What's new in exploration

A decade-and-a-half ago, I was sitting with my fellow employees in the PGS offices in Houston. The topic of conversation, as it had been for a while, was the emerging Ramform design. We were just completing the new Ramform V’s (Valiant, Vanguard and Viking). Two earlier Ramforms (Explorer and Challenger) were working, having been commissioned in 1995 and 1996, respectively. We were proud of—and a bit in awe of—the vessels. Their broad beam astern allowed for a dramatic increase in the number of streamers that could be towed, significantly increasing the amount of seismic data that would be collected. Other companies followed suit, in non-Ramform ways. It was a young, innovative company, driving an important change in the industry.

Fifteen years on, the Ramform design continues to evolve in the Ramform Titan and Atlas. The two 2013 additions to the PGS fleet follow the Ramform Sovereign and Sterling, larger versions of the originals that can tow 22 streamers. The new Titan and Atlas can tow 24 streamers, covering an area greater than 12 km2, the size of 1,500 soccer pitches or 3.5 times the area of New York’s Central Park. They carry over 6,000 tons of fuel and equipment, providing 150 days of endurance. The vessels can accommodate 80 crew members in 60 single cabins and 10 twin cabins. All in all, the new vessels are a significant extension of the older ones but still true to the intent and design. Therein lays the theme of this column—it took a while to get there.

Subsea seismic concept. The U.S. Department of Energy’s National Energy Technology Laboratory (NETL—where I toil away) funds a number of interesting and valuable research projects, both internally and through the Research Partnership to Secure Energy for America (RPSEA). Among the most successful R&D projects funded by NETL, RPSEA, and an industry consortium headed by Lockheed Martin is the project to develop an autonomous underwater vehicle (AUV) with sonar and sensor capabilities that allow it to be deployed autonomously, to inspect and image seafloor topography and underwater structures.

While referencing that project not long ago, my mind began to wander. Why had someone not thought of using AUVs to conduct seismic shoots offshore? The benefits, to my untrained mind, would be enormous. Most importantly, such a subsea seismic system would isolate signals from variations in marine thermal layers and multiple sources of subsea noise. While it might be an engineering challenge, surely it could be made to work, or at least tried. I was not, by a long shot, the first one to think of this. Work on the idea started about the same time that PGS adopted the Ramform design.

The idea of using Ocean Bottom Surveying (OBS) to enhance seismic quality is not new. Discussions began more than 15 years ago, or about the time that Ramform vessels went to sea. Few disagree that OBS produces superior seismic imaging. The problem is cost. Deploying sufficient nodes in a timely, cost effective manner has, generally, been problematic. It can take weeks to deploy subsea nodes precisely over a large grid.  Not long ago, deployment of a 5,000 node subsea spread could take up to 5–6 weeks. Visualize the value added, if that deployment could be cut by a factor of five, to a little over a week.

That was the perceived opportunity 12–15 years ago. AUVs containing nodes would be dropped, one at a time, from a moving vessel at a rate of around one per minute. They would maneuver into precise position on the seafloor and record the shoot. When finished, the AUVs would deballast and rise to surface, to be retrieved by the deployment/shooting vessel. This brilliant idea is not dead yet.

Recent work/development. A recent collaboration between CGG and Saudi Aramco aims at developing just such a system.  According to CGG, under terms of the SpiceRack project, CGGVeritas and Saudi Aramco will work in partnership to develop, manufacture and commercialize an innovative robotized solution for seabed seismic acquisition. Based on the deployment of self-propelled recording nodes, this solution should lead to a step-change in the efficient delivery of reservoir quality seismic data. Should the project be successful, it will bring to fruition one of the two most promising, marine seismic solutions from years past. The other, of course, is a step change in the number of streamers capable of being deployed.

We worked with both challenges at PGS, and across the seismic industry, all those years ago. Deploying more streamers came to pass. Widespread, automated AUV subsea node deployment and retrieval is still in the wings. Why? Some will say costs were too high, the technologies too challenging, the supporting technologies non-existent. Maybe, but, maybe it is the premise that it is an idea, whose time has now come. Consider automated drilling. It was first invented, and built, in the 1930s but it did not gain widespread adoption until the 1990s. Since its adoption, it has cut drilling times and LTIs dramatically. Go figure.