32 

ISSUES RELATED TO SEISMIC ACTIVITY INDUCED BY THE INJECTION 

OF CO2 IN DEEP SALINE AQUIFERS 

Joel Sminchak (sminchak@battelle.org; 614-424-7392)
 

Neeraj Gupta (gupta@battelle.org; 614-424-3820)
 

Battelle Memorial Institute
 

505 King Avenue
 

Columbus, Ohio 43201
 

Charles Byrer (a) and Perry Bergman (b)
 

National Energy Technology Laboratory
 

(a) P.O. Box 880, Morgantown, WV, 26507-0880
 

(b) P.O. Box 10940, Pittsburgh, PA, 15236-0940
 

Abstract 

Case studies, theory, regulation, and special considerations regarding the disposal of carbon 

dioxide (CO2) into deep saline aquifers were investigated to assess the potential for induced 

seismic activity. Formations capable of accepting large volumes of CO2 make deep well injection 

of CO2 an attractive option. While seismic implications must be considered for injection 

facilities, induced seismic activity may be prevented through proper siting, installation, operation, 

and monitoring. Instances of induced seismic activity have been documented at hazardous waste 

disposal wells, oil fields, and other sites. Induced seismic activity usually occurs along 

previously faulted rocks and may be investigated by analyzing the stress conditions at depth. 

Seismic events are unlikely to occur due to injection in porous rocks unless very high injection 

pressures cause hydraulic fracturing. Injection wells in the United States are regulated through 

the Underground Injection Control (UIC) program. UIC guidance requires an injection facility to 

perform extensive characterization, testing, and monitoring. Special considerations related to the 

properties of CO2 may have seismic ramifications to a deep well injection facility. Supercritical 

CO2 liquid is less dense than water and may cause density-driven stress conditions at depth or 

interact with formation water and rocks, causing a reduction in permeability and pressure buildup 

leading to seismic activity. Structural compatibility, historical seismic activity, cases of seismic 

activity triggered by deep well injection, and formation capacity were considered in evaluating 

the regional seismic suitability in the United States. Regions in the central, midwestern, and 

southeastern United States appear best suited for deep well injection. In Ohio, substantial deep 

well injection at a waste disposal facility has not caused seismic events in a seismically active 

area. Current technology provides effective tools for investigating and preventing induced 

seismic activity. More research is recommended on developing site selection criteria and 

operational constraints for CO2 storage sites near zones of seismic concerns. 

Introduction 

Concerns about global warming have prompted investigation into the disposal of carbon dioxide 

(CO2) into deep saline rock formations. This option is attractive, since there are regionally 

extensive aquifers capable of accepting large volumes of CO2 from power plants without the need 

for long pipelines. There is also a substantial amount of research available on the subject from 

projects on enhanced oil recovery and deep well injection of liquid wastes. However, application 

of the technology to populated areas may involve seismic hazards if the injection facilities are not 

properly sited and operated. The objective of this paper is to review induced seismic activity as it 
33 

relates to the injection of CO2 into deep saline aquifers in the United States. Basic theory, 

regulation, monitoring and testing methods, and special considerations on induced seismic 

activity are addressed. A case study on seismic practices in Ohio is also presented to outline 

typical procedures followed to monitor seismic activity during deep well injection. Related DOE 

funded work on geologic storage of CO2 in saline formations conducted at Battelle includes 

compositional reservoir simulations (Gupta et al., 2001), evaluation of geochemical aspects 

through modeling and experiments (Sass et al., 2001a and Sass et al., 2001b), and assessment of 

economic and engineering aspects (Smith et al., 2001). 

Seismic activity was first linked to deep well injection activities near Denver, Colorado, in 1962. 

Since then, seismic activity triggered by injection wells has been noted at locations worldwide. 

Due to the uncertainty associated with deep subsurface investigations, an understanding of the 

lithology, structural geology, and hydrology of the site is critical to determining if injection will 

induce seismic events. To this end, regulation on injection wells exists to ensure that a site is 

properly investigated and monitored for seismic vulnerability. In addition, several distinctive 

processes related to CO2 injection must be considered for the option of CO2 disposal. 

Ramifications of induced seismic events go well beyond the traditional image of earthquake 

activity. While most seismic events triggered by deep well injection are too small to be noticed, 

moderate earthquakes have occurred due to injection activity. Most notably, two earthquakes 

with Richter magnitude of 5.1 and 5.2 were triggered in Denver, Colorado, in 1966. Seismic 

activity may also affect the injection system itself. In the worst-case scenario, a fault or fracture 

causes the rupture of the injection well casing and containment is lost. Fractures may also occur 

in overlying rock units providing a pathway for upward migration of the injection liquid. 

Continual seismic activity may result in the gradual weakening of the well casing. In addition, 

formation alteration may affect the performance of the injection system by reducing or increasing 

the pore space in the injection system. However, through proper siting and operation procedures, 

seismic events may be prevented. In fact, current technology has provided very effective tools 

for investigating potential seismic activity induced by deep well injection. 

Overview of Induced Seismic Activity 

In general, deep well injection weakens the strength of a fault, triggering movement and the 

resulting seismic event. Wesson and Nicholson (1987) note that deep well injection usually 

triggers activity in a seismically unstable area rather than causing an earthquake in a seismically 

stable area. Conceptually, the fluid in a fault is pressurized and assumes the stress of the 

overlying rock and water. Since the fluid has little shear strength, the frictional resistance along 

the fault declines and the fault blocks slip, causing a seismic event. These processes are best 

represented by a stress/strain relationship at very high pressures. Other processes involved in the 

triggering of seismic activity may include transfer of stress to a weaker fault, hydraulic fracture, 

contraction of rocks due to the extraction of fluids, subsidence due to the saturation of a rock 

formation, mineral precipitation along a fault, and density-driven stress loading. Figure 1 shows 

a conceptual model of processes involved in triggering seismic activity by underground injection 

wells. Most of these processes are site specific and can be evaluated through site investigations 

or formation testing. 

In terms of stress equations, deep well injection reduces both the principal and confining pressure 

in the injection formation while keeping the differential pressure constant, moving the system 

toward failure (Figure 2). Represented on a Mohr s circle, it is easy to see how the injection 

pressures may move the rock to the point of failure (Figure 3). With respect to deep well 

injection systems, the confining pressure and the principal pressure may be measured or estimated 

based on lithology and depth. Consequently, injection pressures may be analyzed to determine if 
34 

the changes in pressure may trigger fracture. Key parameters that affect injection pressures are 

formation permeability and porosity. Rock formations with high permeability and porosity are 

more receptive to injected fluids. Low permeability and low porosity rock formations will 

require higher injection pressures and be more susceptible to induced seismicity. Another factor 

which may influence the stress-strain system is formation pressure. Water trapped in a formation 

during deposition may reach very high pressures as sediments are deposited on top of the 

formation throughout time. 

At very high injection pressures, rock formations may fracture in a process termed hydraulic 

fracturing. This process is often used by oil/gas companies to increase the transmissivity of a 

formation around the well. Hydraulic fracturing occurs when the injection pressure exceeds the 

intergranular strength of the rock, creating or expanding fractures. 1996 Joule II proceedings 

suggest that controlled hydraulic fracturing does not induce seismic activity above a magnitude of 

one. However, unmonitored hydraulic fracturing may produce rather extensive fractures several 

meters wide and hundreds of meters long which could possibly trigger more substantial seismic 

activity. 

Seismic events can be correlated to injection activities in several ways. A seismic monitoring 

network is essential to collecting information on earthquakes. Most seismic events triggered by 

deep well injection are too small to be felt, but they are often precursors to larger events. The 

most obvious way to link earthquakes to injection wells is an increase in seismic events once 

injection begins. The frequency of seismic activity compared to previous seismic trends may be 

examined to reveal changes introduced by the injection practices. 

The magnitude of the seismic events is another line of evidence to link earthquakes to injection 

wells. The seismic activity caused by the injection well may be either smaller or larger in 

magnitude than the previous trend in seismic activity. For example, numerous small seismic 

events may happen after injection starts. Trends in the magnitude of seismic activity may be 

recognized by comparing frequency-magnitude charts. The geographic location of the earthquake 

foci should be in the general area of the injection radius of influence. It should be noted that the 

radius of influence of the injection system may be kilometers to tens of kilometers from the 

injection wells. Similarly, the depth of the earthquakes may be in the affected injection interval; 

although, earthquakes have been triggered several kilometers below the injection well. More 

advanced analysis methods can determine the orientation of faults from the seismic response and 

compare the orientations to the location of the injection well to see if the two are somehow 

related. 

Operations data on injection pressure at the wellhead and/or injection volumes can be valuable to 

studying seismic events. The frequency of the seismic activity over time is often related to the 

injection pressure or injection volume history over time. There may be a lag of days to years 

between the two events since an earthquake may be triggered by a propagating pressure wave. In 

addition, sudden pressure changes at the wellhead itself may result from an earthquake event. 

Another method of linking earthquakes to deep well injection is the analysis of critical fluid 

pressures capable of causing failure along a fault. Based on formation pressures at depth and 

induced pressure, the Mohr-Coloumb failure criteria may be used to determine if conditions 

capable of triggering a fault would be created in the injection zone. However, these calculations 

involve several assumptions concerning fault strength and pressures. The method provides less 

certainty than direct evidence from monitoring instruments. For example, Davis and Pennington 

(1989) found that injection pressures at thousands of sites in the state of Texas were high enough 

to trigger seismic activity but do not exhibit seismicity. The value of stress analysis is that the 
 

35 

work may be performed in site selection and system design before any fluid is actually injected. 

Information for evaluation of critical fluid pressure may be obtained from compression tests, 

hydraulic testing, and analysis of the orientation of the stress tensors. 

Reservoir modeling may be used to analyze the migration of injection pressure. Reservoir 

modeling uses the hydraulic properties of the injection formation with analytical or numerical 

equations to simulate the progression of pressure or liquid. These models are useful in 

determining whether deep well injection may have caused seismic activity a long distance from 

the injection well(s). Similar models are available to determine what pressures will trigger 

hydraulic fracture and the extent of the fracturing. 

Seismic activity induced by deep well injection has been observed at locations throughout the 

world. However, only a few case studies have been well studied due to the large amount of 

monitoring and testing required to demonstrate a conclusive relationship between earthquakes 

and deep well injection. Table 1 summarizes documented case studies of induced seismic 

activity. Earthquakes were first linked to deep well injection in 1962 at the Rocky Mountain 

Arsenal near Denver, Colorado (Healy et al., 1968). This remains one of the best-studied 

occurrences of seismic activity triggered by deep well injection. Researchers suggest that these 

earthquakes were likely triggered by pressure waves that continued to propagate after injection 

was stopped. Hsieh and Bredehoft (1981) reassessed the Denver earthquakes with reservoir 

modeling. The authors found that they could use modeling to simulate the arrival of critical 

pressure levels in a faulted zone where earthquakes occurred. The modeling results were 

comparable to the earthquake control studies by Raleigh et al. (1976) that demonstrated that 

earthquakes could be controlled by monitoring injection pressure and seismic activity. Increased 

seismic activity has also been observed at numerous oil/gas drilling sites, due to either fluid 

extraction or injection. Motivated by the Denver earthquakes, the USGS conducted an 

experiment in 1976 to control earthquakes at a nearby oil well site in Rangely, Colorado (Raleigh 

et al., 1976). Injection pressures were increased to critical levels, then decreased. The frequency 

of earthquakes decreased after the initial pressures declined. Similar research was performed in 

Matsushiro, Japan. 

Issues Related to Induced Seismic Activity 

Regulation 

Injection wells in the United States are regulated by the federal Underground Injection Control 

(UIC) program, which provides minimum rules for the siting, testing, installation, operation, 

monitoring, reporting, and abandonment of underground injection wells (Title 40 Code of Federal 

Regulation Parts 146 and 148). UIC rules are enforced by regional and/or state Environmental 

Protection Agency (EPA) offices, which dispense permits for UIC wells. Injection wells are 

classified according to the type of fluid injected and the injection interval in relation to 

underground sources of drinking water (USDW). CO2 disposal wells have yet to be classified by 

the EPA. However, they will likely be held to the same type of seismic regulation as Class I 

wells because of depth considerations. The UIC program requires testing on formation materials 

to ensure that injection pressures will not fracture rock formations in the injection interval. The 

program also requires regular monitoring to retain injection permits. 

Overall, UIC regulation does not extensively address induced seismic activity. However, two 

sections are fairly explicit in providing rules related to earthquake activity: 
36 

40CFR146.13 	 Except during stimulation, injection pressure at the wellhead shall not 

exceed a maximum which shall be calculated so as to assure that the 

pressure in the injection zone during injection does not initiate new 

fractures or propagate existing fractures in the injection zone. In no case 

shall injection pressure initiate new fractures or propagate existing 

fractures in the injection zone. In no case shall injection pressure initiate 

fractures in the confining zone or cause the movement of injection or 

formation fluids into an underground source of drinking water. 

This rule is aimed at preventing formation of transmissive faults and fractures which may allow 

injected fluids to migrate vertically and reach sources of drinking water. The CFR addresses the 

issue of seismic activity induced by deep well injection in 40CFR146.68. The UIC guidance 

provides the enforcing agency more than enough leeway to require extensive testing and 

monitoring: 

40CFR146.68	 The Director may require seismicity monitoring when he has reason to 

believe that the injection activity may have the capacity to cause seismic 

disturbances. 

Testing and Monitoring 

Many types of tests are available to detect faulting or fractures that could lead to induced seismic 

activity including down-hole geophysical tests as well as more traditional testing methods that 

may be performed within the borehole. Another type of testing is pressure fall-off/shut-in testing 

that involves monitoring pressure buildup in the well. Testing methods are summarized below: 

• 2-D or 3-D seismic surveys 

• Core sample collection from major units during drilling 

• Down-hole caliper logging to detect fractures 

• Down-hole resistivity logging to detect fractures and lithologic changes 

• Down-hole spontaneous potential logs 

• Down-hole gamma ray logging to detect formation changes 

• Down-hole density testing 

• Fracture-finder logs to detect fractures 

• Compression tests on formation samples to determine rock strength 

• Geotechnical tests on formation samples (porosity, density, permeability) 

• Compatibility test of injection fluids with formation unit and confining unit 

• Pressure fall-off/shut-in tests 

• Radioactive tracer survey. 

Monitoring is another important part of assessing induced seismic activity from an injection well. 

Table 2 summarizes typical monitoring requirements at an underground injection facility to aid in 

evaluating seismic activity. Monitoring at the well may include recording of injection volume, 

rate, and pressure, continuous monitoring of annulus pressure. Abrupt changes in these 

parameters may signal a seismic event. Well workovers to assure mechanical integrity and detect 

weakening of well casing may also suggest faulting at depth. Other monitoring methods may 

include reservoir pressure/ambient monitoring and groundwater monitoring to detect upward 

migration of injection fluids through fractures. 
37 

Seismic monitoring should be performed before injection activities start to obtain baseline 

conditions. Depending on the frequency of seismic activity at the injection site, months to years 

of monitoring may be required to achieve an adequate depiction of baseline seismic conditions 

prior to injection. This may involve the installation of several subsurface seismic sensors around 

the proposed injection site. Seismic monitoring considerations may also be integrated into well 

installation so that down-hole sensors can be installed while drilling. The Joule II report suggests 

that at minimum a network of subsurface sensors should be installed at the injection site. Another 

monitoring method to consider is measuring changes in elevation due to expansion, subsidence, 

or movement along fault blocks. Tiltmeters may also be considered to monitor changes in 

fracture orientation at depth. Monitoring should be continued once injection activities begin. 

Aside from the frequency of seismic events, the location, depth, and magnitude of the seismic 

events should be analyzed to determine if the events are related. Geophysical methods may also 

be used to determine the extent of injected fluid as proposed for the Sleipner Aquifer CO2 Storage 

operation in the North Sea of Norway (International Energy Agency, 1998). Since seismic 

velocities vary according to the density of the material, the density contrast between the 

formation waters and injected CO2 may provide evidence of the extent of the injected fluid. 

Modeling can be a valuable tool in evaluating the potential for deep well injection to trigger 

earthquakes. Overall, modeling refers to making a simplified representation of actual conditions 

or processes. Reservoir modeling involves using numerical equations to simulate the migration 

of pressure and/or fluid from the injection well. With respect to seismic activity, modeling may 

be used to predict if and when critical pressures are reached in a seismically sensitive area. 

Modeling may also be used to address uncertainty regarding rock strength, formation pressure, 

and other factors to see if more testing is required to characterize the injection system. Simple 

one- or two-dimensional models as used by Hsieh and Bedehoeft (1981) to complex threedimensional models like UTCOMP (Chang, 1990) may be used for CO2 injection simulation. 

Davis and Pennigton (1989) modeled pressure buildup in the Cogdell oil reservoir and showed a 

correlation between earthquake epicenters and zones of high pressure. 

Special Considerations 

Supercritical Liquid Properties 

For deep well disposal, CO2 is generally injected in a supercritical phase at pressures above 6.9 

MPa (1,000 psig) to minimize the injected volume. Consequently, injection formations must be 

deeper than approximately 1,000 m to ensure that CO2 will remain in a supercritical state. 

Supercritical CO2 has a density of about 0.60 to 0.75 g/cc while the density of saline formation 

fluid ranges from 1.0 to 1.2 g/cc. Supercritical CO2 is also less viscous than saline waters, 

resulting in more uniform flow migration. Czernichowski-Lauriol, et al. (1996) note that about 

50 g of CO2 will dissolve in 1 kg of typical formation water. 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 
38 

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. 

Another aspect of deep well CO2 disposal is the compatibility of the injected fluid with the 

formation waters and the formation rocks. There is potential for the injected fluid to precipitate 

out minerals. Mineral precipitation has the potential to significantly decrease formation porosity 

and permeability (Melcer and Gerrish, 1996). These changes may result in unexpected pressure 

buildup and formation faulting or fracture. Minerals may also bond along a previously aseismic 

fault. Thus, stress is increased and builds. The ensuing failure event is much larger than would 

have occurred without precipitation. 

With respect to induced seismic activity, mineral dissolution and precipitation may have the 

greatest potential to affect a fault. Mineral precipitation in the pore space may cause a decrease in 

permeability, resulting in the buildup of pressure and hydraulic fracturing or pressure-induced 

faulting. Many shallow injection wells experience clogging due to similar processes as fine 

sediments accumulate in pore space around the well. Mineral precipitation or dissolution along 

fault planes may affect the stress regime of a fault system. Precipitation along a fault could lock 

up a previously aseismic fault. As stress accumul ates, the potential for a more significant fault 

becomes greater. Conversely, mineral dissolution along a previously bonded fault may reduce 

the strength of the fault. 

Radius of Influence 

Deep well injection activities commonly affect a formation far beyond the location of the 

injection well(s). The earthquakes may occur after injection activities are stopped, as shown by 

the Denver earthquakes which occurred over one year after injection activities were stopped. 

Finally, earthquakes may be induced in formations well below the injection formation. For these 

reasons, the effective radius of influence must be examined for the injection well(s). Injecting 

200 million tons of CO2 into a formation 20 m thick with a porosity of 15% and a storage 

efficiency of 6% will require a radius of influence of approximately 22 km. Thus, it must be 

demonstrated that there are no faults of fractures within the radius of influence that might be 

susceptible to earthquakes. Simple calculations or modeling methods may be used with site 

characterization data to estimate the radius of influence. The radius of influence for the pressure 

front created by the injection practices may be even larger than the injection capacity indicates. 

Therefore, modeling may be necessary to evaluate this aspect of the injection process. 

Density Driven Flow 

Most other waste disposal wells attempt to match the density of the injection liquid with the 

formation fluids. However, the density of supercritical CO2 is 0.60 to 0.75 g/mL while the 

density of most deep saline formation waters ranges from approximately 1.0 to 1.2 g/mL. 

Consequently, this density contrast may produce density-driven flow as the lighter, injected fluids 

migrate upward. Given the large volumes of fluid involved in CO2 disposal operations, the impact 

of the density contrasts could be capable of influencing stress conditions at depth. Conceptually, 

the less dense fluid will migrate upward until it reaches a confining layer/cap rock. Once at the 

caprock, the upward force exerted by the lighter fluid could weaken the caprock or transfer stress 

to overlying faults. Stress transfer due to deep well injection was identified as a potential cause 

of seismic activity in Cogdell, Texas (Davis and Pennington, 1989). Similarly, injected CO2 may 

produce seismic activity related to density-driven flow of free-phase CO2 at depth. It should be 

noted that when the CO2 is injected, much of the fluid will mix and dissolve into the formation 
39 

waters. Whether density-driven flow will pose a significant seismic threat is best addressed with 

multiphase modeling and chemical experiments. 

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. Of the operational facilities, BP 

Chemical injects the most, with a cumulative injection volume of over 20 million metric tons. 

Most deep well injection in Ohio is into the Mt. Simon formation, a fine-grained sandstone with a 

relatively high porosity and permeability. The formation overlies Precambrian basement rock, 

with a top depth of approximately 800 m in northwestern Ohio to over 3,000 m below ground 

surface in eastern Ohio. The unit is generally less than 100 m thick throughout the state and thins 

toward the northeast. Rock formations overlying the Mt. Simon are generally less permeable 

shale, limestone, dolomite and sandstone. However, permeable layers exist at various depths in 

certain areas. In eastern Ohio, many oil and gas wells penetrate the Clinton sandstone 1,000 to 

1,100 m below the surface. In general, there are several intervals of rocks which may be suitable 

for deep well injection in Ohio. The depth intervals and hydraulic properties of the receptive 

formations appear to vary throughout the state, but are fairly constant within the anticipated 

radius of influence of an injection facility. 

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. While many 

faults have been proposed in the area, only a few are well accepted. The faults are mostly 

northeast-southwest or northwest-southeast oriented. Analysis of seismic effects in that area 

suggests that the faults are steeply dipping with strike-slip movement. Seismic activity in the 

Anna area is generally deeper than 10 kilometers. Other major faults southeast of Ohio are 

related to the Kentucky River Fault Zone. Faults have also been proposed in various other areas 

throughout the state, most notably the Ashtabula fault in northeastern Ohio. 

The seismic history of Ohio dates back to 1811 when a series of earthquakes with epicenters near 

New Madrid, Missouri, were felt in Cincinnati. Since then, many seismic events have occurred in 

Ohio. The largest earthquakes have had a Richter magnitude in the range of 5.0-5.5, or a Mercalli 

Modified Index of VII-VIII. 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. Analysis of 

the seismic activity indicates foci in Precambrian bedrock at depths of over 10 km below ground 

surface. 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. However, since most activity is well below potential 

injection formations, the potential for induced seismic activity is not likely. In fact, no substantial 

induced seismic activity has been observed at the BP Chemicals injection facility, which is 
40 

located 50 km northeast of the Anna Seismic Area. Based on the study of Ohio, a properly sited 

and operated injection facility may be located in a region with moderate seismic activity. 

Conclusions and Future Work 

The possibility for seismic activity induced by deep well injection must be considered when 

evaluating the disposal of CO2 in deep saline aquifers. The potential for seismic events is greatest 

in seismically vulnerable locations with a history of faulting and earthquakes. Seismic activity 

may be prevented, through proper siting, installation, and monitoring. To this end, federal 

guidance exists to regulate underground injection facilities. Special considerations related to the 

properties of supercritical CO2 may have seismic effects. 

Future work on induced seismic activity associated with disposal of CO2 into deep saline aquifers 

should involve improving methods for detecting seismic activity induced by injection activities, 

integrating seismic monitoring with the evaluation of the migration of the injected CO2, 

characterization of regional seismic suitability for injection activities, and the assessment of 

fractured rock formation injection capacities and limitations. 

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. 

References 

BP Chemicals. 1991. UIC No Migration Demonstrations. Pursuant to 40 CFR Part 148. 

Chang, Y. 1990. Dev elopment of a Three-Dimensional, Equation-of-State Compositional 

Reservoir Simulator for Miscible Gas Flooding. Ph.D. Dissertation, The University of Texas at 

Austin. 

Czernichowski-Lauriol, B.S., C. Rochelle, K. Bateman, J. Pearce, and P. Blackwell. 1996. 

 Area 5. Inorganic Geochemistry. In S. Holloway (Ed.), The Underground Disposal of Carbon 

Dioxide. Contract No. JOU2 CT92 0031, Final Report. British Geological Survey. February. 

Davis, SD., and W.D. Pennington. 1989. Induced Seismic Deformation in the Cogdell Oil Field 

of West Texas. Bulletin of the Seismological Society of America, vol. 79, no. 5, p. 1477-1494. 

Gupta, N., B.M. Sass, J.R. Sminchak, and J.E. Hicks. 1998. Carbon Dioxide Sequestration in 

Deep Saline Aquifers in the Midwest: Data Compilation and Modeling Aspects, Interim Report. 

Battelle Report prepared for U.S. Department of Energy, Pittsburgh Energy Technology Center. 

Gupta, N., P. Wang, B. Sass, P. Bergman, and C. Byrer. 2001. Regional And Site -Specific 

Hydrogeologic Constraints on CO2 Sequestration in the Midwestern United States Saline 

Formations. Proceedings of Fifth International Conference on Greenhouse Gas Control 

Technologies, Cairns, Australia, August 14-16, 2000. 

Healy, J.H., W.W. Rubey, D.T. Griggs, and C.B. Raliegh. 1968. The Denver Earthquakes. 

Science, vol.161, no. 3848, p. 1301-1310. 
 

41 

Hsieh, P.A., and J.D. Bredehoeft. 1981. A Reservoir Analysis of the Denver Earthquakes: A 

Case Study of Induced Seismicity. Journal of Geophysical Research, v. 86, p. 903-920. 

Holloway, S. (ed.). 1996. The Underground Disposal of Carbon Dioxide. Contract No. JOU2 

CT92 0031, Final Report of the JOULEII Project, British Geological Survey. 

International Energy Agency. 1998. Proceedings of the Sleipner Carbon Dioxide Storage 

Workshop, 25th-26th November 1997, Trondhiem, Norway. Report PH3/1. 

Melcer, A., and H.W. Gerrish. 1996. Effects of Formation Damage on Injection Operations and 

on Pressure Transient Tests. Deep Injection Disposal of Hazardous and Industrial Waste, J.A. 

Apps and Chin-Fu Tsang, eds. p. 277-286. 

Ohtake, M. 1974. Seismic Activity Induced by Water Injection at Matsushiro, Japan. J. Phys. 

Earth, 22, p. 163-174. 

Raleigh, C.B., J.H. Healy, and J.D. Bredehoeft. 1976. An Experiment in Earthquake Control at 

Rangely, Colorado. Science, v. 191, p. 1230-1237. 

Sass, B., N. Gupta, J. Ickes, P. Bergman, and C. Byrer. 2001a. Experimental Evaluation of 

Chemical Sequestration of Carbon Dioxide in Deep Saline Formations. Proceedings of Fifth 

International Conference on Greenhouse Gas Control Technologies, Cairns, Australia, August 

14-16, 2000. 

Sass, B., N. Gupta, J. Ickes, M. Engelhard, D. Baer, P. Bergman, and C. Byrer. 2001b. 

Interaction of Rock Minerals with Carbon Dioxide and Brine: A Hydrothermal Investigation. 

First National Conference on Carbon Sequestration, Washington, D.C., May 15-17. 

Smith, Lawrence A., N. Gupta, B. Sass, T. A. Bubenik, C. Byrer, and P. Bergman. 2001. 

Engineering and Economic Assessment of Carbon Dioxide Sequestration in Saline Formations. 

First National Conference on Carbon Sequestration, Washington, D.C., May 15-17. 

Wesson, R.L. and C. Nicholson. 1987. Earthquake Hazard Associated with Deep Well 

Injection. Prepared by the U.S. Geological Survey. Open -File Report 87-331. 
42 

Figure 1. Conceptual figure illustrating processes involved in seismic activity induced by 

underground injection wells. 
43 

AFTER INJECTION 

BEFORE INJECTION 

PRINCIPAL PRESSURE 

CONFINING
 

PRESSURE
 

CONFINING
 

PRESSURE
 

PRINCIPAL PRESSURE - P PRINCIPAL PRESSURE 

FAULT TRACE 

CONFINING CONFINING - P PRESSURE PRESSURE 

CONFINING - P PRESSURE 

CONFINING 

PRESSURE 

P 

P 

P P 

P 

P 

FAULT TRACE 

PRINCIPAL PRESSURE - P 

PRINCIPAL PRESSURE - P 

CONFINING - P PRESSURE 

CONFINING- P PRESSURE 

PRINCIPAL PRESSURE 

Figure 2. Diagram illustrating how injection pressures (P) reduce the effective confining 

and axial strength of a rock formation. Injection pressure counteracts confining and axial 

pressures, reducing the strength of the rock and causing fracture or faulting. 

FAILURE ENVELOPE 

Pressure (psi) 

She

ar Stre

ss 

principal pressure 

before injection 

confining pressure

 before injection 

principal pressure 

after injection 

confining pressure

 after injection 

Figure 3. Mohr diagram showing how injection pressures bring a faulted rock to the point 

of failure. 
 

 

 

 

 

 

44 

BPCI = BP LIMA INJECTION FACILITY 

1. BOWLING GREEN FAULT 

2. TEAYS TRIBUTARY FAULT 

3. AUGLAIZE FUALT 

4. BOWLING GREEN EXTENSION FAULT 

5. LOGAN-HARDIN FAULT 

6. ANNA-CHAMPAIGN FAULT
 

(DASHED LINES INDICATE PROPOSED FAULTS)
 

Figure 4. Faults in Northwestern Ohio (Source: BP Chemicals, 1991) 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

45 

Table 1. Documented cases of induced seismic activity. 

Location Type Depth (m) 

Injection 

Pressure 

(MPa) 

Maximum 

Earthquake 

Magnitude 

Denver, CO Waste disposal 3,671 7.6 5.5 

Fenton Hill, NM Geothermal 2,700 20.0 <1.0 

The Geysers, CA Geothermal 3,000 (extraction) 4.0 

Matsushiro, Japan Research 1,800 5.0 2.8 

Dale, NY Solution mining 426 5.5 1.0 

Central Michigan Gas storage 320 1.5-4.3 NA 

Germigny Reservoir, 

France Gas storage 750 <3 <1? 

Cogdell, TX Secondary 

recovery 2,071 19.9 4.0 

Rangely, CO Secondary 

recovery 1,900 8.3 3.1 

Gobles Field, Ontario Secondary 

recovery

 884 NA 2.8 

Sleepy Hollow, NE Secondary 

recovery 1,150 5.6 2.9 

Snipe Lake, Alberta Secondary 

recovery 

NA NA 5.1 

Dollarhide, TX Secondary 

recovery 2,590 13.8 ~3.5 

Dora Roberts, TX Secondary 

recovery 3,661 43.1 ~3.0 

Kermit Field, TX Secondary 

recovery

 884 10.6 ~4.0 

Keystone Field I, TX Secondary 

recovery

 975 10.3 ~3.5 

Keystone Field II, TX Secondary 

recovery 2,987 17.6 ~3.5 

Monahans, TX Secondary 

recovery 2,530 20.7 ~3.0 

Ward-Estes Field, TX Secondary 

recovery

 914 11.7 ~3.5 

Ward-South, TX Secondary 

recovery

 741 13.8 ~3.0 

(after Wesson and Nicholson, 1986); NA = not available 
46 

Table 2. Typical Monitoring Requirements for a Class I Underground Injection Facility 

Parameter Monitoring Requirements Reporting Requirements 

Injection Pressure Continuous Monthly 

Bottomhole Pressure Calculated every 4 hours Monthly 

Annulus Pressure Continuous Monthly 

Interannulus pressure Continuous Monthly 

Temperature Continuous Monthly 

Flowrate Continuous Monthly 

Specific Gravity Weekly Monthly 

PH Weekly Monthly 

Composition of Injectate Every 6 months Monthly 

Cumulative Volume Daily Monthly 

Annulus Sight Glass Level Daily Monthly 

Groundwater monitoring Quarterly Quarterly 

Seismic monitoring (if required) Continuous Monthly