What Do Fractures Look Like? A Picture Says A Lot, Even When It is Wrong

Photo courtesy of Terry Engelder, Penn State University.
The 300-ft tall fractured outcrop in upstate New York shows the lower portion of the gray Ithaca shale over the upper part of the black Geneseo gas shale.

When it comes to fracturing, experts argue about many things, but they agree that fractures do not look like lightning bolts, tree roots, or shattered glass.

The sight of an image in a recent National Geographic story showing a hydraulic fracture that looked like a lightning bolt spurred Terry Engelder, a professor of geosciences at Penn State University to call the editor and complain.

The geologist, whose work has long focused on natural fracturing, was spurred to action by a long-standing complaint: “Invariably illustrations of fracturing look nothing like the real thing,” he said. Real hydraulic fractures are likely to look like natural fractures. Hydraulic fracturing typically opens existing cracks, which means the fractures will generally run along the planes of natural fractures.

So the picture of hydraulic fractures used to stimulate wells in the Marcellus Shale should be like the natural fractures crisscrossing the vast formation, which have been studied for more than a century.

Engineers have also noticed the problem with fracturing cartoons, and even SPE has gotten complaints.

“They do not look like tree roots. Things do not shatter like glass and run in all directions,” said Norm Warpinski, a Halliburton fellow for Pinnacle, Halliburton’s geophysical testing service. Fracture “complexity has to be consistent with pre-existing geologic features.”

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What Do Fractures Look Like? A Picture Says A Lot, Even When It is Wrong

Stephen Rassenfoss, JPT Emerging Technology Senior Editor

01 May 2015

Volume: 67 | Issue: 5