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 on 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

Why??? Vancouver Sun

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

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Breaking news! On USA Federal lands:

#9 Escaped fracturing fluids, Innisfail, AB Jan. 2012 http://www.calgaryherald.com/business/Hydraulic+fracturing+have+caused+well+blowout/6003589/story.html?cid=megadrop_story

About 18 incidents have been reported in BC.

“Domestic wells in the area of investigation overlie the Pavillion gas field which consists of 169 #8 production wells which extract gas from the lower Wind River Formation and underlying Fort Union Formation. Hydraulic fracturing in gas production wells occurred 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.”

#7

An aside: Not all fracturing is deep! Fracturing allowed 50 m Many thousands of shallow CBM wells beneath water well already fracked in AB

#6

#5 (Also oil field brines) #4

#8

#3 Man induced, magnitude 4 earth quake, Ohio, Dec 31, 2011 http://www.dispatch.com/content/stories/local/2012/01/09/a-seismic-shift.html

#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/ #1 Burning water: Industry induced Or natural background? http://www.treehugger.com/natural-sciences/alberta-oil-gas-collateral-damage-she-can-light-her-water-on-fire.html

Anthropogenic gas seeps Gas well, leaking 1914-2010, Well Head, Dimock, PA Turner Valley, Alberta http://www.tcgasmap.org/media/Ingraffea%20Slides%207-25-11.pdf

Natural gas seeps NW Alberta, Canada Eternal flame, Chimaera Turkey

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 c a r F t s e w o l l a h S Only two gas wells have SC deeper than deepest water wells! Aquifer USEPA, 2011

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

Soil Gas Watson & Bachu

Innisfail!

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

So, how can we identify the source of fugitive gas in aquifers, soils and surface casings? Isotope ratios of problem gases captured at surface indicate source depths!

s a g Shallow CBM c i n e g o i B T h e r Increasing depth m o g e n i c g a s Methane from deep shale gas M. Schoell

Determining source of migrating gas: Start with Mudlog (NE Alberta) methane C1 C2 100 propane C3 ethane nC4 normal butane 200 300 Depth 400 500 600 -80 -70 -60 -50 -40 -30 -20 -10 δ 13 C

Determining source of migrating gas: Interpret the Mudlog, identify formations C1 C2 100 C3 nC4 200 300 Depth 400 Mannville 500 600 -80 -70 -60 -50 -40 -30 -20 -10 δ 13 C

Determining source of migrating gas: Find best match C2 C3 nC4 C1 Water SCV Well C1 C2 100 C3 Methane -54 -55.5 nC4 Ethane -23.5 -21.1 200 Propane -23.11 -21.1 300 n-Butane -26.1 -23.6 Depth 400 Mannville Source of 500 Migrating SCV gas 600 -80 -70 -60 -50 -40 -30 -20 -10 δ 13 C

Determining source of migrating gas: Same with gas from water well C2 C3 C1 nC4 Water SCV Well C1 C2 100 C3 Methane -54 -55.5 nC4 200 Ethane -23.5 -21.1 Propane -23.11 -21.1 300 n-Butane -26.1 -23.6 Depth 400 Mannville 500 Source of gas in water well 600 -80 -70 -60 -50 -40 -30 -20 -10 δ 13 C

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 of background data available. BWWT?

Gases in selected water wells in central Alberta U of A Database 0 -10 C ethane -20 Thermogenic gases Biogenic gases? - Impacted by gas drilling -30 δ 13 -40 -50 Are all these gases really -60 naturally occurring in domestic water? -70 -90 -80 -70 -60 -50 -40 -30 δ 13 C methane

Gases in selected water wells in central Alberta W h e n w e c o n s i d e r t h e p o s s i b l e s o u m r i c e g s r a o t i f 0 o n g a , s t h e r e a r e m a n y m o r e w a t h e r a v w e e b l l s e e n t h i a t m m p a a c y t e d b y g a s w e l l d r i l l i n g . -10 gases in selected water wells in central Alberta -20 C ethane Alberta thermogenic gases -30 -40 Alberta coals δ 13 -50 commercial biogenic gases -60 from Medicine Hat -70 -90 -80 -70 -60 -50 -40 -30 δ 13 C methane 7/26/2011, BT, U od A

Locations of water well complaints in U of A database. Oil Sands Scollard Formation Horseshoe Canyon Fm. Belly River Group Mannville Group Luscar Group Kootenay Group

Locations of water well complaints in U of A Shallow, biogenic database. gas Oil Sands Water well gases from both the Mixed, biogenic Mannville as well as gas, possibly Mixed, biogenic and overlying shales. with CBM deep thermogenic gas Thermogenic gas Scollard Formation Horseshoe Canyon Fm. Belly River Group Mannville Group Mixed gases, biogenic Luscar Group with CBM, some legacy Kootenay Group thermogenic gas

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

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