Transforming Conventional Wells to Bigbore Completions Using Solid Expandable Tubular Technology
Gas wells completed in prolific reservoirs before the advent of bigbore completions do not produce to full potential because of tubing constraints. This phenomenon was observed in several mature, carbonate gas fields offshore Malaysia developed in the early 1980s. At that time, tubing configuration was limited to 7" completion run in 9 5/8" production casing. Given the size of the production casing, any workover option to enhance outflow performance was limited to recompletion with 7 5/8" tubulars which would result in a 10% gain in well capacity through improved outflow performance. The advent of solid expandable tubular (SET) technology in the new millenium has opened up a revolutionary possibility for transforming a conventional well with 7" tubing to a bigbore producer. The concept involves installing and expanding extended lengths of 7 5/8" solid tubulars inside 9 5/8" casing. This will yield a production conduit with an internal diameter 24% larger than conventional 7” tubulars which translates into a 61% increase in flow area. Thereafter, gas production occurs through the solid expandables based on a philosophy similar to long casing flow monobores. A field trial to test this novel re-completion concept was carried out in a gas field offshore Sarawak in December 2001. Expected benefit of a re-completion to solid expandable tubulars is a 40-50% increase in well deliverability from prolific reservoirs previously tubing constrained. If proven successful, this novel recompletion design will be extended to other tubing constrained gas wells in the area. The paper will present the results and economic benefits of this field trial, which is the first of its kind in the world. Details encompassing the conceptual solid expandable completion design, modifications and improvisation required for a SET gas well workover, the SET installation sequence, and results from the trial will be presented.