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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 EOR and injection conformance monitoring in waterflood projects using (improved) warmback analysis and FO based pressure gauges are deployed commonly. In recent years 1 significant progress has also been made to mature other, new FO based surveillance methods such as the application of Distributed Strain Sensing (DSS) for monitoring reservoir compaction and well deformation, multidrop Distributed Pressure Sensing (DPS) for fluid level determination, and Distributed Acoustic Sensing (DAS) for geophysical and production/injection profiling. For the latter application, numerous field surveys were conducted to develop the evaluation algorithms or workflows which convert the DAS noise recordings into flow rates from individual zones. The applicability of a new graphical user-interface has been expanded to include smart producers and injectors that allows the user to visualize (in real time), QC and evaluate the DAS data. Also, the evaluation methods for the use of DTS for warmback analysis have been significantly improved.There are still improvements to be made in enabling Distributed Sensing infrastructure, such as handling and evaluation of very large data volumes, seamless FO data transfer, the robustness & cost of the FO system installation in subsea installations, and the overall integration of FO surveillance into traditional workflows. It will take some time before all these issues are addressed but we believe that FO based applications will play a key role in future well and reservoir surveillance.In this paper we present a recent example of single-phase flow profiling using DAS. The example is from a long horizontal, smart polymer injector operated by Petroleum Development Oman (PDO).

Frequent surveillance data is essential for optimizing production and recovery, especially in complex reservoir and recovery settings such as waterfloods in highly compartmentalized stacked reservoirs and in IOR and EOR projects. However, in many cases data is acquired infrequently or not at all due to concerns regarding production deferment, costs, HSE exposure, and operational risks. Permanent in-well fibre optic cable installations offer a solution to this problem by enabling frequent measurements across a large section of a well at once without well interventions and without production deferment. The fibres can be utilized to provide distributed temperature, strain and acoustic measurements across the wellbore from which information on well integrity, on well flow behaviour, reservoir conditions and seismic data can be obtained. Although interpreting optical fibre measurements such as Distributed Acoustic Sensing or Distributed Temperature Sensing is not yet straightforward, significant progress has been made to provide actionable information shortly after data acquisition by providing an appropriate in-field infrastructure and easy to use tools for data handling and analysis. In this paper, we present recent examples from Brunei Shell Petroleum, where Distributed Acoustic Sensing data has been used in facile but impactful way for Smart Wells management and flow optimization. This work is a big step forward to make distributed data analysis an integral part of the day-to-day Well, Reservoir and Facilities Management.

Since our previous publication1 significant progress has been made to further mature the application of Fiber-Optic (FO) based Distributed Acoustic Sensing (DAS) for production and injection profiling. A considerable number of new field surveys were conducted to further improve the evaluation algorithms or workflows which convert the DAS noise recordings into flowrates from individual zones. For gas producing wells, a new graphical user-interface has been developed that allows the user to visualize and QC the data in real time. Additional flow and visualization software have been developed for single phase gas producers to enable the user to select and evaluate the data in a user-friendly manner using the most up-to-date evaluation algorithms. There are still improvements to be made in enabling Distributed Sensing infrastructure, such as handling and evaluation of very large data volumes, seamless FO data transfer, the robustness & cost of the FO system installation, and the overall integration of FO surveillance into traditional workflows. It will take some time before all these issues are addressed but we believe that FO based applications will play a key role in future well and reservoir surveillance. In this paper we present two recent examples of single-phase flow profiling using DAS. The first example is from a single-phase gas producer in one of the Unconventional plays in North America and the second example is from a long horizontal, smart polymer injector operated by Petroleum Development Oman (PDO). Introduction In oil and gas field development there is often a lack of high quality Well and Reservoir Surveillance (WRS) data for quality decision making; leaving significant reservoir or well performance uncertainties potentially leading to suboptimal reservoir development. The need for frequent and good quality surveillance data is highest in complex reservoir developments such as Unconventional plays, waterflooded reservoirs, Thermal and Chemical Enhanced Oil Recovery (EOR) projects. One of the reasons that well surveillance data is not acquired in practice is that it often causes significant production deferment. Another reason is that often the data gathering surveys are expensive or create large operational risks associated when using conventional logging methods, particularly in high rate, highly deviated or long horizontal producer wells. In some cases, the small diameter production tubing limits access to the well with conventional logging tools.

Petroleum Development Oman (PDO) is increasingly relying on Enhanced Oil Recovery Technologies to optimize production. Successful implementation and operation of polymer flood field developments in Oman involves dealing with a variety of risks that can impact injection conformance, sweep efficiency, production, and surface facilities. The subsurface risks predominantly relate to Fracture propagation, Vertical Conformance and Areal Conformance. Mitigation of these risks is key to enabling economical field developments and requires implementation of adequate surveillance and control measures.Conventional technologies that may be able to acquire the required surveillance data, like production logging, can be costly and/or give unreliable results. In addition, the extreme high well density makes well entries difficult and complicates conventional surveillance. Fiber Optic Surveillance Technologies are most favorable as an alternative because of their potential applicability in water and polymer injectors as well as oil producers; their non-intrusive nature reduces HSSE exposure; and their low cost and automated on-demand time-lapse surveillance potential.Shell and PDO have collaborated on the development of robust interpretation workflows for Distributed Temperature Sensing (DTS) warm back surveys in mature injector wells, and Distributed Acoustic Sensing (DAS) for injection profiling in polymer injector wells and production profiling in oil producers. Data were gathered during various field campaigns as well as in controlled polymer flow loop experiments.This paper presents one successful and one less successful DTS warmback survey conducted in a water and a polymer injector well, and also the recommendations to improve the quality of warmback surveys. Three other datasets are presented, the first two relate to DAS injection conformance monitoring where DAS was acquired in a polymer injector well and used, together with a PLT survey during the water injection periods, to assess the change in injection conformance. The last test relates to a DAS acquisition in an oil producer well equipped with a Progressive Cavity Pump.