Injection of Waste Fluids into the Arbuckle
Group of the Western Interior Plains Aquifer
System in Kansas
By Zach Faber
For
GO571
At
Emporia State University, Spring 2010
Professor Marcia Schulmeister
Table of Contents:
Introduction: Hydrologic Setting
Aquifer Properties: Hydrologic and Geologic Characteristics
Water Resource: Usage of the Aquifer
Contamination: Sources of Aquifer Quality Reduction
References
Introduction: Hydrologic Setting
The Western Interior Plains Aquifer System (WIPAS) underlies almost all of Kansas, parts of west-central
Missouri, and part of southern and eastern Nebraska (see Figure 1). This aquifer system is similar to the Ozark
Plateau System which lies to the east in parts of Missouri and southeastern Kansas, but unlike the Ozark
Plateau System, yields no fresh water due to naturally high salinity. The aquifer occurs in dolomites,
sandstones, and limestones in deeply buried geologic units of Ordovician and Cambrian Age (USGS, 1997).
Flow in the aquifer occurs from west to east-southeast where the aquifer system discharges into the Ozark
Plateau System.
For many years, industrial waste water and oil-field brines have been injected into the well-confined Arbuckle
Group of the WIPAS. Due to the poor water quality that naturally exists in the WIPAS, the economic
infeasibility of using water from the WIPAS due to its depth, the porosity and permeability of the aquifer, and
the proper confinement above the aquifer, the Arbuckle creates an almost perfect waste disposal zone. The
purpose of this review is to detail the reasoning behind the use of the Arbuckle for waste disposal by
examining its properties and characteristics as a part of the Western Interior Plains Aquifer System.
Figure 1
Areal Extent of the Western Interior Plains Aquifer System (USGS, 1997)
Regional Flow and Recharge
Because this aquifer occurs in geologic structures of similar age and discharges into the Ozark Plateau System,
it is often thought that the Western Interior Plains Aquifer System should not be examined separately from
the Ozark Plateau System which lies to the east of the WIPAS in Missouri (MacFarlane, 2000).
The climate of this area has little to no effect on the Western Interior Plains Aquifer System due to its extreme
depth. However, Figure 2 outlines the precipitation totals in Colorado, Kansas, Nebraska, and Missouri. It is
evident that the western portion of this area is semi-arid with precipitation levels increasing as you travel east.
Figure 2
1-Year Precipitation Totals for Nebraska, Kansas, Colorado, Wyoming, South Dakota, and North Dakota
(HPRCC, 2010)
Recharge for the WIPAS mainly occurs through slow downward movement of upper aquifers or through direct recharge in the semiarid Rocky Mountain front range.
Recharge occurs by way of precipitation in the Front Range of the Rocky Mountains (Jorgensen et al, 1993).
Little recharge occurs through vertical recharge from overlying aquifers. As the aquifer system travels east
toward Missouri, halite evaporites in the Permian confining unit of the Western Interior Plains Aquifer System
are dissolved into the aquifer giving the water its characteristically high salinity.
Figure 3
Generalized Cross-Section of the Plains Region (Jorgensen et al)
As this aquifer system flows eastward, no surface water bodies directly affect it. As the system discharges in
Missouri, a number of saline springs and artesian wells which have developed in Paleozoic carbonates occur in
areas such as Saline County in central Missouri (Jorgensen et al, 1993).
Aquifer Properties: Hydrologic and Geologic Characteristics
The Western Interior Plains Aquifer System is comprised primarily of dolostone, limestone, and shale with the
majority of the Arbuckle Group being made up of dolomite that has gained porosity by way of dolomitization
and weathering that was further enhanced by tectonic activities (Carr et al, 1986). The Arbuckle Group is
generally homogeneous across Kansas and extends across almost all of the state except areas near the
Nemaha anticline and Central Kansas uplift where erosional forces post-Mississippian and Cambrian have
made the Arbuckle absent. A karst-like environment with higher porosity and permeability exists in some
areas of the Arbuckle, but these are historically difficult to locate (Jorgensen et al, 1993).
Stratigraphy
The table below details the stratigraphic units along with the associated geohydrologic units that make up the
WIPAS and the geologic units overlying it. Below the Arbuckle is igneous basement rock of Pre-Cambrian age
which effectively eliminates downward migration of the aquifer. A confining unit of late Mississippian to
Jurassic Age prevents migration upward from the WIPAS or downward into the WIPAS. This confining unit is
composed primarily of limestone, shale, and sandstone with thicknesses ranging from 20,000 feet in basins to
near zero in areas of uplift. The confining unit is primarily composed of Pennsylvanian formations (Jorgensen
et al, 1993)
Table 1
Stratigraphic Units of the Plains from the Quaternary/Tertiary
Units to the Pre-Cambrian/Cambrian Basement Rocks (Carr et al, 1986)
Hydraulic Flow Properties
The Chattanooga and Woodford Shales create a slight confining unit between the lower zone of the WIPAS
and the upper zone of the WIPAS. However, investigation of the hydraulic heads and Total Dissolved Solid
content of both zones indicates they are part of the same system (Jorgensen et al, 1993).
The thickness of the WIPAS can range from 200 to 400 feet in parts of northern Kansas and the formation
thickens toward the south to be from 1,200 to 1,400 feet thick. The hydraulic conductivity of the Arbuckle
unit of the WIPAS averages around 0.37 ft/day. Because of the depth of the formation and the saline
conditions of the aquifer, drill stem tests typically utilized by oil companies were used to calculate this average
hydraulic conductivity. The method employed by Jorgensen et al included the use of intrinsic permeability to
determine hydraulic conductivity. The average intrinsic permeability of the Arbuckle was determined to be
134 millidarcies (Jorgensen et al, 1993).
The permeability of the lower aquifer unit is estimated to be between 1 x 10-11 ft2 and 1 x 10-18 ft2. This
permeability is relatively small when compared to a permeability of 1 x 10-15 ft2 for most confining layers;
making the fluid movement in the WIPAS extremely slow (Carr et al, 1986). The hydraulic conductivity and
permeability of the WIPAS increases in areas of uplift and decreases in basin areas which suggests that
permeability is a function of fracturing caused by uplift.
The storage coefficient of the Arbuckle Formation of the WIPAS ranges from 6.8 x 10-5 to 3.2 x 10-3 with an
average specific storage of 3.25 x 10-6 ft-1 (Jorgensen et al, 1993).
Chemical Characteristics
The salinity of the Arbuckle ranges from slightly below 10,000 ppm in north-central Kansas to above 100,000
ppm in south-central Kansas (See Figure 4 below). It is typical that groundwater salinity increases in most
areas of the country with depth, however this is not true of the Arbuckle. The table below details
groundwater chemistry of the Arbuckle and the overlying aquifers. This data reveals that salinity in Kansas is
highest in aquifers of Permian age due to the presence of the Hutchinson Salt Member and natural solutioning
of halite from Permian geologic units. It is possible that the salinity of the Arbuckle is generated from
migration of saline water from the Lansing and Kansas City aquifers that exist above the Arbuckle. This is due
to faults and fractures developed by the Central Kansas Uplift that created conduits for fluid migration
downward through the confining layers of shale overlying the Arbuckle. This relatively high salinity has been
exacerbated by brine injection from oil field injection wells (Jorgensen et al, 1993).
Figure 4
Chloride Concentration Map of the Arbuckle Aquifer in Kansas (Jorgensen et al, 1993)
Table 2
Chemical Characteristics of the Arbuckle Aquifer and Overlying Aquifer Zones (Carr et al, 1986)
Water Resource: Usage of the Aquifer
Due to the high chloride levels found in the Arbuckle Aquifer and extreme depth throughout most of Kansas,
water is typically not withdrawn from the aquifer for use. Water use in the state of Kansas is governed by the
Kansas Division of Water Resources (KDWR) which falls under the purview of the Kansas Department of
Agriculture. More information on the KDWR can be found at http://www.ksda.gov/dwr/. Water protection
and groundwater remediation is governed by the Kansas Department of Health and Environment (KDHE)
Bureau of Water. The KDHE Bureau of Water homepage can be found at
http://www.kdheks.gov/water/index.html.
In southeastern Kansas, where the Western Interior Plains Aquifer System meets the Ozark Plateau System,
the Arbuckle (which is no longer called the Arbuckle in this area of the state) does produce some usable
groundwater. However, a discussion of water usage from this part of the aquifer is beyond the scope and
purpose of this review of the Arbuckle.
Oil Production
Oddly enough, the Arbuckle Formation does produce some oil and gas in Kansas and Oklahoma. Withdrawal
of oil from the formation does bring a high volume of water up to the surface from the naturally occurring
aquifer that is also within the formation. This water is disposed back into the Arbuckle via deep injection
wells.
Figure 5
Oil Production in Kansas Based on Producing Formation (Franseen et al, 2004)
Contamination: Sources of Aquifer Quality Reduction
Besides producing oil and gas, the Arbuckle Aquifer provides a safe and convenient disposal zone for industrial
wastewater and oil-field brines. As stated in the previous section, oil and gas derived from the Arbuckle typically
generates a large volume of water from the aquifer within the Arbuckle. To prevent contamination of usable
groundwater sources and surface water sources, this brine (high salinity water) is typically injected back into the
formation.
Class I Disposal Wells
The KDHE governs the use of deep injection wells for non-hazardous industrial wastewater disposal under the UIC
(Underground Injection Control) Program. Wells of this type are termed Class I injection wells. More information on the
KDHE UIC Program can be found at http://www.kdheks.gov/uic/index.html.
Figure 6
Class I Disposal Well (EPA, 2010)
Class II Disposal Wells
The use of deep injection wells for oil-field brine disposal is governed by the Kansas Corporation Commission (KCC).
These wells are termed Class II injection wells. More information on the KCC can be found at
http://www.kcc.state.ks.us/index.htm.
Figure 7
Class II Disposal Well (EPA, 2010)
Because of the depth, confinement, and porosity of the Arbuckle Group, many geologists in Kansas believe it
to be an adequate sink of CO2 sequestration. With the current development of cap and trade and green
house gas emission regulations, a number of companies are currently looking to create methods of
compressing or dissolving in water CO2 emitted from power plants and industrial facilities. The CO2 could
then be injected into the Arbuckle. This process is currently already in use in the oil field by way of Enhanced
Oil Recovery Wells. These wells are used to inject inert CO2 into the oil-producing formation to enhance the
recovery of oil from nearby production wells.
Permitted and Continued Contamination of the Western Interior Plains Aquifer
Studies conducted by Jorgensen et al have determined that the Arbuckle Group is an almost perfect geologic
formation for current injection and disposal activity to occur in Kansas. Areas of uplift have high permeability
and, thus, can accept large volumes of fluid without causing increases in fluid pressure that would allow for
upward migration of waste fluids. Basin areas maintain lower permeability, but have thicker confining layers
that prevent migration from the Arbuckle to freshwater aquifers above. Therefore, the basin areas of Kansas
represent a superior location for disposal into the Arbuckle (Jorgensen et al, 1993).
Under the Safe Drinking Water Act of 1974, the EPA was granted authority to regulate drinking water
contamination. The UIC Program falls under these regulations in that their purpose is to protect usable
drinking water sources. While it seems haphazard to continue to allow injection of wastes into an aquifer, the
EPA has set strict guidelines as to the construction, maintenance, and operation of such wells. Furthermore,
injection wells must not inject into or harm drinking water sources in any way. If it were deemed a threat to
inject wastewater into the Arbuckle Group in Kansas, the KDHE and EPA would have authority to cease such
actions and determine an alternative source of disposal. Deep injection wells are a simple and cost-effective
method of disposing of large quantities of wastewater that would otherwise require some other method of
disposal.
What about Our Neighbors?
A key point that was briefly touched upon by many authors was the possibility of groundwater contamination
in southeastern Kansas and parts of Missouri from wastewater disposal into the Arbuckle. In these areas,
geologic units that are in connection with the Arbuckle are used as a source of groundwater. As noted
previously, groundwater flow in the WIPAS occurs in an east-southeasterly direction toward Missouri. In
addition, it was noted that the Western Interior Plains Aquifer System meets the Ozark Plateau Aquifer System
in southeastern Kansas and western Missouri. It is possible that fluids injected into the Arbuckle in Kansas
could possibly move toward fresh water sources in Missouri causing contamination. This, however, has not
yet been documented.
References







Carr, J.E., H.E. McGovern, T. Gogel. “Geohydrology of and Potential for Fluid Disposal in the Arbuckle
Aquifer in Kansas.” A Study by the U.S. Geological Survey Open-File Report 86- 491. Washington:
Department of the Interior, 1986.
Franseen, E.K. et al. “The Geology of Kansas Arbuckle Group.” Kansas Geological Survey, Current
Research in Earth Sciences Bulletin 250 Part 2 (2004): 1-43. 11 April 2010
http://www.kgs.ku.edu/Current/2004/franseen/franseen1.html.
High Plains Regional Climate Center. “Current Climate Summary Maps – Powered by ACIS.” Climate
Products. HPRCC, 2010. Web. 11 April 2010
http://www.hprcc.unl.edu/maps/current/index.php?action=update_daterange&daterange=Las
t12m.
Jorgensen, D.G., J.O. Helgesen, J.L. Imes. “Regional Aquifers in Kansas, Nebraska, and Parts of Arkansas,
Colorado, Missouri, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming.” USGS
Professional Paper 1414-B. Washington: United States Government Printing Office, 1993.
MacFarlane, P. Allen. “Revisions to the Nomenclature for Kansas Aquifers.” Kansas Geological Survey,
Current Research in Earth Sciences Bulletin 244 Part 2 (2000): 1-14. 8 April 2010
http://www.kgs.ku.edu/Current/2000/macfarlane/macfarlane1.html.
Miller, James A. and C.L. Appel. “Ground Water Atlas of the United States Kansas, Missouri, and
Nebraska.” U.S. Geological Survey HA 730-D (1997). U.S. Geological Survey. 17 April
2010
http://capp.water.usgs.gov/gwa/ch_d/index.html.
U.S. Environmental Protection Agency. “Industrial & Municipal Waste Disposal Wells.” Underground
Injection Control Program. U.S. EPA, 2010. Web. 25 April 2010
http://www.epa.gov/safewater/uic/wells_class1.html.