Since the early decades, through-tubing wireline (WL) interventions have been a necessary routine of the oil and gas industry. The practice of well intervention has benefited from the evolution of WL tools on its imposed quest to keep up with the trend of increasing complexity in wellbore and completion development.
Deployment of WL tools through tubing, from early and simple devices (e.g., gauge cutters, lead impression blocks, tubing plugs) to state-of-the-art logging and well intervention prototypes, experienced a significant leap forward with the application of electric line (e-line) tractors in the mid-1990s. Since then, many oil companies have implemented the use of tractors to make a great variety of rigless well interventions feasible, both technically and economically.
Over these lines, WL perforating of long, highly deviated wells through tubing, especially those with relevant ID restrictions, indubitably requires challenging, ingenious, and risked-assessed selection of the most convenient perforating and deployment systems. Working in remote locations, where availability of specialized tools and qualified personnel on short notice are often limited, adds an extra burden to the everyday complexity of operations.
This paper describes the unconventional, but successful, use of a WL tractor to (1) investigate a tubing-conveyed perforating (TCP) completion failure and (2) save the highly deviated "S-shaped" well from a costly offshore rig workover by perforating with a strip gun deployed more than 14,000 ft from surface. The well is located in Angola at a water depth of 1,206 ft.