Seismic Data: The Hunger for the Lowest Frequencies Takes Data Gathering in New Directions

The Western Trident, the second vessel equipped with IsoMetrix technology. With 4.2 Petabytes of disk storage, at the time of launch it represented the third-largest computer center worldwide for Schlumberger Geosolutions.

The word “broadband” is used to sell a lot of what is new in offshore seismic. It can mean different things depending on who is speaking. But most often, it is applied to things used to gather scarce signals at the lowest frequencies.

Gathering more low-frequency data is the “holy grail’ in broadband, said Craig Beasley, chief geophysicist at Western­Geco, which is part of Schlumberger.

They are valuable for determining rock properties and imaging deep formations. Seemingly small gains can be big. “Moving down from “3 to 1.5 (Hz) does not sound like a lot. But in octaves, it is a whole other octave,” he said.

The appetite for these scarce signals has driven innovation is many forms, which reflect how marketing, science, and patent law combine to differentiate products in this competitive sector.

The methods used to maximize the low-end signals include varying the depth of the streamers, towing streamers at an angle, which also varies the receiver depths, and adding different types of sensors to receivers. All rely on processing to extract the maximum amount of usable signals, and some rely on processing alone.

The range of options exists because the goals, budgets, and evaluations of what works varies from job to job and operator to operator.

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Seismic Data: The Hunger for the Lowest Frequencies Takes Data Gathering in New Directions

Stephen Rassenfoss, JPT Emerging Technology Senior Editor

01 October 2015

Volume: 67 | Issue: 10