Well intervention has seen significant growth in recent years because of increases in both new completions and workover operations on older wells. This has lead to development of larger and higher-grade coiled tubing (CT) for deeper and more challenging wells. The equipment, on the other hand, still needs to catch-up with the demands of bigger and heavier coil. Offshore installations present a challenge with weather and crane limitations. Onshore, road and bridge conditions often hamper shipment of large spools of CT. These issues lead to breaking the spool into two or three manageable sections and joining them on location. The increased cost, time, and equipment required to make a field butt weld make a mechanical connection the only acceptable alternative.This paper presents the five-year development, testing, and deployment history of a mechanical, spoolable connector (SC) that has provided innovative solutions to one of the most challenging well-intervention problems (i.e., weight management of the CT string). SCs in sizes ranging from 1.5-to 2.875-in. OD were designed, built, and tested. A highly accurate finite element analysis (FEA) model was used to virtually test the design, resulting in industry-leading fatigue life. Correlation of FEA results with fullscale fatigue tests on 1.75-and 2.375-in. OD SCs, along with a case history of a 1.5-in. OD string, will be discussed.A tapered OD (TOD) string with a SC enables two different outer diameters to be joined together on location, resulting in 30 to 80% weight reduction during transportation, compared to conventional strings. Combining it further with tapered wall thickness opens up new possibilities for deeper and more challenging deployments with depths exceeding 35,000 ft. Details on design and virtual testing of these strings is also shared.
