What are we going to talk about? Hydraulic Fracturing: How to assess - - PowerPoint PPT Presentation

What are we going to talk about?

Hydraulic Fracturing: How to assess its impact

• n groundwater: Lessons from Alberta, Canada

Karlis Muehlenbachs Department of Earth and Atmospheric Sciences University of Alberta Edmonton, Alberta, Canada Karlis.muehlenbachs@ualberta.ca

Method proven to be extremely $$$ effective for production

Vancouver Sun

Why???

http://democrats.energycommerce.house.gov/index.php?q=news/committee-democrats-release-new-report-detailing- hydraulic-fracturing-products

#10

“ “

Breaking news! On USA Federal lands:

http://www.calgaryherald.com/business/Hydraulic+fracturing+have+caused+well+blowout/6003589/story.html?cid=megadrop_story

#9 Escaped fracturing fluids, Innisfail, AB

• Jan. 2012

About 18 incidents have been reported in BC.

“Domestic wells in the area of investigation overlie the Pavillion gas field which consists of 169 production wells which extract gas from the lower Wind River Formation and underlying Fort Union Formation. Hydraulic fracturing in gas production wells

• ccurred as shallow as 372

meters below ground surface with associated surface casing as shallow as 110 meters below ground surface. Domestic and stock wells in the area are screened as deep as 244 meters below ground surface. With the exception of two production wells, surface casing of gas production wells do not extend below the maximum depth of domestic wells in the area of investigation.”

#8

#7

Fracturing allowed 50 m Many thousands of shallow CBM wells beneath water well already fracked in AB

An aside: Not all fracturing is deep!

#6

(Also oil field brines)

#5 #4

#8

http://www.dispatch.com/content/stories/local/2012/01/09/a-seismic-shift.html

#3 Man induced, magnitude 4 earth quake, Ohio,

Dec 31, 2011

#2

Methane carbon isotope value

http://shakespearessister.blogspot.com/2011/09/holy-shit.html http://inafutureage.wordpress.com/2010/06/22/your-land-my-land-gasland/ http://www.treehugger.com/natural-sciences/alberta-oil-gas-collateral-damage-she-can-light-her-water-on-fire.html

Burning water: Industry induced Or natural background? #1

Gas well, leaking 1914-2010, Turner Valley, Alberta

http://www.tcgasmap.org/media/Ingraffea%20Slides%207-25-11.pdf

Well Head, Dimock, PA

Anthropogenic gas seeps

Natural gas seeps

Eternal flame, Chimaera Turkey NW Alberta, Canada

Yes, but, what happens if the job is not done right? How frequently are instances of poor cementing and casing problems encountered?

Wells are encased in a variety of casings to capture gas migrating up well bores.

How often are there errors in 1)setting the surface casings 2) cementing etc.?

Well completions at Pavillion, WY.; revisit #9

USEPA, 2011 Only two gas wells have SC deeper than deepest water wells! S h a l l

• w

e s t F r a c

Aquifer

Problems and poor cementing are common and lead to gas migration and sustained casing pressure

Data from off shore Gulf of Mexico, USA

From Schlumberger, Oilfield review

Watson & Bachu

Soil Gas

Innisfail!

But note, induced fractures may be up to 600m long, and impact may be take 6 to 10 years to show up. Natural fractures may be up to 1100m long

Isotope ratios of problem gases captured at surface indicate source depths! So, how can we identify the source

• f fugitive gas in

aquifers, soils and surface casings?

• M. Schoell

Increasing depth

B i

• g

e n i c g a s

Shallow CBM

T h e r m

• g

e n i c g a s Methane from deep shale gas

Determining source of migrating gas: Start with Mudlog (NE Alberta)

600 500 400 300 200 100

• 80 -70 -60 -50 -40 -30 -20 -10

δ13C Depth C1 C2 C3 nC4

methane ethane propane normal butane

Determining source of migrating gas: Interpret the Mudlog, identify formations

600 500 400 300 200 100

• 80 -70 -60 -50 -40 -30 -20 -10

δ13C Depth C1 C2 C3 nC4 Mannville

Determining source of migrating gas: Find best match

600 500 400 300 200 100

• 80 -70 -60 -50 -40 -30 -20 -10

δ13C Depth C1 C2 C3 nC4 Mannville

C1 C2 C3 nC4

• 54
• 23.5
• 23.11
• 26.1
• 55.5
• 21.1
• 21.1
• 23.6

Methane Ethane Propane n-Butane SCV Water Well

Source of Migrating SCV gas

Determining source of migrating gas: Same with gas from water well

600 500 400 300 200 100

• 80 -70 -60 -50 -40 -30 -20 -10

δ13C Depth C1 C2 C3 nC4 Mannville

C1 C2 C3 nC4

• 54
• 23.5
• 23.11
• 26.1
• 55.5
• 21.1
• 21.1
• 23.6

Methane Ethane Propane n-Butane SCV Water Well

Source of gas in water well

Locations of SCV gases in U of A database

n = 3304

Source of leaking gases

• In most cases SCV, soil and water

gases are not from production horizon

• 75% of SCVF gases have a shallower

source (well integrity issues)

• In some fields, certain formations more

prone to gas migration!

• Isotope fingerprinting works best if lots
• f background data available. BWWT?

• 90
• 80
• 70
• 60
• 50
• 40
• 30
• 70
• 60
• 50
• 40
• 30
• 20
• 10

C methane δ13 C ethane δ13

Gases in selected water wells in central Alberta U of A Database

Biogenic gases? Are all these gases really naturally occurring in domestic water? Thermogenic gases

• Impacted by gas drilling

• 90
• 80
• 70
• 60
• 50
• 40
• 30
• 70
• 60
• 50
• 40
• 30
• 20
• 10

C methane δ13 C ethane δ 13

Alberta coals Alberta thermogenic gases commercial biogenic gases from Medicine Hat gases in selected water wells in central Alberta

7/26/2011, BT, U od A

Gases in selected water wells in central Alberta

W h e n w e c

• n

s i d e r t h e p

• s

s i b l e s

• u

r c e s

• f

g a s m i g r a t i

• n

, t h e r e a r e m a n y m

• r

e w a t e r w e l l s t h a t m a y h a v e b e e n i m p a c t e d b y g a s w e l l d r i l l i n g .

Kootenay Group Luscar Group Mannville Group Belly River Group Horseshoe Canyon Fm. Scollard Formation

Oil Sands

Locations of water well complaints in U of A database.

Kootenay Group Luscar Group Mannville Group Belly River Group Horseshoe Canyon Fm. Scollard Formation

Oil Sands

Locations of water well complaints in U of A database.

Water well gases from both the Mannville as well as

• verlying shales.

Shallow, biogenic gas Mixed, biogenic and deep thermogenic gas Mixed, biogenic gas, possibly with CBM Thermogenic gas Mixed gases, biogenic with CBM, some legacy thermogenic gas

To protect and identify specific sources of gas contamination in groundwater we need to mandate baseline isotopic fingerprinting of methane, ethane and propane for: –Pre-development water wells –Post-fracing surface casing vents of new wells –Retest SC of preexisting wells near new frac jobs. –Production gases –Detailed gas isotope stratigraphy (mudgas isotope log)

Conclusions and suggestions to Industry and regulators: *The above requirements are not onerous, CAPP has similar recommendations.

http://www.capp.ca/aboutUs/mediaCentre/NewsReleases/Pages/operating-practices-for-hydraulic-fracturing.aspx#SKte9VA4ViuM