Over the last three years, a long endurance wireless sensor network designed and manufactured by Sonardyne International Ltd. has continuously logged almost 90 million sensor readings as part of a major life of field system. In depths of up to 1,200 metres (approximately 3,900 feet), the company’s Autonomous Monitoring Transponders (AMTs) log nine measurements every three hours from a range of sensors built into each unit including pressure, temperature, roll and pitch. In addition each logging event consists of measuring highly repeatable ranges to every other AMT up to four kilometres apart and recording local and remote sound velocities.
The monitoring system in place is halfway through its planned six year operation to meet an oil major’s research and production monitoring requirements. It has been continuously deployed since 2010 following an initial three year prototype trials phase to assess the performance of the new technology. Over the course of 24 hours, approximately 400 data records are collected resulting in 4KB of accumulated binary data from each transponder on the sea floor. This adds up to a total of 29 million measurements per year producing 2GB of data for analysis.
The time-stamped data logged within each AMT is available for recovery at the surface via the integrated high-speed acoustic telemetry modem. Every six months, a vessel of opportunity is tasked with wirelessly recovering the data using a Sonardyne modem transceiver deployed through the hull of the vessel. At each AMT location it takes approximately 10 minutes to upload the data at 15kbits/second to the vessel, from where it is immediately sent to a client FTP site while the vessel continues to move around the site.
“This project really gave us a chance to showcase our customer engineering services where we designed and manufactured this AMT version to fulfil specific requirements. The client has been impressed with the fact that the Wideband 2 acoustic communications allows reliable collection of high speed data to their chartered vessel in weather conditions and sea states that are normally considered well beyond the cut off point for most survey operations. Not to mention that the project is halfway through and the AMTs are still showing a battery life of more than 50%.”
Sonardyne’s Autonomous Monitoring Transponder is a long-endurance Compatt 6 based transponder that is extensively used for subsea survey tasks and is capable of autonomously acquiring acoustic ranges and sensor data without surface control. Available with a range of omni and directional transducers, depth ratings and pressure housings dependent on deployment duration and application, additional external sensors can also be easily integrated via the power and communications port.
For more information about Autonomous Monitoring Transponders, click here.