Freeze Ops Deliver Innovative Plug Solution
Wild Well Global General Manager of Special Services Carlo Mazzella has published the results of an innovative fluid cryogenics project completed in conjunction with Saudi Aramco. The “pioneering operation” presents a “tested, proven alternative method for a successful” secondary annular barrier with the presence of a kill fluid column in the annulus.
Titled “Pioneering Utilization of Fluid Cryogenics in Mimicking Shutoff Barrier Characteristics,” the paper appears in the Spring 2016 Saudi Aramco Journal of Technology and had been presented at the SPE/IADC Middle East Drilling Technology Conference in January.
The use of a cryogenic freeze plug as a barrier is primarily applied when conventional methods are not possible. In this particular operation, Saudi Aramco sought to effect a seal so that dual shutoffs would be available prior to removing the production tree.
Specific to Saudi Aramco, the policy requires two independent shutoff barriers to be in place for the tubing and tubing casing annulus prior to the decompletion of wells that contain downhole packers.
In addition to the above requirements, the shutoffs must operate independently of each other and be pressure tested separately.
Under normal operations, tubing plugs and tubing hanger backpressure valves are capable of providing dual shutoffs. But when the operator prepared to remove the production tree, crews discovered that the production tubing had collapsed and parted, leaving the kill fluid column as the only annular barrier.
Who does an operator call when a well challenges conventional methodologies and requires innovative solutions? Wild Well, of course.
To create the plug, the temperature surrounding the casing is dropped to a range of 0 to −80°F by installing a metal container around the pipe and filling it with liquid nitrogen. The kill fluid inside the pipe freezes as a result of the surrounding temperature, creating an effective barrier capable of being pressure tested.
“Our clients have become receptive to new isolation techniques as case history in the region is becoming more common,” says Mazzella. “Wild Well will remain consistent in improving its service offerings by innovations in technology to better serve our clients worldwide.”