I received this letter from Susan Hovarka of the Gulf Coast Carbon Center at the University of Texas, which is reproduced in its entirety.
Our University of Texas monitoring experiment that you blogged about last year has started collecting data at Cranfield oil field 10 miles east of Natchez on highway 84. Let me update you on what is happening as it is important that local people know before press releases go out. I will tell you first about what Denbury is doing, then the reason for our experiment, then what we found out so far, and then what you can do about it, if you want to become more involved.
What Denbury is doing
Cranfield oilfield was developed by The California Company (now Chevron) in 1945, and production of oil and gas from the deep zones (Tuscaloosa Formation) stopped in 1965 when the field “watered out” meaning too much water, not enough oil was being produced. Some production of gas from shallower zones (Wilcox Formation) continues today, as well as aggregate mining, farming, and timber cutting. Denbury Resources International has been working for about 10 years to bring this field back to production, as they have done with other Mississippi oil fields ( for example Brookhaven, Little Creek, Mallalieu, Soso). The technique that they use is to produce naturally occurring CO2 from Jackson Dome, Mississippi and ship it as a compressed liquid by pipeline to new or retrofit injection wells in oilfields. The CO2 goes down tubing in wells and is pushed into the oil-bearing formation. There it mixes with the oil, causing it to swell and become less viscous, and pushes the CO2-oil mixture toward retrofit production wells, where the oil+CO2+water will be lifted to the surface. The fluids are then separated: the oil to market, the salt water back underground, and the CO2 recycled to injectors to move more oil. The process is called CO2 enhanced oil recovery (EOR) and it works; fields in west Texas have been sustained for 35 years. Because of CO2 EOR, Mississippi is the only state in the US where oil production has recently increased. The limit on CO2 EOR is availability of CO2, only a few places (Colorado, Wyoming, Arizona, New Mexico, Mississippi) have had the geologic history to have significant natural CO2 deposits.
The reason for our test
We now know that emission of large volumes of CO2 produced by combustion of fossil fuels is perturbing climate. All the options are hotly debated right now – costs and environment, economics inside the US and globally. How fast and at what cost can we bring on alternatives to fossil fuel, and how do we get from here to there? One of the many ways to reduce climate impact is to capture the CO2 at point emitters (power plants and other large heater and refiners), and inject it back underground, a process called carbon capture and storage or sequestration (CCS). CCS is usually described as a bridging technology, something at could be started quickly at large volumes, it would lets us continue to use fossil fuel power plants as part of the US energy mix but with decreased environmental damage. Environmentalists are divided on the value of CCS. Environmental Defense and Natural Resources Defense Council support CCS as one of the technologies to be considered because it could be started relatively quickly (5 years) and at large scale, they favor market-drive for changes, and they see evidence that makes them think that CCS should be effective and safe. Some environmental organizations, for example Green Peace, are opposed to further consideration of CCS; they prefer to get off fossil fuels as fast as possible, making up the energy losses with conservation and efficiency and more aggressive deployment of wind and solar, and are concerned about the safety of CCS.
Our project is to provide one small but important data set to inform this debate – is large volume injection of CO2 effective in reducing emissions and safe? Large amounts of CO2 has been safely injected in Scurry County TX for 35 years, as well as at about 80 other EOR fields, so we feel quite confident that the Cranfield injection will be safe for people living nearby, and Mississippi State agencies charged with oversight evidently agree because they have permitted the activities. However, before anyone commits to even larger scale more widespread injection, we have an opportunity to make highly precise measurements – is this quality of the storage not only safe but high enough quality to benefit the environment? If this process was used very widely, what would be the risk to water? How do we best select, monitor and test these sites to see they are performing correctly? This test is one of about 10 underway world wide – Frio test in Dayton Texas was our last test, also underway or complete are in Gaylord Michigan, Wabash County, Illinois, Simon/Pump Canyon New Mexico, SACROC in Scurry County TX, Zama in Alberta Canada, Weyburn Saskatchewan, Canada, Nagaoka, Japan, Siepner, in the North Sea, InSalah, Algeria. Ketzin, Germany, Otway, Australia; more are planned. *
This weeks discoveries
Our first experiment at Cranfield is to determine if any CO2 leaks upward. The possible leakage pathways would be flaws in the engineering of any of the many old wells. To study this, we designed a research well, a retrofit of an old well that that been plugged and abandoned. We put one pressure gage at 10226 feet below surface, in the injection zone, and packed off the well above this. As the CO2 flood started about 10 days ago, we saw expected changes in pressure right away, which have now increased by about 100psi (bike tire inflation pressure). We also perforated the well at 9860 feet, and hung a gage to sample pressure in thin sheet of sandstone at this depth. If pressure increases at this 9860 “monitoring sandstone” layer, it suggests that water or CO2 are starting to leak upward, sort of a trip-wire to monitoring system. We sample the read-out and ship out the data to the operator and us in Austin every 10 minutes.. We can measure pressure changes to hundredths of a psi. So far, no pressure increase on the upper gage, so CO2 is staying where it should in this part of the field It looks like those guys who built those wells in 1945 did OK. I know some of them are retired in the Natchez area, so congratulations to them on a job well done. We will keep observing as long as our monitoring system works. If we see changes, we have several tools to test what is going on, which would give an opportunity to repair any wells that are not tight. We are also testing this data working with researchers at Stanford to see how reliable this system is, and if it could help assure the safety of a big injection. This is a world’s first test of this system.
Our collaborators at Ol’ Miss and Mississippi State have started a program to monitor water quality. As long as no fluids cross our “trip wire” we do not expect to see any change in ground water or surface gases caused by CO2 injection. So part of the research will be to assess what leakage could do to groundwater, if it should happen. Water from many areas with naturally high CO2 is sold as drinking water (Perrier) , but is possible that damage such as mineralization or salinization could occur at some site. Our research program will help determine the realistic risk of damage over 100’s of years, as well as test to make sure that damage is not occurring at Cranfield while we are monitoring.
The decisions on the choices to reduce greenhouse emissions in the US lie with voters and energy consumers. US Environmental Protection Agency (EPA) was charged by Congress in 1974 to oversee all injection by the Safe Drinking Water Act, Underground Injection Control program. EPA hass just released for 120 day public comment draft rules for CO2 injection for storage, so this in an opportunity for individuals and organizations to be involved in water protection and by connection to CCS. Details are at http://www.epa.gov/safewater/uic/pdfs/prefr_uic_co2rule.pdf Both our states (Texas and Mississippi) have primacy in enforcing these federal laws; we develop state rules that are at least as strict as the federal ones. So we will get a second review of these rules during state processes.
Our project has an obligation to provide education; if you or your readers would like more information, we would be pleased to provide it. In our last experiment in Dayton, TX I was invited by the Rotary Club to speak at their lunch meeting. If you our your readers know of a church group, civic club, school or other setting that would be interested in hosting a forum for more information, questions, and debate related to these topics, please let me know, we could work to set something up.
* you may note that nearly all these first tests are somehow related to oil and gas, which seems suspect. Let me explain that they this is because of relatively low budgets, it has been necessary to save money by piggy-backing tests on other subsurface operations, so that researchers do not have to drill many new wells, put in roads etc and have money for research. Also, the possibility of increased availability of CO2 is of very significant interest to oil producers, it is their best hope of increasing domestic oil production, so they are in favor, as are parts of the coal lobby e.g .“clean coal”. However, the people who need to make the big decisions are energy consumers, these special interests should not drive the show.. The first test I can think of with no oil connection at all will be in Southern Company’s Plant Daniel, in Jackson County Mississippi. A big one is also planned at Decatur, Illinois, at ADM’s new ethanol plant.
I myself am a water quality researcher, I am concerned that climate change is a big risk to water and would like to make sure that any mitigations for climate change protect water. (Please consider me a possible environmental ally although a an adopted Texan and a consider-all-options pragmatist).
Susan D Hovorka, Gulf Coast Carbon Center
Bureau of Economic Geology, Jackson School of Geoscience
The University of Texas at Austin