THE MARCELLUS SHALE GAS PLAY

Geology, Development, and Water-Resource 

Impact Mitigation 

 

 

 

 

 John H. Williams

 https://profile.usgs.gov/jhwillia/

 

New York Water Science Center

Troy, New York
Marcellus shale play is located in the Appalachian basin and covers 

parts of New York, Pennsylvania, Maryland, and West Virginia

Marcellus shale play is the one of three overlapping 

shale plays that includes the older Utica shale and 

the younger Devonian shales

Lash and Engelder (2009)

Union Springs

Cherry Valley

Oatka Creek

High gamma 

radiation 

High gamma 

radiation

Geophysical Log

Marcellus Stratigraphy

Onondaga

Marcellus
Lash and Engelder (2009)

Union Springs

Cherry Valley

Oatka Creek

High gamma 

radiation 

High gamma 

radiation

Geophysical Log

Marcellus Stratigraphy
Darker gray = more organic rich

Smith (2010)

Highest TOC (up to 20%) 
Seismic survey from Otsego County 

Gamma log 

Seismic image courtesy of Gastem
Lash and Engelder, 2009
 Shale Gas Development 

• First commercial gas well in the United States was a 

 Devonian shale gas well drilled in 1821 near Fredonia, NY

 

Site of first gas well in the United States
Hydraulic Fracturing and Horizontal Drilling 

4,000 ft

3,000 

– 8,000 ft

Marcellus Shale Gas Development

Source: Independent Oil and Gas Association of Pennsylvania 
 Hydraulic Fracturing

• First hydraulic fracturing of oil & gas well was in 1948

• Medina Sandstone, a tight gas reservoir, was extensively

 fraced in western New York and Pennsylvania during the 1970s

 

• 100,000 oil & gas wells are fraced per year 

 
 Horizontal Drilling

• First horizontal well was drilled in 1948

 

• First horizontal shale gas well was drilled

 in 1988 in the Antrim Shale, Michigan

• First horizontal gas well in New York was 

 drilled in 1989

 

Trenton/Black River well
Horizontal Drilling

at Multi-Well Pad Sites in Black Shale

4,000 ft

3,000 

– 8,000 ft

Marcellus Shale Gas Development
Orthogonal joint sets

East-northeast trending J1 

fractures and northwesttrending J2 fractures 

Drill horizontal wells to the 

north-northwest or southsoutheast perpendicular to 

major horizontal stress and 

J1 fractures 

Dual porosity gas reservoir 

where fractures drain rapidly 

and matrix drain slowly 

Connect matrix porosity to 

the wellbore by intersecting 

multiple J1 fractures 

Free gas and adsorbed 

gas in matrix

Terry Engelder PSU
Multi-Well Drilling Pad Site

With Six Horizontal Laterals

Horizontal Lateral
Multi-Well Drilling Pad Site

With Six Horizontal Laterals

Horizontal Lateral

Minimizes surface disturbance but 

concentrates industrial activity
Directional rig for drilling 

horizontal leg

Top-set rig for drilling vertical 

surface- and intermediatecased interval
Walking legs on 

directional drilling rig 

Wellheads of first two of six 

horizontal wells 

~15 ft
Teff (2011)

Horizontal wells target basal Marcellus Shale 
Target horizon (Union Springs Shale) mapped 

using offset well logs and seismic

Logging-while-drilling used to steer lateral 

within target beds

Schlumberger (2010)

Gamma

Density
Tompkins County, NY

High TOC and 

elevated radioactivity

in basal Marcellus Shale

Levanthal and others (1981)
Uranium & Thorium to Radium & Radon 

Radioactive Decay Series 

Radioisotope and half life
Drill Core Sample Analysis

Lash and Engelder (2009)

Gamma Log

High TOC and abundant pyrite in basal Marcellus Shale
• Elevated uranium and abundant pyrite in high-TOC black shale 

• Multi-horizontal well site will generate more than 500 times the volume

of shale cuttings than single-vertical well site 

Drill Cuttings

Core of target interval Drill cuttings
Lined pit 

Mixed with sawdust 

Closed-loop system 

Offsite disposal in landfill

Drilling Fluids and Cuttings
4,000 ft

3,000 

– 8,000 ft

Marcellus Shale Gas Development

Multi-Stage High-Volume Hydraulic Fracturing of Horizontal Laterals
3 to 5 million gallons of water for hydraulic 

fracturing of each horizontal lateral
Typical Components of Frac Fluid

. • For a 3 million gallon frac job, the 0.5 percent is 

equivalent to 15,000 gallons of “chemistry”

•Re-fracing may be needed due to proppant crushing, 

scale, etc.
Infill Drilling Refrac

Devonenergy.com

Barnett Shale 
Water Withdrawals for Frac Water

• Water-availability 

issues are seasonal in 

nature

• Withdrawal of 5 MGD

during high water 

insignificant, during low 

water exceeds 10 

percent of flow

• If surface water becomes 

more restrictive, industry 

will look to groundwater 

• Surface-water

withdrawals and 

municipal supply in PA

• Surface water and 

groundwater – a single 

resource

• Cumulative impacts of 

multiple withdrawals
Chloride (mg/L)

0

20,000

40,000

60,000

80,000

100,000

120,000

1 2 3

Total dissolved solids (mg/L)

0

50,000

100,000

150,000

200,000

250,000

1 2 3

Gross Alpha (pCi/L)

0

5000

10000

15000

20000

1 2 3

Barium (mg/L)

0

2500

5000

7500

10000

1 2 3

Water quality of flowback (1.5 million gallons) from Marcellus shale well after completion of hydraulic 

fracturing (Samples were taken at 1, 2, and 3 third intervals of the 2-week flowback period, PADEP)

1,160

22

19,000

668

6,100

8,730

18,600

80,500

109,000

34,600

134,000

192,000
TDS and Radioactivity of Flowback Water
Uranium & Thorium to Radium & Radon 

Radioactive Decay Series 

Radioisotope and half life

Brine from a Marcellus Shale-Gas Well

Gross Alpha 20,800 pCi/L

Gross Beta 2,390 pCi/L

Radium 226 10,200 pCi/L

Radium 228 1,250 pCi/L

Thorium 228 47.5 pCi/L 

Thorium 232 0.0 pCi/L

Uranium 234 0.5 pCi/L

 
Reuse flowback, onsite treatment for 

 solids / blend with 70 % freshwater 

Municipal wastewater treatment 

plants not designed to handle 

flowback chemistry 

Limited number of disposal 

wells in Ohio 
Microseismic Monitoring of Hydraulic Fracturing
•Produces readily detectable microseismic events (400 per frac) 

•Frac half lengths greater than 1,000 feet 

•Frac azimuths typically east-northeast parallel to J1 joint sets

•Reactivation of pre-existing joints by strike-slip failure

Marcellus Hydraulic Fracturing 

Microseismic for five Marcellus laterals Joint sets in the Appalachian Basin

Duncan and Williams-Stroud (2009)
1000

500

3500

4000

4500

5000

5500

6000

Modified from Kostelnick (2010)

Upper Hamilton Group

Stratigraphy and Frac Barriers 
Marcellus shale

Onondaga limestone

Tully limestone

Upper Hamilton shale
 (Marcellus SPE 131783)

Microseismic

Monitoring 

of Marcellus Fracs
Fisher (2010)

Microseismic Mapped Frac Tops and Bottoms

Marcellus Shale
Sharma and others (2003)

Fracing near faults
Trenton

Salt

Marcellus

Utica

Lockport

Onondaga

Seismic Line from South-Central New York

Smith (2010)

Tully
Teff (2011)

Avoid Structures 
Valley-Fill Aquifers 

Saturated deposits of glacial sand and gravel
Fractured zone in Catskill Formation

Upper Devonian Fractured-Bedrock Aquifers
Braun and others (2011)

Bedding fracture and joint in Lock Haven Formation

Upper Devonian Fractured-Bedrock Aquifers
Depth of Water Wells in USGS and NYSDEC Databases

South-Central New York 
Water Wells that Penetrated Saltwater in South-Central New York 

Modified from Williams (2011)
Water Wells that Penetrated Saltwater in North-Central Pennsylvania

Williams and others (1998)
344 588

7,800

40

10

13

2.1 0.2

36

NS

30

3.1

Water Quality of Typical Freshwater and Salty 

Water Wells in Upper Devonian Bedrock

Salty water wells

(Williams and others, 1998)

3

4,600

304 Tioga 

County, PA
Depth of Freshwater Zones Penetrated by Gas Wells 

South-Central New York 
Modified from Williams (2011)

Wells that Penetrated Gas above the Marcellus Shale

South Central New York 
Freshwater and Gas in Close Vertical Proximity 
Methane in Water Wells 

Marcellus/Utica Gas-Play Area

Osborn and others (2011)

Sampling sites
FRESH WATER AQUIFER ZONE

SHALLOW PRODUCING ZONE

INTERMEDIATE PRODUCING ZONE

CONDUCTOR PIPE

SURFACE CASING

PRODUCTION CASING

Good Zonal Isolation

TARGET PRODUCING ZONE
Poor Zonal Isolation

PRESSURE 

BUILDS UP

CONDUCTOR PIPE

SURFACE CASING

PRODUCTION CASING

FRESH WATER AQUIFER ZONE

SHALLOW PRODUCING ZONE

INTERMEDIATE PRODUCING ZONE

TARGET PRODUCING ZONE

CASING

CEMENT

FORMATION
2,500 – 4,000 feet

 Characterization of deep freshwater

and shallow gas and saltwater 

 Engineered zonal isolation by multiple

casings, cement, packers, and venting 

Protection of Freshwater Aquifer
Freshwater 

Transition 

Saltwater 

Geophysical Logs and Base of Freshwater Aquifer

Log data courtesy 

of Shell Appalachia
• Cemented surface casing may not be 

 deep enough to protect freshwater aquifer

• Open annulus interval between top 

 of production casing cement to bottom of

 surface casing may allow upward

 migration of salty water and gas

• Drilling and frac fluid storage in surface 

 impoundments and burial of drill cuttings

 onsite may contaminant shallow 

 groundwater and surface water

• One-time use of frac fluid wasteful of 

 freshwater resources and creates disposal

 issue

Shale Gas Development 

Typical past practices

- 500 feet 

 Top of cement

2,750 ft 

• No water-well sampling before 

 drilling/hydraulic fracturing operation
• Surface casing/cement deep 

enough to protect freshwater aquifers

Shale Gas Development 

Best practices based on state-of-the-art

technology and science

• Cement-bond logging and pressure

 testing to ensure good seals

• Water-well sampling before and 

 after drilling/hydraulic fracturing operation

• Microseismic monitoring of hydraulic fracs

• Drilling and frac fluid storage in tanks 

 and offsite burial of drill cuttings

• Reuse of frac fluid reduces freshwater 

resource impacts and disposal issue

• Intermediate and production 

casing/cement/packers to prevent upward 

migration of salty water and gas 

• Geophysical logging to delineate base 

 of freshwater aquifers

• Avoid hydraulic fracturing near structures