Field A is a gas field located in Malaysia-Thailand Joint Development Area. As the field matures after 10 years of production, the number of idle gas wells has been increasing due to various issues such as low tubing head pressure, mechanical problems and sand fill. Currently, the operator has embarked on an aggressive, reactivation campaign to restore production through interventions.

Well A became idle in January 2013 due to unknown reasons and was selected as a pilot well for the re-activation campaign. Tubing Retrievable – Surface Controlled Subsurface Safety Valve (TR-SCSSV) cycling and Critical Device Function Test (CDFT) were performed successfully, but did not impact the production. In August 2013, lubricator valve (LV) diagnostics were performed using a Lead Impression Block (LIB) tool which indicated that the lubricator valve above the TR-SCSSV was only 80% open. As such, this malfunctioning lubricator valve (LV) prevented any future interventions for diagnostics, zonal isolation or the addition of perforations in order to fulfill the objectives of the idle-well reactivation campaign.

An in-depth, internal review had been conducted previously to evaluate all the available solutions in the market from both a technical and economic perspective. To enhance the chances of success, an innovative e-line conveyed core milling bit solution was selected for the pilot job in well A to restore full access to the well.

A customized solution using a 4.55 inch milling core bit run on e-line managed to successfully mill the malfunctioning lubricator valve and restore access to the well with substantial cost savings and lower risk compared to coiled tubing (CT) operation. Both milled coupons were retrieved with the aid of a catcher and brush combination designed into the bit. This managed to restore the access for the future intervention, zonal isolation and additional perforations in this well.

This paper shares a detailed case study of Well A in terms of technology selection, operation execution, lessons learnt, and future recommendations. It is evident that e-line conveyed, core milling bit technology is technically and economically feasible to mill malfunctioned lubricator valve, thus eliminating the need of expensive solutions such as CT or rig intervention.

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