SEISMIC ACQUISITION SYSTEM
There is consensus that the different marine seismic acquisition systems offered to customers each have limitations: towed streamers deliver great productivity, but suffer from the limitations of an essentially linear shooting and recording array, and the noise generated around the streamer at 5 knots average speed. Sea bottom systems using cables or nodes deliver superior full azimuth data, but their low productivity results in very high costs and long survey durations. The FreeCable system is the result of 5 years of concepts, designs, prototypes and full scale trials. It started with a challenge to offer customers better quality data without the time-consuming and onerous aspects of sea-bottom acquisition systems. The outcome exceeds expectations.
REDEFINING MARINE SEISMIC DATA QUALITY
This totally new concept delivers the broadband data you need, with full and well-distributed offsets and full azimuth coverage. And the productivity is truly amazing, with a typical production of 15km2 per day and upwards depending on survey parameters.
The receiver array consisiting of 10 to 20 MSC units is placed in mid-water, at a depth well below sea swell, and it is kept stationary or near-stationary to reduce noise to a minimum. 4C sensors eliminate notches and record valuable additional information. The shot lines are perpendicular to the receiver cables, with long offsets.
Leveraging the power of autonomous robotics to maintain 10 to 20 independent cables stationary at depths from 10 to 100 meters, the FreeCable system is the answer to the E&P industry’s quest for the best data quality delivered within tight time-frames.
THE SUPERIOR DATA QUALITY AND AZIMUTH RICHNESS
YOU EXPECT FROM SEA-BOTTOM SYSTEMS,
WITH THE PRODUCTIVITY OF TOWED STREAMERS.
The data you need
Full azimuth coverage, with near and far offsets (up to 16km) that are evenly distributed, and with fold in the 100s for 12.5m x 12.5m bin sizes. The frequency content goes from 2-3Hz to 150Hz and above, without ghost or notch to worry about.
Environmentally friendly
Marine mammals and other environmental concerns can be handled using lower energy sources; with a 23dB signal-to-noise advantage compared to towed streamers, FreeCable can operate using smaller airgun arrays.
Full 4C recording
Straightforward and easy deghosting through simple PZ sum Separation of downgoing and upgoing waves
Unique flexibility
Go where you need to acquire data, FreeCable can operate in shallow water as well as in the high seas, and even in closed water bodies such as lakes. The system is fully operable in congested areas around production platforms, facilities and natural obstacles. The receiver geometry (cable length and spacing) can be adapted to operational and geological requirements.
Field proven
The FreeCable system has been deployed for full-scale acquisition projects, and delivered on its promise of round-the-clock production, realtime monitoring of data, accurate cable depth and position control, highest standards for HSE and outstanding data quality.
“...they do see signal [...] which they couldn’t see before from other acquisitions in the same areas.”
THE MIDWATER STATIONARY CABLE CONCEPT
A Midwater Stationary Cable or MSC, consists of a neutrally buoyant cable comprising 4C sensors, depth sensors and automatic ballast units, positioned by two Recording Autonomous Vehicles (RAVs) at each extremity that also provide power to the cable and depth control system, and host the recording equipment. The RAV transmits the data to the control vessel, where real-time QC ensures the integrity of the data recording process.
FreeCable is simple and elegant, with a wealth of new technologies developed specifically to position a stationary receiver array at water depths that avoid wave and weather noise, and independently of the source vessels. This allows total freedom to design the offset ands pacing that best addresses the proper illumination of the target formations. Full azimuth, a full range of offsets, a broadband frequency range, a high signal-to-noise ratio, all delivered at remarkable daily production rates.
FULL INDUSTRY STANDARD PROCEDURES
The FreeCable system has been deployed for full-scale acquisition projects, and delivered on its promise of round-the-clock production, realtime monitoring of data, accurate cable depth and position control, highest standards for HSE and outstanding data quality.
THE BENEFITS OF A SMALLER FOOTPRINT
Go where you need to acquire data, FreeCable can operate in shallow water as well as in the high seas, and even in closed water bodies such as lakes. The system is fully operable in congested areas around production platforms, facilities and natural obstacles. The receiver geometry (cable length and spacing) can be adapted to operational and geological requirements.
