Wellbore Investigation and Perforation of a Highly Deviated Well Using a Wireline Tractor and Strip Guns Offshore Angola

Abstract

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. IntroductionWithin the oil and gas industry, the term "WL" usually refers to a cabling technology used by operators to lower equipment or measurement devices into a well for the purposes of well intervention, reservoir evaluation, and pipe recovery.WL operations, and more specifically e-line interventions, have remained an essential tool for geological and reservoir evaluation (i.e., openhole logging), as well as a means to determine hole integrity and proper well construction (i.e., cased hole logging). Additionally, well intervention by means of e-line is a cost-efficient method of reaching operational objectives. The tools and equipment are conveyed into wells either through an "open hole" without surface pressure, or through special pressure retaining equipment, which allows the toolstrings to be conveyed into live wells with full production pressure. Key e-line workover activities include the setting of downhole tools (e.g., bridge plugs, packers, cement retainers, tubing cutters and punchers), perforating (casing and through tubing), and the use of diagnostic workover tools, such as casing collar/gamma rays (CCL/GRs), multifinger imaging tools (MITs), thermal multigate decay-lithology (TMDL) etc.The natural drive for e-line tools into the wellbore's target depth is gravity. E-line interventions, however, have been traditionally limited by wellbore deviation, and the conveyance of e-line tools through deviated tubing, would at be...