The 85th anniversary of SEG’s Annual Meeting provides an opportunity to reflect on the technological progression of onshore seismic acquisition equipment. While great strides have been made in improving acquisition systems and sensors to meet more demanding imaging requirements, great progress also has been made in the area of vibrator source technology.
In 1995, Input-Output acquired vibrator technology from Western Geophysical. Six years later, the company purchased the Pelton line of source controllers. These acquisitions extended Input-Output’s portfolio beyond seismic systems to include a complete line of source products. Input-Output later changed its name to ION Geophysical and in 2010, together with BGP Inc., formed INOVA Geophysical in a joint venture focused on land seismic equipment.
Through INOVA’s history of vibrator vehicles, the articulated hydrostatic vehicle (AHV) series of large-scale vehicles has had the greatest longevity. First introduced in 1989 and in production at the time of purchase from Western Geophysical, the AHV-III 362 model offered 61,000 lb of peak force and a frequency range of 5 Hz to 250 Hz. In a similar weight class, the AHV-IV 362 model vibrator followed in 1996 with frame and baseplate improvements as well as a patented mass structure design to prolong mechanical life and enable long-term field reliability. Demand for greater peak force to image greater depths over long offsets and to allow greater energy penetration on less-than-ideal surface conditions prompted the advancement of the AHV-IV 380 heavy vibrator in 2006, which offers up to 80,000 lb of peak force.
More recently, increased interest in broadband recording resulted in the AHV-IV 364 Commander vibrator. With a peak force of 61,800 lb and a frequency limit of 1 Hz to 250 Hz with maximum peak force from 5.18 Hz, the 364 unit was the first in a series of INOVA vehicles specifically designed for broadband frequency generation. The 364 large-scale vibrator included mechanical, supply pressure and servo valve system improvements designed for better low- and high-frequency performance.
Broadband requirements, coupled with the need for a smaller footprint to access difficult or environmentally sensitive areas, propelled the recent development of UNIVIB. This small-class vehicle provides flexible holddown weight variable from 18,000 lb to 26,000 lb and a wide frequency range from 1 Hz to 400 Hz, dictated by ground conditions and source controller settings, including drive level, peak force and hold-down weight. A second version, UNIVIB 2 is under development with the gross vehicle weight range shifted upward from the first UNIVIB, encompassing 24,500 lb to 36,000 lb.
These source vehicles are part of INOVA’s CLARITY Broadband Solution, which includes broadband digital sensors, high-performance cable and cableless acquisition systems, and advanced source controllers.
Source control has been an integral part of INOVA’s vibroseis technology. Beginning with the acquisition of the Pelton Co., the Vib Pro source controller experienced success due to its ability to control amplitude, phase and distortion. Launched earlier this year and developed in partnership with Seismic Source Inc., the Vib Pro HD (high definition) is the latest source controller from INOVA and offers a modern digital platform.
