In the past decade, fiber-optic (FO) -based sensing has opened up opportunities for in-well reservoir surveillance in the oil and gas industry. Distributed-temperature sensing (DTS) has been used in applications such as steam-front monitoring in thermal enhanced oil recovery and injection-conformance monitoring in waterflood projects. FO-based pressure gauges are deployed commonly. Significant progress also has been made in maturing other new FO-based surveillance methods such as distributed acoustic sensing (DAS). In this paper, the authors present a recent example of single-phase-flow profiling with DAS.
FO-based surveillance allows for a complete, instantaneous data set from the top to the bottom of the well vs. traditional logging methods that can consume many hours to collect a single trace of a limited interval of the well. A recent development is the use of DAS, which converts a standard fiber deployed over an entire wellbore into a permanent array of microphones. DAS has proved its utility for monitoring of hydraulic-fracturing (HF) operations and for acquisition of vertical-seismic-profile (VSP) surveys and microseismic. A third promising application under development is that of measuring downhole production or injection-flow performance, where DAS can replace the conventional production-logging-tool (PLT) survey for a number of flow regimes and well types.
Because the same FO cable can be used for different measurements by connecting the appropriate interrogation unit to the cable, it is, for instance, possible to use DAS for first monitoring the HF treatment during the initial well completion, followed by time-lapse production profiling surveys to assess the (change in) flow behavior for optimizing well inflow/outflow performance or improving the completion design of future producers....
Distributed Acoustic Sensing for Downhole Production and Injection Profiling
20 February 2016