Founded on Innovation
The Strong and Silent Type
In 1993 PGS was getting ready to launch its latest 3D seismic ship, the Nordic Explorer, towing up to 5 seismic streamers – almost twice as many as its competitors. Acquisition Manager Einar Nilsen was at Langsten yard on the west of Norway, when he saw a pale gray vision of the future: the mysterious Marjata, a Norwegian navy spy-ship. This delta-shaped maritime Mata Hari was designed to lie quietly and listen for Russian submarines in the Arctic. Extremely stable and broad in the beam, she was built to withstand top-ice but all that space had other potential in Einar’s mind. He met the designer Roar Ramde and explained a bit about multi-streamer seismic operations. Then he got on the phone to the PGS offi ce at Lysaker to tell them that the holy grail of seismic had been found. Within a few weeks PGS agreed to build the first two seismic Ramforms, tying the design indelibly to the PGS brand.
Ocean Bottom Seismic (OBS) is one of the best technologies not to make it big in seismic. Pressure and velocity sensors collocated in the same cable are placed on the seafl oor, well out of the weather window, offering clearer 3D images in shallow water and obstructed areas, and more effective multiple attenuation. PGS attempted repeatedly to get the idea to work in the mid 1990s, with towed and dragged arrays, using two sensors 2C and four sensors 4C (FourCe) before dropping out of the fi eld in 2005. Unfortunately the market was too small to make it a profitable business. Though OBS fans insist that its time will come, this technology has so far failed to thrive. Processing remains a challenge, especially those pesky converted waves and operational efficiency is low compared to modern towed streamer operations. Technologists still like the science, but economists are not keen on the ROI.
Funny Shaped Boats
In 1996 PGS' Chief Operating Officer declared his vision of PGS as “the company with the funny shaped boats”. The Ramform seismic design was a fantastic success. Unfortunately, attempts to bend the shape to fit everything from a floating production vessel, to a well intervention ship and drilling platform proved increasingly difficult to pull off. The Ramform production ship was not destined to have the same revolutionary effect as the high-tech Ramform seismic vessel. While the delta-shaped seismic vessel has become an icon for PGS, the production and drilling boats may have been a case of blurred vision.
Stand Up and Be Counted
Using the vertical cable method, strings of seismic receivers were suspended vertically in the water column, held at the surface by submerged floats and fixed to the seabed by anchors. In theory, the 3-dimensional receiver grid allowed endless flexibility in acquisition geometry, both azimuth and offset. It seemed ideal for smaller complex surveys, especially in obstructed areas. However, the model was difficult to emulate in real life, as currents twisted the perfect lines into less desirable formations. The market never materialized. Just one customer was interested in sponsoring this technology.