Case History: Steam-Injection Monitoring With Optical-Fiber Distributed-Temperature Sensing
- Dennis Denney (JPT Senior Technology Editor)
- Document ID
- Society of Petroleum Engineers
- Journal of Petroleum Technology
- Publication Date
- June 2010
- Document Type
- Journal Paper
- 75 - 76
- 2010. Society of Petroleum Engineers
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- 106 since 2007
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This article, written by Senior Technology Editor Dennis Denney, contains highlights of paper SPE 127937, "Case History - Steam-Injection Monitoring with Optical-Fiber Distributed Temperature Sensing," by Marcelo A.P. Batocchio, SPE, Halliburton, and Adriana L.C. Triques, Hardy L.C. Pereira Pinto, Luis A.S. de Lima, Carlos F.S. Souza, and Ronaldo G. Izetti, Petrobras, prepared for the 2010 SPE Intelligent Energy Conference and Exhibition, Utrecht, The Netherlands, 23-25 March.
A project was initiated by Petrobras to map the steam-front progress in a steam-assisted-production heavy-oil field. A distributed-temperature-sensing (DTS) system was installed to monitor the temperature distribution in a wellbore of a pilot program having three producers and one continuous-steam-injection well.
In heavy-oil fields produced by steam injection, companies seek information to improve the drive mechanism that moves the crude oil into the wellbore. Monitoring equipment and interpretive-software tools help to achieve production requirements, maintain economic feasibility, and promote safety. In this project, high-temperature conditions were factors also.
Optical-fiber DTS is a downhole-monitoring technology that provides permanent and continuous well-temperature profiling. This method enables real-time data collection, whereas traditional downhole monitoring during production provides temperature data only at a fixed point for each reading. Alternatively, wireline temperature logs can be run, but this method does not offer continuous monitoring and it affects production. With the DTS technique, the optical fiber typically is attached to the tubing and provides a complete log of the well temperature for each reading, enabling permanent and continuous monitoring without production interruption. Steam-front progress, which can improve the understanding of the reservoir geological model, can be followed; steam-breakthrough can be identified; and improved injection-efficiency then can be achieved.
Estreito is an onshore field in northeast Brazil, 180 km from the city of Natal. This field is part of the Potiguar basin. The main reservoirs are Açu 100 and Açu 50/60, which are part of the Açu formation. These shallow reservoirs (approximately 200 m deep) originated from a fluvial depositional system. They have strong heterogeneities, have a strong active bottom aquifer (Açu 100), and are controlled by an ensemble of faults known as Carnaubais. The 15°API oil has high viscosity (2,000 cp).
Cyclic steam injection began in 1984 as an improved-recovery process. This method is no longer economically viable and is being replaced by continuous steam injection.
The efficiency of continuous steam injection is related directly to knowledge of heat-flow paths, which is reflected in the steam/oil ratio and the recovery factor of the area. Therefore, the operator has monitored heat transfer throughout the field since the beginning of steam injection.
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