TI's RFID tagging system tracks and acoustic transponders in offshore seismic exploration

Citation

(2000), "TI's RFID tagging system tracks and acoustic transponders in offshore seismic exploration", Assembly Automation, Vol. 20 No. 1. https://doi.org/10.1108/aa.2000.03320aaf.006

TI's RFID tagging system tracks and acoustic transponders in offshore seismic exploration

TI's RFID tagging system tracks and acoustic transponders in offshore seismic exploration

Keywords: Track, Acoustic, RFID, Acoustic RF tags

One of the major operational problems in seismic oil/gas exploration is how to accurately and easily log the drop positions and identities of thousands of acoustic listening devices or transponders as they are laid on the seabed during shallow water marine seismic surveys. Passive radio frequency identification (RFID) read/write tags from Texas Instruments (TI) provided an extremely effective solution allowing tags to be read at long range as the transponders leave the vessel at speeds up to 14 knots. They also operate reliably in one of the most hostile and difficult environments imaginable - where salt water, corrosion, bad weather, rough handling and the presence of substantial amounts of metal are just some of the problems.

In this new application, Sonardyne, one of the UK-based leaders in underwater positioning technology, has developed a system that uses RFID technology to identify and track the acoustic transponders used in undersea oil and gas exploration. Their systems are already in use with four different exploration companies in the Gulf of Mexico, off the east Indian coast, near Indonesia and soon in the Arctic.

The task was how to identify and record the position of up to 1,500 acoustic transponders attached to a cable as it is lowered from the survey vessel to the seabed, so that the seismic hydrophones can be positioned accurately and the seismic data correlated to that position.

The solution devised by Sonardyne International was to attach a multi-page TIRIS RFID tag to each transponder. Tags can also be attached to each section of the cable to provide improved asset management of the expensive cables sections. Each tag is programmed with a unique identity code and operators can use the tag's multi-page read/write capabilities to add data such as transponder serial number, battery date, cable identification, manufacturing and servicing history, date of next service etc., as required.

By reading the tag identity for each transponder as the cable is deployed over the stern, and logging its details along with accurate position information from a differential GPS system, the "drop" co-ordinates for each transponder can be automatically recorded and stored on a PC. These data are used to create a computer pre-plot file, which associates each transponder with its related acoustic ID and drop position. Once the seismic cables are laid, an acoustic survey is carried out where the exact positions of the transponders and, therefore, associated hydrophones are determined. Following this the seismic survey itself happens, an energy release is triggered - usually a high-pressure air bubble. The resulting energy travels through the seabed and the reflections obtained by the hydrophones from the different seismic layers are transmitted via the cable back to the ship. The seismic data are then correlated with hydrophone positions already determined by the acoustic survey and stored away. These data allow geophysicists to determine where oil-bearing rocks might be.

Sonardyne chose TI's TIRIS large 4.75in. x 0.75in. diameter cylindrical tags for their extremely long read range which allows tags to be read reliably at distances of 1.5 to 2m, even when leaving the vessel's fore or aft chutes at speeds of 14 knots or more. The tags are read by special antennae and readers located in the chute areas and the data passed to a PC in the control room.

"TI's tags feature a large ferrite area, which makes them ideal for use in difficult conditions where long read range has to be maintained even in the presence of large areas of metal and when the tags are moving at speed through the chute at 14 knots", said Simon Partridge, of Sonardyne. "They had the longest read range and highest data capacity of all the tagging systems we evaluated", he added. "Also their passive design means there are no batteries to discharge or replace and they operate indefinitely without any maintenance."

Another advantage of the RFID system is that it can also be used for asset tracking of cables. Any or all of the tag's 17 individual pages can be programmed to store data on the cable's history, manufacturer, purchase data, cable type, head type, repair data, etc. Since the tags are read/write types, the data can be updated as often as required. Sonardyne also provides a complete software package based on Microsoft Access for asset tracking and management.

The RFID system is also completely independent of the main seismic data recording system and so no modification of the seismic system is required. It is fully automatic with advanced error checking algorithms to eliminate data errors.

For more information contact: Graham Lane, RFID Components Ltd, Wolseley Road, Kempston, Bedford MK42 7UP. Tel: +44 (0) 1234 840102. Fax: +44 (0) 1234 840707; http://www.tiris.com