stratigraphic characterization of the birds nest aquifer ......the birds nest aquifer’s spatial...

AAPG-RMS 2011 - Cheyenne, WY

During deposition of the upper Green River Formation in the late Eocene, Utah’s Lake Uinta transitioned from a balanced-filled basin dominated by organic-rich, lami-nated marlstone, to an underfilled restricted basin. During this time, the saline mineral nahcolite formed within the deep-lake sediments (depocenter in central Uintah County) as isolated crystals, nodules ranging up to one foot in diameter, and beds ranging from less than an inch to 2 feet thick. Post-deposition, the saline mineral short-ite was deposited in fracture zones several feet thick. More recently, the Birds Nest aquifer formed from the dissolution of these saline minerals and is targeted by natural gas producers as a potential saline water disposal zone. Recently completed core descriptions, measured sections, and five newly constructed stratigraphic cross sections show that the total thickness of the Saline zone ranges from <100 feet on the basin’s eastern and southern margins to >300 feet in the basin’s depocenter. Only in the basin’s depocenter, where the Birds Nest aquifer comprises two stratigraphic zones of dissolution each between ~40 and ~100 feet thick, is there potential for extensive saline water disposal. Ongoing research and monitoring pro-grams seek to determine if these individual zones are hydraulically connected or if the Birds Nest as a whole is vertically connected via fractures/joints (possibly gilsonite veins) to other water-bearing zones both above and below. Regional water sampling shows that the Birds Nest’s water chemistry in the north (averaging >10,000 mg/L TDS and as high as 100,000 mg/L TDS) is distinct from that in the south (averaging <10,000 mg/L TDS and as low as about 1000 mg/L TDS). This abrupt change in water chemistry is most likely due to the differing amounts of saline mineral dissolution in the two areas; the southern area may have been flushed clean, whereas saline minerals in the northern area are still actively dissolving. The presence of intact nahcolite in the Utah State 1 core (section 26, T. 9 S., R. 21 E.) – on display with this poster – demonstrates that there are still zones of no dissolu-tion north of the 10,000 mg/L TDS line. Just to the south of this well, the saline minerals in the Birds Nest show significant dissolution, as seen in the Utah State 13X-2 core (section 2, T. 10 S., R. 21 E.) – also on display. Separating these two areas is a prominent gilsonite vein that cross-cuts the Birds Nest aquifer. The northwest-trending gilsonite veins in the area seem to influence groundwater flow patterns in the Birds Nest by creating “channels” of dissolution and impermeable barriers to flow. The Birds Nest aquifer’s spatial and stratigraphic extent and variability, water chemistry, and zones of differential dissolution will determine possible saline water dis-posal volumes and safe disposal practices, both of which could directly affect the success of increased petroleum production and potential oil shale development in the region.

Natural gas, crude oil, and water production in the Uinta Basin, Utah, 2002-2010

Source: Utah Division of Oil, Gas, and Mining

8-year increase in natural gas production - 169%8-year increase in crude oil production - 139%

8-year increase in water production - 72%

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More than 25,000 oil and gas wells are currently proposed for drilling in the Uinta Basin

This future drilling will greatly increase the amount of produced water needing proper disposal

• West Tavaputs Natural Gas Full Field Development Project - 626 new wells - approved• Uinta Basin Natural Gas Development Project (Gasco) - 1491 new wells - proposed, draft EIS• Greater Natural Buttes Area Gas Development Project - 3675 new wells - proposed, draft EIS• South Unit Oil and Gas Development Project - 400 new wells - proposed, draft EIS• Greater Chapita Wells Natural Gas Infill Project - 7028 new wells - proposed, EIS in process• Greater Monument Butte Project - 5570 new wells - proposed, EIS in process• Bureau of Indian Affairs - 4899 new wells - proposed, EIS in process• River Bend Field Development Project - 484 new wells - proposed, EA in process• Big Pack Natural Gas Development Project - 664 new wells - proposed, EA in process• Southam Canyon Field Development Project - 249 new wells - proposed, EA in process

Source: U.S. Bureau of Land Management

0 9 18 27Miles

Duchesne River

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White River

DUCHESNE

UINTAH

WASATCH

UTAH

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West Tavaputs Natural Gas Full Field Developoment Project - 626 wells

Uinta Basin Natual Gas Development Project (Gasco) - 1491 wells

South Unit Project - 400 wells

Greater Monument Butte Project - 5570 wells

Bureau of Indian Affairs - Oil and Gas Development on the Uintah and Ouray Reservation - 4899 wells

Greater Natural Buttes Area Gas Development Project - 3675 wells

Southam Canyon Field Develop-ment Project - 249 wells

Big Pack Natural Gas Develop-ment Project- 664 wells

Greater Chapita Wells Natural Gas Infill Project - 7028 wells

River Bend Field Develop-ment Project - 484 wells

Area currently leased for oil and gas development

The Birds Nest aquifer is poorly understood and needs further study to determine potential impacts of using this aqui-fer as a saline water disposal zone.

• What is the aquifer’s areal and stratigraphic extent?

• How is this aquifer related to Utah’s oil shale deposits?

• What causes the aquifer’s differing zones of dissolution and salinity?

Eastern Uinta Basin natural gas producers have identified the Birds Nest aquifer, located in the Parachute Creek Member of the Green River Formation, as the most promising reservoir suitable for large-volume saline water dis-posal. This aquifer formed from the dissolution of saline minerals which left behind large open cavities and fractured rock. Understanding the aquifer’s areal extent, thickness, water chemistry, and zones of differential dissolution will help determine possible saline water disposal volumes and safe disposal practices, both of which could directly impact the success of increased hydrocarbon production in the region. The Birds Nest aquifer is typically several hundred feet above the richest oil shale interval called the Mahogany zone. A significant concern is that saline water disposal into the Birds Nest by conventional gas producers could hinder oil shale development by creating unforeseen water disposal problems.

Origin of the Birds Nest aquifer name, mud swallow nests in nahcolite cavities.

25E24E23E

0 4 82Miles

EX-1

13X-2

14-36

14X-34

42-34

Red Wash 1

Coyote Wash 1

Asphalt Wash 1

Corehole 10 CRU-1

SUB 12

Suicide Canyon 1

P-3DP

X-13P-2 P-4

Corehole 2

P-1

Utah State 1

White River

Skyline 16

Corehole 9

Anadarko BNdisposal wells

EOG BNdisposal wells

Questar BNdisposal wells

22E21E20E

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10S

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Colorado

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Duchesne River

Green River

Explanation

Cross-section well

BN disposal well (red = proposed)

Horsebench/Saline zone outcropGilsonite vein

River

County boundary

Township and range

Birds Nest Aquifer - Upper and lower zone

Birds Nest Aquifer - Lower zone and partial upper zone

Birds Nest Aquifer - Lower zone only

UGS core - partial Birds Nest zoneUGS core - complete Birds Nest zone

USGS core - partial Birds Nest zoneUSGS core - complete Birds Nest zone

Mahogany zone outcrop

Well used to define BN zoneMeasured section (*not yet completed)

Major road

6SMaximum areal extent for possible saline Maximum areal extent for possible saline water disposal into the Bird Nest aquiferwater disposal into the Bird Nest aquifer - Areal extent of large saline nodules/beds - in one or two zones - Chemistry of water currently in aquifer will be a limiting factor - Some areas may be lacking suffient dissolution of the saline minerals, further limiting extent suitable for dispsoal

BitterCreekSection

Long DrawSection

WatsonSection

EvacuationCreek

Section*

UINTAH CO.DUCHESNE CO.

Darkest blue shadingUpper and lower BN aquiferLarge saline nodules/bedsAs seen in the 13X-2 core (right)

Lightest blue shadingOnly lower BN aquiferLarge saline nodules/bedsAs seen in the P-4 core (right)

No shadingSmall saline mineral crystals in BN aquiferAs seen in the SUB 12 core (right)

BuckCanyonSection*

This map records where large saline mineral nodules/beds are present based on geophysical logs and core descriptions; the dissolution of such nodules creates the space for potential large-scale water disposal.

Lower Birds Nest Aquifer IsopachLower Birds Nest Aquifer Isopach

0 4 82Miles

20-40 ft

40-60 ft

60-80 ft

Thickness of Birds Nest

80-100 ft

100-120 ft

This map records where large saline mineral nodules/beds are present based on geophysical logs and core descriptions; the dissolution of such nodules creates the space for potential large-scale water disposal.

Upper Birds Nest Aquifer IsopachUpper Birds Nest Aquifer Isopach

0 4 82Miles

20-40 ft

40-60 ft

60-80 ft

Thickness of Birds Nest

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100-120 ft

120-140 ft

ABSTRACTABSTRACT

PROBLEMPROBLEM

• Conduct comprehensive literature review and historic data collection (finished, but not presented on this poster)

• Evaluate the Birds Nest aquifer in core: - 22 wells have been identified as having all or part of the Birds Nest captured in core; 21 of the 22 cores have been examined (The DP core was not examined becasue of its close proximity to the examined X-13 core) (see below)

• Evaluate the Birds Nest aquifer on outcrop: - Good outcrop exposures can be found on the southeastern side of the basin (3 measured sections have been completed (see map below), but are not presented on this poster)

• Evaluate the Birds Nest aquifer on geophysical logs (~330 wells examined, 5 regional cross sections completed, see map below)

• Determine how disposal into the Birds Nest aquifer could affect future oil shale development (ongoing)

• Determine how gilsonite veins might influence water flow and saline mineral dissolution (see panel 2)

• Create a GIS database and maps showing: - Outcrop (see map below)

- Thickness (see maps below and right)

- Lateral extent (see map below)

- Water quality (see panel 2)

- Interburden between Birds Nest and “economic” oil shale zones (see panel 2)

RESEARCH / DELIVERABLESRESEARCH / DELIVERABLES RESULTS: SPATIAL EXTENT AND THICKNESSRESULTS: SPATIAL EXTENT AND THICKNESSResearch methods: Core, outcrop, and geophysical log examinations

The Saline zone is nearly 400 feet thick in the basin’s paleo-depocenter. Within the Saline zone, the Birds Nest aquifer is separated into an upper and lower zone where dissolution of the saline minerals has created significant porosity and permeability for the transmission of water (see 13X-2 core log). The large saline mineral nodules and beds in the paleo-depocenter are recorded as spikes to low density on geophysical logs. To the east, the upper zone disappears and only the lower zone exists (as seen in the P-4 core). Radiating out from the depocenter, the Saline zone thins to ~130 feet and contains much smaller saline mineral crystals (<1 inch) as compared to the large (up to 1 foot) nodules found near the basin’s center, and the bulk density signature is lost (there is still a zone of dissolution in the lower por-tion of the Saline zone which could transport water and is roughly equivalent to the lower Birds Nest zone found in the basin’s center). This transition is confirmed to the south where cores and outcrop ex-posures are present (see SUB 12 core log). It is presumed that the same transi-tion to small saline crystals exists to the north and west, but no cores exist to con-firm this suspicion.

• Highlight: Using geophysical logs, UGS has mapped the spatial extent and thickness of the Birds Nest aquifer where large nodules exist in both an upper and/or lower zone. This represents the maximum area with potential for saline water disposal, but only where water currently within the zone is greater than 10,000 mg/L TDS and where saline mineral dissolution has already taken place.

Photo 11532 ftShortite dissolution

Photo 21774 ftDissolved nahcolite nodule lined with pyrite

Operator: Tosco Corp.Location: T10S, R21E, Sec. 2, UTM E 625912, UTM N 4425960Cored interval: 120 - 2191 ft, 3.5 inch diameter (only examined 1289-1818 ft)Core location: UGS and USGS Core Research Center

m c

Utah State 13X-2 exhibits extensive saline mineral dissolution (see dissolution log) in two distinct zones, the upper aquifer is 56 feet thick (1516-1572 ft) and the lower aqui-fer is 101 feet thick (1690-1791 ft). This well is very near Anadarko’s saline water disposal wells.

13X-213X-2 - Upper and lower Birds Nest aquifer

clay silt

Upper R-62263 ft

Big Three1872-1890 ft

Stillwater1912-1923 ft

Four Senators1942-1970 ft

R-81352 ft

Uinta Form

ation

Green R

iver Formation - Parachute C

reek Mem

ber

Lithologic Units

-300 300SP

Depth (ft)

1.7 2.7Bulk Density (g/cc)

6 10Caliper (in)

Core Logsand

Middle R-62361 ft

A-Groove2078 ftMahoganyZone2091 ft

B-Groove2181 ft

MahoganyBed 2126 ft

fvf

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Saline MineralDissolution IndexNone Total

Saline Zone 1408-1797 ft

SP shift

0.1 10000Resistivity - Laterolog-8 (ohms)

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Lower BirdsNest aquifer1690-1791 ft

Top of economicoil shale - 1872 ft

Photo 1

Photo 2

Bed 761625 ft

Uinta Fm.

Upper BirdsNest aquifer1516-1572 ft

Birds Nest aquifer in outcrop along Evacuation Creek, eastern Uinta Basin. The large cavities resulted from the dissolution of nahcolite nodules, creating the aquifer’s porosity and permeability.

Birds Nest outcrop atWhite River water level- Recharge area

Evacuation CreekCanyon

White River

Horsebench Sandstone

Birds Nest aquifer

Photo 4365 ftShortite dissolution

Photo 2 354 ft Dissolved nahcolite nodule

Only the lower Birds Nest aquifer is present on the eastern side of the basin, as shown by core from the P-4 well. The aquifer is defined by very large nahcolite nodules (up to 1-foot in diameter, seen better in outcrop near the well) and almost total saline mineral dissolution. Significant, porous sand beds (Horsebench) overlay the Saline zone and could be part of the aquifer system. The sand deposition might represent fresh water entering the lake which changed the local water chemistry, stopping the saline mineral deposition.

Operator: White River Shale ProjectLocation: T10S, R25E, Sec. 19, UTM E 659426, UTM N 4421812Cored interval: 214 - 1173 ft, 3.5 inch diameterCore location: Utah Core Research Center

P-4 P-4 - Lower Birds Nest aquifer only

Photo 3362 ftDissolved nahcolite nodule and warped bedding

Dissolvednahcolitenodule

clay siltvf


B-Groove785 ft

Upper R-6822 ft

Big Three487-504 ft



Wavy Tuff635-638 ft

MahoganyBed 719 ft


R-8?? ft

Uinta Form

ation

Green R


reek Mem

berLithologic Units

0 250Gamma Ray (api)

0 1000Resistivity (ohms)

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6 10Caliper

Curly Tuff779-782 ft

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Core Log

f m csand

Lower BirdsNest aquifer

334-411 ft

Photo 2Photo 3Photo 4


Horsebench Ss.

Si-dominatedmudstoneSiltstone /vf sandstone

Abundant fracturesfilled w/ shortite

Ca-dominatedmudstone

Nahcolite nodule

Small saline mineral crystals

Thin saline mineral layers

Dolomite-dominatedmudstone

Named tuff bed

Close-up of cavity, notice how the nodule growth warped and fractured the surrounding sediments.

Photo 1300-306 ftPorous sandstone with mud rip-up clasts

Horsebench Sandstone

} Photo 1

Si- and Ca-dominatedmudstoneSiltstone /vf sandstoneAbundant fracturesfilled w/ shortite

Nahcolite nodule



Bitumen

Near vertical fracture

Photo 1221-231 ftNahcolite/shortite crystals - partially dissolved

Shortite fracture fill - Bitter Creek outcrop

Operator: U.S. ERDA-LERCLocation: T12S, R24E, Sec. 19, UTM E 648046, UTM N 4402078Cored interval: 91 - 621 ft, 1.8 inch diameterCore location: Utah Core Research Center

South Uinta Basin 12South Uinta Basin 12The South Uinta Basin 12 (SUB 12) core and nearby outcrop sections (Long Draw and Bitter Creek) display how the saline mineral crystals within the Birds Nest aquifer are much smaller to the south, closer to the basin margin; no large saline nodules are present. The SUB 12 core displays a 39-foot zone (202-241 ft) where the <1-inch nahcolite crystals show significant disso-lution indicating that water passes through this section despite the small crystal size. However, only where the large nodules exist farther to the north, is there the possibility of large volume saline water disposal. The smaller saline mineral crystals are not recognized by geophysical log measurements, making core and outcrop the only way to characterize the Birds Nest zone in this area.


B-Groove551 ftUpper R-6559 ft

Big Three332-343 ft



Wavy Tuff436.7-438.5 ft

MahoganyBed 504 ft

R-8surface

Green R


reek Mem

ber

Lithologic Units

Curly Tuff ?548.1-549.3 ft

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Oil Yield - from Fischer Assay (gal/ton)

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200Significant saline mineral

dissolution 202-241 ft


Bed 76(178 ft)

clay siltCore Log

m csand

fvf

} Photo 1

Possible Horsebench Ss.

Si- and Ca-dominatedmudstoneSiltstone /vf sandstone

Abundant fracturesfilled w/ shortite



Bitumen

Near vertical fracture

Named tuff bed

UINTABASIN

Salt Lake City

Project funded by: U.S. Department of Energy - National Energy Technology Laboratory and Utah Geological Survey

Project Web site: http://geology.utah.gov/emp/UBwater_studyProject Web site: http://geology.utah.gov/emp/UBwater_studyMichael D. Vanden Berg, Stephanie Carney, Craig D. Morgan, and Danielle Lehle Utah Geological Survey, Salt Lake City, Utah

Stratigraphic Characterization of the Birds Nest Aquifer in the Uinta Basin, Utah: Updated Research Regarding the Aquifer’s Potential as a Significant Saline Water Disposal Zone Panel 1

ExplanationWell used in study

Disposal well into BN

Horsebench/Saline zone outcrop

Major river

County boundary

Township and range


Overburden contour

ExplanationWell used in study

Disposal well into BN

Horsebench/Saline zone outcrop

Major river

County boundary

Township and range


Overburden contour

4000 ft

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4500 ft

4000 ft

3500 ft

3000 ft

2500 ft

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1000 ft

500 ft

Transition uncleardue to lack of data

Transition uncleardue to lack of data

stratigraphic characterization of the birds nest aquifer ......the birds nest aquifer’s spatial...

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