Well Miller® with Expandable Bit enables safe deployment of bridge plug

Challenge
Downhole access
JABZ213181 1712 X 963
  • Well type Oil producer
  • Max deviation 60˚
  • Depth 9659 ft (2944 m)
  • Pressure 3752 psi (258 bar)
  • Temperature 192˚F (89˚C)
  • Distance cleaned 103 ft (31 m)

Background

In the North Sea, an operator, after running a production logging tool (PLT), discovered that a particular zone was producing 99% water along. The PLT also uncovered significant scale deposits present in the tubing and liner below the chemical injection valve.

The well was originally completed in 2007 as a 5-1/2” production well, and currently produces approximately 25,750 barrels per day at 88.4% water cut with gas. To curb the water cut, the operator needed to regain access to the liner to install a bridge plug that would isolate the zone.

Prior to this case, the operator always used coiled tubing (CT) for scale removal; however, the design of the Christmas tree would have to be changed out entirely to allow for a traditional CT cleanout operation. Performing such a changeout would be costly, so the operator began to consider trialing new technology to remedy the issue. The operator had never run an e-line scale milling job and turned to Welltec® for an effective solution.

Operations

Welltec came up with a solution using the Well Miller® with Expandable Bit (Well Miller EB) to allow the client to meet the objective while reducing milling risks and increasing the odds of successfully setting a plug in scale.

Welltec’s proposed method was to remove as little scale as possible while creating a clean surface on which to install the plug. The Well Miller EB is designed with a fixed 4" scale bit at the bottom of the tool to establish safe passage to target depth (TD) while removing the least amount of scale possible. After completing a successful systems integration test (SIT), the tool was deployed to the well and run in hole.

In this case, when the EB arrived at TD, it engaged and cleared a 40-foot stretch of tubing to full inner diameter (ID), providing both the client and the plug supplier confidence that the plug could be set successfully. After the plug was set, data received from the plug setting tool showed the bridge plug set in 4.64” ID. The water-producing zone had been effectively isolated.

Achievements

In this operation, the Well Miller EB confirmed access with a 4” bit to the plug-setting area and cleaned a 40-foot section to full tubing ID in the same run while simultaneously minimizing the amount of scale that had to be removed.

Each stage of the job—from the technical meeting to the SIT to the operation itself—was carried out efficiently and with excellence. From loadout to backload, the operation was completed in 11 days, which saved the client approximately 21 days of time and significant cost over a CT cleanout.

This operation was the very first e-line scale milling operation for the client. Welltec’s efficiency and innovation led to the operation completed ahead of time and under budget. The client believes that no other company can match Welltec’s knowledge and expertise in e-line milling, and the operator is now reviewing standard practice for scale