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T7 Global: Thru-Tubing Milling of Premium Bridge Plug in Deviated Well

01 Mar 2024
OTC Asia Stage, Hall 5, Ground Level

A detailed torque and drag analysis were used to optimally mill a premium bridge plug using a mill bit assembly on a macaroni pipe. The success of performing this operation safely and in timely manner enabled the operator to continue with the remaining scope of plug and abandonment of the well.

The bridge plug tool string encountered a holdup depth (HUD) about 5000 ft above the intended bridge plug set depth. Overpull up to 2 klb attempt was made but unable to free the stuck tool string so it’s decided to control cut the slickline wire by dropping a weight bar and wire cutter. Upon the successful cut of the slickline wire, Lead Impression Block (LIB) tool was used to tag top of rope socket to verify that no wire was left inside of the well. Then fishing operation were performed and successfully to retrieve the tool string however the premium bridge plug was left in the well. 

An analysis on the torque and drag were carried out to study the effect of stress factor, weight on bit (WOB), maximum overpull and other parameters to prevent pipe buckling during milling operation. The milling operation started by running in hole (RIH) milling bottom hole assembly (BHA) and soft tag to correlate the depth. Then the bridge plug milling commenced followed by pumping of high viscosity pill when necessary. After the slip of the bridge plug has been milled, the bridge plug was able to be pushed down all the way to the target depth.

This work provides novel insights on bridge plug milling, aiding future plug and abandonment campaigns. The analysis and field results deliver an important reference for mitigating stuck tool & bridge plug milling challenges. This improves operational efficiency and reduces costs.

Mohd Zaki Razali, Project Manager - T7 Global Berhad
Muhammad Nuradi Mohd Zaharri, Field Engineer - T7 Global Berhad