World’s first fiber-optic acoustic sensor for reservoir monitoring installed

UK-based Fotech Solutions has installed the world’s first dedicated downhole distributed acoustic optical-fiber system using its new Helios monitoring solution.  In service for one month in a coalbed methane (CBM) well, the system has already provided valuable data on gas-flow profiles across the production intervals, the company says.

The system comprises two elements—a low-cost telecoms-grade optical-fiber cable and the Helios interrogator, which Fotech calls “the heart of the system.” Helios provides acoustic or vibration information along the entire length of the installed optical fiber to obtain multiple-event information, event characterization, and highly accurate event location.

An acoustic signal is recorded at each meter along the fiber, meaning that the system can detect and position an event to an accuracy of 1 m and can distinguish separate events more than 2 m apart. The fiber can be laid near a pipeline or installed in a borehole.

The system was installed in a CBM well in Scotland for Composite Energy of Stirling, UK in August 2009. In addition to downhole flow data, the system has also provided information on the condition of the downhole pump, the location of the water level, and vibrations at the wellhead.

Other potential benefits of the system for this application include:

• Locating and monitoring sand production
• Casing/tubing integrity
• Cross flow

The easily installed Helios system also has remote-control capability and can be deployed in a range of other oil and gas applications, including production monitoring, integrity assurance, flowline movement, flow assurance, and leak detection.

Don Sharples, technical manager, Composite Energy, said: “Initial results from the Fotech fiber are very encouraging. The technology collects data which is not available from other downhole sensors and will give Composite the ability to determine which coals are producing in any given well.”

Alan Piesse, cofounder and executive vice president of Fotech Services, said: “We see a strong future for the system in monitoring gas flow in CBM wells and other applications. For the first time, flow can be seen and heard entering and moving in the well and quantified in real time. We hope to continue monitoring Composite Energy’s CBM wells and look forward to a close working relationship with them.”

Further information can be obtained from the Fotech Solutions website.