Introduction
Wisconsin's Paleozoic sand deposits have been mined for over 100 years and have served a variety of purposes: water filtration, casting molds, glass production, construction, and recreation. Today, Wisconsin's abundant sand (frac sand) deposits are harvested in order to satisfy the global appetite for hydrocarbons. According to the Wisconsin department of natural resources (DNR), the state currently hosts 63 active mining sites (fig. 1). The issue of sand mining in Wisconsin is one of contention among citizens of the state and as such is a highly regulated process. In order to ensure efficiency geospatial programs, like ESRI's ArcGIS, are used to monitor production volume of frac sand and to find the most efficient transportation routes from mining/processing facilities to railways where the sand is then distributed across the country. The purpose of this report is to provide background information regarding Wisconsin's sand deposits, mining and processing of such deposits, investigate the debates surrounding the mining of frac sand, and how ArcGIS can be used to ensure sand mines are adhering to regulatory standards and mining efficiency.
Figure 1. Map of active and inactive sand mining locations in the State of Wisconsin. Information on the map is current as of May 1, 2014 (DNR map: Wisconsin DNR, 2012 ; placer map: Initiative and Referendum Institute, 2014).Hydraulic Fracturing
Vertical hydraulic fracturing is a hydrocarbon extraction method that has been used for over forty years, according to the Wisconsin DNR (Silica Sand Mining in Wisconsin, 2012). During the vertical and horizontal hydraulic fracturing processes (fig. 2), a hole is bored into the rock formation of interest, typically a shale; the shale is sometimes weakened by an explosive charge. Chemical- and sand-laden water is pumped into the borehole under pressure. Sand particles in the water fill the fractures created by the explosives and prop them open. When the water is pumped out of the borehole natural gas entrained within the shale can permeate through the borehole to be collected (Silica Sand Mining in Wisconsin, 2012).
Figure 2. Cartoon showing the general process of hydraulic fracturing (Frac Free Somerset, 2015).
The current boom in hydraulic fracturing is the result of a modification to the boring process, whereby the borehole can be directed horizontally through a shale deposit, as to vertical-only boring methods. Following is a link to a video that describes the process of horizontal hydraulic fracturing in detail:
Video link showing the hydraulic fracturing process for extracting hydrocarbons.
Frac Sand
One reason for that sand from Wisconsin is so useful in hydraulic fracturing is that it is of the perfect size, shape, and composition for such processes (fig.3). For example, well rounded, well sorted, fine grained quartz sand is perfect for prying open the fractures induced in shales during the extraction process. If the sand were made of a different, weaker material then the high pressures found in subterranean shale deposits might break the sand grains and a closing of the fractures might result. Similarly, if the sand were poorly sorted and angular, only some of the sand would hold open the fractures which would likely result in a lower volume of hydrocarbons being taken from the formations (Frac Sand in Wisconsin, 2012).
Figure 3. Well sorted, well rounded, fine-grained sand like frac sand extracted in western Wisconsin (Forbes, Sand image).
Three formations are found in Wisconsin that supply frac sand: the Cambrian (~500+Ma) Wonewoc and Jordan formations and the Ordovician (~450+Ma) St. Peter formation (Silica Sand Mining in Wisconsin, 2012). Sand suitable for hydraulic fracturing is mostly confined to western Wisconsin (fig. 4) because of two important factors. First, during Cambrian-Ordivician times, these areas were located in a marine environment. Wave energy in such an environment eroded less resilient minerals and left mostly well rounded, fine grained quartz. Also, much of the area in the map in figure 4 lies inWisconsin's "driftless" zone, called so because much of it was unaffected by the erosional effects of Quaternary glaciation (Silica Sand Mining in Wisconsin, 2012).
Figure 4. Extent of Cambrian-Ordovician sands in Wisconsin (http://www.isthmus.com/media/2014/03/20/586CoverIndustrialSandPotential3912.jpg).
Another reason why frac sand from Wisconisn is so sought after is because it is easy to process. Once sand has been mined it is then washed and sorted on site (Industrial Sand Mining, 2014). Much of the sand used for frac sand is loosely held together, like at the Fairmont facility in Menomonie, Wisconsin, and can be broken up using the excavation equipment like frontend loaders. Once the sand has been processed it can be shipped to oilfields throughout the nation (fig. 5).
Figure 5. Location map showing "tight gas" oilfields where Wisconsin frac sand is used (University of Texas Austin, Shale gas map).
Regulation of Frac Sand Mines in Wisconsin
The question of whether or not to mine frac sand in Wisconsin is an issue that has divided residents of the state. As demands for frac sand increased in conjunction with increasing hydrocarbon production (fig. 6), the number of companies applying to extract the states sand resources did as well (Industrial Sand Mining, 2014). For example, the Texas-based company, Insight Equities, has invested about $91 million in Wisconsin mining operations and is expecting a return of more than ten times that amount. In fact, Insight expects its Wisconsin facility to double production by the end of 2015 and increase by 22% over the next several years (Zuckerman, 2014).
a.
b.
Figure 6. Figure 6a shows increasing frac sand production between 2001 and 2011, while figure 6b shows an increasing demand in US natural gas production between 200 and 2012 (6a: Prengaman, 2012; 6b:Bipartisan Policy, 2013).
Residents of the state, particularly those who lived in close proximity to potential mining/processing site questioned what such locations would have on their communities and the environment. As a result, a series of regulations, enacted by the Wisconsin DNR to ensure that frac sand mines would have as little impact on the environment as possible. However, an article from the Lacrosse Tribune published in November of last year claims that 43% of 47 sand mines investigated were in violation of at least one Wisconsin DNR regulation (Geyer, 2014 ).
One way the Wisconsin DNR ensures that sand mines do not have an adverse affect on the environment is through air quality monitoring. For example, the opening of some sand mines, like Chippewa Sand Company's facility in New Auburn, Wisconsin, is contingent on them providing the DNR with air monitoring data at regular intervals (fig. 7). Similarly, water quality data near mine sites is regularly monitored by the DNR as well.
Figure 7. Air quality data from the Chippewa Sand Company's New Auburn Facility; from April 2012 till September 2014 (Wisconsin DNR, 2012).
Another major responsibility that the DNR has with regards to frac sand mining in Wisconsin is enforcing reclamation, as per the NR 135 Nonmetallic Mining Reclamation (Wissconsin DNR, 2015). NR 135's purpose is to ensure that once the frac sand mining process is complete within a location that the area of the site is rehabilitated. Such rehabilitation includes, but is not limited to, removing roads no longer in use, the replacement of topsoil, and a reestablishment of vegetation. The legislative measure also goes ensures that former sand mining sites are safe after operations in such locations are completed; for example, by ensuring that slopes in such areas are stable.
How Does ArcGIS Fit Into the Frac Sand Equation?
Geospatial information system (GIS) software, like ESRI's ArcGIS, is beneficial to the Wisconsin's frac sand industry in several ways. First off, such software can directly benefit the frac sand companies by ensuring that production demands are met. Volumetric calculations of sand could be conducted using spatial analyst tools in ArcMap to ensure that the required amount of sand is mined each month or week. However, such realtime volume calculations with ArcGIS may have to wait until data collection methods, like Lidar, are more readily available.
Secondly, sand mines could use ArcGIS to plan the most effective routes to rail depots for exportation across to the oilfields. For instance, in Dunn county, Fairmont Minerals is prohibited from driving its trucks through the town of Menomonie to the railroad depot in the village of Wheeler. GIS could find the quickest possible route to Wheeler from Menomonie, potentially saving the company time and money in vehicle maintenance and fuel costs.
Sources
Bipartisan Policy, 2013:
February 2015).
Forbes, Sand image: http://b-i.forbesimg.com/christopherhelman/files/2013/08/sand-minn-dept
e-q.jpg (accessed February 2015).
Frac Free Somerset, 2015, What is fracking?: http://www.frackfreesomerset.org/what-is-fracking/
(accessed February 2015).
Geyer, A., 2014, Lacrosse Tribune, New report finds majority of frac sand mines committed environ-
mental violations: http://lacrossetribune.com/news/local/new-report-finds-majority-of-frac
sand-mines-committed-environmental/article_0aefa8f6-dba8-5af4-b427-0446726f6288.html
(accessed February 2015).
Initiative and Referendum Institute, 2014, Wisconsin: http://www.iandrinstitute.org/Wisconsin.htm
(accessed February 2015).
Prengaman, K., 2012, Minnesota Post, Wisconsin frac sand sites double:
February 2015).
University of Texas at Austin, Shale gas map: http://www.jsg.utexas.edu/news/files/map-shale
gas700.jpg (accessed February 2015).
Wisconsin DNR, 2015, Mines: http://dnr.wi.gov/topic/Mines/ISMMap.html (accessed February
2015).
Wisconsin DNR, 2012, Silica sand mining in Wisconsin, pp 1-43.
Wisconsin DNR, 2012, Nonmetallic mining reclamation:
http://docs.legis.wisconsin.gov/code/admin_code/nr/100/135.pdf (accessed February 2015).
Zuckerman, G., 2014, Wall Street Journal, Small firm strikes it big with fracking sand:
(accessed February 2015).
