Mudlog Arco Totek Hills #1 1984 TD 3,590’

Drilling costs (1984) = $2.146 MM less $0.678 MM State drilling credits

10 ¾”

7 5/8”

5”

4”

Note in “VIII Well Summary”: “Temperature log problems” – (quoted as part of the reason for time delays with final logs, no explanation and unsure what this refers to)

BHT at TD 3560’ (3545’ Tvd) = 160-165◦F Corrected BHT = 167-172°F (accounts for circ. cooling) T gradient = 2.7-3.0°F/100’ using assumed surface T of 65°F (Arco estimate) (Note: with surface permafrost, surface T must be close to 32°F or less, which yields minimum 3.9°F/100’ gradient) Nenana #1 well had 87°F @ 3052’ in meta. basement

Alaska GMC has core from the intervals 1443-2670’ and 2984-3577’

3163’ Top basement schist

Sanctuary Fm

Healy Creek Fm

Suntrana Fm

Grubstake Fm and/or

Lignite Creek

Nenana Gravel

Oligocene-Eocene pebble conglomerate and sandstone

Usi

bel

li G

rou

p

Surficial fill

Formation picks estimated by GVK (2012) based on lithologic similarity with Nunivak #1 and outcrop data.

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HI

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S2 (

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TOC

TOC vs S2 -- Totek Hills #1 and Nunivak #1

Nunivak #1

Totek Hills #1

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HI vs TOC, Totek Hills #1 and Nunivak #1

Nunivak #1

Totek Hills #1

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Oxygen Index (mg CO2/g org C)

Circles from USGS (Stanley et al, 1989). Open circles are mudstones, filled circles are coal samples from the Usibelli Group at Suntrana, Alaska. Triangles are Arco Alaska field samples, Healy Creek Fm, Lemmerman and Podsen, 1983.

Outcrop samples of Miocene Usibelli Group coal and mudstone

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Oxygen Index (mg CO2/g org C)

Coal and mudstone samples from the Totek Hills #1 well, Nenana basin, Alaska. From Lemmerman and Podsen

Nunivak #1 well, Usibelli Group

N = 28, TOC = 11-61%

Mixed oil and gas

Oil prone

Gas prone

Totek Hills Rock Eval datavr visual

depth Tmax S1 S2 S3 TOC HI OI VR sample kerogen

220 0.26 coal

520 0.27 coal

1060 0.29 coal

1300 0.31 coal

1360 0.31 coal

1518 411 0.18 2.87 0.78 1.59 180 49 0.27 core Am-W,H

1556 421 0.84 37.37 2.52 9.72 384 25

1616 0 0.07 0.13 0.17 41 76

1676 0.01 0.08 0.15 0.26 30 57 0.32 core H,W

1736 425 0.01 0.49 1.74 0.93 52 187

1796 416 0 0.55 2.37 0.87 53 272

1856 413 0.02 0.89 3.71 1.12 79 331 0.36 core W,H,Am

1916 420 0.24 12.37 0.78 3.74 330 20

1976 422 0.98 21.28 0.91 4.51 471 20

2036 414 0.03 0.19 0.22 0.3 63 73 0.35 core W, ,H

2096 421 0.03 1.41 1.85 1.42 99 130

2156 413 0.1 3.36 0.6 1.68 200 35

2216 416 0.02 0.87 1.27 1.21 71 104 0.37 core Am-W,H

2276 416 0.02 0.89 1.71 1.14 78 150

2337.2 420 0.29 22.7 2.95 12.33 184 23

2397 417 0.13 8.34 0.82 3.95 211 20 0.35 core W, Am-H

2463.5 418 0.08 5.4 0.53 2.43 222 21

2520 419 0.7 47.77 3.88 17.76 268 21

2580 422 0.49 24.7 2.42 10.36 238 23 0.38 core W, Am-H

2670-2710 428 0.02 0.37 0.31 0.68 54 45

2730-2790 425 0.07 1.47 0.39 0.95 154 41

2790-2850 428 0.01 0.08 0.13 0.31 25 41 0.41 core H, ,W

3172.2 0.01 0 0.15 0.22 0 68 0.39 core B,H,-

3204.3 0.01 0 0.11 0.21 0 52

3236.5 0.02 0 0.09 0.18 0 50 no vitrinite B,H,W

3283-3302 384 0.21 0.4 0.66 0.36 111 183

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Oxygen Index (mg CO2/g org C)

Coal and mudstone samples from the Totek Hills #1 well, Nenana basin, Alaska. From Lemmerman and Podsen

Totek Hills #1, Usibelli Group

Source Rocks: Nenana Basin

Totek Hills #1 Stratigraphy and Source Rocks

The Totek Hills #1 was drilled by Arco Alaska in 1984 and penetrated about 3000’ of clastic sedimentary rocks of the Usibelli Group. The

well was drilled on a basement high along the southern margin of the Nenana basin and metamorphic basement was encountered at 3163’

(drillers log). The Tertiary section was thinner than expected and basement was about 3000’ shallower than expected. No significant oil and

gas shows were encountered in the well.

The well logs are more useful in reconstructing the well lithology than the mud log. The mud log is highly generalized from surface to 1425’

at which depth continuous coring commenced with the slim-hole drilling rig. Continuous small-diameter core was taken from 1443’ to 2674’

and cutting returns during drilling were very poor due to pulverization of cuttings by the coring bit. The hardcopy mud log was scanned and

converted to digital format for this display, but the well logs are preferred to pick lithology and interpret the stratigraphy in the well.

Stratigraphy

Coals are common throughout the Tertiary section and these rocks in general correlate to the Miocene Usibelli Group which is well exposed

in outcrop and mined extensively for coal at Healy, Alaska. A paly pick at 1200’ assigns an Early-Middle Miocene age with this horizon

being Upper Healy Creek. If this paly pick is accurate, the Healy Creek Fm in Totek Hills #1 is about 1300’ thick compared to 240’ in

Nunivak #1. This discrepancy in thickness is considered unlikely and this paly pick is ignored when assigning formation tops. The

formation tops shown on this display are lithologic picks made using the mud log and wireline logs.

The Suntrana Formation is dominated by sand in the Nunivak #1 well and in Totek Hills is chosen to include most sands in the upper part of

the Tertiary section. The Sanctuary Formation in Nunivak #1 is fine-grained and dominated by shale and siltstone. The Sanctuary Formation

in Totek Hills is picked to include the dominantly fine-grained section from about 1650’ to 2600’. The contact between the Sanctuary and

Healy Creek Formations is uncertain as both of these formations are dominated by fine-grained clastic rocks. In Totek Hills the contact is

somewhat arbitrarily chosen at about 2600’.

The lower about 500’ of Tertiary sediment (~2690 to 3126’ wireline) is primarily sand, lacks coal, and a paly pick assigns an Early Oligocene

age at 2507’ and an Eocene age at 2970’. Sediments of this age are missing in the Nunivak #1 well where Miocene sediments overlie Late

Paleocene rocks with an intervening erosional unconformity. The Oligocene and Eocene rocks in Totek Hills are thick sands which

underlying the potential seal facies of the Usibelli Group. This potential reservoir/seal couplet could have significant resource potential in

the Nenana basin.

Source Rock Potential Good to excellent source rocks for mixed oil and gas are found in Totek Hills #1, Nunivak #1 and outcrops of the Tertiary Usibelli Group.

Plots of RockEval data from Totek Hills #1 show HI (hydrogen index) values up to 471. Although samples in Totek Hills were taken at

systematic intervals rather than high-grading attractive zones, 8 of 26 samples have HI values of 200 or above. Three samples have HI above

300. These samples are similar to many other analyses from Nunivak #1 and outcrop samples and confirm that Tertiary mudstones and coals

contain good to excellent source potential in Nenana basin.

The three samples in Totek Hills with HI above 300 are all described as “shale dark green gray”. No mention is made of coal, although coal

is described as present in other samples. The lack of coal raises the possibility that the dark green gray shales are lacustrine and these

samples are lacustrine source rocks. If so, documentation of true lacustrine source rocks capable of oil and gas generation in Nenana basin

would be a significant finding. Further sampling of the intervals near 1525’, 1950’ and 2500’in Totek Hills is recommended.

By Gerry Van Kooten

Gas show C1 500-600’ Max 74 units

Gas show C1 845’ 44 units

Gas show C1 1080’ 100 units

Gas show C1 2060-75’ 30 units

Gas show C1, C2, C3 2138’ 43 units

Gas show C1, C2, C3 2365-86’ 53 units max

No Tests attempted No sidewall cores Heaviest gas detected: C3 No oil shows

Paly: 1200’ - Top E-M Miocene – U. Healy Creek Fm

Possible unconformity Sanctuary Fm and lower part of

Suntrana Fm may be missing

Paly: 2507 - E. Oligocene

Paly: 2970 - Eocene

105’ Top Nenana Gravel

145’ Top Coal-bearing Group

1,719’ of slim-hole core was cut; 1,228’ (71.4%) was recovered. Core diameter is 1.875” and 1.434”

Porosity and Permeability 15 samples from 1500’ to 3050’. Avg porosity 17.4% (range 7.1-27.5%) 9 samples for permeability Avg permeability 11.65 md (range 0.44 to 43 md)

Sand composes 55% of Tertiary section from 150-3160’

1719’ por=27.5% pm=10md ss vf-fg

1884’ por=22.4% pm=0.44md ss vf-fg

1902’ por=26% pm=53 md ss f-mg

1985’ por=23.9% pm=8.66 md ss vf-cgr

2141’ por=19.9% pm=7.01 md ss vf-mgr

2206’ por=23.1% pm=16 md ss f-mgr

2253’ por=18.9% pm=3.65 md ss vf-fgr

2269’ por=21.5% pm=5.12 md ss vf-fgr

2490’ por=18.7% pm=0.94 md ss vf-fgr

2535’ por=20.4% ss vf-fgr, frac

2550’ por=15.7% ss f-cgr, frac

2613.5’ por=15.9% cgl, frac

3050.3’ por=7.1% cgl, frac

Depths shown in this column are drilling depths, which are 23 to 38’

deeper than wireline log depths

Source rock interval 1 52’/43’ net (Arco) Excludes coal and sands

Source rock interval 2 88’/68’ net (Arco) Excludes coal and sands

Source rock interval 3 71’/58’ net (Arco) Excludes coal and sands

Source rock interval 4 272’/164’ net (Arco) Excludes coal and sands

Nenana Basin Lithostratigraphy Nunivak #1 well

DT

DT

DT density

dotted - NPHI

dashed - SPHI

dotted - NPHI

dashed - SPHI

dotted - NPHI

dashed - SPHI

dotted - NPHI

dashed - SPHI

DT

Coal

Coal

Coal

Coal

Coal

Coal Coal

Coal

Coal

Coal

Bottom 7 5/8” casing

Coals 0-1400’ picked by GR

Coals 1400’-TD picked by NPHI

Top Basement 3163’ drill log 3126’ wireline log

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TOC = 1.59 mudstone gray grn HI=180

TOC = 9.72 shale dk grn gray HI=384

TOC = 0.17 mudstone grn gray HI=41

TOC = 0.26 siltstone olive gray HI=30

TOC = 0.93 shale brn gray HI=52

TOC = 0.87 shale olive gray HI=53

TOC = 1.12 shale dk grn gray HI=79

TOC = 3.74 shale dk grn gray HI=330

TOC = 4.51 shale dk grn gray HI=471

TOC = 0.3 mudstone olive gray HI=63

TOC = 1.68 siltstone olive gray HI=200

TOC = 1.21 mudstone dk grn gray HI=71

TOC = 1.14 siltstone olive gray HI=78

TOC = 12.33 shale with coal HI = 184

TOC = 3.95 mudstone dk grn gray HI=211

TOC = 2.43 shale with sltst olive gray HI=222

TOC = 17.76 shale olive black HI=268

TOC = 10.36 shale with coal, olive gray

HI=238

TOC = 0.68 sandstone, trace shale HI=54

TOC = 0.95 sandstone, trace shale HI=154

TOC = 0.31 sandstone, trace shale HI=25

TOC = 0.22 shale med. Dark gray HI=0

TOC = 0.21 shale med. Gray HI=0

TOC = 0.18 shale med. dark gray HI=0

TOC = 0.36 shale med. dark gray

HI=111

TOC = 1.42 mudstone dk grn gray HI=99

Coals picked by low GR and low neutron

Density run only below 2935’

Arco Totek Hills #1 1984 TD 3,590’

Sanctuary Fm

Healy Creek Fm

Suntrana Fm

Grubstake Fm and/or

Lignite Creek

Nenana Gravel

Usi

bel

li G

rou

p

Surficial fill Nenana Gravel

Metamorphic basement schist and

phyllite

3163’ Top basement

schist (drill log) 3126’ wireline

log

Oligo-Eocene pebble

conglomerate and sandstone

Formation tops were picked from mudlog using

lithology and adjusted slightly to wireline logs

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Hydrogen Index

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