JOB TYPE
Sour Well Re-Entry
DURATION
It took 4 months of Engineering and Pre-Job Planning; 10 days of daylight operations to complete.
THE SITUATION
While drilling a Montenay horizontal well, a major operator took a kick resulting in a blowout. After capping operations and killing the well, another drilling rig was mobilized. Drill pipe backed off at 2400m. A 4 1⁄2 liner was hung in the 9 5/8" surface casing and cemented in place. A 60m cement plug was spotted above the liner top packer, and the well was suspended. Years later, gas started migrating to the surface around the lease.
THE SOLUTION
The oil company contacted us, and plans were made to re-enter the well and log casing for cement bond. Complications with milling the cement plug included the risk of gas migration through the 4-1/2" liner (up to 6,000 psi), creating a piston effect buckling and ejecting tubing while milling with 360,000 lbs of lift under the plug. Other complications arose from the suspected gas-bearing zone being sour.
Together, we engineered a solution of rigging up a 285k jack with a full 11" stack; RIH with 8-1/2" tri-cone bit and 3-1/2" IF drill pipe. We milled cement while holding 21 MPa on the annulus with two choke manifolds and a P-tank. If a kick was encountered, the gas cap could be bled off to continue milling to the liner top packer. POOH and RIH with 3 5/8" bit, six drill collars and 3-1/2" string to mill cement out of the liner. POOH and RIH with 3-5/8" bit, drift string mill, and L-80 tubing was cleaned down to the 2,400 m plug-back.
