Well-Intervention System Focuses on Better Measurement

Abstract

Technology Update Until recently, most wells were of a relatively simple geometry, with the most complex having an initial vertical section followed by a straight tangent section that ended with a liner dropping into a vertical reservoir section. Workovers and wellbore-intervention operations in these well profiles were also comparatively simple, where the biggest challenge to evaluating the operation of service tools was overcoming sliding friction in the tangent section. Well profiles now are more complex and three-dimensional. In creating these complex well profiles, the drilling industry has developed some sophisticated and reliable downhole technologies to operate in extremely hostile physical environments. The next phases of a well's life, however, present significant challenges in workover, cased-hole sidetracking, or any wellbore-intervention operation that has to manipulate service tools, whipstock systems, or fishing tools—often at great depth—in these same complex well profiles. Now the sophisticated drilling systems are missing, and the tool operators revert to relying on surface measurements of hookload, revolutions per minute (rpm), torque, etc. While these surface readings were reliable indicators for verifying a service tool's manipulation cycle position or condition decades ago, they are now often positively misleading. In these new well profiles, it can be difficult to ascertain, for instance, if a mill is rotating off-bottom, operating with optimum weight on mill (WOM), or crushing the cutters with excessive set-down weight. The more delicate the operation—retrieving a lightweight latch or fish for instance—the more difficult and risky the operation becomes. With many of these intervention operations, the situation is further complicated by having to wait for a trip out of the hole to view the tool before the status of the downhole operation can be verified. Problems with performing intervention operations in this manner include technical risk (cost of failure), nonproductive time, and the cost of tripping in and out the hole to ascertain tool condition and job status. New Intervention System To try to counter these problems, a "smart" system has been developed for wellbore intervention. The new system aims to take accurate measurement of all static and dynamic downhole physical forces on intervention tools and transmit them to surface for real-time viewing on the rig floor. The system is integrated into current rig-data systems, such as Wellsite Information Transfer Specification, where the information can be forwarded on to offsite locations for evaluation. Decisions can also be made in real time, rather than having to wait for status-verification trips in and out the hole.