In a tool stuck situation, wireline conveyance systems incorporate a downhole mechanical weakpoint to safely release and retrieve the logging cable during or prior to pipe conveyed fishing operations. In wells with high tension profile and long open hole sections, the weakpoint strength should be carefully selected to ensure high pulling capabilities in shallower sections of the well while not exceeding the cable safe working load (SWL) in deeper sections of the well. To overcome this limitation, electrically controlled release devices (ECRD) were introduced in the past. Release is only possible with a surface command. As such full pulling capability is maintained at all times and depths. The swap however, introduced new sets of challenges such as full tension drop requirement for mechanical release and a labor intensive tool preparation procedure. As a result non-release incident rate increased leading to high risk and costly recovery operations. To minimize this risk, clients often have to reduce or cancel wireline logging programs leading to missed critical well data.

To address the limitations of ECRD type weakpoints, Chevron Thailand E&P, LTD commissioned Schlumberger to address such challenges. The project was completed in Dec 2011 with the introduction of SureLOC 12000. Improvements include release with 1000 lbf of cable tension, 12,000 lbf (up from 8,000 lbf) of safe operating pull and substantial reduction in maintenance and redress procedures. Reliability has since improved by 75% allowing Chevron to acquire full data in wells where logging operations would have been otherwise cancelled. The improved reliability and increased operational range of the new device have allowed Chevron to safely carry out Wireline logging operations and achieving well data acquisition targets with substantial financial benefits.

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