Unconventional ResourcesWhat are Unconventional Resources?

Shale Gas/ Shale oilTight Gas SandsOil ShaleCoalbed MethaneMethane Hydrates (Not Producible…..Yet)

Differences: Unconventional Shale Gas and Conventional Plays

Approach to prospectingi.e. Not looking for “clean” unitsDepositional Environments

Deposition of unitsDriving factors of production

i.e. not porosityTOC is the driving geologic factor

US Unconventional Gas Projections

Holditch and Ayers 2009

Unconventional Resources:USA

http://www.mapwv.gov/website/unconventionalresources/index.htm

MarcellusShale

Barnett Shale

Bakken Shale(oil)

Global Shale Gas

Global Unconventional Gas

Holditch and Ayers, 2009

How Does Shale Produce

Low porosity (6%)Very low permHigh TOCBrittle rockNatural fractures

Economic Problems: Unconventional Resources

Cost of Drilling ($4 million for Marcellus wells)Pipe and casing costCompletionEnvironmental RestrictionsEstimation of Reserves

Estimation of Reserves

Jenkins 2009We don’t know how wells will evolve

Depositional Environments: Black Shale

Sub-Oxic Environment

Oxic Environment

Anoxic Environment

-Aerobic bacteria useoxygen to break downorganic matter

-Oxygen is virtually exhausted-Dyserobic bacteria use nitratesas an oxidant-Process is slower

- No oxygen present-Anerobic bacteria use sulfatesas an oxidant-Process is very slow

Need a low amount of sediment input, low circulation and a high amount of organic input in order for a stratiphied water column to develop

Black Shale Modern Analogs: Black Sea

http://blacksea-education.ru/images/map.jpg

Paleo Structure ???

West Limb of the Rome Trough

Onondaga LimestoneOnondaga Limestone Shale Marker

SW NE

Local highsand lows

Black shale is deposited across the study area

Shale appears to be sourced primarily from the NE

Thicker Marcellus deposits exist in Onondaga lows and to the NE

Organic matter extends across the study area, however more organic matter

accumulates in the paleo-topographic lows

Shelf break at A and B

Paleo Structure ???

Marcellus Shale

Anoxic Conditions

Oxic Conditions

Local highsand lows

West Limb of the Rome Trough

OM OM OMOM OM OM OM OM

Onondaga Limestone

Onondaga Limestone Shale Marker

NESW

BA

Depositional Model:Marcellus Shale

West Limb of the Rome Trough

Onondaga Limestone

Onondaga Limestone Shale Marker

Purcell Limestone

Oxic Conditions

Anoxic Conditions Mahantango Siliciclastics

Mahantango Limestone Bed

Mahantango Black Shale Bed

NESW

Tully Limestone

? ?? ?Erosion

OM OM

Harrell Shale

Harrell Shale

Paleo Structure ???

Lower Marcellus Shale

Upper Marcellus Shale

Marcellus Shale

Local highsand lows

Subsidence

? Non-Deposition?

West Limb of the Rome Trough

Onondaga Limestone

Onondaga Limestone Shale Marker

Purcell Limestone

OM OM OM OMOxic Conditions

Anoxic Conditions

Mahantango Siliciclastics

Mahantango Limestone Bed

Mahantango Black Shale Bed

NESW

Tully Limestone?

?

? ?Erosion

OM OM

Harrell Shale

Harrell Shale

Paleo Structure ???

Lower Marcellus Shale

Upper Marcellus ShaleMarcellus Shale

Subsidence

Local highsand lows

Subsidence continues

Anoxia allows for Harrell Shale deposition

The thickest deposits are in paleo-lows

B

A

Depositional Model:Harrell Shale

Data Resources:Unconventional Plays

LithostratigraphyPetrophysical Data

Spectral Gamma LogsXRD and SEMPermeabilityWater Saturation

GeoChemTOC data is essential

Thermal maturity3D Seismic

For optimal well design to avoif structural complexity

Surface to Sub-Surface

Marcellus Shale

Thickness Maps: Marcellus Shale

BA

Spectral Gamma Ray SuiteTh/U ratio is linked to TOC

Spectral Gamma Ray Analysis

Th/U RatioOxidizing

IlliteIllite--PinkPinkSmectiteSmectite--GreenGreen

Th/K RatioTh/K Ratio

Spectral Gamma Ray

XRD and TOC

Establishes if rock can be fracturedEstablishes TOC or Reservoir potential

Regional MappingOrganic RichMarcellus at 15ppm

CI = 5ft

15 ppm

Summary on Marcellus:High TOC 5-15%Very brittle (i.e. fracable)Relatively shallowWide extent Possible 4,359 trillion cubic feet of gas (Engelder 2001)Overall economics can make one Marcellus well more profitable than three shallow wells???????Price of gas is a big issue

Bakken Shale- Williston Basin• ~3.6 billion barrels of oil (recoverable)• Porosity 5%• Perm 0.05 milli Darcy• Recovery Factor 1-5%

Coal Bed MethaneCoal is the most abundant fossil fuelProduce Methane adsorbed to coal surfacesCoal stores 6 times more gas than a conventional reservoir by volumeGas content is 100-800 SCf/ton of coalEconomic production from 0.5 ft-thick coal is possible

Water/Gas production history

Coal Bed Methane Extraction

Drill wellPump water out to decrease pressureProduce desorbed gas

Water Production170K bbls/day

1 Million bbls/day

Coal-Bed-Methane Produced Waters

Tar Sands

Athabaska Tar Sands(or oil sands)Reserves: 1.7 trillion

barrels (assuming 10% recovery)

Venezuelan Oil Sands:

500 billion barrels

Tar Sands- Strip Mining

Tar Sand Extraction methodOpen Pit MiningCrushMix with hot waterBitumen floats (60% bitumen, 30%water, 10% solids)1200 SCF of gas needed to process 1 bbl of bitumen (about 5x energy gain)Upgrading: remove water, sand, impurities, sulfur, catalytic hydrocracking, hydrogenation

Bitumen Separation Cell, Alberta

Suncor Energy Inc.

Canadian Tar Sand Production Canadian Oil Data

Total Production 2,600,000 Barrels/DayExports to US 2,500,000 Barrels/DayToday, about half is from the Oil Sands#1 foreign supplier for USA

Oil ShaleKerogen-rich immature shaleHeating the shale releases oil by pyrolisis

Green River Shale- USA

Green River Shale Resource

1.2 to 1.8 trillion barrels in placeRecoverable?

Global Resource: 2.8 to 3.3 trillion barrels

Oil Shale Production Method

Mining and crushingRetortingOil UpgradingRefining

Disposal and reclamation

Economics

Viable at $70 to $95/bbl in USA

Energy Produced/Energy Used = 3 to 4

Environmental impact is significantWater usage is a problem

Stuart Oil Shale Facility,Queensland, Australia

In-Situ conversion (unproven)

Electric heaters in holes2-3 years heating to 650-700 degrees C

Methane Hydrates(Clathrates)

Crystal Structures

1 mole methane for 5.75 moles water1 liter hydrate= 168 liters methane at STP

Stability

www.nrcan.gov

Gas Seeps on the Seafloor Gas Hydrate Occurrence

ResourceTwice the amount found in all fossil fuelsHow can we produce it?