An INTRODUCTION TO ISSUES IN ENVIRONMENTAL GEOLOGY OF OIL SHALE AND TAR Sands Jeremy Boak, Colorado School of Mines Justin Birdwell, U. S. Geological Survey.

An INTRODUCTION TO ISSUES IN An INTRODUCTION TO ISSUES IN ENVIRONMENTAL GEOLOGY OF OIL SHALE ENVIRONMENTAL GEOLOGY OF OIL SHALE AND TAR SandsAND TAR SandsJeremy Boak, Colorado School of Mines

Justin Birdwell, U. S. Geological Survey

OutlineOutline

‣ Oil shale and tar sand overview

‣ Environmental issues

‣ 30th Oil Shale Symposium highlights

November 1, 20102

What is oil shale?

‣ Organic rich sedimentary rock

‣ Formed in lake or marine environments– Commonly carbonate rich; many not be

classical shale (fissile argillaceous mudstone)

– Contains kerogen – solid hydrocarbon

– Primarily algal and bacterial precursor

– Immature precursor to oil & gas

‣ Produces oil upon heating

‣ Or deeper burial

November 1, 20103

What is shale?

November 1, 20104

Petroleum system perspective

Shale gas?

Shale-hosted oil

Oil shale

November 1, 20105

Oil shale resource estimates

November 1, 20106

In situ vs. external extraction – oil shale

November 1, 20107

In situ vs. external extraction – oil sands

November 1, 20108

Environmental issues for oil shale & tar Environmental issues for oil shale & tar sand sand

‣ Novel versions and combinations of familiar problems

‣ Consumption of water

‣ Potential contamination of water & atmosphere

‣ Challenges to habitat and range

‣ Interactions of ground water, surface water, soil, rock, air and ecosystem create a linked system

– Exciting challenge to the research community to define & execute

– Challenge to communicate research results & implications effectively

– In a politically charged environment

November 1, 20109

Energy and carbonEnergy and carbon

‣ Extraction of useable hydrocarbons requires a larger input of energy than traditional hydrocarbons

– Separation of heavy oil from poorly consolidated tar sands

– Pyrolysis of solid kerogen in oil shale

‣ Raises questions of energy return on investment & carbon footprint

‣ Can alternative energy sources merge with these unconventional hydrocarbon resources to mitigate GHG emissions?

November 1, 201010

Water use and qualityWater use and quality

‣ Water use potentially higher – despite advances in conservation & reuse of process water

‣ Mobilization of hydrocarbons underground – Target of some production schemes for oil shale and tar sand

– Carries potential for contamination of ground water

‣ Particulate air emission – Surface mining & processing may contaminate surface & ground

water

– A novel contaminant pathway not yet clearly addressed

November 1, 201011

Land and ecosystem issues

‣Large areal extent of both types of resources

‣How to manage land to preserve ecosystems where these resources exist

‣Migration corridors of significant concern

‣High areal density of oil shale may mitigate concern

‣Disposition of spent materials

November 1, 201012

Multiple use issues for oil shale

‣Current development of deeper tight gas sands of Mesa Verde Group

‣Other possible deeper targets

‣Dual resource issues– Saline minerals of Green

River Formation

‣Environmental baseline?

November 1, 201013

Oil Shale Symposium environmental Oil Shale Symposium environmental themesthemes

‣ Water consumption

‣ Groundwater contamination

‣ Water systems evaluation

‣ Climate change impacts on water supply

‣ CO2 emissions from oil shale production

‣ Reuse of spent shale

‣ Species threats

November 1, 201014