Well into the shale revolution, operators still don't fully understand where proppant goes or how much reservoir rock they’re actually accessing. Could robots help?
Experts repeatedly returned to some of the industry’s biggest challenges, including the need for methods that can verify whether completion designs are working as expected and how to scale successful pilots during the “Breaking Through the Recovery Factor Barrier—Novel Approaches To Increase Estimated Ultimate Recovery (EUR) From Existing Reservoirs” panel at SPE’s Annual Technical Conference and Exhibition in Houston on 22 October.
Matthew Jones, chief completions engineer at Occidental Petroleum Corp., said while much work has been done to understand where proppant is being placed within fractures, a key unknown remains: where it goes beyond the fracture network.
“Anything that can be done to further inform that would potentially be a game changer,” he said.
Birlie Bourgeois, general manager for Chevron’s applied technology solutions shale and tight business, said certain diagnostics offer indicators about where proppant is going.
“Fiber will tell us where the stress is going. Tracers can kind of tell me maybe how far away it got, but we really don’t know. And that’s a really important problem for us to understand where our proppant is. I would love for the labs or someone to come and say, ‘I’ve got some great proppant robots that can report back and give you almost like an anthill view of where it’s going.’ But until we get that, it’s good old-fashioned reservoir engineering.”
The ability to break rock differently to "fundamentally change how we’re going to get access to the rock” rather than generating planar fractures would increase the surface area and lead to better reservoir recovery, he added.
“Pumping high-pressure, high-volume water and sand makes a lot of oil and gas production,” he said. “The technology system does not exist to break the rock differently. And we did a fairly broad and public call for technology earlier this year to try to open that aperture. I mean, there’s really cool ideas out there, but there's nothing that’s really even yet at the pilot or proof-of-concept stage.”
Testing Ideas
Alexandra Hakala, activating director for the US Department of Energy’s Oil and Gas Center of Excellence at the National Energy Technology Laboratory, said her group “loves looking at crazy questions.” Presenting the team with a problem offers the opportunity to figure out how to answer it. That may come in the form of lab work to explore the questions, she said.
“Crazy questions” aside, a lot of what the DOE has focused on centers on fundamentals, she said.
“What are the actual mechanisms and processes that are happening in the reservoir that we even know how to monitor and diagnose? Are we interpreting signals correctly?” she asked.
She sees an opportunity to continue evaluating new treatments “and making sure that whatever we’re seeing happening in the field, it’s verified by some types of physics-based effort, either experimentation or modeling or some combination of all of the above” as the center works to put the puzzle pieces together to answer the industry’s big questions.
Kishore Mohanty, W.A. Moncrief Centennial Chair Professor in petroleum engineering at The University of Texas at Austin, said the industry needs better facilities for testing ideas.
“We do experiments in the lab, but they don’t simulate all the physics in the field.” He said the question is how to make experiments more realistic, particularly when working with small samples or at small scales.
“We need to build bigger equipment, and all of us at university can’t do that. We need national labs. We need facilities where we can do high-pressure, high-temperature, low permeability, large-scale experiments, which emulate what’s happening in the field,” Mohanty said.
Centralized testing facilities are needed, he said, because universities alone cannot handle such tests. And when an idea progresses to the pilot stage, he said, it’s important to focus on the right goals.
“The goal of a pilot is not to make oil. It’s to get the information that will help you in a lot of different places. When we design our pilot, that’s what we should do; not just to make the oil, but get the information,” he said.
Bourgeois said the important thing when it comes to pilots is to focus on uncertainty reduction rather than funding a science project.
“My goal in a pilot is [that] I’m not really as concerned about the cost. Are we doing the right pilot to solve the uncertainty and make the business decision we need to make?” he said.
Jones said it’s not always clear what a pilot project will reveal and hopes future pilots can be approved with less stringent criteria.
“When you go to present a pilot and say, ‘This is what the objectives are, this is what I want to learn,’ there’s still a lot of times where we don’t know what we’re going to find. But I guarantee we’re going to learn something that will be beneficial and further inform our decisions in the future,” he said.
And once a pilot does work, Bourgeois said, scaling presents its own challenges because every asset is different.
“As I look to scale across multiple basins, we have to understand the mechanism because it’s just not going to magically work in that next place,” he said.
