In this second article in our Seismic and Carbon Storage series, based on a conversation with Lee Hunt and Eric Street of Carbon Alpha, we dive into the revival of 2D seismic data and how it is tied to Carbon Capture and Storage (CCS).
In our last article, we described how 2D gave way to a preference for 3D seismic data. Factors like technological advancements, economic considerations, and geological insights led to the decline of 2D seismic data. However, the situation has changed, and 2D seismic data has made a comeback in North America due to unique circumstances. These circumstances revolve around a strong focus on economic factors and the scale of operations, both of which have played a significant role in the resurgence of 2D seismic data in the context of CCS.
Today’s CCS exploration approach closely mirrors that of international oil and gas exploration in new or less developed fields. In both cases, 2D is widely used to cover vast swaths of land and build a regional understanding of the subsurface structural complexity.
Eric explains, “Oftentimes you don’t know where to focus initially and where to site a 3D. So 2D is a very effective tool for such regional exploration of areas. It helps us to decide where we should focus further investments in information, in a method called play-based exploration. And so, in the international realm, [2D] has seen a lot of usage, but definitely in Canada, that’s fallen to the wayside.”
The infrequent use of 2D in North American onshore plays is likely because of basin development and evolution. There is now a high density of wellbore penetrations to draw insight from. That and conventional opportunities have largely been mapped. Over time, the focus has shifted to localized and highly specific, small-scale project development that tends to require the acquisition of 3D seismic data.
But that is changing. “Speaking about bringing 2D back and going ‘back to the future’, it’s a little bit like going back in time here in Canada,” muses Lee. “The rise in CCS projects, worldwide – there’s something like 200 or so that we know of that are in progress – this is a lot of projects suddenly. It’s brought a real new emphasis [on 2D] in Canada and on land. And like Eric said, many of these storage complexes must be treated as if they are in an exploratory stage,” says Lee.
CCS storage complexes are very large – some of them 150 or more townships in size. “How are we going to get an understanding of the gross fabric? Of structures and risks?” asks Lee, “This is a big area to cover.”
As it turns out, 2D is the perfect tool to gain this regional understanding.
—> Curious about CCS? Read the recent Carbon Alpha CSEG RECORDER article
Companies may explore a large region or multiple potential sites before making an investment decision. In this scenario, 3D is inadequate – both from a cost and a coverage perspective. For some actors (initiators of CCS projects), this is not a problem. Lee clarifies, “If I was a company like Shell, which has Quest, or another E&P company, I might have come with a legacy of [seismic] data…I might have just owned a lot of seismic data because I was using it for other things.”
However new actors may not be oil and gas companies with the benefit of seismic data and expertise. “Say I’m a power plant company or a cement factory,” Lee explains. “It’s very unlikely that those kinds of companies, even pipeline companies for that matter, are going to own a significant amount of seismic data. And so, for these people now, they’ve got these big areas. They’re thinking about storing a lot of CO2. They may be considering numerous potential storage sites and therefore need to cover a lot of subsurface but [have] no legacy data. So, they’ve got to build that up. And it’s almost like starting all over. You’ve got to decide – where should I focus? And maybe later you get into things like 3D. It’s very circumstantial.”
For companies without the benefit of a seismic catalog, the purchase of 2D is the best solution to identify and characterize potential storage targets while keeping costs down.
Scale and economic circumstances have resulted in 2D seismic making a big comeback. Price and widespread availability in Canada and North America make 2D an attractive option for exploring large areas.
Unfortunately, when 2D was displaced by a preference for 3D seismic data, training and expertise also shifted toward 3D seismic, causing a skill gap. With the resurgence of 2D, we may have a big problem ahead of us. In our next article, we explore the issue of 2D bias and expertise in today’s CCS sector. On to Part 3!
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