Looking at Trenton–Black River Reservoirs: Outcrops Analogs in Kentucky Dave Harris Kentucky Geological Survey University of Kentucky

R O M E T R O U G H

Outline Trenton/Black River in Kentucky NYSERDA project at KGS and NYSM Tectonic dolomite examples from outcrops and shallow cores

RegionalStructure

Upper and Middle Ordovician OrdovicianStratigraphy Units affected by fault-controlled dolomitization

Type Log Upper and Middle Ordovician, Central Kentucky

Study Area

Shelby Co. Jeptha Knob ClarkCo.

Tectonic Dolomite, Clark Co., Ky.

Ordovician oil shows, central Ky. Lexington Ls. (Trenton) Walker Quarry, Montgomery Co., Ky. Calloway Creek Fm (dolomitized), Clark Co., Ky.

Why look at outcrops in Kentucky? Regional scale –Understand distribution of tectonic dolomite –Timing of faulting, dolomitization, and hydrocarbon migration Local scale –Reservoir scale porosity and permeability distribution –Depositional facies controls

Tectonic Dolomite Model, Steuben Co., New York

Need Better Geological Model Model for dolomitization process –Stratigraphic control on dolomite –Structural control on dolomite –Source/pathways for fluids Timing of dolomitization –relation to hydrocarbon migration Hydrocarbon source

NYSERDA Project 2-year project to study central Kentucky dolomites and apply results to subsurface N.Y. dolomite reservoirs Co-funded by Triana Energy, KGS and U.S. DOE Focus: outcrops and new continuous cores Approach: petrography, geochemistry, shallow high-resolution seismic, integration with New York reservoirs

NYSERDA (cont.) Geochemical techniques –oxygen and carbon stable isotopes –microprobe (trace elements) –fluid inclusions (salinity and temperature) Cores: 2 continuous cores through Trenton and Black River to top Knox

Integration with New York Reservoirs Collaborating with T. Smith at the NYSM Data to be compared with similar work on New York rocks DOE funding shallow seismic acquisition in central Kentucky P-wave and shear wave sources to image shallow dolomites

Tectonic Dolomite Outcrops Hydrothermal mineralization present in central Kentucky: barite, galena, sphalerite, saddle dolomite Upper Ordovician limestones replaced by dolomite adjacent to faults in outcrop Black et al., (1981 USGS Professional Paper 1151A) mapped 33 T-dolomites

From Black and others, 1981 Ordovician Dolomite Localities Top Black River shaded relief

Fault-controlled dolomite, Clark Co., Ky. From Black et al., 1981

Saddle Dolomite, Clark Co., Ky.

Fracture-fill in core CK-15 stained with alizarin-red calcite barite or celestite calcite dolomite

Shelby Co. Jeptha Knob ClarkCo.

Jeptha Knob, Shelby Co., Ky. Circular, fault-bounded structural and topographic high About 2.5 miles in diameter, central uplift core, with flank area of annular and radial faults Cryptoexplosive structure or meteor impact? Ordovician limestones extensively dolomitzed

Jeptha Knob Geology

Jeptha Knob cores Cored for mineral exploration 3 continuous cores, from surface to about 2,000 ft Breccias and dolomite with high-angle dips; high porosity and permeability in dolomitized Trenton Hydrothermal? – no saddle dolomite observed

JK78-1, 341 ft JK78-1, 361 ft

JK78-1, 341 ft High angle dips, chaotic bedding, and breccias Skeletal grainstones and packstones (Trenton lithologies) dolomitized Abundant moldic and intercrystalline porostiy

JK78-1, 433 ft

JK78-1, 462 ft JK78-1, 409 ft

Conclusions Fault-related, hydrothermal dolomites occur in Trenton–Black River outcrops in Kentucky Good laboratory to develop models for hydrothermal dolomitization that will be applicable throughout the basin

Acknowledgements New York State Energy Research and Development Authority U.S. Department of Energy, National Energy Technology Laboratory Triana Energy, Inc.