USGS Oil and Gas ResourceAssessments and Hydraulic Fracturing

Brenda Pierce, U.S. Geological Survey

June 8, 2012

Total Petroleum System

24803

Petroleum System ElementsPetroleum System Elements

120° F120° F

350° F350° FGenerationGeneration

MigrationMigration

Seal RockSeal Rock

Reservoir RockReservoir Rock

OilOil

WaterWater

Gas CapGas Cap

EntrapmentEntrapment

Source Rock

Armentrout, 2001

Conventional Reservoir

Medium-grained,

cross-bedded sandstone

Thin section photomicrograph

Spiro Sandstone

Core slab

Continuous Reservoir

Weakly Laminated

Shale

Strongly Laminated

Shale

(Slatt and others, 2011)

Thin section photomicrographs

Woodford Shale

QOQO

Photomicrograph of an uncemented sandstone from the Jurassic Morrison Fm. Blue is epoxy that fills primary pores (between grains) and some secondary pores that have developed from partial dissolution of some detrital feldspar grains.

Photomicrograph from a tight sandstone in the Bossier Fm. It is tight due to abundantquartz overgrowths (QO), and porosity exists between adjacent quartz overgrowths

Goal of USGS Assessments

Continuous Methodology

Geologic characterization of assessment units Drainage areas of wells (cell sizes) Number of potential cells (tested and untested) Engineering data –

well production and

performance EUR (estimated

ultimate recovery)

distribution

Woodford Shale – Horizontal Well Density

USGS Continuous Oil and Gas Resource Estimates

http://energy.usgs.gov/OilGas/AssessmentsData/NationalOilGasAssessment/AssessmentUpdates.aspx

USGS Shale Gas and Tight Gas Resource Estimates

Source rocks of the Alaska North Slope: estimates (95-percent to 5-percent probability) range from zero to 2 billion barrels of oil and from zero to nearly 80 trillion cubic feet of gas.

Example: Bakken Formation (2008)

Mean total = 3.65 BBO (F95=3.0 BBO; F5=4.3 BBO)

Changes result from improved geologic understanding, technological developments, other factors

USGS 1995 Bakken Assessment: Mean total = 151 MMBO

973 MMBO

909 MMBO

868 MMBO

410 MMBO

485 MMBO

Resource Assessments Change Over Time

http://www.eia.gov/todayinenergy/detail.cfm?id=3750

Bakken Oil Production

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

0

500

1000

1500

2000

2500

3000

3500

U.S. Unconventional Gas ProductionB

illio

ns o

f Cub

ic F

eet

Year

Coalbed Methane

Shale Gas

Source: Energy Information Administration

Hydraulic Fracturing• Water use• Chemicals used• Fate of injected fluid• Flowback quality

Collection of produced water

Characterization, Impacts, and Use of Produced Waters

USGS produced waters database and extent of U.S. shale gas plays

Bakken Formation – extent of USGS assessment units and hydraulically , fractured wells.

http://energy.usgs.gov