Fiber-Optic DTS Flow Profiling Installed in Advanced MRC Well

Abstract

Technology Update The current decline in crude oil prices has created major interest in methods that significantly reduce overhead and improve efficiency in operations. Distributed temperature sensing (DTS), used for advanced, in-well permanent monitoring, is a technology that can deliver on both of these objectives. DTS has demonstrated long-term reliability, high performance, and application benefit in a range of production- and injection-well types. An area of particular interest is the application of monitoring in horizontal and advanced well completions. While allowing significant improvements in production and reservoir depletion, these wells have caused data-gathering disruptions for the operators. In particular, the options for performing well logging are much reduced, and the costs of performing a production log extremely high. These factors are related to the costs of both the more advanced horizontal well-logging tools and the more expensive logging methods—such as coiled-tubing and tracker systems—used to convey these tools into the wellbore. DTS allows this monitoring gap to be closed. In line with advancements in this technology, Sensornet and FloQuest have developed a real-time digital flow-profiling system, which aids increased production, reduces operating costs and improves recovery. Digital flow profiling with DTS is used to determine distributed flow-allocation profiles in production and injection wells. The system combines DTS fiber-optic technology with software modeling and data interpretation (Figs. 1a and b). The combination of the two technologies enables accurate location of fluid entry points across an entire reservoir. The result is a permanently installed system providing continuous data similar to that obtained from a production-logging tool (PLT), even before the completion is locked down. The key to obtaining accurate and reliable flow information across the reservoir interval by means of DTS data relies on two principal factors. First, the DTS system must be able to detect very fine temperature changes. (The DTS system discussed here can measure temperature changes of less than 0.01°C at all points along the reservoir.) Second, to extract valuable information from the temperature data, it is essential to combine it with information on the geology, reservoir fluids, and the completion. In the system under discussion, this information is obtained by means of interpreting data from software models.