An operator had a well producing 100 percent water-cut and wanted to identify the origin of the water production using fiberoptic sensing technology. The vertical well was cased, perforated, and hydraulically fractured. A production string that included an electric submersible pump (ESP) at the bottom was run into the hole to a depth immediately above the top perforations. An additional 1,500 ft. of one-inch diameter rods were hung from the bottom of the ESP to convey fiber-optic cable into the perforated region. Fiber-optic cable was clamped onto the outside of the production tubing, ESP, and rods as they were being run in hole. Distributed temperature sensing (DTS) and distributed acoustic sensing (DAS) data were collected from the fiber and used to identify the water ingress locations using several techniques including DAS energy computation, DTS temperature trace evaluation, and DTS heat transfer models. The analytical methods were in agreement on the distribution of fluid entering the well. The effect of an operating ESP on DAS measurements was also investigated.

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