A few holdouts remain, but most geologists today would never consider trying to generate prospects – or attempt most any E&P pursuit – without the aid of some form of 3-D seismic data.
In fact, it’s only natural to think of geologists and geophysicists as being totally in sync these days, eagerly discussing inversions, spectral decomposition, etc., even while socializing in their off time over a cold brew.
Think again.
There’s work to be done on the part of both groups before they each can fully understand and best utilize what the other brings to the table, according to Bruce Hart, director of Shale, Seal and Pressure Systems Group at ConocoPhillips in Houston.
The good news: This is certainly doable, as Hart points out when he discusses new directions in seismic stratigraphy.
“In the 1970s, the good folks at Exxon gave us seismic stratigraphy,” Hart said. “This was a method of using reflection geometries – terminations, facies, etcetera – to evaluate sea level change, try to predict lithologies in exploration settings, and so on.
“That approach eventually morphed into sequence stratigraphy,” Hart continued, “where people integrate seismic data with well information or outcrop or core or other types of information.”
Out of Tune?
Typically when most sedimentary geologists are working with seismic data, they work with conventional seismic. With the advent of 3-D seismic, stratigraphers could see plan-view images of depositional systems, which considerably enhanced the interpretability of the seismically imaged strata.
“While all that was going on, geophysicists were developing a whole suite of tools to independently predict rock properties,” Hart said, “independently in the sense it’s independent of seismic sequence analysis.
“So, they have things like seismic inversion that allows them to predict acoustic impedance in various ways, and they use seismic attributes to try and help predict rock properties,” he noted. “And sometimes they use multi-component seismic data – or shear wave seismic rather than P-wave – to look at rocks.
“My observation has been that in a lot of companies, the sedimentary geologists, the stratigraphers tune out when they see inversion results or seismic attribute-based results,” Hart said. “Either that, or they’re not granted access to those types of volumes even though sometimes these volumes can show stratigraphic features you can’t see in original seismic data.”
“In a lot of cases, sedimentary geologists will hear people talk about simultaneous inversion or Lambda-Mu-Rho volumes or various other things related to physics,” Hart said. “Then the geologists get cold feet and back off.”
Stratigraphic Gap
He proposes that stratigraphers should become more involved in working with the results of these physical properties predictions or the multi-component seismic data, emphasizing this will help them to be better stratigraphers.
Hart noted that in the 1960s and 1970s, members of the sedimentary geology community jumped onto the physics bandwagon when they decided they needed to understand how fluids transport sediments.
“I think a modern crop of sedimentary geologists could do the same,” Hart said. “They could jump on the geophysics learning curve and become better stratigraphers because they understand how to use the new technology.”
Given the growing recognition globally that the industry needs to be focusing more on stratigraphic plays, understanding the stratigraphy is key.
It’s becoming essential to remove the roadblocks to doing so.
“If the stratigraphers don’t understand the geophysics and the geophysicists don’t understand the geology, there’s a gap in communications,” Hart said. “There’s a crack things can fall through.
“I think there’s a real need for people to comprehend how to milk the stratigraphic features out of the seismic data,” he emphasized, “and I think in a lot of cases that’s just not happening.
“Traditionally, I think new hires come out of geology programs not understanding a lot about seismic data,” Hart said. “On the other hand, geophysicists come out not necessarily understanding a lot about stratigraphy.
“With time, hopefully the corporate culture will allow those people to get closer together,” he added.