Imagine powerful land-based seismic sources that can be controlled and monitored remotely from a desk. Envision small yet powerful marine vibratory sources that can project variable frequency energy into the water for days in precisely programmed sweeps that are consistent and repeatable. GPUSA Inc. has integrated factory automation technology, programmable logic, touchscreen control and variable frequency drives with downhole and marine vibratory sources.

Marine vibrator
Airguns are small, powerful, reliable and have been a staple in the marine seismic industry for 40 years. For more than a decade, the oil and gas industry has been searching for an alternative to the airgun, with a marine vibrator replacement being seen as the “holy grail.” But designing a high-power, low-frequency marine vibrator with a reasonable size, weight and cost is challenging. To be practical, a marine vibrator must have dimensions much smaller than the wavelength of the sound that it produces. For example, at 100 Hz the acoustic wavelength is about 15 m (50 ft), but an acceptable size for a marine vibrator is probably .91 m (3 ft) or less. Achieving high power at low frequencies from a small transducer requires very large volume displacements. The “in the box” solution is to use a magnetostrictive material with very high displacement. However, even a .91-m stack of Terfenol-D, which has the highest magnetostriction of any alloy, provides only about 1/16 in. of displacement. Despite this, several companies have developed innovative transducer designs that leverage these small displacements into larger ones. GPUSA’s approach uses small, powerful motors capable of producing displacements up to 100 times larger than equivalently sized magnetostrictive actuators.

Downhole vibrator
Most in the industry would agree that using a downhole source is like trying to use a squirt gun to put out a forest fire; it just doesn’t have enough power to do the job. Times have changed. GPUSA’s downhole vibrator 2.5-in.-diameter tool that can be held in one hand. It also includes a built-in accelerometer tested to withstand a gravity force of 5,000 to track the vibrator’s output for real-time quality control and deconvolution post-processing with the received signals. No clamps are necessary, and all the bells and whistles needed to synchronize with the rest of the seismic equipment are accessible via water-tight connectors without opening the front panel.

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