Over the course of recent decades advances in seismic data acquisition, signal processing and modeling have made subsurface imaging better than ever. Seismic surveys have evolved from 2D to 3D with the introduction of more sophisticated towed streamer and positioning systems. To allow the detailed investigation of both seabed and shallow subsurface structures, high-resolution or ultrahigh-resolution 3D imaging is needed.
Projects related to offshore construction, shallow exploration and risk assessment, can greatly benefit from the use of these high-resolution techniques. It is specifically applicable to the challenges brought by renewable offshore industry. The search for fully fit-for-purpose systems has been on-going and the industry has been keeping a close watch for improvements that can increase data quality in a cost-effective and environmentally responsible manner.
It is towards these goals that Sercel has channeled research and development efforts. The leader in seismic equipment has partnered with Kappa Offshore Solutions(1) to integrate its well-proven Sentinel® streamer and Seal recording system into a completely new hydrodynamically efficient solution that will meet industry requirements for precision high resolution mapping. Born out of this collaborative work is PIKSEL, a high resolution 3D marine seismic solution that promises the sharpest and most accurate images of the subsurface thanks to its innovative and efficient design.
Less noise, better signal for enhanced data quality
One of the main challenges in seismic surveys is to limit unwanted noise and vibrations that interfere with the signal being acquired and degrade final data quality.
The PIKSEL's hydrodynamically efficient design contributes significantly to overcoming these noise and vibration affects. One of the principal innovations incorporated is the system’s ingenious rigging system (one feature of which is the use of a novel horizontal deflector design) as developed by Kappa Offshore Solutions to reach greater towing depths and therefore mitigate swell noise. Extensive work has also been carried out to ensure as “clean” a hydrodynamic design as possible. Parasitic effects due to cumbersome cables are reduced while the overall shape of the system itself helps to attenuate any noise induced by cross-cable vibration.
In addition to this portfolio of characteristics that contribute to noise immunity, PIKSEL is also fully compatible with the entire range of Sercel Sentinel streamers. The Sentinel design incorporates a clever hydrophone design - each hydrophone element being isolated from the hydrophone carrier, which is itself isolated from the cable. With field proven design and materials, Sentinel streamers are less sensitive to noise originating from sea swell effects and provide industry leading immunity to towed equipment induced vibrations. As a result, Sentinel provides unsurpassed signal to noise performance with improvements of 20 dB over that of fluid filled streamers. For maximum bandwidth and even sharper definition, PIKSEL can be combined with Sercel’s top of the range Sentinel MS streamer. Over and above pressure measurements, this multi-sensor streamer features two accelerometers offering directional measurements for both cross-line and vertical wave fronts, thus providing a complementary signal that is used to compensate for frequency losses due to ghost effects.
Higher productivity for a cost-effective approach
Productivity levels and operational optimization are key metrics when considering a project’s economic efficiency. We can in fact infer that the research and development work carried out to minimize adverse noise effects also serves to achieve superior productivity levels.
Due to PIKSEL’s reduction in vibration-induced noise, towing speeds of up to 5 knots are now achievable. This compares favorably with conventional systems whose speeds are generally limited to under 4 knots. Consequently data acquisition can be appreciably faster, reducing the time for project completion and data delivery for processing and interpretation.
Thanks to the combination of the optimized rigging system and the exceptional de-ghosting performance and robustness of the Sentinel MS streamer, towing depths of up to 10m can be achieved, while systems up until now could only achieve 3m. This deeper towing capability enlarges the operational weather window and facilitates continuous data recording, resulting in still better productivity.
Downtime due to maintenance and repair is also drastically reduced for two key reasons. Firstly, Sentinel is recognized to be the strongest streamer available on the market with a unique design that provides superior protection against hydrophone damage even under poor weather conditions. Secondly, to avoid the risks of streamer entanglement and damage, a double deployment process on each side of the vessel guarantees easy handling and a smooth launch. This configuration also offers the major advantage of being able to recover one half of the streamer array while leaving the other half deployed, a very significant time-saver when in-field maintenance measures are required.
Last but not least, PIKSEL is a flexible and compact system adaptable to all vessels including vessels of opportunity. This containerizable solution allows easy and safe handling, while, optimizing deck operations for better productivity and overall efficiency.
Environmentally friendly solution for environmental applications
In compliance with its in-house environmental policy, Sercel is excited to be able to provide its expertise in seismic surveys that address offshore construction for the marine renewable energy market. With the PIKSEL high resolution 3D marine acquisition solution, Sercel provides geophysical and geotechnical data acquisition with pinpoint accuracy for more efficient offshore wind farm construction.
Still in the context of environmental protection, measures must be adopted to avoid any harm or disturbance to marine mammals during seismic acquisition. In response to this requirement, PIKSEL can be equipped with QuietSeaTM, Sercel’s Passive Acoustic Monitoring system, designed specifically to detect & locate marine mammals in the vicinity of seismic operations. Seamlessly integrated within the Sentinel streamer, QuietSea ensures marine seismic operations can be carried out in an environmental friendly manner.
This unmatched portfolio of advantages is sure to make PIKSEL the system of choice for future high resolution marine seismic acquisition needs.
(1): Kappa Offshore Solutions is a marine engineering company, specialized in offshore seismic data acquisition. Since its inception in 2012, Kappa Offshore Solutions has delivered more than 130 projects in more than 30 countries, providing technical assistance services and seismic equipment for major clients in the Oil & Gas, Defense, Maritime and Oceanographic Research industries. More information about Kappa Offshore Solutions is available at www.kappaoffshoresolutions.com.