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Oil and water don't mix
and what the Kansas Corporation
Commission is doing to protect fresh water aquifers
by Doug Helmke, LG, Source Water Tech
In recent months, operators and administrators of water systems have been inquiring about the legality and appropriateness of oil and gas wells being drilled in the vicinity of their water wells. People have also been asking questions about domestic water wells being drilled near municipal wells and within the boundaries of cities. Although most of these latter concerns are probably not related to water quality protection, these domestic wells could pose a threat. These threats to a water system's source of supply are real. In this article, oilfield activities and controlling them will be discussed. This discussion should also be pertinent to the threats of domestic water wells and other potential sources of contamination.
Oil and gas well drilling is one of the most dangerous occupations in the world today. Even though many safety advances have been made, the use of large, noisy, moving equipment that can become unstable can be a recipe for disaster. Using this dangerous equipment during the extremes of weather to obtain an explosive product, which can be trapped at very high pressures, compounds the danger. With 98 deaths attributed to oil and gas extraction in the United States by the Bureau of Labor Statistics in 2001, it can easily be concluded that accidents that affect the integrity of oil and gas wells are also happening.
Although rare, blow-outs, or uncontrolled flows of fluids, can occur during drilling in Kansas. In Oklahoma and Colorado, blow-out prevention equipment can be specifically required on the drilling site by the drilling permit. Kansas Corporation Commission (KCC) regulations require this equipment in specific counties based on the well construction materials used and the targeted hydrocarbon storage formation. The State of Missouri is less specific in this regard, only requiring the equipment to be present when it is needed. Nebraska regulations require that surface casing be properly installed to prevent pollution of other oil and water producing horizons in the strata and that the amount of casing be sufficient to prevent blow-outs.
Another hazard to groundwater supplies are the fluids used to drill water wells. Kansas and the surrounding states all have rules regulating the use and disposal of these fluids. As most drilling mud is removed from the well as part of the completion process, very little of it comes in contact with groundwater for a long period of time. A bigger hazard from this material is the chlorides that may be concentrated and eventually leached from the drilling mud left in the pits used to drill the well.
The KCC has designated the areas of Kansas above alluvial aquifers, the area within the boundaries of Equus Beds Groundwater Management District No. 2 and Big Bend Groundwater Management District No. 5, and Barber and Comanche Counties, to be Sensitive Groundwater Areas needing more stringent regulation. The pits constructed for oil well drilling in these areas must have liners with hydraulic conductivities equal to or less than 1 x 10-7 centimeters per second. These liners can be made of:
1. Natural clay liner;
2. Soil-mixture liner composed of soil mixed with cement, bentonite, clay type or other additives to be applied to pits whose walls do not exceed a slope of three to one;
3. Recompacted clay liner composed of in situ or imported clay soils which are compacted or restructured to be applied to pits whose walls do not exceed a slope of three to one;
4. Manufactured liner composed of synthetic material to be applied to pits in such a manner as to ensure its integrity while the pit is open;
5. Combination of types of liners described above;
6. Any other liner or groundwater protection system acceptable to the Conservation Division of the KCC.
The most important item in an oil or gas well that protects aquifers is the surface casing. The casing is constructed of a series of connected steel pipes. Its purpose is to separate the geologic formations, aquifers and groundwater above the oil and gas horizons from the fluids extracted from below. Just as oil and salt water can contaminate fresh water, fresh water can contaminate the oil that is to be removed.
It is in everyone's interest that this important tool be properly designed and constructed. Based on the known depths of the various horizons, a predetermined length of pipe is lowered into the drilled hole. A cement mixture is pumped down inside the surface casing and back up the outside between the casing and the hole wall in most situations. This cement mixture supports the surface casing and seals the hole from any water encountered to that point. The amount of surface casing required is specified in the KCC regulations by county and by more specific geographic location, such as the distance of the well from major river valleys. After this cement cures, drilling can continue to the horizons where oil and gas will likely be found.
In my opinion, the salt water that is produced with petroleum is a bigger hazard than the oil well that may be located in areas where fresh water is pumped for human consumption. When brine is present with the petroleum, it is separated from the oil after the fluids are brought to the surface. Once separated, it is stored in holding tanks and later transported to injection wells. Injection wells are designed to withstand high injection pressures and are tested regularly to insure that no leakage occurs. The injection system is designed to not exceed the pressure that would cause fracturing of the rocks that confine the waste fluids.
The transportation of brine between the production wells and the injection wells is the weakest link, whether this fluid is transported by buried pipelines or trucks. Overflows, leaks and spills, including intentional dumping, could create a serious problem. At least one area near Burrton, Kansas, within the boundaries of Equus Beds Groundwater Management District No. 2, still show the effects of the use of "salt water disposal ponds", which were primarily used between 1931 and 1943. A report to the Chief Engineer of the Division of Water Resources from the Burrton Task Force dated February 21, 1984, estimates that 1.9 million tons of salt entered the groundwater near Burrton, Kansas. In an area of approximately 70 square miles, there are between 180 and 225 observation wells which allow the collection of water samples from various depths of the aquifer. With the information from the samples, the horizontal and vertical movement of the salt water plumes can be determined. Generally, water near the top and near the bottom of the aquifer is usable for irrigation and drinking use. Because of clay lenses in the aquifer, a stair-stepping of contaminated water occurs as the denser salt water sinks. Chloride in concentrations greater than 3,000 mg/l is still found in some locations in the "middle zone". This far exceeds the Maximum Contaminant Level for drinking water of 250 mg/l. Estimates are that the saltwater plumes are moving horizontally 1 to 3 feet per day, threatening the future use of irrigation wells and some City of Wichita wells. Equus Beds G.M.D. No. 2 is participating in a modeling project to better understand the movement of the plumes.
In recent years, a new industry has been established in eastern Kansas. (See graphic at right by the Kansas Geological Survey). Natural gas is now commercially produced from subsurface coalbeds. According to the Kansas Geological Survey's Public Circular No. 19, coalbed methane accounts for 7% of the total annual natural gas production in the United States. According to a report by the Energy Information Administration-U.S. Department of Energy, titled Natural Gas Productive Capacity for the Lower 48 States, the 17,000 gas wells completed in 2002 were not enough to replace the declining capacity of the older existing gas wells in the United States. With shrinking supply and higher demand for natural gas, there will likely be higher prices for gas, helping this new industry expand.
Gas is withdrawn from coalbeds by drilling water wells into the coal formation. The removal of this water significantly reduces the pressure in the formation, which helps the volatile methane to be released from the coal. Gas wells are then able to collect the released gas for distribution to nearby pipelines. The water removed from the coalbeds in Kansas is typically salty, and must be disposed in injection or disposal wells. The entire series of Public Information Circulars published by the Kansas Geological Survey can be viewed at http://www.kgs.ukans.edu/Publications/pubCirculars.html.
Free vs. risks
The danger that abandoned water wells can allow the contamination of aquifers has been preached for years. But what do they have to do with the drilling and operation of oil and gas wells? Many oil wells rely on a water well located very close to the drilling site for the water needed to make the drilling fluid. Often, the oil well driller will have a water well drilled and transfer the responsibility of it to the landowner after the oil well has been completed. The landowner thinks getting a free well for allowing the oil well driller access to the water on his property is a good deal, whether he or she can use it or not. If the landowner does not really need the well, it may fall into disrepair and be forgotten, becoming a direct conduit for surface contaminants to reach the aquifer. This example of aquifer contamination is not limited to the oilfield; it can happen anywhere. Not only is the well transferred to the landowner, but also all the responsibility to maintain it and the liability if a problem results.
How real is the problem?
I am unaware of any survey or report done in Kansas which estimates how many domestic water wells have been contaminated by oilfield activities to the point that they cannot be used. The City of Stockton has added customers living outside of the city boundary because of improper handling of the brine produced from oil wells. The City of Jennings has had to suspend the use of one of their municipal wells because of salt water contamination. It is likely that other water systems have had similar experiences. The City of Kiowa's primary water wells were threatened by a blow-out in 1981. Water under extreme pressure was encountered at a very shallow depth very early in the process of drilling a new oil well. Initial reports said that a secondary oil recovery injection well was probably to blame. Salt water flowed out of the ground and spilled into the Medicine Lodge River approximately 10 miles upstream of Kiowa's two primary wells. One published report stated that the flow of saltwater may have been as high as 84,000 gallons per minute.
Kiowa was notified of the event and ceased pumping immediately. Residents were also told of the problem and were asked to use water for only essential activities. The plume of salt water did pass the alluvial wellfield and approximately four days after the blow-out, the water quality was sufficient to allow pumping to resume. Those alluvial wells have since been abandoned since it has been determined that the water supply was under the influence of surface water, requiring compliance with surface water treatment standards. The City of Kiowa drilled two replacement wells and installed an 18-mile long transmission pipeline to replace them.
The City of Kiowa example shows that mistakes and accidents have occurred in the past and are likely to happen again. Providing some measure of distance between oil and gas wells and municipal water supplies is an idea that should be considered. Currently, there are no regulations in Kansas specifying a minimum distance from municipal water wells for the location of oil and gas wells.
Can more be done?
Since 1986, when the National Wellhead Protection Program was established under the Clean Water Act, water systems have been encouraged to maximize their efforts to protect the water on which they rely. The Oklahoma Corporation Commission understands that it is important to protect fresh water and has adopted regulations that appear to go farther than the regulations in Kansas, Nebraska, Colorado and Missouri. For example, to assist water systems with wellhead protection plans, some of the Oklahoma regulations specifically refer to wellhead protection areas. Their regulations specifically prohibit commercial disposal wells from being located within designated wellhead protection areas. New enhanced-recovery injection wells and newly converted disposal wells are not to be approved if they are located with one-half mile of a municipal water supply well without a hearing. Substantial evidence must be presented at the hearing showing that pollution of the aquifer will not occur for approval to be granted. Water-based drilling fluid containment pits must have a geomembrane liner if located within a wellhead protection area or within one mile of any municipal water well for which no wellhead protection area has been established. Commercial pits are not permitted within wellhead protection areas or within one mile of municipal wells for which no wellhead protection area has been established.
Are we doing enough?
Further study of the costs of prevention and the costs of remediation and replacement would probably show that more can be done. Oklahoma's recognition of wellhead protection areas and the need to protect the aquifers on which people rely for basic human existence is good to see. As a political matter, Kansas water systems must show that they are truly interested in protecting the water they use and will continue to use, for as long as their water system exists.
The most important thing a water system can do is to decide that their water supply is too important to do nothing. Make the decision to put this topic on your next board or council meeting agenda. Find out the steps needed. A simple plan is more effective than no plan. It's been said that Rome wasn't built in a day. Wellhead protection plans can be viewed the same way. Start simple and increase the effectiveness of the wellhead protection plan in the future, if necessary. When more wellhead protection plan areas are established across Kansas, it is likely that regulations for all potentially polluting activities will be passed to protect our water supplies. For further information, contact me through my email address firstname.lastname@example.org or the KRWA office at 785/336-3760. I'll be happy to come visit your board/council meeting.
From July 2003 issue of The Kansas Lifeline © 2003 KRWA