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MAY 2015

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www.rockproducts.com Frac Sand Insider May 2015 | 49 Geology In these areas, portions of the deposit have undergone diagenet- ic alteration that has resulted in secondary grain overgrowths, dissolution, and cementation of the sand (Winfree, 1983; Kelly, 2006; and Kelly and others, 2007). For example, shallowly bur- ied (<1 km) quartz arenites of the St. Peter Sandstone in an area of southwestern Wisconsin and southeastern Minnesota show authigenic overgrowths on detrital quartz grains that are inter- preted to have originated during the formation of silcretes by precipitation from meteoric water during paleofuid fow events early in the St. Peter Sandstone's history (Kelly, 2006; Kelly and others, 2007). Quartz grain overgrowths were also observed in the St. Peter Sandstone in south-central Wisconsin (Clayton and Attig, 1990). These grain overgrowths reduce roundness and sphericity, and introduce weaker planes along authigenic crystal boundaries. The precipitation of silica cement occludes porosity and reduces friability. In other post-depositional settings, sand- stones that were originally cemented with carbonate minerals can develop increased friability as a consequence of dissolution during early diagenesis or later-stage post-depositional exposure to groundwater fow or surface weathering. COMPETITION AMONG FRAC SAND OPERATORS FOR NEW DOMESTIC SOURCES The challenges to fnding new frac sand reserves include identifying additional sand sources that have the following criteria (Rock Products, 2014d): • meet API specifcations, • have suffcient contiguous volume to be economic, and • are in close proximity to oil and natural gas reservoirs or have rail access needed for cost-effcient transportation to major shale basins (Figure 1). Successful exploration for additional frac sand reserves will likely be somewhat guided by the following set of geological char- acteristics of known deposits (Zdunczyk, 2007): • lower Paleozoic supermature quartz arenites deposited on a broad, low-relief (shallow) marine shelf (Sloss, 1988), border- ing a slowly subsiding, relatively stable, continental interior basin (Sloss, 1988; Runkel and others, 2007); • quartz arenites that have undergone extensive chemical weath- ering in a warm, wet climate, and have experienced a long his- tory of transport and reworking (Sloss, 1988); • transgressive sheet sands laid down on a regionally extensive unconformable surface (Barnes and others, 1996); • shallow marine paralic (at or near sea level) and shelf sands laid down on an unconformable surface of a regressive marine shale (Barnes and others, 1996); and • post-depositional burial in areas free of intense tectonic or metamorphic activity to ensure preservation of original textures such as monocrystallinity of grains (absence of diagenetic over- growths), crush resistance of quartz grains (absence of tectoni- cally induced weak planes), and minimal intergranular cementa- tion (Zdunczyk, 2007). CANADA'S PURSUIT OF FRAC SAND SOURCES Canada is a major consumer of premium frac sand from the Mid- west of the United States, although they have sources that are cur- rently mined in Alberta and Saskatchewan, with others in Manitoba scheduled to come online in 2015 (Figure 14). To improve their independence from the U.S. market, Canadian companies and provincial agencies have undertaken an extensive effort to identify and develop their own frac sand sources. Production and reserve values are shown in units as published in the cited references. No standard use of either metric or English units is implied in cases where the unit is reported only as "ton" by the original source. 14. Index map of place names, provinces, and features mentioned in the description of mined and potential sources for frac sand in Canada. alBerta Peace River: The Peace River (Figure 14) Frac Sand Quarry, which is owned and operated by Canadian Silica Industries, pro- duces frac sand from the Lower Cretaceous Paddy Member of the Peace River Formation. The Peace River Frac Sand Quarry reportedly has a total annual capacity of 500,000 tonnes of silica sand. This operation is located in close proximity to the Horn River and northwestern Deep Basins (Figure 1), and is central to the frac sand market within northwestern Alberta (The Wall Street Journal, 2014). Fort McMurray: A frac sand deposit known as the Firebag de- posit is north of Fort McMurray (Rock Products, 2014a) (Figure 14). Athabasca Minerals has a prospective frac sandstone deposit in this area with an estimated capacity of 1,000,000 tons per year (tpy) (Claim Post Resources Inc., 2013). Preliminary testing indi- cates that the Firebag sand meets or exceeds API/ISO specs for frac sand. A location that is 1,200 mi (about 2,000 kilometers) clos- er to key Canadian markets makes this project advantageous. CHALLENGES TO THE FRAC SAND INDUSTRY

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