CASE STUDY

well control

WELL CONTROL

JOB TYPE

Well Control; pipe milling due to string ejection

  • DURATION

    3 weeks of engineering and planning; 35 days of 24-hour operations to complete.

  • THE SITUATION

    A major oil company drilled a wilrich horizontal well with a ball drop completion liner and stage tool. A service rig had been used to mill out the stage tool. Upon milling through the debris sub, the rig took a kick. A competitor’s rig assist unit was mobilized, and packers were run to isolate and find where the leak was. Upon tripping out of hole the rig assist unit slips failed and ejected 7 joints of tubing. The well was secured with a snubbing annular bop.

  • THE SOLUTION

    Piston’s well control personnel was mobilized and froze the wellbore. BOP doors were opened and folded pipe was confirmed. The rig assist unit was stripped off and pipe was cut at the primary annular and a 7-10 master valve was installed. The service rig and rig assist unit demobilized with 80 jts of tubing bha and packers left in well.

    Piston rigged up a 285k rigless unit with substructure on top of the 7-10 master valve to a workfloor height of 32m. Pipe was milled out of the stack with a 6-15/16” mill on custom 4” pipe centralized mill to mill through the master valve while holding 4000psi on the annulus. Once pipe was milled into 4 1⁄2 casing, e-line was rigged up and a camera was run to determine pipe was round. We latched onto the tubing with an overshot, cut above packer and installed permanent plugs. The tubing was snubbed out and rih with overshot to attempt to jar the packer free. After being unable to free the string, pooh, rih with washpipe and washover slips on packer. Several runs were needed due to debris from milling pipe in the stack. Once the slips were gone, rih latch onto packer, jar free, pooh, rih with venturi tool and cleaned the heel section to the top port.

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