GEOL40310_LectureA12_Unconventionals_2023.pdf

Geol 40310 Fossil Fuels and Carbon Capture & Storage (CCS) Lecture A12: Unconventional oil and gas Autumn 2023-24 T. Manzocchi, University College Dublin 1 1 Unconventional oil and gas Conventional vs. Unconventional oil and gas Shale Gas and Shale Oil Tight Gas and Tight Oil Other unconventional...

Geol 40310 Fossil Fuels and Carbon Capture & Storage (CCS) Lecture A12: Unconventional oil and gas Autumn 2023-24 T. Manzocchi, University College Dublin 1 1 Unconventional oil and gas Conventional vs. Unconventional oil and gas Shale Gas and Shale Oil Tight Gas and Tight Oil Other unconventional Gas: Coalbed methane Sour Gas Methane Hydrates Other unconventional Oil: Heavy oil Extra Heavy Oil, Bitumen Oil Shale Oil and gas supply cost curves 2 2 Geol 40310 Lecture A12 1 Conventional and unconventional fluids Unconventional Conventional Based on viscosity and liquid gravity.  API = 141.5 oil  water − 131.5 3 3 Conventional Petroleum System A functional petroleum systems comprises a combination of several geological processes Stratigraphic necessities: Geometrical necessity: Seal rock Trap Required Processes: Accumulation and retention Reservoir rock Migration Source rock Maturation 4 4 Geol 40310 Lecture A12 2 Production mechanisms for conventional reservoirs 5 Unconventional oil and gas Fluids UC C C C: Conventional UC: Unconventional Sour gas Petroleum System UC C Tight Gas Tight oil Heavy oil UC Shale Gas Shale Oil Coal bed methane Extra Heavy oil, Bitumen Oil Shale Gas Hydrates 6 6 Geol 40310 Lecture A12 3 Shale gas, tight gas and coal bed methane “tight” means low permeability Wyoming State Geological Survey7 https://www.wsgs.wyo.gov/energy/oil-gas-resources.aspx 7 Tight gas and Tight oil vs. Shale gas and Shale oil • Tight gas and tight oil have conventional petroleum systems but low permeability reservoir rock. • Shale gas and shale oil have unconventional petroleum systems. • Because they have similar recover processes (hydraulic fracturing) these unconventionals are often bracketed together. 8 8 Geol 40310 Lecture A12 4 Outcrops of source rocks for oil and gas • • • Thermally matured organic rich marine clays Source rocks for conventional reserves Source and reservoir rock for unconventional “shale gas” reserves Ordovician Utica Shale, New York State Jurassic Kimmeridge Clay, Wessex Basin 9 Michael C. Rygel via Wikimedia Commons 9 Shale Gas and Shale oil 10 10 Geol 40310 Lecture A12 5 11 11 Marcellus Shale Gas Reservoir Gamma Resistivity Density Typical Marcellus Porosities 5-15%, permeabilities 200-2000 ηD (0.2-2 μD; 0.0002-0.002 mD) (these are very good permeabilities for a shale gas reservoir) 12 12 Geol 40310 Lecture A12 6 Shale reservoirs: closely-spaced well pads 13 13 Hydraulic Fracturing Viscous polymer gel Generalised fracking process: 1. One or more wells (typically horizontal) are drilled. 2. The reservoir succession is fractured by pumping thickened fluid under pressure into the wellbore and fractures. 3. The injected material carries proppant, supported by thickened fluid (polymer gel) into the fractures. 4. The polymer breaks down over 12-24 hours to lose its viscosity. 5. When pressure is decreased at well head, de-polymerised fluid returns to surface but proppant remains and keeps fractures open. 6. Gas flows out following the returned fluid. Typical propping agents Source: LaFollette, R. 2010. Key considerations for hydraulic fracturing of gas shales. AAPG Search and Discovery Article #80100. 14 14 Geol 40310 Lecture A12 7 Stress-map and micro-seismic events from 7-stage hydrofracture in a well σHmin 100 mi N σHmax Fracture orientation 500 ft. The less brittle limestones above and below the shale act as “frac barriers” dampening fracture propagation 500 ft. 500 ft. Tully Lst Marcellus shale Onondaga Lst 15 15 Production decline curves in the North Dakota Shale Oil province • Very rapid decline from initial production rates. • Restimulation is expensive but can lead to partial rejuvenation • Delaying the decline is a function of both geology and engineering. 16 16 Geol 40310 Lecture A12 8 US Shale Gas and Tight Oil production Shale gas: 79% of total US production in 2021 Tight oil: 64% of total US production in 2021 17 17 US Tight oil and shale gas projections Tight oil and shale gas remain resilient despite huge changes in oil and gas prices – performance consistently exceeds projections BP’s 2020 scenarios forecast for 2030 Actual: 2015-2020 BP Energy outlook, 2016 18 18 Geol 40310 Lecture A12 9 Ireland hydrocarbon Concessions 2014 2018 Lough Allen Basin Clare basin 19 19 European Shale gas Hostility Balcombe, Sussex, 2013 Differences from the US: Concerns: Mineral rights. Population densities. Fracking: Polluted aquifers. Polluted surface water. Induced earthquakes. General: High carbon footprint of fossil fuels. 20 20 Geol 40310 Lecture A12 10 Induced sesimicity from hydraulic fracturing Fayetteville, Arkansas, USA, 2010 Schultz et al. (2020), Review of Geophysics, 10.1029/2019RG000695 21 21 ML: Local Magnitude Scale (same as Richter scale) From Wikipedia 22 Geol 40310 Lecture A12 11 Induced sesimicity from hydraulic fracturing Presse Hall (2011) Lanchasire, England Bowland Basin, England 2013: UK Government requirement to suspend operation for events > 0.5 ML Preston New Road (2018-19) ML 2.9 event 23 Schultz et al. (2020), Review of Geophysics, 10.1029/2019RG000695 23 Induced sesimicity from hydraulic fracturing “It is not currently possible to accurately predict the probability or magnitude of earthquakes linked to fracking operations”. UK Oil and Gas Authority report, November 2019 ML 2.9 event Schultz et al. (2020), Review of Geophysics, 10.1029/2019RG000695 24 24 Geol 40310 Lecture A12 12 European shale gas extraction bans Banned by: 2012 2016 2019 25 25 US Tight oil production Despite its comparative lack of success elsewhere, tight oil is of tremendous economic and strategic importance to the US (all oil, not just tight oil) 26 Geol 40310 Lecture A12 13 Unconventional gas Fluids UC C C Sour gas Petroleum System UC C Tight Gas Shale Gas UC Coal bed methane Gas Hydrates C: conventional UC: Unconventional 27 27 Coalbed Methane • • Methane forms during the process of coalification. Some escapes but most remains within the coal. Wells are drilled into the coal seams and water is pumped out. The resulting pressure drop in the vicinity of the borehole causes methane to bubble into the well bore. Produced water is reinjected elsewhere for disposal. 28 Wyoming and Kansas State Geological Surveys 28 Geol 40310 Lecture A12 14 Australian Gas Western Australia: Abundant conventional gas but little local demand: Solution: LNG plants. LNG plants Eastern Australia: Abundant coal but increasing local demand for gas. Solution: CBM with enough production to additionally support LNG plants 29 29 Shah Sour gas field, Abu Dhabi. Natural gas reservoir with 23% H2S and associated CO2 Began commercial production mid 2015: • One billion cubic feet (BCF) a day of sour gas. • Conversion to: 500 million cubic feet of fuel, and 10,000 tonnes of solid sulphur, per day for sale. • UAE looking to become global leader in sulphur production 30 30 Geol 40310 Lecture A12 15 Methane Hydrates Water molecules (1 red oxygen and 2 white hydrogens) form a pentagonal dodecahedron around a methane molecule (1 gray carbon and 4 green hydrogens). This represents 2 of the 8 parts of the typical Structure I gas hydrate molecule. Scanning electron microscope image of gas hydrate. • Gas hydrates are a crystalline structure formed by water molecules enclosing a low molecular weight gas (e.g., methane, ethane, carbon dioxide) molecule. • They occur naturally in some shallow marine sediments and within and beneath permafrost. • The USGS estimates (2009) that the world’s gas hydrate deposits may contain more organic carbon than all coal, oil and conventional natural gas combined. Gas hydrate recovered from just below the seafloor from the Gulf of Mexico. 31 USGS website 31 Methane Hydrates Methane Hydrates stability field in a marine setting USGS website 32 32 Geol 40310 Lecture A12 16 Offshore methane hydrate production test site, Nankai Trough, Japan • Gas production by reservoir depressurisation. • Gas production rates of 10,000 m3 /day but associated with very high water production rates. Fijil et al. 2015, Yamamoto et al. 2019 33 Unconventional oil Fluids C UC C Petroleum System UC C Tight oil Heavy oil Extra Heavy oil, Bitumen UC Shale Oil Oil Shale C: conventional UC: Unconventional 34 34 Geol 40310 Lecture A12 17 Extra heavy oil and Bitumen: Heavier than water Biodegradation of conventional hydrocarbons. Similar setting in Alberta and the Orinoco belt (Venezuela) 35 35 Steam Flooding – Heavy oil Kern River Field, California Reduce viscosity by increasing the temperature 36 Huc (2011) 36 Geol 40310 Lecture A12 18 Extra Heavy oil recovery methods 37 37 Stream Assisted Gravity Drainage • Two horizontal wells ca. 6m apart. Upper one injects steam, which rises due to lower density. • Heats and mobilises oil, which is produced by the lower well. 38 38 Geol 40310 Lecture A12 19 Bitumen Mining Canada’s tar sands are the only significant reserve being mined. Upgrading to synthetic crude oil before shipping 4.27 tons of material 1,152,000 t/d 39 39 Unconventional oil Fluids C UC C Petroleum System UC C Tight oil Heavy oil Extra Heavy oil, Bitumen UC Shale Oil Oil Shale C: conventional UC: Unconventional 40 40 Geol 40310 Lecture A12 20 Conventional Petroleum System A functional petroleum systems comprises a combination of several geological processes Stratigraphic necessities: Geometrical necessity: Seal rock Trap Required Processes: Accumulation and retention Reservoir rock Migration Source rock Maturation 41 41 Petroleum System – Shale Gas, Shale Oil, Coal-bed methane Stratigraphic necessities: Geometrical necessity: Seal rock Trap None of these other factors are necessary Reservoir rock Non in a shale gas reservoir : no migration occurs and the source rock, reservoir rock and seal rock are one and the same. Required Processes: Accumulation and retention Migration Source rock Maturation 42 42 Geol 40310 Lecture A12 21 Petroleum System – Oil Shale • A functional petroleum systems comprises a combination of several geological processes Geometrical Stratigraphic necessities: Required Processes: The only part of the conventional petroleum necessity: system still required for an oil shale is an Seal rock rick source rock – it is not even mature organic Accumulation and for these potential reserves. retention Trap Reservoir rock Migration Source rock Maturation 43 43 Oil Shale Oil Retort, built 1924 Lower Lias Shales, Kilve Oil Shale: An organic carbon rich shale that has not been heated sufficiently during its geological burial to generate hydrocarbon. The rock can be mined and heated in a furnace to produce oil, or heated in situ with the resultant oil produced through wells. Oil Shale must not to be confused with Shale Oil, where the shale has reached maturity, and the hydrocarbon already exists in liquid or gaseous form in the rock. If heated in situ, an Oil Shale will produce Shale Oil. 44 44 Geol 40310 Lecture A12 22 Ca. 20,000 bbl / day Historic Oil Shale production Allix et al. (2011) 45 45 The top twenty CO2 emitters in the European trading Scheme, 2016 March 2021: Estonia’s new government has promised to phase out Oil Shale electricity production by 2035 46 https://sandbag.org.uk/project/state-eu-carbon-market-2017/ 46 Geol 40310 Lecture A12 23 Oil Shale 7cm Extent of Green River Formation • • • Areas where oil shale is > 10ft thick and yields more than 25 gal/ton of oil. Reserves in oil shales are estimated to be 3-5 trillion barrels, with 60% located in the USA. Most important deposit is the Green River Formation. Processing of oil-shales to generate oil is expensive and produced large quantities of heavy metals and other environmentally damaging by-products. Oil shales have not been the target of modern exploration efforts, and oil shale is unlikely to be a significant source of oil in the foreseeable future. 47 Allix et al. (2011) 47 Supply / cost curves for oil and gas Oil Gas Mainly conventional Mainly unconventional Mainly conventional Mainly unconventional • There is plenty of oil and natural gas remaining, but future production will increasingly be unconventional and more expensive McGlade and Ekins (2015) 48 48 Geol 40310 Lecture A12 24 GEOL 40310 - Fossil Fuels and CCS Part A. Petroleum Geology and Reservoir Engineering: Geological setting of oil and gas, hydrocarbon exploration and production, reservoir studies. Assoc Prof Tom Manzocchi Reschedules Lab 3: Friday 13th October (Room E0.61-SCE) Part B. Refining and Chemical Engineering: Starts Friday 13th October (Room B003-04GIS) Coal and petroleum refining processes, petroleum products Professor Ravi Thampi Part C. Carbon Capture : Principles and practices of carbon capture Assoc Prof Damian Mooney Starts Tuesday 17th October Part D. Geosequestration: Geological aspects of sequestration, results from pilot studies, evaluation of CCS potential for Ireland Assoc Prof Tom Manzocchi Next lecture from me is Thursday 2nd November 49 49 Geol 40310 Lecture A12 25