WORLD’S FIRST RLWI CROWN PLUG PULLING WITH WELL STROKER

Well Stroker for MECHANICAL SOLUTIONS

Background

In subsea wells with Horizontal XmasTrees (HXT), two crown plugs are installed with tight spacing as the primary and secondary barriers against reservoir pressure. Typically, slickline services both install and remove these barriers. Sometimes, however, crown plugs do not yield to slickline pulling techniques due to either a high hydrostatic pressure or high differential over the upper plug. In these instances it is crucial to have a reliable back-up plan. The Well Stroker® is a proven, reliable contingency solution to remove the plugs and proceed with the operation as it can apply a significantly higher, non-jarring force, up to 60,000 lbs, exactly where needed downhole. On a recent RLWI operation in the Gulf of Mexico the Well Stroker was put into action when the upper crown plug failed to release despite hundreds of jarring attempts on slickline. Over the course of two days, several slickline runs were performed. On the first slickline attempt, 148 jarring attempts failed to free the plug. On the second run another 199 jar impacts yielded the same result. It was believed that these attempts may have broken the seal, which would then have resulted in saltwater inflow creating hydrates. 25% Methanol Ethanol Glycol (MEG) was pumped while jarring, but when no progress was made Welltec® was called upon to assist.

OPERATION

Offshore the Well Stroker was rigged up into the subsea lubricator (SSL) and deployed. Upon SSL connection to the HXT the Well Stroker was lowered down latching the pulling tool into the upper crown plug’s internal pulling profile. E-line then pulled the toolstring up extending the Well Stroker’s piston rod and verifying that the pulling tool had latched. The Well Stroker was then activated, setting the anchors in the pre-planned location and applying sufficient force to pull the plug free. Then the entire assembly and the SSL were retrieved to surface. Although the Well Stroker has a bi-directional ram, only up-strokes were performed in this operation as down-strokes would have resulted in releasing from the plug.

ACHIEVEMENTS

In just 14 strokes, the Well Stroker accomplished what 347 slickline pulling attempts couldn’t; freeing the upper crown plug. The excessive amount of strokes required to pull the plug is likely due to hydrate formation between the plugs as saltwater entered during slickline attempts. The alternative to the Well Stroker contingency would have been to bring in a workover rig with full surface riser capability. This would have increased the operational costs significantly as well as delaying any production. However, the use of an e-line solution facilitated the continuation of the RLWI operation with minimal NPT and at a much lower costs. The Well Stroker can be fitted with the Well Key® for further mechanical services and combined with a number of other e-line intervention tools. Together they offer a perfect solution for contingency planning on RLWI operations.

DEVIATION OVER ZONE OF PACKER: 53,80° TO 57,89°
MAX. TEMPERATURE: 143° F (290°)
MAX. PRESSURE: 2,992 PSI

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In just 14 strokes, the Well Stroker accomplished what 347 slickline pulling attempts couldn’t; freeing the upper crown plug.