Rhonda Duey, Contributing Editor
The Permian Basin has gotten so much ink lately that it might seem like poking a hole anywhere will result in a barnburner well. But that’s not actually true. Sometimes seismic can actually make a difference between a great well and a dud.
That was the message delivered by David Paddock of WesternGeco at a recent Geophysical Society of Houston luncheon. While WesternGeco is no longer actively engaged in seismic acquisition, it still prides itself on processing and interpreting seismic data. Paddock outlined two projects in the Delaware Basin where seismic made a difference.
“The industry tries to pigeonhole us early in the life of the asset,” he said. “They want to use us for structure [and] for landing these wells. But really, we use seismic over and over again.”
He added that this recent work includes characterizing stress, the rock and natural fractures. “That really gets you into the realm of the completion design, and once you get the wells under production, you start to understand what the production drivers are and utilize those learnings. You keep going back to seismic throughout the life of the asset,” he said.
According to Paddock, 72% of the wells in the Wolfcamp are economic. But WesternGeco geophysicists were challenged with determining why 28% of the wells weren’t.
The company chose 22 wells based on multiple sources of data. Based on its estimates, only 10 of the wells in the study area were economic. “It’s actually a bit of a train wreck,” he said.
While the study checked for silicaceous rock, even the best rock had only 7% porosity. Some of these wells had a very small ROP. The seismic showed that the reservoir was not consistent across the entire area despite previous models.
“You can’t just frack your way to success,” he said. “You need hydrocarbon-filled porosity for this to work.”
Some of his examples showed wells where either the operating company didn’t believe in using seismic or a company had a rig on location and had to drill up its acreage before seismic was available. These wells often missed their targets.
Paddock said most companies working in this area are drilling up the Wolfcamp A Formation and will soon be turning their attention to the Wolfcamp B. “You can actually start to do some exploration here, which as a geophysicist I find exciting,” he said, adding that current data indicate the quality of the shale. For instance, the more silica that is involved, the more porosity is likely to exist.
Water is another issue. Faulting in the region can bring in water not only from the Pennsylvanian and Mississippian formations but also from the shallower Delaware Formation. “If you drill too close to these faults, it will be an issue,” he said. Fine-tuning the fault attributes has helped the company in the North Sea and is likely to be useful in the Permian Basin as well.
“This is the cool stuff you can do with seismic,” he added. “The dirty little secret of 3-D mechanical earth modeling is that you have a pretty good idea of your tectonic stresses. You know what the stiffness is.
“You can go into your mechanical earth model and dial up and down the ‘stickiness’ until it matches the model. We think that you can predict induced seismicity using seismic data as your primary measurement.”
Rhonda Duey’s Exploration Technologies column originally appeared in the December 2018 issue of E&P.