A newly developed thru tubing underreamer which can expand from its OD of 2.2” to the ID of 9–5/8”  casing was recently used to remediate a well which had been inadvertently cemented (ref. 1). The location of the operation was a field underlying some 60 meters of water offshore West Malaysia. The field was discovered in the late 1980’s and  its’ development was performed from several platforms with directional wells, one of which was drilled in 1991 and completed as a dual zone producer with 2 strings of 2–7/8” tubing inside 9–5/8” casing.  Production was from a single sand in the long string and two comingled sands in the short string with both strings being equipped with gas lift equipment for enhanced production.  By the beginning of 2008 the long string sand was no longer economically productive due to the 95% water cut and so it was decided to shut off the existing perforations and reporforate higher in the zone to establish acceptable production.

To achieve this a procedure was derived to squeeze cement the existing perforations using thru tubing intervention by means of Coiled Tubing (CT) techniques rather than a full workover approach which was economically unviable.