Stress not Pressure Shows the Way

Stress not Pressure Shows the Way

Rosemary Jackson  •  

Well interference: It’s a multivariate question. knows how to address multivariate.

Well interference: It’s controversial. knows how to analyze a complex controversial system.

Well interference or cross-well communication between existing production wells (parent wells), and newly fractured infill wells (child wells), is a story of constantly changing conditions. New incursions into the Permian shale alter the factors for the next layer of production. Pressure and stress are just two of the interconnected variables that create a tangled geomechanical system that's hard to read accurately or conclusively, as observed in a study assessing interference between parent, child wells in horizontal pad developments.

“Engineers look at pressure responses,” Dr. Troy Ruths, CEO of cautions. “They monitor the pressure in the nearby wells to see the response. That’s expensive. And people don’t stop even if they are getting the pressure ramp.”

“The key is to know if you’re going to frac into a well, even before you do the frac job,” Ruths continues.

“People talk a lot about frac hits, but a frac is going to hit lots of wells. These things are very planar, they’re very high energy and they go very far. The question is, are those frac hits affecting production? And you don’t see that right away. Are you going to stop a job because you see a pressure response on a nearby well? No. Instead, what you need to do is actually plan how you’re developing your acreage and make sure that you’re frac hitting parent wells that have produced for a long period of time and they’re past 80% of their production.”

The oil and gas industry is at a critical juncture where determining optimal spacing is more important than ever but it’s still not a straightforward process. A reflection in the Journal of Petroleum Technology underscores this difficulty, “Within the SCOOP/STACK play, child wells completed in 2017/2018 have been half as productive as their 2015/2016 parent wells, a trend theorized to be directly related to negative fracture interactions.” Predicting and watching pressures change at the wellhead is difficult, while the direction of SHmax stays the same. v5.5

With the Frac Hit Scenario app in the platform, you can explore the options before they happen. Embedded in the software is the stress map created by Dr. Mark Zoback of Stanford University.

Kyle LaMotta, VP of Analytics at explains, “It doesn’t matter which way you drill the well, the frac is going to go the way the frac wants to go. And the frac wants to go in the direction of SHmax. What our tool lets you do is identify what might have affected or will affect production.” v5.5

Right now, the Frac Hit Scenario resources the horizontal SHmax. Soon, the vertical frac gradient will be added. “It’s so important,” Ruths urges, “All you need to do is characterize the stress. Then, you’ll know if your wells are fracking into each other in reasonable ways even before you put the well in.”

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