WesternGeco and Teledyne have partnered to advance seismic exploration technology with the development of the eSource, a bandwidth-controlled seismic source aimed at reducing sound exposure to marine mammals.
This innovative solution effectively suppresses frequencies outside the main seismic range while ensuring the energy output required for reliable surveys.
The Project
Evolving environmental regulations worldwide demand more advanced tools for seismic exploration. As we learn more about the hearing sensitivities of marine mammals, the need for an acoustic energy source tailored to environmentally responsible seismic exploration has grown.
The airgun, a well-established method, was selected for modification to meet the requirements of eco-friendly oil and gas exploration.
Challenges
Offshore seismic survey energy sources typically operate at sound levels that may disturb marine mammals, including whales, dolphins, and pinnipeds (seals and sea lions).
The challenge was to develop a bandwidth-controlled seismic source that reduces sound energy in the frequency range to which cetaceans are most sensitive, while still providing the necessary seismic bandwidth for effective survey operations.
The project required a high level of engineering precision due to the need for greater mechanical control and sophistication. The airgun’s mechanism had to be re-engineered to exert more accurate control over acoustic spectral emissions.
It was also essential that the new design meet or exceed current reliability standards while being a direct drop-in replacement for existing sources, compatible with all current array infrastructure and airgun controllers.
Evaluating Technical Innovations
WesternGeco and Teledyne collaborated to develop the eSource, a bandwidth-controlled seismic source that suppresses frequency content outside the main seismic range. This reduces marine mammals’ exposure to sound while still providing the energy required for a reliable survey.
Alternative technology options included retrofitting current airguns with mechanical mufflers and using marine vibrators designed to emit continuous acoustic energy rather than impulsive signals.
While these alternatives have significant merit and advantages for seismic surveys, none match the reliability of a purpose-built airgun mechanism.
Learn more about the Teledyne Marine eSource >>
The Final Technical Solution
The final design incorporates a mechanical acoustic filter that combines two complementary technologies.
First, the exit ports expelling air into the water were specially designed using computational fluid models to limit higher-frequency content during the airgun’s actuation.
Second, the internal airgun mechanism was re-engineered to apply more precise control over the fast-moving valve that releases air through the ports.
This design achieved the target of up to 40dB less spectral amplitude above 100Hz, while maintaining the necessary energy below 100Hz for seismic exploration.
Benefits of the new approach
This environmentally conscious airgun design allows for more favorable negotiations with environmental organizations during the permitting process for seismic surveys.
Benefits include potentially faster survey completion and reduced costs, as fewer alternative mitigation measures may be required to protect marine life.
For large-scale surveys, this could lead to significant savings, potentially in the millions, and increase competitiveness when bidding for contracts.
Learn more about the Teledyne Marine eSource >>
