Saturday, June 13, 2009

MRCSP Project- Greenville, Ohio - Darke County

To find the latest information regarding the Darke County (Greenville) project please continue to check The Daily Advocate CO2 blog. This is a special blog set up to keep residents informed.

The proposed seismic testing area can be found there - they have a map and have listed the streets and off-road areas involved.

A special thanks to The Daily Advocate for this service to your community.

Injection Induced Earthquakes AND Special Considerations Supercritical Liquid Properties

When most people think about Carbon Capture and Storage they think it means putting bubbles in the ground or carbonation, like we find in soda pop. The reality is not even close to anything resembling bubbles and it is dangerous.

Before the CO2 they capture can be put into the ground it must be transformed into SUPERCRITICAL CO2 which is considered a Supercritical Liquid - which is a supersolvent and comes with a lot of risks.

The article below comes from:
Joel Sminchak and Neeraj Gupta

I could not find a date on this abstract. Some random quotes from it are listed below.

Please read the entire article - I have just excerpts here.

The live link to this article is here
(bold areas in the quoted material below have been done by me to help those who skim over articles)

Consequently, the injected CO2 must be addressed as a multiphase system. Special considerations for underground disposal of CO2 are mostly related to the unique properties of supercritical CO2.

"Formation Dissolution/Weakening
Supercritical CO2 has the potential to dissolve, weaken, or transform the minerals in the injection formation. In the supercritical state, CO2 becomes a “supersolvent.” Thus, there is potential for the fluid to dissolve and weaken the rocks in the injection formation. If the rock formation is weakened, the potential for hydraulic fracturing increases. Dissolution of minerals precipitated along a fault will reduce the strength of the fault, possibly moving the fault to frictional sliding conditions where failure is more likely to occur."

Case Study: Seismic Aspects of Deep Well Injection in Ohio
Deep well injection practices and seismic activity in Ohio were examined to determine the potential for induced seismicity in the state. All five active deep well injection systems in Ohio have been investigated for seismic hazards to some extent.
Most faults in Ohio are associated with Precambrian basement rocks at depths over 1 km below land surface. Several faults have been identified in northwestern Ohio, while relatively few faults have been identified in the rest of the state. The Anna Seismogenic Region is one of the most active seismic zones in Ohio (Figure 4). The zone is located in west-central Ohio. (Note by me - Greenville, OH is considered to be part of the Anna fault)

"In general, most seismic activity indicates strike-slip movement along steeply dipping faults. Based on the USGS Seismic Hazard mapping project, there is a low probability for damage from earthquakes for Ohio, except in the Anna Seismic Area, which has a moderate hazard.

The Anna Seismic Seismogenic Region in west-central Ohio has been identified as one of the most active seismic areas in the Midwest. The area has a substantial history of seismic activity dating back to the mid-1800s. The largest earthquake observed in the area had a Modified Mercalli intensity of VIII in 1937. In general, seismic activity indicates northeast-southwest strike-slip movement oriented perpendicular to the predominant stresses in the area."

"A number of faults have been proposed in the area, but most activity appears to occur near the trend of the proposed Anna-Champaign Fault. Overall, the Anna Seismic Area is considered a seismically active area."

Acknowledgement: The work presented here was conducted with funding from the U.S. Department of Energy’s National Energy Technology Laboratory as part of project number DEAF26-99FT0486."

To read the entire abstract click here

A Fluid--Injection Triggered Earthquake Sequence in Ashtabula, Ohio: Implications for Seismogenesis and Hazard in Stable Continental Regions (SCR)

From the web site:

A persistent earthquake sequence in northeast Ohio includes many distinct fore--main--aftershock sub--sequences, illuminates two faults, and was triggered by fluid injection. The first known earthquake from within 30~km of Ashtabula was an mb(Lg)~3.8 mainshock that shook the downtown area in 1987. Seismicity has continued at an average of about one felt event per year. The largest magnitude so far, mb(Lg)~4.3, caused slight damage (MMI VI) 26 Jan. 2001. The latest subsequence started July 2003 with mb(Lg)~2.6. Accurate hypocenters and focal mechanisms are available from three local seismograph deployments in 1987, 2001, 2003 and from regional broadband seismograms. These hypocenters are in the Precambrian basement, 0--2 km below the 1.8~km deep Paleozoic unconformity, and illuminate two distinct planar E-W striking sources zones 4 km apart, one in 1987 about 1.5~km long, the other in 2001 and 2003 about 5 km long. We interpret them as steep sub--parallel faults slipping left--laterally in the current regime. Like many of the faults that ruptured in hazardous SCR earthquakes, these faults were previously unknown and probably have small post--Precambrian displacements. The 1987 source was active a year after onset of class 1 fluid injection only 0.7~km north of the fault. The second fault, 5 km south of the injection well, became active in 2000, while the 1987 source was inactive. The well injected about 164 m3/day of waste fluid into the 1.8 km-deep basal sandstone with about 100 bars of well head pressure from May 1986 to June 1994. An annular high pore--pressure anomaly is expected to expand along this hydraulically confined horizon at the top of the basement even after injection ends and pressure drops near the well. Over 16 years, seismicity has shifted southward from ˜1 to 5--8~km from the point of injection. It seems to initiate when and where a significant pore pressure rise intersects pre--existing faults close to failure and to be turned off when pressure starts dropping back. The largest earthquakes postdated the end of injection at both Ashtabula and at the Rocky Mountain Arsenal near Denver, Colorado. Anthropogenic earthquake hazard may thus persist after the causative activity has ceased but can generally be closely monitored. High--stress and low strain rates in the eastern US and other SCRs can account for a larger proportion of triggered earthquakes in these regions than in active ones. Unlike hazard from natural SCR earthquakes, hazard from potential sources of anthropogenic earthquakes could generally be precisely identified in time and space. Anthropogenic triggering may have raised significantly the overall level of SCR seismicity during the last half century. Models that assume constant seismicity through the historic period may thus underestimate the overall hazard.
Keywords: 7209 Earthquake dynamics and mechanics, 7223 Seismic hazard assessment and prediction