a concealed geothermal system near corner canyon, salt lake county, utah

A CONCEALED GEOTHERMAL SYSTEM NEAR CORNER CANYON,

SALT LAKE COUNTY, UTAH

ABSTRACT

In March 2008, an irrigation company completed a water supply test well along the Wasatch Front at Corner Canyon near the southern edge of Salt Lake County, southeast of Draper, Utah. The well was drilled to 1270 feet (387 m). Static water level rose to 85.6 feet (26.1 m) below ground level. Air-lifting produced water at temperatures between 175°and 185°F (79°-85°C). Temperature measurements during well logging three months after well completion revealed a maximum temperature of 202°F (94.4°C) from 472 to 499 feet (144 to 152 m), which likely coincides with the zone of most geothermal fluid movement into the well. The bottom-hole temperature was 195°F (90.6°C). Lithologic and geophysical logging show that monzogranite of the Tertiary Little Cottonwood Stock was encountered at 60 feet (18 m) and multiple fracture zones and possible faults are present in the upper 500 feet (152 m) of the hole. Analyses of fluid samples collected during a 24-hour pump test yielded 300 gallons per minute (1136 L/min) and water with total dissolved solids content of 7360 mg/kg. The water is sodium-chloride type and more similar to Ogden Hot Spring in Weber County than to geothermal systems much closer to Corner Canyon. Silica concentration (SiO2 = 179 mg/kg) was exceptionally high compared to other Wasatch Front thermal waters (SiO2 ranges from 12 to 41 mg/kg), suggesting that a component of the Corner Canyon well water has equilibrated with one or more SiO2 mineral phases at temperatures above 302°F (150°C). The chalcedony and K-Mg chemical geothermometers suggest equilibrium reservoir temperatures ranging between 302° and 358°F (150°-181°C).

The well was sited along the surface trace of the Wasatch fault, near the southern end of the fault’s Salt Lake City segment, and was drilled into fractured granodiorite of the 30.5-million-year-old Little Cottonwood Stock. The Wasatch fault juxtaposes Eocene-Oligocene volcanic rocks and Pennsylvanian sandstone of the Oquirrh Group in the Traverse Mountains, down to the west and southwest, against rocks of the Tertiary Little Cottonwood Stock of the Wasatch Range, up to the east and northeast. The Traverse Mountains mark the boundary between the Salt Lake City and Provo segments of the Wasatch fault. These segments are linked by the Fort Canyon fault, which trends east-west through Corner Canyon and which has a long history as the northern ramp of the Sevier-age Charleston thrust fault and the middle Tertiary Deer Creek detachment fault.

Based on the chemistry and geologic setting of the well, the fluids encountered at Corner Canyon may be part of a much larger geothermal system that is mixing with fresh ground water encountered as fluids move along fault conduits.

by Robert E. BlackettUtah Geological Survey

88 E. Fiddler Canyon Rd. Ste. C, Cedar City, Utah 84721 [email protected]

J. Lucy Jordan, Kevin Thomas, Janae Wallace, and Robert F. BiekUtah Geological Survey

P.O. Box 146100 Salt Lake City, Utah 84114

[email protected]@utah.gov [email protected]

[email protected]

INTRODUCTION

Background

This paper provides details on the discovery of a potentially important geothermal resource along the Wasatch Front of northern Utah. In December 2007, WaterPro, Inc., contracted to drill and complete a water supply well for the growing com-

munity of Draper, Utah, located in the southeastern part of the Salt Lake Valley (figure 1). Mike Zimmerman Well Service began drilling on December 29, 2007. During the early stages of drilling, the temperature of the return fluid became ele-vated suggesting a geothermal source at depth. Zimmerman completed the drilling phase of the well in early March 2008, creating a 10-inch- (25-cm-) diameter well to a total depth of 1270 feet (387 m). Since the discovery and well completion, WaterPro has enlisted the help of the Utah Geological Survey

Robert E. Blackett, J. Lucy Jordan, Kevin Thomas, Janae Wallace, and Robert F. Biek236

(UGS) and others to do preliminary geothermal assessments of the pilot well and help evaluate options for future develop-ment.

Location and Access

The City of Draper is situated about 15 miles (24 km) southeast of Salt Lake City. The well is located in the SW1/4SE1/4NE1/4 section 4, T. 4 S., R. 1 E., Salt Lake Base Line and Meridian (SLBM) at a latitude of 40°30'4" N. and longitude of 111°50'18"W. The approximate land surface elevation at the well head is 4890 feet +/- 20 feet (1490 m +/- 6 m). The site is in the lower part of Corner Canyon near the southern edge of Salt Lake County. Corner Canyon sits at the southeast edge of the Salt Lake Valley where the base of the Wasatch Range intersects the Traverse Mountains (figure 2). The Salt Lake County/Utah County line lies about one mile to the southeast from the well. Corner Canyon trends southeastward along the juncture of the two mountain ranges eventually turning due east. The site lies at the edge of the recently expanded urban area of Draper and is accessed by traveling on paved roads through new subdivisions encroach-ing into the foothills of the Wasatch, then by dirt track for a few hundred feet into Corner Canyon. The well is near the base of the canyon.

GEOLOGY, HYDROGEOLOGY, AND GEOTHERMAL SYSTEMS

Regional Setting

Davis (1983) described the geology of the central part of the Wasatch Front as very diverse with rocks representing nearly every geologic period from Precambrian to Recent. The Wa-satch Range comprises the westernmost range of the Middle Rocky Mountains physiographic province with peaks reach-ing elevations in excess of 11,000 feet (3350 m). The range has about 7000 feet (2130 m) of relief. Rocks in the Wasatch Range have undergone at least two major episodes of moun-tain building. The first episode was thrust faulting and fold-ing of strata during the Sevier orogeny (Cretaceous to early Tertiary). Biek (2005b) describes events leading to the current geologic features seen in the study area including: 1) Sevier-age compression where great thicknesses of Oquirrh Group rocks were folded and thrusted eastward, 2) regional uplift and collapse of the orogenic belt along low-angle detachment faults (Deer Creek fault) with contemporaneous volcanism and intrusions of the Wasatch igneous belt occurring from about 40 to 20 million years ago (mya), and 3) extension and differential uplift that produced normal faulting beginning in Miocene time and continuing to the present. This third epi-sode, beginning about 17.5 mya (Hintze, 2005) and extending to the present, produced the Basin and Range physiographic province with numerous north-south-trending, tilted moun-tain ranges bounded on at least one side by high-angle normal faults.

Wasatch Fault Zone

The Wasatch fault zone marks the western margin of the Wa-satch Range and represents the boundary between the Mid-dle Rocky Mountains province to the east and the Basin and Range province to the west. Hecker (1993) describes Qua-ternary tectonics in northern Utah as concentrated within a 124-mile- (200-km-) wide zone centered on the Wasatch fault zone and coincident with the Intermountain seismic belt. The Wasatch fault zone extends 211 miles (340 km) from south-ern Idaho through northern, and into central Utah. It is the most tectonically active structure in this region and exhibits abundant evidence of recurrent surface rupture during the Holocene (Machette and others, 1992; Schwartz and Copper-smith, 1984).

Geologists recognize several segments of the Wasatch fault (figure 2). Each segment is bounded by a bedrock projection (often called a spur) or a significant step-wise offset to the sur-face trace. The Salt Lake segment is bounded on the north by a spur called the Salt Lake salient that projects westward from the Wasatch Front between Salt Lake City and Bountiful. On the south, the Traverse Mountains, extending west from Al-pine, separates the Salt Lake segment from the Provo segment

Figure 1. Location of the study area detailed in figure 2.

UGA Publication 38—A Concealed Geothermal System near Corner Canyon, Salt Lake County, Utah 237

(see Hintze, 2005). Between Alpine and Corner Canyon, the Wasatch fault offsets bedrock, down-dropping Pennsylvanian Oquirrh Group rocks and Tertiary (late Eocene to Miocene [?]) volcanic rocks and alluvial deposits of the Traverse Moun-tains relative to the Tertiary Cottonwood Stock of the Wa-satch Range.

At Corner Canyon, which marks the southern end of the Salt Lake segment of the Wasatch fault, the fault makes an abrupt bend to the east-southeast, coincident with the trace of the Sevier-age Charleston thrust fault. Machette (1992) referred to this east-trending part of the Wasatch fault, which links the Salt Lake City and Provo segments, as the Fort Canyon fault,

Figure 2. General geology of the Jordan Valley region, northern Utah. Geology from Hintze and others (2000).


which dips about 25° south and exhibits a significant amount of down-to-the-southwest oblique slip (Evans and others, 1997; Bruhn and others, 2005). The Charleston thrust fault is the northern boundary fault (edge) of the Charleston-Nebo thrust sheet. The Charleston thrust resulted from a protracted period of compressional deformation between about 100 and 40 million years ago (early Late Cretaceous to late Eocene). The Charleston thrust fault separates allochthonous terrain to the south (displaced roughly 50 miles [80 km] from the west) from autochthonous terrain to the north exposed in the Wa-satch Range near Park City. Part of the Charleston thrust fault was reactivated during extensional collapse of the Sevier oro-genic belt about 40 to 20 mya (late Eocene to early Miocene); this early phase of extension occurred along the Deer Creek detachment fault, a major low-angle normal fault that accom-modated 3 to 4 miles (5-6 km) of west and southwest displace-ment (Constenius and others, 2003). Strata of Mount Timpa-nogos are part of the 25,000-foot- (7600-m-) thick Oquirrh Group rocks on the upper plate of the Charleston-Nebo thrust sheet (Hintze, 2005). North of the Charleston-Deer Creek-Fort Canyon fault, Hintze (2005) indicated that age-equivalent strata in the Park City area are only one-tenth as thick.

Subsurface Lithology, Fracturing, and Alteration

Parry and Bruhn (1986), Evans and others (1997), and Bruhn and others (2005) described hydrothermally altered and me-chanically deformed monzogranite and granodiorite of the Little Cottonwood pluton at Corner Canyon. Alteration and fracturing are most intense along the Wasatch-Fort Canyon fault zone and decrease inward toward the intrusion, forming a shell or carapace on the south and west flanks of the intru-sion that is several hundred feet thick. Altered rocks exposed at Corner Canyon formed at estimated depths of 4.5 to 7.1 miles (7.2–11.4 km) and record inception of faulting on the Wasatch fault beginning about 17 million years ago (Parry and Bruhn, 1986). Biek (2005a) showed the distribution of these altered rocks in the Lehi quadrangle immediately south of the well. The alteration assemblage grades from greenish, highly altered rocks (phyllonite and cataclasite) near the Wasatch and Fort Canyon faults to brownish, less altered rocks toward the interior of the pluton.

We compiled a detailed description of cutting samples from the well and a geologic interpretation (figure 3). The well pen-etrated alluvial deposits from the surface to about 60 feet (18 m) depth. From there the cuttings consisted of disaggregat-ed igneous rock crystals and clay minerals that suggest fault gouge. From about 120 feet (36 m) to about 160 feet (49 m) the well penetrated a suspected fault zone consisting of altered igneous rock including foliated minerals, hematite, and mag-netite. From about 160 feet (49 m) downward to total depth of 1270 feet (387 m) the well penetrated mostly monzogranite(?) of the Little Cottonwood stock, described on the lithologic log (figure 3) as “. . . Green, gray, white, and black phaneritic and

porphyritic igneous rock composed of biotite, feldspar, and quartz; some chlorite and epidote?. . . Some xenoliths of lime-stone and volcanic rock fragments?” The log suggests that one or more fault zones were penetrated within the upper 160 feet (49 m) of the well. The location of the Wasatch fault is marked by several fault scarps in the Corner Canyon area (Personius and Scott, 1992; Biek, 2005b). The presence of chlorite and epidote suggests that the well penetrated the altered carapace of the Little Cottonwood stock, which is well exposed to the east in Corner Canyon.

Jordan Valley Hydrogeology

Surface Water

The Jordan Valley of northern Utah is comprised of upper (southern) and lower (northern) parts. The upper or southern part is Utah Valley which contains Utah Lake and its tributar-ies. The Jordan River begins at an outlet on the north end of Utah Lake and flows northward through a water-gap in the Traverse Mountains (known as the Jordan Narrows) and into the lower Jordan Valley, commonly referred to as the Salt Lake Valley. The Wasatch and Oquirrh Mountains are drained by multiple large and small perennial streams, some of which reach the Jordan River. The Jordan River continues north-ward through the Salt Lake Valley terminating at the Great Salt Lake – a distance of roughly 40 miles (64 km). The Salt Lake Valley has an area of about 400 square miles (1036 km2) and forms the lowlands of Salt Lake County.

Ground Water

Ground water occurs in the unconsolidated basin-fill deposits beneath the Jordan Valley floor under confined and uncon-fined conditions. Recharge to the valley aquifers takes place along the margins of the valley from water percolating into the bedrock units from snow-pack in the Wasatch, Oquirrh, and Traverse Mountains and from seepage from perennial streams. In the northwest portion of the Salt Lake Valley, ground-water movement is mainly toward the Great Salt Lake. Through-out the remainder of the valley, ground water moves toward the Jordan River, which drains both surface and ground water from the valley (Haraden, 2003).

The basin-fill aquifers in Salt Lake Valley include (1) a deep, unconfined aquifer near the mountains, (2) a confined aquifer in the central and northern parts of the valley, (3) a shallow, unconfined aquifer overlying the confined aquifer, and, locally, (4) unconfined, perched aquifers (Hely and others, 1971; An-derson and others, 1994; Lowe and others, 2005). Together, the confined aquifer and the deep unconfined aquifer form the “principal aquifer”—most of the ground water discharged from wells in Salt Lake Valley is from the principal aquifer.

The deep, confined aquifer consists mostly of Quaternary de-posits of clay, silt, sand, and gravel, which, although layered,


Figure 3. Geologic well log of cutting samples from the Corner Canyon well.


are all hydraulically interconnected (Hely and others, 1971). The Quaternary deposits range in thickness from zero to over 2000 feet (600 m) (Arnow and others, 1970). Underlying these Quaternary deposits are relatively impermeable consolidated and semi-consolidated Tertiary and pre-Tertiary deposits. However, a few areas exist where the Tertiary deposits consist of permeable sand and gravel that yield water to wells; these areas are also considered part of the principal aquifer (Hely and others, 1971; Lowe and others, 2005).

Jordan Valley Geothermal Areas

Warm Springs Fault Area

The Warm Springs fault geothermal area extends about 3 miles (4.8 km) in length and ¾ mile (1.2 km) in width, lying along the base of the Wasatch Range, just north of Salt Lake City. Beck’s Hot Spring, Wasatch Warm Springs, and Hobo Warm Springs occur along this segment of the Wasatch fault (figure 2). (The term Warm Springs fault is a local name given to this section of the Wasatch fault.) Discharge temperatures in this system range from 81°F (27°C) at Clark Warm Springs, to 131°F (55°C) at Beck’s Hot Spring (Klauk and Darling, 1984). Geothermal springs in the area are known, but have not been recently utilized. Lutz (2004) described the first use of the springs for therapeutic bathing (balneology), by Mor-mon settlers, beginning about the year 1850. The area ex-perienced several periods of development for recreation and balneological use, each followed by economic collapse or some catastrophe. The most recent effort to use the resource began following a 1984 study by the Oregon Institute of Technology Geo-Heat Center to establish a geothermal heating system for the Children’s Museum of Utah (Karlsson, 1984). Lutz (2004) reported that the hot water was still used to heat the museum building, which originally housed a swimming pool.

Crystal (Bluffdale) Area

The Crystal (Bluffdale) Hot Springs geothermal area is located at the south end of the Salt Lake Valley, near the Utah State prison, about 2 miles (3.2 km) north of the Traverse Moun-tains and the feature called “Point of the Mountain” (figure 2). Klauk and Darling (1984) reported that spring surface tem-peratures vary between 131° and 183°F (55° and 84°C). Sub-surface temperatures in excess of 185°F (> 85°C) have been reported in production wells ranging from about 600 to 1000 feet (183-305 m) in depth. Three production wells are cur-rently available for geothermal-heated greenhouses and space heating for part of the Utah State prison. One well is owned by the Utah Department of Corrections (UDC) and dedi-cated to the prison heating system, the other two are owned by Bluffdale Flowers. A fourth well owned by the prison was reportedly “re-discovered” after being “lost” about 20 years ago and may be available for future use. The springs normally issue from valley alluvium into several ponds. When produc-tion wells are in operation, the surface springs and ponds re-portedly dry up.

Currently, UDC uses their well to provide space heat and do-mestic hot water for 332,665 square feet (30,905 m2) of the prison (five buildings housing 1460 inmates). Produced fluid flows through a heat exchanger transferring thermal energy to a closed-loop system containing domestic water. The spent geothermal fluid is cooled and cascaded to an aquaculture fa-cility (tropical fish rearing) located about 0.5 mile (0.8 km) west of the well (Greg Peay, UDC, verbal communication, March 4, 2009).

Bluffdale Flowers, known as Utah Roses prior to 1998, op-erates a 250,000-square feet (23,225-m2), geothermal-heated greenhouse complex producing 40 varieties of cut roses and other flowers. The complex has operated successfully at the site since its establishment in 1981. The facility uses two wells (600 and 900 feet [183 and 274 m] deep) to supply geother-mal water at a temperature of about 185°F (85°C) to a sur-face heat exchanger, which is coupled to a closed loop fluid/heat distribution system serving the greenhouses (Blackett and Powlick, 2006).

Murphy and Gwynn (1979) studied the geologic aspects of the Crystal Hot Springs geothermal system. The Utah Energy Office (1981) and Morrison-Knudson Company, Inc. (1982) also analyzed technical and economic aspects of the system as part of DOE-sponsored studies in the early 1980s. Klauk and Darling (1984) presented a description of the system in the context of a study of the entire lower Jordan Valley. Crystal Hot Springs is located between two inferred range-front faults with fractured Paleozoic quartzite (at depth) leaking warm wa-ter to the surface through unconsolidated material.

Saratoga Area

Saratoga Hot Springs issue from unconsolidated Quater-nary deposits along the northwest shore of Utah Lake in SE1/4SW1/4 section 25, T. 5 S., R. 1 W., SLBM in Utah County (figure 2). Other hot springs, known locally as Crater Springs, issue beneath Utah Lake about 0.5 mile (0.8 km) east of Saratoga Springs. Infrequent measurements since the early 1900s show that spring temperatures have ranged from 100° to 111°F (38° to 44°C). The springs are spatially related to the trend of the Utah Lake fault zone (Mundorff, 1970).

Corner Canyon Well

Well Completion and Geophysical Logging

WaterPro contracted Mike Zimmerman Well Service to drill and complete the Corner Canyon pilot well. Zimmerman be-gan drilling on December 29, 2007 and completed the drill-ing phase of the well in early March 2008, completing an ap-proximately 10-inch- (25-cm-) diameter well to a total depth of 1270 feet (387 m). Zimmerman completed the well by in-stalling a 10-inch- (25-cm-) diameter casing to 150 feet (46 m) depth, leaving the interval from 150 feet (46 m) to total depth uncased. During drilling, Zimmerman recorded mud tem-


peratures of 132°F (56°C) at 980 feet (299 m) and 139°F (59°C) at total depth. On April 22, 2008, the lower 70 feet (21 m) of the well were tested by first installing a packer at 1200 feet (366 m) and air lifting approximately 55 gallons per minute (gpm) (208 l/m) from the open hole below the packer for approximately seven hours. The water temperature of this air-lifted water was 175°F (79°C), and pH and electrical conductivity were 8.1 and 10,820 micro-Siemens per centimeter (mS/cm), respectively. The packer was removed, and the well was air-lifted again for approximately 24 hours, yielding approximately 100 gpm (380 l/m) of 185°F (85°C) water having pH of 7.7 and conductivity of 12,600 mS/cm.

The static water-level measured on June 19, 2008, was 85.6 feet (26.1 m) below land surface which is equal to an elevation of about 4805 feet (1465 m) above mean sea level.

Initial geophysical logging attempts by UGS were unsuccessful be-cause water temperatures exceeded the design limits of the logging tools. As a result, WaterPro, along with their consultant, Loughlin Water Associates LLC, hired Schlumberger to obtain geophysi-cal logs of the well (figure 4). Schlumberger recorded gamma ray, resistivity, self potential (SP), sonic, porosity, and caliper logs on March 5, 2008. A general summary of geophysical well logs is pre-sented below.

Caliper: The caliper tool measures the diameter of the well, which can be used to determine borehole conditions, identify frac-ture zones, and locate washouts (where the borehole has eroded away to a larger diameter). Knowing the borehole diameter allows us to assess the stability of the borehole walls. Since some logging tools are affected by the diameter of the well (for example, the natural gamma log), the caliper log permits us to account for vari-ations in borehole diameter when interpreting those logs. The cali-per tool recorded major washouts, interpreted as fracture zones, in the Corner Canyon well through the following depth intervals: (1) from 150 to 178 feet (46–54 m), (2) from 225 to 242 feet (66–74 m), and (3) 350 to 380 feet (107–116 m).

Sonic: The sonic tool measures the time it takes a sound wave to travel one foot through the material surrounding the well. The travel time is dependent on the density of the material and can be used to estimate porosity. Porosity data are useful for identify-ing water-bearing layers and fracture zones. In the Corner Canyon well, the sonic log somewhat mimics the caliper log, showing in-tervals of likely higher permeability, interpreted as fracture zones.

Natural gamma (gamma ray): The natural gamma log records the amount of naturally occurring gamma radiation with-in the well. Since clay minerals generally contain relatively high concentrations of radioactive elements (typically potassium, ura-nium, and thorium), the natural gamma log can be used to identify low-permeability clay and shale beds. The dominant litho-type en-countered in the Corner Canyon well is intrusive “monzogranite” as described by Biek (2005a), which typically yields uniformly high gamma radiation, as seen in figure 4. Wash-out zones, previously described, (150 to 178 feet [46–54 m]) containing clay alteration may be reflected in a small way on the gamma-ray log, though the lower gamma-ray values in this interval may simply reflect the Figure 4. Geophysical well-log composite of the Corner Canyon well.


interval’s larger borehole diameter.

Temperature: The temperature log records the tempera-ture of the fluid inside the well; temperature gradients help identify layers where water is flowing into or out of the well, trace movement of injected water or waste, and define the ge-othermal gradient. Temperature logging in the Corner Can-yon well is described in detail in a subsequent section.

E-logs: The electric logs (E-logs) measure the resistivity of the borehole strata. Clays and shales are relatively good conduc-tors and will have lower resistivities. Other rocks and sediments are generally poor conductors of electricity, so most of the current will flow through pore-space water in these materials. The E-log response in these materials is related to the amount of water present (which is related to the porosity), the quality of the water (more dissolved solids in the water results in lower resistivity), and the temperature (higher temperatures reduce resistivity). E-logs can be used to determine lithology, identify fracture zones, and estimate water quality. By using several different electrode spacings, the depth to which the current penetrates the surrounding material can be varied, reducing the effects of the borehole on the log. However, in order to achieve deeper penetration into the formation, you must sacri-fice vertical resolution. Schlumberger’s E-logs include AHF30, AFH60, and AHF90, which have depths of penetration into the surrounding formation of 30, 60, and 90 inches (76, 152, and 229 cm), respectively.

These resistivity logs show that the granite from 150 feet (46 m) to 530 feet (162 m) has been disturbed and altered, pre-sumably by faulting and fracturing. From 530 feet (162 m) to 1220 feet (372 m), the granite is mostly undisturbed but with frequent 5- to 10-foot (1.5- to 3-m) disturbed intervals. We

believe that the altered and fractured zones, indicated on the E-logs, may point to different parts of the altered carapace of the Little Cottonwood pluton that is exposed farther to the southeast in Corner Canyon (Biek, 2005a) and described in detail by Parry and Bruhn (1986).

Temperature Logging

UGS personnel used a NP Instruments brand, high-precision, thermistor probe and temperature-depth logging equipment to record a temperature-depth profile of the well. Instrument characteristics and periodic calibrations result in a tempera-ture measurement precision of 0.018°F (0.01°C), but convec-tion within the well often reduces measurement accuracy to ± 0.09°F (0.05°C). The first down-hole temperature survey was done on April 3, 2008, when a maximum temperature of 200°F (93°C) was recorded at a depth of 465.9 feet (142 m). A blockage in the well at 905.5 feet (276 m) prevented the probe from reaching total depth. The temperature at 905.5 feet (276 m) was 195.8°F (91°C). Following this, drillers re-entered the well to remove the blockage and develop and test pump the well. On June 19, 2008, following several weeks when the well was left undisturbed, a second temperature profile was record-ed (figure 5, Appendix A). The static water-level, measured with an electronic water-level sounding device, was 85.6 feet (26.1 m) below land surface. Temperatures were measured to a depth of 1220.5 feet (372 m). Maximum temperature re-corded was 202.2°F (94.6°C) within the depth interval from 470.9 to 498.7 feet (143.5-152 m). Bottom-hole temperature was 195.1°F (90.6°C) at 1220.5 feet (372 m). Since no tem-perature variation was noted from 1194.2 feet (364 m) to total depth, we are suspicious that the probe may have stopped at 1194.2 feet (364 m).

Figure 5. Detailed temperature survey of the Corner Canyon well.


Hydrochemistry and Stable Isotopes

Water samples were collected from the Corner Canyon well during a 24-hour pump test on January 17, 2009. Three aliq-uots were collected in 1.18 pint (560 ml) polyethylene bottles as follows (1) raw, unfiltered; (2) filtered (0.45µm [.000018 in]); (3) filtered (0.45 µm [.000018 in]) and diluted 1:4 with deion-ized water. The samples and a deionized-water blank sample were analyzed by Thermochem Laboratory & Consulting Services in Santa Rosa, California. The results of Thermo-chem’s analyses indicate the water is of sodium-chloride type (table 1).

The chemistry of the Corner Canyon well was compared to other Wasatch Front geothermal systems and three fresh-water wells in Draper and the nearby city of Sandy (table 2, figure 6, Appendix B). The Corner Canyon well has water chemistry most similar to Ogden Hot Spring, and relatively similar to Becks Hot Spring and Udy Hot Spring, although the silica content of the Corner Canyon well is much higher. Water in the basin-fill aquifers in southeast Salt Lake Valley is of good quality as shown by three representative non-thermal well water analyses taken from Thiros (1995) (table 2).

The Corner Canyon well water had stable isotopes ratios of hydrogen (D/H) and oxygen (18O/16O) in water of -116.9

Figure 6. Piper diagram illustrating variation in water chemistry for selected Wasatch Front geothermal systems and three non-geothermal wells in south-west Salt Lake Valley.

Analyte mg/kg

Sodium 2320

Potassium 287

Calcium 255

Magnesium 4.85

Boron 3.06

Silica 179

Iron 1.20

Chloride 3860

Sulfate 209

Total Alkalinity (as HCO3-) 244

Carbonate Alkalinity (as CO32-) <2

Bicarbonate Alkalinity (as HCO3-) 244

TDS (calculated) 7360

Lab measured pH 6.75

Stable Isotopes of Water ‰ *

δ2H -116.94

δ18O -14.88

*Measurements relative to V-SMOW = 0 with uncertainty of +/- 1.0% for δ2H and +/- 0.1% for δ 18OV-SMOW = Vienna distribution of water sample repre-senting Standard Mean Ocean Water

Table 1. Water chemistry results for the Corner Canyon well, sampled 1/17/09.


Table 2. Water chemistry of selected Wasatch Front geothermal systems and non-geothermal wells in southeast Salt Lake valley. Concentrations given in parts per million unless otherwise noted.

Site County Location

Sample

Date Type1

Temp-

erature

(°C)

Depth

(ft)

Dis-

charge

(L/min) Reference pH Na K Ca Mg Fe SiO2 B Li HCO3 SO4 Cl F TDS2δ

18O (‰) δ2H (‰) Cl/B Cl/K

Corner Canyon Well Salt Lake (D-04-01)04adc 1/17/09 W 94.6 372 1136 this paper 6.8 2320 287 255 5 1.20 179 3.1 244 209 3860 7360 -14.88 -117 1261 13

Ogden Hot Spr. Weber (B-06-01)23ccd 6/1/80 S 56 - 20 Cole, 1983 7.0 2989 315 315 6 - 41 3.6 5.7 244 96 4930 3.8 8775 -16 -136 1369 16

Utah Hot Spr. Weber (B-07-02)14ddc 6/1/80 S 58 - 121 Cole, 1983 6.4 6588 821 974 23 - 28 4.1 10.5 223 181 12850 4.0 21551 -15.1 -136 3134 16

Crystal-Bluffdale Salt Lake (C-04-01)11&12 6/22/78 S 58 - -Mundorff, 1970; Cole,

19837.3 405 55 141 28 - 50 - - 216 378 337 1500 -15.9 -141 - 6

State Prison Salt Lake (C-04-01)12bbd 1/1/80 W 82.6 306 3028 Utah Energy Office, 1981 7.0 495 78 154 30 0.63 40 1.6 - 416 71 750 2.1 1785 - - 482 10

Saratoga Hot Spr. Utah (C-05-01)25ccc 6/1/75 S 44 - 719 Cole, 1983 7.4 210 24 88 49 0.30 21 0.9 - 260 300 430.0 1.0 1230 -16 -137 478 18

Udy Hot Spr. Box Elder (B-13-03)23bad 6/1/75 S 53 - 6050 Cole, 1983 7.6 2800 130 205 60 0.10 24 1.0 - 300 100 4700 1.4 8144 -15.3 -113 4700 36

Wasatch Hot Spr. Salt Lake (B-01-01)25dbd 1/1/81 S 42 - 240 Cole, 1983 7.9 1558 52 339 69 0.14 12 0.9 0.7 263 643 2490 1.6 5282 -16 -128 2767 48

Hooper Hot Spr. Davis (B-05-03)27cbd 6/1/80 S 57 - - Cole, 1983 Cole, 19842463 204 459 72 - 24 0.7 1.8 235 30 4640 1.0 7985 -15.8 -140 6629 23

Beck Hot Spr. Salt Lake (B-01-01)14dcb 1/1/81 S 56 - 870 Cole, 1983 7.6 4625 161 746 109 0.10 24 2.8 3.0 237 877 7570 2.9 14208 -16.8 -129 2704 47

Crystal-Madsen Box Elder (B-11-02)29dad 6/1/75 S 54 - 3600 Cole, 1983 7.1 15800 720 840 130 4.70 22 5.0 400 300 28100 1.5 46093 -13.1 -110 5620 39

Utah Roses (Sandy) Salt Lake (C-03-01)01cbb 1/1/83 W 48 1527 756 Klauk, 1984 7.8 754 5 55 17 0.04 19 2.3 0.07 147 934 654 0.8 2492 - - 284 131

(D-03-01)6dad-1 Salt Lake (D-03-01)6dad-1 9/17/90 W 17.0 1000 - Thiros, 1995 8.1 19 3 42 10 - 14 - - 112 7 66 0.3 217 -16.20 -118 - 24

(D-03-01)29ddd-1 Salt Lake (D-03-01)29ddd-1 11/1/90 W 15.5 48 - Thiros, 1995 7.6 44 5 89 30 - 39 - - 328 130 80 0.3 580 -14.60 -114 - 16

(D-03-01)31abb-1 Salt Lake (D-03-01)31abb-1 8/16/91 W 16.0 138 - Thiros, 1995 7.6 17 9 42 19 - 37 - - 257 1 11 0.3 265 - - - 1

granite borehole Salt Lake (D-03-02)07acd 1/1/88 W - - - Thiros, 1995 - - - - - - - - - - - - - - -15.45 -119 - -

1 Type: S = spring, W = well2 Total Dissolved Solids is calculated based on sum of analytes in all analyses except from Thiros, 1995, which was laboratory analyzed.


Site County Location

Sample

Date Type1

Temp-

erature

(°C)

Depth

(ft)

Dis-

charge

(L/min) Reference pH Na K Ca Mg Fe SiO2 B Li HCO3 SO4 Cl F TDS2δ

18O (‰) δ2H (‰) Cl/B Cl/K

Corner Canyon Well Salt Lake (D-04-01)04adc 1/17/09 W 94.6 372 1136 this paper 6.8 2320 287 255 5 1.20 179 3.1 244 209 3860 7360 -14.88 -117 1261 13

Ogden Hot Spr. Weber (B-06-01)23ccd 6/1/80 S 56 - 20 Cole, 1983 7.0 2989 315 315 6 - 41 3.6 5.7 244 96 4930 3.8 8775 -16 -136 1369 16

Utah Hot Spr. Weber (B-07-02)14ddc 6/1/80 S 58 - 121 Cole, 1983 6.4 6588 821 974 23 - 28 4.1 10.5 223 181 12850 4.0 21551 -15.1 -136 3134 16

Crystal-Bluffdale Salt Lake (C-04-01)11&12 6/22/78 S 58 - -Mundorff, 1970; Cole,

19837.3 405 55 141 28 - 50 - - 216 378 337 1500 -15.9 -141 - 6

State Prison Salt Lake (C-04-01)12bbd 1/1/80 W 82.6 306 3028 Utah Energy Office, 1981 7.0 495 78 154 30 0.63 40 1.6 - 416 71 750 2.1 1785 - - 482 10

Saratoga Hot Spr. Utah (C-05-01)25ccc 6/1/75 S 44 - 719 Cole, 1983 7.4 210 24 88 49 0.30 21 0.9 - 260 300 430.0 1.0 1230 -16 -137 478 18

Udy Hot Spr. Box Elder (B-13-03)23bad 6/1/75 S 53 - 6050 Cole, 1983 7.6 2800 130 205 60 0.10 24 1.0 - 300 100 4700 1.4 8144 -15.3 -113 4700 36

Wasatch Hot Spr. Salt Lake (B-01-01)25dbd 1/1/81 S 42 - 240 Cole, 1983 7.9 1558 52 339 69 0.14 12 0.9 0.7 263 643 2490 1.6 5282 -16 -128 2767 48

Hooper Hot Spr. Davis (B-05-03)27cbd 6/1/80 S 57 - - Cole, 1983 Cole, 19842463 204 459 72 - 24 0.7 1.8 235 30 4640 1.0 7985 -15.8 -140 6629 23

Beck Hot Spr. Salt Lake (B-01-01)14dcb 1/1/81 S 56 - 870 Cole, 1983 7.6 4625 161 746 109 0.10 24 2.8 3.0 237 877 7570 2.9 14208 -16.8 -129 2704 47

Crystal-Madsen Box Elder (B-11-02)29dad 6/1/75 S 54 - 3600 Cole, 1983 7.1 15800 720 840 130 4.70 22 5.0 400 300 28100 1.5 46093 -13.1 -110 5620 39

Utah Roses (Sandy) Salt Lake (C-03-01)01cbb 1/1/83 W 48 1527 756 Klauk, 1984 7.8 754 5 55 17 0.04 19 2.3 0.07 147 934 654 0.8 2492 - - 284 131

(D-03-01)6dad-1 Salt Lake (D-03-01)6dad-1 9/17/90 W 17.0 1000 - Thiros, 1995 8.1 19 3 42 10 - 14 - - 112 7 66 0.3 217 -16.20 -118 - 24

(D-03-01)29ddd-1 Salt Lake (D-03-01)29ddd-1 11/1/90 W 15.5 48 - Thiros, 1995 7.6 44 5 89 30 - 39 - - 328 130 80 0.3 580 -14.60 -114 - 16

(D-03-01)31abb-1 Salt Lake (D-03-01)31abb-1 8/16/91 W 16.0 138 - Thiros, 1995 7.6 17 9 42 19 - 37 - - 257 1 11 0.3 265 - - - 1

granite borehole Salt Lake (D-03-02)07acd 1/1/88 W - - - Thiros, 1995 - - - - - - - - - - - - - - -15.45 -119 - -

1 Type: S = spring, W = well2 Total Dissolved Solids is calculated based on sum of analytes in all analyses except from Thiros, 1995, which was laboratory analyzed.


and -14.88‰, respectively, which is slightly enriched in the heavier isotopes compared to wells in the principal aquifer in Salt Lake Valley (figure 7). The δ18O “shift” to less negative values often observed in geothermal systems (Clark and Fritz, 1997) is not as pronounced in the Corner Canyon Well as it is in other thermal waters of Utah, such as Crystal-Madsen, Utah Hot Spring, and Saratoga Springs (Cole, 1983; Mayo and Klauk, 1991). Cole (1983) suggested intermediate isotopic concentrations such as observed in the Corner Canyon well may result from geothermal waters mixing with fresh ground water. A water sample collected from a borehole through Lit-tle Cottonwood Stock granite in Little Cottonwood Canyon (figure 7), the same pluton type in which the Corner Canyon well is completed, may be one end member of such a mixing relationship. Indeed, conservative mixing calculations using 14% highly saline Crystal (Madsen) Hot Spring water with 86% fresh well water (Appendix B) yields a water of similar ionic composition, with the exception of silica, to the Corner Canyon well.

Geothermometry

Standard chemical geothermometers were applied to the wa-ter analyses from the Corner Canyon well samples (table 1). Geothermometry results are shown on table 3 and described

in Appendix C. A wide range of values are noted, but the most likely indicators of reservoir temperature would be the chal-cedony geothermometer (302°F [150°C]) and the potassium-magnesium geothermometer (358°F [181°C]).

DISCUSSION

The Corner Canyon pilot well, drilled in early 2008 as a pos-sible source of water for the community of Draper, penetrated a concealed, previously unknown geothermal system along the Wasatch front in northern Utah. Borehole temperature, lithologic, and geophysical logs all suggest that fracture zones or faults intersected by the well in the upper approximately 500 feet (152 m) are likely producing the most geothermal wa-ter. Water produced from the well during flow-testing yielded sodium-chloride-type water of moderate salinity (7360 mg/kg total dissolved solids) at temperatures of about 195°F (90.6°C). Silica content is anomalously high and applying geothermom-etry to this and other chemical constituents suggest reservoir temperatures ranging from 302 to 358°F (150 to 181°C).

The geothermal system occurs at the junction of the north-trending Wasatch Range and the southwest-trending Traverse

Figure 7. Relation between δD and δ18O values for Wasatch Front geothermal systems and non-thermal wells in southwest Salt Lake Valley.


Mountains near a segment boundary of the Wasatch fault. Near the well, the Wasatch fault makes an abrupt bend to the east, where the Wasatch fault links with the east-trending Fort Canyon fault (a reactivated part of the Charleston thrust fault and Deer Creek detachment fault). Rocks south of the Fort Canyon fault have experienced several episodes of de-formation, including eastward-directed transport of perhaps 50 miles (80 km) as part of the upper plate of the Charle-ston thrust fault, westward transport of 3 to 4 miles (5 to 6 km) in the upper plate of the Deer Creek detachment fault, and southwest-directed, oblique slip beginning about 17 mya and continuing to the present as part of modern Basin and Range extension. It is no surprise that the Pennsylvanian-age sandstone of the Oquirrh Group and overlying Eocene to Oli-gocene volcanic rocks in the Traverse Mountains are highly fractured and locally pulverized. Quartz monzonite of the Lit-tle Cottonwood stock, exposed in the footwall of the Wasatch and Fort Canyon faults also exhibits evidence of significant extensional deformation. As exposed in Corner Canyon, and encountered in the discovery well, the outer several hundred feet of the intrusion show mechanical and hydrothermal al-teration, including cataclasis, intense fracturing, and low-tem-perature metamorphic mineral assemblages.

Connection of the Corner Canyon system to other identified geothermal systems in the region is unknown. The Crystal (Bluffdale) Hot Springs geothermal area is less than 5 miles

(8 km) southwest of Corner Canyon and is located near the intersection of two buried Basin-and-Range-type faults, and the Utah Roses well is located less than 8 miles (13 km) north-west of Corner Canyon. Saratoga Springs is located about 12 miles (19 km) south-southwest of Corner Canyon near the north shore of Utah Lake where a number of north-trend-ing, normal faults lie buried beneath the most recent lake and valley-fill sediments. Water analyses from these three sources are similar (relatively low-salinity [1230 to 1785 mg/kg TDS] fluids) as shown by high correlation coefficients based on ma-jor ion chemistry (Appendix B). With the exception of silica content, water from the Corner Canyon well is more similar to water from Ogden Hot Spring (Weber County) than any other thermal spring along the Wasatch Front. Both are mod-erately saline (7360 and 8775 mg/kg TDS, respectively) and have similar chloride-boron and chloride-potassium ratios. Mixing of more saline geothermal waters similar to Crystal (Madsen) Spring with fresh ground water may produce the waters found in these moderately saline hot springs. The cause of the high silica content (179 mg/kg in the Corner Canyon well compared to less than 41 mg/kg in other Wasatch Front thermal waters) is poorly understood and may be a topic of future discussion.

We speculate that the Fort Canyon fault and the southern part of the Salt Lake segment of the Wasatch Fault may serve as conduits for southward and westward groundwater flow off of the southern flank of the Little Cottonwood Stock. The rela-tively shallow, fresh ground water may be mixing with a deep highly saline geothermal fluid along these conduits to produce the water found in the Corner Canyon well.

ACKNOWLEDGEMENTS

We thank David A. Gardner, Assistant General Manager of WaterPro, Inc., for providing access to the well and cutting samples. We also thank Hugh Klein and William Loughlin of Loughlin Water Associates, LLC for down-hole information and other assistance with this project. Joseph Moore of En-ergy and Geoscience Institute at the University of Utah pro-vided valuable guidance in interpretation of these data.

REFERENCES

Anderson, P.B., Susong, D.D., Wold, S.R., Heilweil, V.M., and Baskin, R.L., 1994, Hydrogeology of recharge areas and water quality of the principal aquifers along the Wasatch Front and adjacent areas, Utah: U.S. Geological Survey Water-Resources Investiga-tion Report 93-4221, 74 p.

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Geothermometer Notes EQ Temp (°C)

1. Quartz - no loss 173

2. Quartz - max loss T = 0-250 C 162

3. Chalcedony 150

4. α-Christobalite 123

5. β-Christobalite 73

6. Amorphous Silica 49

7. Na/K (Fournier)

T > 150C 236

8. Na/K (Truesdell)

212

9. Na-K-Ca β = 4/3 235

10. K-Mg 181

1 See Appendix C. References for geothermometers are as follows: 1 through 9 from Fournier (1981) and 10 from Giggenbach (1988).

Table 3. Results of chemical geothermometry applied to the Corner Canyon well water analyses.


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