Finite Element Based Dynamic Analysis of a Device in Coiled Tubing Drilling

The need for flexibility in operation and minimized drill time has necessitated the extended use of coiled tubing drilling technology. Among others, the technology eliminates the time to connect drill pipes and thus enables a quick retraction and insertion of different tools in the well. On the other hand, the complexity of the operating conditions makes the task of testing functionality of components in the system, and getting full understanding of the acting loads is difficult. For example, recent studies show that the working mechanism of a jar device (Down Tor Hammer (DTH®)) used in coiled tubing drilling is not fully understood. There exists no well established mathematical description of the mechanism that can be used to ensure a proper functionality of the device. Furthermore, the device works in an extremely complex environment involving several fields such as dynamics of fluids, solid and structural mechanics that are in iterative interaction. This paper presents a Finite Element Method (FEM) based study of DTH® used in coiled tubing drilling. After giving a short description of the operation principle of the device, the paper illustrates the dynamic modeling technique used to get better understanding of the stress distribution in the device.