What is Seismicity?

Seismicity is the measure of the occurrence (i.e., frequency and magnitude) of earthquakes in a region. Under certain circumstances some human activities can cause or increase the likelihood of seismicity – this is known as induced seismicity.

Many human activities have been associated with localized seismic events including construction and infrastructure projects, quarrying and excavation, and energy development. However, most induced localized seismic events are not felt and pose little to no risk to the public.

In fact, according to the Texas Railroad Commission, a seismic event must have a magnitude greater than or equal to 3.5, as determined by the U.S. Geological Survey (USGS) and TexNet, to be considered a seismic event of significance (SES). While SES do occur, the average magnitude of induced earthquakes is low to moderate with a magnitude between 1 and 3.

Texas has experienced increased seismic activity that many attribute to induced seismicity from the injection of produced water resulting from oil and natural gas development. The Texas oil and gas industry, alongside various other stakeholders, has taken a holistic approach to managing seismicity risk – reducing operations' environmental impact while supporting our energy needs. 

Energy Production and Seismicity

According to the USGS, “Most induced earthquakes are not directly caused by hydraulic fracturing (fracking). The increase in earthquakes in the United States is primarily caused by disposal of waste fluids that are a byproduct of oil production.”

Hydraulic fracturing involves the injection of approximately 3 to 5 million gallons of water that includes sand and additives at high pressure down and across into horizontally drilled wells as far as 10,000 feet below the surface. The water that is injected is mostly recycled from previous extractions to reduce use of the state’s freshwater systems. This pressurized mixture causes the rock layer to establish micro-fissures. These fissures are held open by the same particles allowing oil and natural gas from the shale formation to flow up the well to the surface.

At the same time, naturally occurring saline water is found in the very formations that contain oil and natural gas. As these energy resources are extracted, this water – known as produced water – returns to the surface. The Texas Produced Water Consortium (TPWC) estimates that every barrel of oil produced in the Permian Basin is accompanied by approximately three to five barrels of produced water. That’s about 14 million barrels of produced water per day from both the Permian’s Delaware and Midland basins. Roughly 11 million of these barrels of produced water are recycled by the oil and gas industry – further reducing reliance on freshwater resources for the Lone Star State.

Most produced water is disposed of using a process known as underground injection, where it is often stored a mile or more below drinking water sources and separated by billions of tons of low-permeability rock.  In the Permian, disposal wells inject fluid into subsurface formations that are thousands of feet deeper than any freshwater levels.

The U.S. Geological Survey has stated that out of the tens of thousands of waste fluid disposal wells used for oil and natural gas operations, “only a small fraction of these disposal wells have induced earthquakes that are large enough to be of concern to the public.”

Produced Water Management in Texas

Texas industry alongside regulators and researchers are working together to improve water management and develop innovative tools and solutions to repurpose the water produced from operations. From beneficial reuse methods such as fire control, power generation, equipment washing and more – Texas’ dedication to water management is paving the way for responsible resource preservation. More importantly, this collaborative approach will continue to support energy that is critical for modern life.  Check out the tremendous achievements from local industry so far:

• 78% of produced water in the Permian Basin is reused by operators, reducing the use of freshwater supplies.
• For example, in 2023 more than 99% of Chevron’sPermian Basin water demand was met using brackish groundwater and produced water that was recycled.
• Apache’s use of innovative technologies and treatment process has enabled 61% of water used during their U.S. hydraulic fracturing operations to come from recycled produced water in 2023 – an increase from 32% in the previous year.
• In 2022, Exxon sourced more than 130 million barrels of recycled produced water from Permian operations, comprising over half of their water needs for hydraulic fracturing operations.
• Ovintiv has recycled more than 8 billion gallons of water from its Permian operations since 2017 and built more than 800 million gallons of recycled water storage & transfer capacity.
• In 2023, more than 50% of the water ConocoPhillips used for fracking of new wells in the Permian was sourced from recycled produced water.

Working Together

Texas Seismological Network and Seismology Research (TexNet)

The mission of TexNet is to serve as an independent scientific body that monitors earthquake activity, analyzes associated data, and distributes findings and data to the government, industry, and the public for their benefit and the benefit of the State of Texas. TexNet also receives input via a Technical Advisory Committee (TAC) that includes state agencies and Permian oil and gas producers working together to increase the knowledge related to earthquakes occurring within the state and improve the safety of our citizens, environment, infrastructure, and economy. In 2021, the Railroad Commission of Texas and TexNet created the Injection Volume Reporting Tool to facilitate more transparency surrounding injection report filing and data accessibility, resulting in daily data being uploaded either voluntarily or as a condition of certain permits.

Texas Produced Water Consortium (TxPWC)

Created by the Texas Legislature through Senate Bill 601 (2021), the group is comprised of energy companies and state agencies to implement resources related to the economics and technologies of produced water. The Consortium will also develop economic models and guidance standards that include environmental and public health concerns to better enable the use of wastewater technologies.

Texas Railroad Commission

In 2021, the RRC created seismic response areas (SRAs) in Texas to address the intensity and frequency of earthquakes in the state and reduce high-magnitude seismicity. Since its establishment, the SRA boundary has expanded to areas near the Texas/New Mexico border to monitor over 2,600 miles of potential activity. In 2024, the RRC also released its framework for pilot programs to enhance produced water recycling methods in the state. 

Center for Injection & Seismicity Research (CISR)

CISR is a consortium at the University of Texas Bureau of Economic Geology funded by approximately 30 member companies along with the New Mexico Oil Conservation Division (NMOCD) and the Texas Railroad Commission (RRC). CISR’s goal is to understand injection and induced seismicity to optimize water management and to understand and mitigate its risk.