dr. adrian f. park geological background to shale-gas in new brunswick
TRANSCRIPT
Dr. Adrian F. Park
Geological background toShale-gas in New Brunswick
Outline
1. Conventional & unconventional petroleum
2. Fracking
3. Shale gas potential in NB4. Outstanding issues
CLASTIC SEDIMENTS
Classified by composition and grain-size
Environments of deposition(Sediments sorted by grain-size and energy of water flow)
Deltas - Lake Ayikum, TibetSand and gravel in river channels
Fine sand and silt on delta front
Mud plumes
Environments of deposition (organics)
Delta-top swamp/forest (peat)
Off-shore algal blooms & detritus(sapropelic mud)
Organic detritus(sapropelic mud)
Mississippi delta, Gulf of Mexico
4. Traps
gas
oil
trap
Permeable layer with water (aquifer)(oil and gas float)
Impermeable layer (aquitard)
Conventional Oil and Gas
Unconventional Oil and Gas - directly exploiting the ‘source rocks’(the trick is extracting the hydrocarbon content)
OIL SHALE - the first petroleum industry
Scotland 1780s to 1860s
The ‘bings’ of West Lothian c. 2000
Albert Mines, NB1840s to 1880s
North America’s first petroleum industry
Images courtesyNB Museum and NB Archives
AND A LITTLE CLOSER TO HOME
Abraham Gesner1797 - 1864
US EIA
Frederick Brook, NB
Horton Bluff, NS
RESERVEv.
RESOURCE
Estimated reserveProven reserve
Recoverable reserve
1 GJ ≈ 0.5 bbl oil ≈ 28m3 gas
Marysvillesubbasin
?
??
Courtesy Steven Hinds, NB DNR, 2013
With unconventional oil and gas the problem isgetting the oil and gas out
In 19th century thisinvolved mining andmajor environmentaldegradation
21st century thisinvolves ‘fracking’
‘Fracking’ (also ‘fraccing’) - enhancing permeability by fracturing
Images courtesy of NB DNR
Oil workers ‘fracking’ an oil well with nitroglycerine, 1903, NB
Natural pressure gradient with depth(between 2.6 and 3.0 tons/metre2
for each metre down)
Between 250 and 300 m depth fractures arenaturally sealed by lithostatic load
Drinking water aquifers usually lie above this zone
Deep aquifers where water pressure = loadusually salty and non-potable
Fractures created in one rock layer generally donot spread into other layers because ofdifferent mechanical properties between rocktypes (even within rock types)
Corridor hydrofracturing tight sandstone reservoirat McCully, Sussex since c. 2003
‘Hydraulic fracturing’ or ‘hydrofracking’(first used 1948, last two decades more widespreadalongside horizontal drilling)
Causes for concern (shale-gas):
1.Leakage of gas (or oil) in drinking water aquifers through induced fractures
2.Leakage of wells into aquifers
3.Hydrofracturing liquids and possible toxic effects
4.Hydrofracturing noise and air quality
5.Surface leakage and contamination (waste water disposal)
6.Hydrogen sulfide, heavy metals, radioactive materials
7.Earthquakes induced by hydrofracturing and deep well injection disposal
Hydrofracturing operationsWaste waterSeismicity
‘Hydraulic fracturing’ or ‘hydrofracking’
Hydrofractured shale
Freshwater aquifers
2 + km
CANDOR – this is a hydrofrac operation
Well-pad
Pumps & compressorsSlickwater
storage
Producingwell-pad
Fracking additives from the Apache/Corridor Elgin project
Sodium hydroxide used in manufacturing soap (lye, caustic soda)Carboxymethyl cellulose ingredient in laxatives and toothpasteBentonite clay - used in water filtersXanthan gum polymer food additive and food processingSodium bicarbonate component of baking powderBarite medical uses as an X-ray blocker (barium meals)Base oils (e.g. HT 40) synthetic oil and mineral oilCalcium chloride food preservative, de-icing fluids, electrolyte drinksPolyamide/fatty acid blend
(Novamul) comparable to linseed oilCalcium hydroxide ‘lime’ – whitewash and fertilizerGlutaraldehyde biocide, surgical & dental disinfectant
Manufactured by Petrocan under Federal license(proprietory)
FULL DISCLOSURE
Some concern as carcinogenUsed to prevent formation of H2S
Waste waterRecovered hydrofracturing liquids
Production water
Drilling fluidsHydrogen sulfide, radionuclides, heavy metals
have not been an issue thus far.Waste water is a strong brine (2 – 3X seawater)
Treatment and disposal:Until 2012 – waste water treatment and disposal at Debert, NSCurrently transported by road to Levis, Quebec
Deep-well injection currently not an option
Alternatives to slick water hydrofracturingLiquid propane, nitrogen foam, carbon dioxideRemove hydrofracturing water from consideration
Microseismic monitoringduring hydrofracturing
Required in North Dakota,and BC(used at Elgin)
Microseismic activity during a hydrofracturing process, Barnet Shale, Texas
18 July – 18 August 2015
Seismicity in Canada
UK draft regulations consider
‘acceptable levels’ of seismic activity
?