Case Studies

Reducing water cut for a Supermajor Operator in Brunei

Intervention with Wel-lok™ Water Shut Off (WSO) Tool.

A supermajor operator in Brunei had a well producing 75-90% water-cut, reducing the gas production rate of the well. The operator wanted to run a tool through 4.5″ tubing to isolate inside a 7″ production liner.


High expansion, through tubing solution:

The customer desired a solution that could pass through a 3.9″ restriction and seal inside a 7″ perforated liner to shut off water. This required a tool that was 3.5″ diameter, which meant that high expansion was necessary to create an effective isolating barrier.


A BiSN Wel-lok™ WSO tool was deployed in the well to the isolation zone inside the 7″ production liner. The thermite heater was activated, melting the bismuth alloy. The low viscosity, liquid bismuth alloy flows like water, and was able to flow out to seal the 7″ liner and the perforations. The bismuth alloy then solidified, creating a barrier to shut off water.


  • WSO tool deployed through tubing
  • Plug set in 7″ liner successfully
  • Water cut reduced from 75-90% to 30-40%

Business Value

BiSN provided the customer with a highly effective, high expansion Water Shut Off solution. This significantly reduced water-cut, allowing the operator to produce more gas and requiring less disposal of waste-water. BiSN was able to help the operator reduce HSE risks, operation time, and cost.


To repair the production packer in situ, bismuth alloy beads had to be injected in the annulus from surface. These beads then fell down to stack up on top of the leaking packer. Logging was completed to confirm the placement of the beads in the annulus.