Old oil fields may be less prone to earthquakes

The Southern Delaware Basin earthquake (red dot) occurs where there has been no historical production from the Delaware Range (purple circle, circle size indicates the amount of oil and water produced). Credit: Dvory et al.

Underground carbon sequestration (the storage of carbon deep in the earth) provides a partial solution to removing carbon from the atmosphere. When used in conjunction with emissions reductions, geological carbon sequestration may help mitigate anthropogenic climate change. However, like any other underground business, there are dangers such as earthquakes.

Geophysicists are still working to understand what has been documented since the 1960s that can cause man-made earthquakes, new research published in the Journal of Geology has discovered why some mass-producing oil fields in the United States were hit Thursday and others did not. For the first time, the authors show that the effects of oil drilling in the past alter fault pressure, making fluid injection less likely to cause or trigger today’s earthquakes.

This study focuses on the Delaware Basin, an oil and gas source that straddles the border between West Texas and New Mexico. Drilling has been there since at least the 1970s, and more than 10,000 active individual wells are spread across the region. There, Stanford University geophysicists Noam Dvory and Mark Zubak observed an interesting pattern of seismic activity, with the most recent shallow earthquakes occurring mainly in the southern half of the basin, and the northern half seismically quiet, despite the pumping of shallow wastewater throughout the basin. .

“So the burning question is why shallow earthquakes are confined to one area and not spread more than that,” Zubak says.

Earthquakes can be caused by injecting fluids such as sewage underground. When wastewater is injected into the rocks, the pressure rises and puts great stress on the existing rocks and faults. When those stresses and pressures are high enough, an earthquake can occur.

Injectable earthquakes in the southern Delaware Basin tend to be shallow and of relatively small size, usually strong enough to cause a plate rattle, but not sufficient to cause damage. However, when deeper faults are activated, larger earthquakes can occur and cause damage. For example, in March 2020, there was a 4.6-magnitude earthquake in Menton, Texas. This may be due to the deep injection reacting to a defect in the crystal bedrock near 5 miles underground.

“The magnitude of the earthquake is limited by the size of the slip fault,” Dufoury explains. If the fault is shallow and small (its size is only a few kilometers), then the magnitude of the earthquake tends to be small. “You can still feel it, but it’s less serious.”

Reducing earthquake risk is the goal of any underground work, whether oil or not. Gas production or carbon sequestration. As a result, the Delaware Basin, with its peculiar seismic pattern, has become a prime target for Duvory and Zoeback. It was a natural experiment in geomechanics and the “why” behind the causative earthquake.

To decipher the pattern, Dvory and Zoback first modeled the underground pressure required to trigger the trough fault and correlated these values ​​with the estimated stress values. Once the baseline was established, they calculated the pore pressure around the Delaware Basin. Their results showed a clear pattern: in the northern strata where hydrocarbons were previously produced, the pressure of pore waters was lower than in the “undisturbed” rocks and there were no earthquakes. The southern basin, which had little previous production of the same formation, had higher initial stresses and seismicity.

“In some areas, there is evidence of oil and gas development since the 1950s,” Dvory says. “Where large quantities of hydrocarbons were produced, the pressure decreased and the formation became essentially more stable.”

Now, when the fluid is injected back into those “settled” rocks that were previously excavated, the starting pressure will be lower than when it was first drilled.

“So, where previous oil production occurred, the current injections slightly reduce the pressure, reducing the likelihood of an earthquake,” Zwieback explains. “At some point, it is unlikely that sufficient injection will cause an earthquake, but in the areas we looked at here, what has happened previously is that the current operational process can be documented to have a strong impact on how it affects the probability of an earthquake.”

Targeting these sites that have been producing oil in the past with low seismic hazards can be a good carbon sequestration approach.

“There is a global challenge to store large amounts of carbon dioxide underground in the next 10 to 20 years,” Zobak says. “We need a place to store large amounts of carbon dioxide safely for hundreds of years, including clearly not allowing it. The pressure increases to cause an earthquake. The importance of geoscience in meeting this challenge cannot be overstated. It is a huge problem, but geoscience is an important place. To start. “

Geologists have discovered that shallow wastewater injections cause deep-focus earthquakes in Texas

For more information: Noam Z.Dvory et al Previous oil and gas production could limit the occurrence of leakage seismicity: a case study in the Delaware Basin of West Texas and Southeast New Mexico, USA, Geology (2021). doi: 10.1130/G49015.1

Submitted by the Geological Society of America

Quote: Old oil field from induced earthquake (29 June 2021) Obtained from https://phys.org/news/2021-06-oil-fields-prone-earthquakes.html on 29 June 2021. May be less susceptible

This document is subject to copyright. No part may be reproduced without written permission, except for fair dealings for personal investigation or research purposes. The content is provided for informational purposes only.

What Are The Main Benefits Of Comparing Car Insurance Quotes Online

LOS ANGELES, CA / ACCESSWIRE / June 24, 2020, / Compare-autoinsurance.Org has launched a new blog post that presents the main benefits of comparing multiple car insurance quotes. For more info and free online quotes, please visit https://compare-autoinsurance.Org/the-advantages-of-comparing-prices-with-car-insurance-quotes-online/ The modern society has numerous technological advantages. One important advantage is the speed at which information is sent and received. With the help of the internet, the shopping habits of many persons have drastically changed. The car insurance industry hasn't remained untouched by these changes. On the internet, drivers can compare insurance prices and find out which sellers have the best offers. View photos The advantages of comparing online car insurance quotes are the following: Online quotes can be obtained from anywhere and at any time. Unlike physical insurance agencies, websites don't have a specific schedule and they are available at any time. Drivers that have busy working schedules, can compare quotes from anywhere and at any time, even at midnight. Multiple choices. Almost all insurance providers, no matter if they are well-known brands or just local insurers, have an online presence. Online quotes will allow policyholders the chance to discover multiple insurance companies and check their prices. Drivers are no longer required to get quotes from just a few known insurance companies. Also, local and regional insurers can provide lower insurance rates for the same services. Accurate insurance estimates. Online quotes can only be accurate if the customers provide accurate and real info about their car models and driving history. Lying about past driving incidents can make the price estimates to be lower, but when dealing with an insurance company lying to them is useless. Usually, insurance companies will do research about a potential customer before granting him coverage. Online quotes can be sorted easily. Although drivers are recommended to not choose a policy just based on its price, drivers can easily sort quotes by insurance price. Using brokerage websites will allow drivers to get quotes from multiple insurers, thus making the comparison faster and easier. For additional info, money-saving tips, and free car insurance quotes, visit https://compare-autoinsurance.Org/ Compare-autoinsurance.Org is an online provider of life, home, health, and auto insurance quotes. This website is unique because it does not simply stick to one kind of insurance provider, but brings the clients the best deals from many different online insurance carriers. In this way, clients have access to offers from multiple carriers all in one place: this website. On this site, customers have access to quotes for insurance plans from various agencies, such as local or nationwide agencies, brand names insurance companies, etc. "Online quotes can easily help drivers obtain better car insurance deals. All they have to do is to complete an online form with accurate and real info, then compare prices", said Russell Rabichev, Marketing Director of Internet Marketing Company. CONTACT: Company Name: Internet Marketing CompanyPerson for contact Name: Gurgu CPhone Number: (818) 359-3898Email: [email protected]: https://compare-autoinsurance.Org/ SOURCE: Compare-autoinsurance.Org View source version on accesswire.Com:https://www.Accesswire.Com/595055/What-Are-The-Main-Benefits-Of-Comparing-Car-Insurance-Quotes-Online View photos