technical considerations for hydraulic fracturing and ... · petroleum geology basics,...

GWPC meeting – Houston January 23, 2012

Technical considerations for Hydraulic Fracturing and Groundwater Protection:

Overview of geology, depositional environments, thickness, and areas of

major frack plays in TX

Eric Potter Bureau of Economic Geology

Leftover business: Shallow flanks of basins in frac plays

• Frac targets are closer to groundwater • Large operators may not be interested, but

small ones might be… • Anticipate and prevent a Pavillion, Wyoming

situation

Sources: NY DSGEIS; Wrightstone, 2008

Marcellus Shale

Marcellus Outcrop belt

Utica Shale Outcrop belt

Utica Shale

Geological Cross Section, Utica to Binghamton No vertical exaggeration

10 miles

0

+2000

-2,000

-4,000

-10,000

-8,000

-6,000

0

-2,000

-4,000

-10,000

-8,000

-6,000

Utica Clinton

Oriskany Falls

Hamilton

W. of Norwich Near

Binghamton

Pennsylvania border

valley elevations Base of groundwater

need buffer (frac no-go)

Why deeper is better • Higher pressures = more reserves, higher

rates • Better geotechnical conditions for long

horizontals; more wells per pad • Chances of upward frac excursion extremely

low • 40,000 “lost” shallow wells in NY, more in

other states • Leaves a thick buffer zone betw frac and GW • Less experience with large-scale fracing at

shallow depths

Texas frack plays

Wolfberry

Ozona TGS

Cleveland

Haynesville & Cotton Valley

Eagle Ford

Cotton Valley Lime, Bossier Sands

Barnett

Oil migrates upward

Oil is trapped where reservoir

rocks occur in trapping configuration

Earth’s surface

About 1.5 to 3 miles down…

seal

seal

Tens of miles

Petroleum Geology Basics, cross-section

Reservoir rock

Source rocks generate oil and gas

Petroleum Geology Basics, cross-section

Earth’s surface

About 1.5 to 3 miles down…

And they go nowhere! Source rocks generate oil and gas

Unconventional resources – poor reservoir rocks, in or near source rocks.

>30,000 wells fraced in the past 5 years

BARNETT SHALE

HAYNESVILLE SHALE

EAGLE FORD SHALE PEARSALL SHALE

SHALES

TIGHT GAS

Granite wash, Cleveland, Marmaton

BOSSIER SHALE

Cotton Valley, Travis Peak

Wolfberry

Canyon Sands

Vicksburg, Wilcox

Olmos

WOODFORD SHALE BARNETT SHALE

JP Nicot, 2011

V

V

V

V V

Permian Basin Permian shale and limestone frac targets

Fort Worth Basin Mississippian shale and limestone frac targets

Anadarko Basin Pennsylvanian shale and tight sand frac targets

Gulf Coast Basin Jurassic and younger targets

Texas Frac Plays • Wide variety of ages • Many lithologies

– Black shale, tight sandstones, tight limestones

• Varying thicknesses – Barnett, Eagle Ford,

Haynesville shales ~300’ – Wolfberry 100s of feet

• Commonality: – in or near thermally

mature source rock – no flow unless fracked

-- Eagle Ford Shale

-- Haynesville-Bossier Shales -- Cotton Valley Sandstones

-- Wolfberry limestone/shales

-- Barnett Shale Anadarko Basin shales and sands

Eagleford gets deeper towards the coast

Outcrop areas

Eagle Ford roadcut near Del Rio, Texas

Thickness of Lower Eagle Ford Shale

Outcrop

25 mi

≥ 175 ft

<25 ft

Maverick Basin

100 mi 50

Stuart City shelf margin

Tucker Hentz, BEG

Most wells are drilled in this lower zone

Carbonate Debris Flows (blue and pink)

Shales (Green)

“Wolfberry Trend” carbonate debris flow facies, seismic cross sectional view

Courtesy Vecta O&G

Hund

reds

of f

eet

From DrillingInfo website

BakerHughes.com

Questions/Discussion