Abstract

Distributed Acoustic Sensing (DAS) technology from optical fibers is already identified as very promising for reservoir monitoring1  and especially for seismic applications2  with many stakes today in all Oil&Gas companies. DAS surveys can also have more "production" oriented applications for in-well surveillance and more specifically in complex well configurations and completions. This paper relates an in-well trial from permanent optical fibers installed in a horizontal, multi-lateral and ESP (Electrical Submersible Pump) activated well.

Two types of fibers had been installed permanently in this well: a multi mode fiber and two single mode fibers linking FBG’s (Fiber Bragg Gratings) optical gauges. These fibers were used to simultaneously acquire distributed temperature from DTS and distributed acoustic data from DAS.

The first objective of this in-well trial was to use the DAS data to improve or better constraint the temperature interpretation to get more reliable flow profiles. The acquisition sequence was designed to generate several temperature disturbances using different ESP frequencies leading to different production rates.

DTS interpretation has been performed and results are now more in accordance with previous interpretations. However, the ESP location introduced noise which made difficult to interpret the DAS signal from the close producing zones. For that reason, the first objective was not fully reached. It should be noticed that this was the first DAS acquisition in a well equipped with an ESP. The paper describes also how DAS data were investigated to open a new application on the understanding of pump behavior and possible optimization of pumps.

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