A recent series of published studies provides an in-depth analysis of how water injected into the Permian Basin during oil and gas extraction is affecting underground pressures and leading to earthquakes.
The Permian Basin, located in West Texas, is the most productive energy region in the U.S., contributing over 40% of the nation’s oil and approximately 15% of its gas. Nonetheless, the extraction of these energy resources has resulted in earthquakes and other difficulties recently, especially as operators now manage around 15 million barrels of wastewater daily. This salty water is a byproduct of energy extraction, and most of it is disposed of by reinjection into the ground.
The new research, conducted by scientists from The University of Texas at Austin, examines the geology of the Permian Basin—particularly the Midland Basin—and its relationship with injected water throughout time. The study not only clarifies the issue but also provides valuable data for energy operators and regulators to mitigate seismic events and their associated risks in the future.
“There have been numerous recent papers discussing seismic trends in the Permian Basin, but no one has really paused to think, ‘How can we analyze this within a geological and engineering framework to gain a clearer understanding?'” explained Research Professor Peter Hennings, who leads the Center for Injection and Seismicity Research (CISR). “Our goal is to create a more comprehensive understanding of the effects of wastewater injection in the Permian Basin by integrating geological data and information to evaluate patterns and impacts.”
Since 2016, CISR, part of the UT Jackson School of Geosciences’ Bureau of Economic Geology, has been studying the connection between seismic events and water injection. Their research has already contributed to a reduction in seismicity across various areas of the Permian Basin.
Hennings is the editor of the recently published seven-paper collection on the Permian Basin, featured in the December issue of the AAPG Bulletin (https://pubs.geoscienceworld.org/aapgbull/issue/108/12). These papers build on one another to provide a cohesive understanding of the sources and patterns of water injection, subsurface reservoirs, faults, pressurization, and earthquakes. The geological maps, pressure models, and data trends presented in this research can guide operators and regulators in identifying problematic areas and conditions in the past, aiding in future mitigative strategies.
According to Research Associate Professor Katie Smye, the CISR team has discovered numerous potentially earthquake-inducing faults within the Midland Basin by integrating 2D and 3D seismic data with insights from recent seismic events and the horizontal wells drilled in the region.
“In some instances, these wells reveal structural changes underground, so the thousands of horizontal wells drilled in the past decade provide significant insights for our fault mapping initiatives,” she remarked.
The researchers categorized the recent seismic activity in the Permian Basin into seven distinct induced seismicity systems. Smye noted that this distinction is critical as each system presents unique geological characteristics and seismic challenges. For example, injecting water deep within geological formations tends to trigger earthquakes more frequently than shallow injections. However, simply pivoting to shallow injection poses its own complications, such as increased pressure that can complicate drilling and possibly damage existing wellbores, risking the contamination of groundwater with produced water.
Looking ahead, researchers anticipate that production levels in the Permian Basin will remain stable for the foreseeable future, presenting long-term challenges for wastewater disposal. Understanding the availability of pore space for wastewater injection in the Permian region is essential for sustainable oil operations and environmental protection.
“Pore space for injection has typically not been managed as a valuable resource; instead, it has been treated as something to utilize swiftly,” Smye observed. “We need to change our perspective to align with the sustainable production strategies, allowing us to optimize pressure space for future waste disposal.”
