Analogs for Fault-controlled Analogs for Fault-controlled Ordovician Dolomite Ordovician Dolomite

Reservoirs, Appalachian Basin:Reservoirs, Appalachian Basin:Geological and geophysical characterization of Geological and geophysical characterization of

Central Kentucky outcropsCentral Kentucky outcrops David C. Harris

Kentucky Geological Survey

Clay A. WilcoxWilliam F. Reid

Department of Geological SciencesUniversity of Kentucky

OutlineOutline

• Outcrop analogs: petrography and geochemistry– MS thesis by Clay Wilcox

• Seismic reflection work– MS thesis by Bill Reid

• Recently drilled corehole at Stoner Branch locality

AcknowledgementsAcknowledgements

New York State Energy Research andDevelopment Authority

U.S. Department of Energy, National EnergyTechnology Laboratory

Triana Energy, Inc.

Outcrop Project GoalsOutcrop Project Goals

Characterize shallow Ordovician tectonic dolomites to improve exploration

strategies

• Approach: petrography, geochemistry, shallow high-resolution seismic, integration with New York reservoirs

30 0 30 60 90 Miles

GeologyWATERALLUVIUMTERTIARYCRETACEOUSPENNSYLVANIANMISSISSIPPIANDEVONIANSILURIANORDOVICIAN

Surface Faults

Central Kentucky Study AreaCentral Kentucky Study Area

Chronostratigraphic Units

Global NorthAmerican

System/Series

Series Stage

DrakesFm

BullForkFm

AshlockFm

GrantLake

Limestone

CallowayCreek FmGarrard Slts.

Fairview/Leipers

Fm

ClaysFerry Kope

LexingtonLimestone

High BridgeGroup

QueenstonFm

LorraineGroup

Utica Fm

TrentonGroup

Black RiverGroup

JuniataFm

TrentonLimestone

Black RiverGroup

Central andEastern

Kentucky

WestVirginiaEastern

Ohio

New York

Upper and MiddleUpper and Middle OrdovicianOrdovicianStratigraphyStratigraphy

Units affected byfault-controlleddolomitization

Structural FeaturesStructural Features• Northern

boundary fault of Rome Trough

• Left-lateral wrench fault system

• Central Ky. Mineral District

Winchester GeologyAlluvium depositsHigh-level fluvial depositsDolomite of uncertain age and originCrab Orchard Formation & Brassfield DolomiteDrakes FormationAshlock FormationCalloway Creek LimestoneGarrard SiltstoneClays Ferry FormationUpper part of Lexington Limestone (Trenton equivalent)Tanglewood Limestone Member No. 4Tanglewood Limestone Member No. 3Tanglewood Limestone Member No. 2Brannon Member, Lexington LimestoneTanglewood Limestone Member No. 1Lower part of Lexington LimestoneTyrone Limestone (Upper Black River Gp.)Artificial fill

FaultsFaultConcealed fault

Tectonic Dolostones

Index Map toTectonic Dolostone

Localities,Clark and Fayette

Counties, Ky.

0.5 0 0.5 1 1.5 2 2.5 Miles

Austerlitz FaultDolostone (16T)­

Lyndale FaultDolostones (9U and 10T)

­

­

­

­Clubhouse

Dr.

McClureRd.

LightbulbDolostone (8T)

Stoner BranchDolostone (11T)

Eagle Nest FaultDolostones (12T)

Walnut HillDolostone (6T)

LEGEND

Kentucky River Fault Zone

(Boonesboro Fault)

Eagle Nes

t Fault

Coletown Quadrangle Ford Quadrangle Winchester Quadrangle

Austerlitz Quadrangle

Lightbulb Sample IndexLightbulb Sample Index

C3-4 C3-3 C3-2C3-1

B3-3B3-2 B3-1

A3-2 A3-1

C3-5

D 3-4 D3-3

D3-2D3-1

E2-6

E2-7 E2-5

E2-2

E2-3

E2-4

E2-1 E1-1

E1-2E1-3

D1-1

D1-2 D1-3D1-4

C 1-1C1-2C 1-3

C1-4C1-5

B1-1B1-2B1-3B1-4

A1-1A1-2A1-3A1-4A1-5A2-9 A2-8

A2-7 A2-10 A2-6

A2-4 A2-3 A2-2A2-1

A2-5

B2-1B2-2B2-3B2-4

B2-5

B2-13

B2-14

B2-12

B2-11

B2-10

B2-6

B2-7B2-8B2-9

C2-7

C2-1

C2-2

C2-3

C2-4

C2-8

C2-9C2-11

C2-5

C 2-12

C2-10

C 2-13C 2-14

C2-6

C2-15

D 2-2

D2-3

D2-1D2-5

D2-6

D2-4

D2-7

D2-10

D 2-11

D2-8

D2-9

Saddle Dolomite, Clark Co., Ky.Saddle Dolomite, Clark Co., Ky.

SB1

SB

14

SB

6SB8

SB12

SB5SB

3

SB9

SB

7

SB10

SB

1 1

SB

4

SB13

SB

2

Stoner Branch Dolostone Sample Locality Index

0 0.25 0.5 0.75 1 Mile

Ordovician OutcropsOrdovician Outcrops

• Petrography: conventional and CL• Geochemical techniques

– oxygen and carbon stable isotopes– microprobe (trace elements)

• Cores: continuous core through Trenton and Black River to top Knox

• MS theses by Clay Wilcox and Bill Reid

PetrographyPetrography

• Multiple generations of dolomite and calcite

• Early dolomite: euhedral rhombs, replacive, non-Fe with some Fe zoning, luminescent

• Later calcite cement, non-Fe to Fe• Late dolomite: Fe-rich, saddle dolomite,

fills pores and replaces other grains/cement, non-luminescent

Early DolomiteEarly Dolomite

Multiple dolomite and calcite Multiple dolomite and calcite generationsgenerations

Late dolomiteLate dolomite

Late dolomite / calcite cement Late dolomite / calcite cement relationshipsrelationships

Stable Isotope Data –Early Stable Isotope Data –Early Dolomite, LightbulbDolomite, Lightbulb

Isotopic Analysis of Dolomite I for the Lightbulb Locality

-7.000

-6.500

-6.000

-5.500

-5.000

-4.500

-4.000-3.500

-3.000

-2.500

-2.000

-1.500

-1.000

-0.500

0.000

-7.500 -7.000 -6.500 -6.000 -5.500 -5.000 -4.500 -4.000 -3.500 -3.000

18O

13 C

B2-12 D1-1 D2-10 D2-4 D3-3

Stable Isotope Data – Saddle Stable Isotope Data – Saddle Dolomite, LightbulbDolomite, Lightbulb

Stable Isotope Analysis for Dolomite II (Saddle Dolomite) for the Lightbulb Locality

-2.00

-1.50

-1.00

-0.50

0.00

-9.00 -8.50 -8.00 -7.50 -7.00 -6.50 -6.00 -5.50 -5.00 -4.50 -4.00 -3.50 -3.00

18O

13 C

A2-10 B2-12 C2-11 C2-9 D2-5 E2-5 D2-7 D3-4

Stable Isotope Data – Stoner Stable Isotope Data – Stoner BranchBranch

Stable Isotope Analysis of Selected Dolomite Types for the Stoner Branch Loclality

-8.00

-7.00

-6.00

-5.00

-4.00

-3.00

-2.00

-1.00

0.00

-12.00 -11.00 -10.00 -9.00 -8.00 -7.00 -6.00 -5.00 -4.00 -3.00 -2.00 -1.00 0.00

18O

13C

Dolomite I Dolomite II Saddle

Stoner Branch Seismic Location Stoner Branch Seismic Location MapMap

USGS1 Allen

CNR CoreLocation

LINE 1

LINE 2

LINE 3

LINE 4

Seismic imaging of dolomitesSeismic imaging of dolomites

• Data collected at lightbulb and Stoner Branch

• P-wave and S-wave (shear) data

• Data used to locate corehole

Line 1B Shear WaveLine 1B Shear Wave

Depth

40m

58m

76m

23m

Core Location

Line length: 240 meters

KYRiverFault

Line 1A (P-wave)Line 1A (P-wave)

Extent ofDolomitization

N S

Line length: 240 meters

Line 3B (shear wave)Line 3B (shear wave)

NS

Extent ofDolomitization

Line length: 154 meters

Stoner Branch CoreholeStoner Branch Corehole

• Provide data on vertical distribution of dolomite• Evaluate dolomite in Black River• CNR drilled continuous HQ and NQ core from 27

to 1005 ft (306m); TD reached Oct. 23• Penetrated several small faults in shallow

section• Penetrated Ky. River Fault Zone in the Black

River: 175 ft (53m) of fractured limestone and breccia

• TD in Knox on footwall, 280 ft high to downthrown block

Stoner Branch Well LocationStoner Branch Well Location

ROME OIL & GAS CO 1 ALLEN JAMES BCOLUMBIA NATURAL 825470 ALLEN JAMES B

FEET

0 1,250

PETRA 11/7/2004 6:17:28 PM

CNR 3-04 AllenCNR 3-04 Allen

ROME OIL & GAS COALLEN JAMES B

1

COLUMBIA NATURAL RES LLCALLEN JAMES B JR

3-04

<507FT>0 200

GR

30 -10

CNPOR

2 3

RHOB

0 200

GAMMA_NEU

30

100

200

300

400

500

600

700

800

900

1000

1100

1200

1300

Knox GroupSt. Peter Sandstone

Wells Creek Dolomite

Pencil Cave Bentonite

Garrard Siltstone

Trenton Ls

Black River Group

Clays Ferry Formation

Subsea Depth960

860

760

660

560

460

360

260

160

60

-40

-140

-240

-340

SW NE

280 ft faulted out inBlack River/Wells Creek

20 ft faulted out inGarrard/Clays Ferry

Preliminary Core ObservationsPreliminary Core Observations

• Dolomitization limited to upper 220 ft: Trenton and Black River not pervasively dolomitized along fault

• Fabric-selective dolomitization present in Trenton

• Breccias in fault zone are dolomitized- but very limited alteration outside of fault zone in deeper section

Calloway CreekCalloway Creekdolomitedolomite

49-53 ft49-53 ft

Trenton LimestoneTrenton Limestone

335-339 ft335-339 ft

Black RiverBlack Riverfault breccia with fault breccia with multiple calcite multiple calcite

generationsgenerations

823 ft823 ft

Black River fault Black River fault brecciabreccia

847 ft847 ft

Black RiverBlack Riverbreccia withbreccia withsphaleritesphalerite

698 ft698 ft

675-685 731-741 805-814

Fault BrecciasFault Breccias

• Calcite, dolomite, sphalerite, barite, pyrite mineralization present

• Abundant evidence of multiple reactivation

• Cross-cutting relationships and structural features will allow relative timing of fault movement and mineralization to be determined

ConclusionsConclusions• Distribution, petrography and

geochemistry of central Ky. Ordovician dolomites suggests hydrothermal origin

• Complex diagenetic history, with multiple dolomitization events

• Facies selectivity differs for different dolomite types

• Fault conduits are primary control on distribution, but other factors control alteration zones

Final Project ReviewFinal Project Review

• PTTC-sponsored core workshop and final project review: Spring, 2005

• KGS Core and Sample Repository, Lexington, Kentucky

• Optional field trip if there is interest