Shale Gas:- What is it?, Where is it? How can we get it and when? Professor Peter Styles, Applied and Environmental Geophysics Research Group 1
Outline Introductory comments What is Shale Gas? What is Fracking? What chemicals are used? Environmental issues / Water Contamination/Visual Amenity/Well Integrity Seismic issues Concluding comments
What is shale gas? Organic matter trapped during the deposition of fine-grained shale rocks. Rocks mostly formed between Cambrian to Cretaceous (spanning 500 Ma) and deposited in very extensive (across Europe and globally) low energy marine and lake environments Conventional resources Oil and gas that migrated from the shale source rock to more permeable sandstone and limestone formations. Unconventional resources Oil and gas that remains trapped in the shale source rock. Shale gas has not been traditionally considered an attractive option due to the low permeability of shale rocks (0.01-10 D). www.oceanexplorer.noaa.gov
What s Unconventional?
Conventional? Unconventional? Yes you CAN tell the difference!
Unconventional? Conventional? NO you CAN T tell the difference!
Shale Gas releases methane held in fractures and micropores in thick shale deposits that are the source rocks in conventional hydrocarbon settings
Bowland Shale, organic-rich and thick Formby natural oil seepage Age Marcellus (U.S.) Lublin (Poland) Bowland (UK) Devonian (350-410Ma) Extent <246000km 2 covering 5 U.S. and 1 Canadian states Silurian (410-435Ma) <23000km 2 covering the Lublin region of South- East Poland Carboniferous (300-360Ma) <17500km 2 covering West Lancashire Thickness Up to 270m (900ft) thick Up to 150m (490ft) thick Up to 790m (2600ft) thick Composition Sandstone, siltstone, black (organic) shale and grey shale Organic rich black shale Total organic carbon <20% 4 20% 0.7 15% Gas in place (estimated) 360 Tcf (trillion cubic feet) =10.2 Tcm 222 Tcf =6.2 Tcm Organic rich black shale, grey shale, sandstones and limestones 200 Tcf (North Sea 170 Tcf) =5.7 Tcm
Permeability Shale: Tighter than a Canard s Orofice
Whats in a hydrocarbon: Lots of stuff!
Geopolitical Context And things have not improved at all with events of the last week or so
European Shale Gas and CBM plays
However we need to consider the Goldilocks Effect This porridge(shale) is too Cold This porridge (shale) is too Hot This porridge(shale) is just Right!
Probably a more realistic appraisal (plus South Wales)
Approximately 25 to 50 years of UK Gas Consumption even at an extraction ratio of 10%! GS Estimates of Resource available from Shale Gas in Northern England The estimate is in the form of a range to reflect geological uncertainty. The lower limit of the range is 822 tcf and the upper limit is 2281 tcf, but the best estimate for the resource is 1329 tcf.
After penetrating the shale, the rock must be hydraulically fractured, or fracced, to maximize the production of natural gas. Fresh water, sand, and additives are injected into the well under high pressure to enhance fractures in the rock and free more gas. These fractures start at the wellbore and extend as much as several hundred feet into the shale. Hydraulic Stimulation : Fracking Sand, is pumped into the fractures to keep the rock from closing when the pumping pressure is released, allowing the natural gas to migrate from the rock pores to the surface wellbore. Water and sand typically make up 99.5 percent of the liquid phase of fracturing fluids.
3D micro-seismic mapping in real time (National Energy Board Canada) Maxwell (2012)
Early Fracking in the UK
Hydrofracturing in the UK Not new!! >200 fracs Carried out for water, Carried out for Geothermal Energy Carried out for Coal Bed Methane Microseismicity Monitored as long ago as 1988 Beckingham, Lincolnshire Hydrofrac Monitored by my (PS) Research Group (while at Liverpool) in 1988/1989 with BP!! 22
A commonly held view! And perhaps with some justification in the US!
Fraccing Chemicals other 0.5%
Shale Gas & Aquifers
Howver, May be a much more critical Issue in some Regions but not the UK Water Usage: CONTEXT About 2.5 Million Gallons of water / well
Atmospheric Methane Emissions McKay & CSIRO Reports
Surface spills of Flowback Water Important and perhaps one of the most serious risks Can be avoided by fully lined and bunded pads
Exploration phase is temporary Before During After (Exploration Phase) Courtesy IGas, Willoughbridge
Visual Intrusion Single wells Dimock, Pensylvania Multiple Wells from Single pad Originally weak Federal and state regulation Minerals owned by the landowner Complete buy in by the landowners No financial benefits to tenants
O S Corfe Castle World Heritage Site Heritage Coast Dorset coast Site of Special Scientific Interest (SSSI) Two Nature Reserves Poole and Bournmouth (pop 400k) Wytch Farm Largest onshore oil field in western Europe 110,000 bpd Directional drilling Careful screening
Where s Wytch Farm?
Cuadrilla Preese Hall 1 Borehole Induced Seismicity
Hydrofracturing Stages and Associated Seismicity at Preese Hall: Blackpool Earthquakes Earthquake activity was caused by fluid injection into a fault zone which failed repeatedly in a series of small earthquakes 34
Oakham (Rutland) Earthquakes of a few weeks ago :Note 3.5ML at 2 km and no damage!!! 50 times more energetic than the Blackpool Events and much shallower!!
Seismicity: thousands of fracking operations in USA Barnett Shale USA x 30,000 Lancashire, UK (2011) exceptional x 1,000 1.5 2.0 2.5 Not felt felt Our Threshold for Action
O The health, safety and environmental risks can be managed effectively in the UK.. Fracture propagation is an unlikely cause of contamination. The risk of fractures propagating to reach overlying aquifers is very low Well integrity is the highest priority. Independent, specialist experts should review the design of every onshore well.
The evidence suggests that, provided appropriate monitoring programs are undertaken and a robust and transparent regulatory regime put in place (and enforced), there will be a low risk that shale gas production will result in contamination of aquifers, surface waters or the air, or that damaging induced seismicity will occur
The Triangle of Truth for Shale Gas Technically possible Economically Deliverable Societally Acceptable
How long until and for how long?