perforated liner in 6" open hole such as severe dogleg in three dimension trajectory,144mm packer OD and rubber property, 1300m length open hole in higly deviated section and friction force etc. In the first 12 wells in N.Azadegan field, there are 4 wells’ cases of stuck 4-1/2" perforated liner with two or three packers. By reviewing the typical field cases of stuck perforated liner with packers in two wells, this paper analyzes several possible reasons include i.e. mud properties change, frequent trips to cause wellbore destruction, the severe dogleg, quick expansion after rubber absorb oil molecular and present the main reasons for stuck liner, then develop a solution that would allow the well of stuck perforated liner to be completed, finally focuses on modification of oil swelling packer from rubber element design to evaluation test based on in-suit mud. One of intentions in this paper is to give a case history and the lessons learned for further enhance the reliability of this kind of oil swelling packer, avoiding the risk of sticking perforated liner and promoting the use of swellable packer in the other field.