UTAH GEOLOGICAL SURVEYDEPARTMENT OF NATURAL RESOURCES

PA R A D O X F O R M AT I O N R E S E R V O I RC H A R A C T E R I S T I C S

• Net pay – 9 to 57 ft (3-17 m); 165 ft (50 m) at Greater Aneth field

• Primary producing zones – Ismay and Desert Creek

• Depositional environments – shallow-shelf and shelf-margin marine,carbonate buildups (phylloid algal and bryozoan mounds), oolitic banks,beach, and stabilized grain flats

• Carbonate fabrics – bafflestone, grainstone, packstone, and wackestone(limestone and dolomite)

• Pore types – shelter, moldic, intercrystalline, vugs

• Porosity - averages 8-12%

• Permeability – less than 1 md to greater than 500 md, averaging 25 md

• Diagenesis – early marine cementation, dolomitization (early and late),freshwater dissolution and cementation, and anhydrite and bitumen plugging

P A R A D O X F O R M A T I O N O U T C R O P C H A R A C T E R I S T I C S

MERIDIANCherokee 33-14NW SE Sec. 14, T37S-R23EKB 5,572 ft

Hovenweep Shale

Lower Ismay

Gothic Shale

Desert Creek

Chimney Rock ShaleAkah

Upper Ismay

Completed 6/9/1987TD 6,115 ft

IPF 336 BO, 346 MCF, + 0 WTR

CORE

6100

6000

5900

5800

5700

5600

6380

09

43

10%

Type Log

PorosityGR

DPHI

NPHI

Typical gamma ray-compensated neutron-litho density log ofthe Paradox Formation, Cherokee field, San Juan County, Utah.

N

Cherokee

Monument

Cajon Mesa

Ismay

Ismay

Tower

Greater

Aneth

ClayHill

Flodine Park

Cache

Desert Canyon

Marble Wash

RoadrunnerTowoac

Sage Hen

McElmoMesa

RockwellFlat

Cone Rock

Tin Cup Mesa Squaw Canyon

Cutthroat(McClean)

HatchKachina

Patterson Canyon

Little Nancy

Squaw Point

Bug

Bradford CanyonDoveCreek

Cahone

Papoose

Cajon Lake

Mustang Flat

Wild Station

Rock Canyon

Grayson

Alkali Point

McCracken Spring

Caballo

Alkali Canyon

Deadman Canyon

Cave

Gothic Mesa

Brown Hogan

Desert Creek

Chinle Wash

CleftBoundary Butte

Tohonadla Hogan

Turner BluffRecaptureBluff Bench

Broken HillsBluff

Rabbit Ears

Anido Creek

River Bank

Yellow RockAkah

Ucola

Squaw Creek

Bannock Kiva

UTA

H

CO

LOR

AD

O

Cowboy

Deadman

Boundary Butte East

Heron

UTAH

ARIZONA

UTAH

0

0 3 6 9 km

6 mi3

Jack

Canyon

Runway

HeronNorth

AnasaziMuleBlue Hogan

IslandButte

Ismay moundtrend(predominantlylimestone)

Northern DesertCreek beach/mound trend(predominantly dolomite)

Desert Creekshelf margintrend

Sleeping Ute

T41N

T43S

R 26 E R 27 E R 28 E R 29 E R 30 E

R 21 E R 22 E R 23 E R 24 E R 25 E

T36S

T37S

T38S

T39S

T40S

T41S

T42S

R 26 ER 19 W20

W

T32N

T39N

T38N

T37N

T36N

T35N

T331/2

N

T33N

T 34 N

T35S

T40N

Map of Paradox Formation play area and fields within the Ismay andDesert Creek zones producing trends, Utah and Colorado.

Location of Paradox Formation outcrops in the Eight-Foot Rapidarea and The Goosenecks/Honaker Trail, San Juan River,

southeastern Utah.

Goosenecks of the San Juan River. Photographby Tom Till, courtesy of the Utah Travel Council.

Stacked complex of four phylloid-algal moundsin the Akah and Barker Creek zones of the

Paradox Formation, river mile 39.8.

Ismay zone algal banks near Eight-Foot Rapid

Paradox Formation algal bank/mound topography, morphology,and facies relationships as seen along the San Juan River, Utah

(from Brinton, 1986).

Schematic diagram of Paradox Formationalgal banks (from Brinton, 1986).

Photomosaic of a large phylloid-algal mound complex composed of algal bafflestone, skeletal grainstone,and packstone in the Barker Creek zone of the Paradox Formation, river mile 40.5.

Typical cement-rich algal bafflestone exposed in a phylloid-algal mound, Ismay zone, Eight-Foot Rapid area. Originalsheltered pore spaces were filled with mud; cement rinds

are developed around algal plates. Well-developed cross-bedding in peloidal and oolitic grainstone in

the cap and intermound facies of the Barker Creek zone of the ParadoxFormation along the Honaker Trail. Close-up shown in inset photo.

Mound flank material – part of the large phylloid-algalmound complex in the Barker Creek zone, river mile 40.5.

Schematic diagram of drilling targets in a Paradox carbonatebuildup by multilateral (horizontal) legs from an existing field well.Block diagram displaying depositional interpretation of a mound complex

and associated features in the Eight-Foot Rapid area. This interpretation isa composite of inferences made from outcrop and subsurface data.

Flooding surface (4th-order sequence boundary),Ismay zone along the Honaker Trail. Noteabundant intact and fragmented productid

brachiopods in the medium gray limestone matrix.

Pennsylvanian Paradox Formation Reservoir, Paradox Basin – Outcrop Analogs along the San Juan RiverPennsylvanian Paradox Formation Reservoir, Paradox Basin – Outcrop Analogs along the San Juan River