CASE STUDY

HIGH PRESSURE WELL CONTROL

High Pressure Well Control

JOB TYPE

Well Control; pipe milling due to string ejection

  • DURATION

    7 days of engineering and pre-job planning; 16 days of daylight operations to complete.

  • THE SITUATION

    A vertical multi zone gas well was drilled in the foothills region where BHP varies from 1,100psi to 7500psi. After completion operations, the producer decided to abandon the bottom zone with a bridge plug, move up hole and land the tubing. A competitor was contracted to snub the bridge plug and completion, who chose to use a conventional un-guided unit and install 10k bops. Surface pressure was 5300psi. As they snubbed in the hole after 3 joints, the lower stripping rams failed and pipe had buckled in the stack. A decision was made to attempt to pull out of hole, but the pipe wouldn’t move and personnel suspected a hydrate. Upon pulling, the pipe came free and launched, tagging top stripping ram and ejecting a joint from its connection. The well blew out, and eventually hydrated off. A freeze job was done to further secure the well and remove the snubbing jack. A 7-10 master valve was installed on top of the stripping rams to secure well and the freeze plug was melted.

  • THE SOLUTION

    After attempts were made with coil tubing to fish pipe, Piston was contacted, piston suspected pipe was folded inside the 7 icnh primary bop stack, the operator wanted to remove tubing and safely secure well with 4 1/16 master valves, a 285 k unit was rigged up with a 9 ram bop stack to ensure redundancy due to the delicate nature of job, workfloor height was 125’, a 6 15/16” mill was run on 2 7/8 slh90 drillpipe into stack, and pipe was milled out of 7 inch stack holding 7500psi, an eline unit was then mobilized to determine with a camera if tubing was fishable, camera showed tubing was buckled across 4-10 x 7-10 crossover and across master valves, concerns over milling the offset tubing arose, the concerns were that the mill would walkover and cut out side of gate valves, piston designed a 4 inch convex mill with a 6 15/16 floating centralizer on the shank to keep mill centered through valve, pipe was then milled out of valves, next a skirted mill was run and pip[e was milled 6 m past master valves, well was secured and rig demobilized until further programing was done

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