Industry Article: Engineered Workflow Delivers Strategy to Fish Nearly 10,000 ft of CT Offshore Mexico

In an unplanned operation, valuable lessons were learned about how effective integration of conventional tools could enable the successful execution of a complex fishing operation with significant equipment restrictions.

Publication: World Oil
Publication Date: 11/01/2017

by Andres Merchan, Petróleos Mexicanos; Carlos Deolarte and Mauricio Sosa, PICO Energy; Ernesto Franco, Awad William, Gabriel Ponce, and Jose Cervantes, Schlumberger

Trial-and-error often paves the way for developing strategies that facilitate production expansion campaigns. After multiple attempts to retrieve a coiled tubing (CT) pipe that broke in the course of an acid stimulation job to boost production, Schlumberger collaborated with Petróleos Mexicanos and well operator PICO Energy to engineer a workflow to pull nearly 10,000 ft of CT from the well so secondary recovery efforts move forward.

CT Enables Secondary Recovery

After encountering issues of unwanted gas in connection with conventional secondary recovery methods, Petróleos Mexicanos and PICO Energy implemented an approach that integrates a fit-for-purpose polymer foam system with the ACTive Services CT real-time fiber optic telemetry. The objective was to bullhead pump the FoamSEAL stable crosslinked foam gel to create a seal in gas-producing zones, trapping and stopping gas flow to oil channels. Acid stimulation is then performed, with new perforations added away from the gas zones. Accurate placement and activation of the foam system is facilitated by CT conveyance of downhole gauges to monitor downhole pressure and temperature throughout the pumping stages.

However, in January 2016, the CT that had been so critical to the secondary recovery effort suffered a mechanical failure during the initial stage of the acidizing job. After reaching TD of 10,669 ft, the pulling weight of the CT suddenly dropped from 36,000 lbf to 0 lbf. In attempting to retrieve the pipe to the surface the operator recovered only 653 ft of the CT, leaving 9,977 ft in the vertical section as a fish.

An Unplanned Fishing Job

Engineers determined the well condition and extent of the damage was significant. Furthermore, the well restriction of 4 1/16 in was too large for the well control equipment available in Mexico, meaning indexing or rotating tools would be required to increase the chances of latching onto the fishing neck to retrieve the broken pipe.

After multiple attempts using CT to extract the pipe, the team decided on a new strategy using the more weight-sensitive and versatile slickline to fish the CT end. Slickline, combined with a positive displacement motor and milling shoe, was run in the hole with a GS profile retrieval tool, an overshot tool and a 3 7/8-in modified fishing guide. The retrieval tool latched onto the CT end as the new fish neck. Slickline was disconnected, and CT was rigged up with an indexing tool and 3 5/8-in fishing tool, which successfully latched the fish to recover the pipe.

After 43 runs over 20 days, the CT pipe was recovered to surface. The project demonstrated how the effective integration of conventional tools delivered the successful execution of a complex fishing operation with significant equipment restrictions.

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