Geology and gas in Northern Ireland. Derek Reay Geological Survey of Northern Ireland

Geology and gas in Northern Ireland Derek Reay Geological Survey of Northern Ireland Talk Outline Introduction - Geology of Northern Ireland Petrol...
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Geology and gas in Northern Ireland

Derek Reay Geological Survey of Northern Ireland

Talk Outline Introduction - Geology of Northern Ireland Petroleum Exploration – History of exploration – Conventional and unconventional gas resources – Basins and exploration plays • Northeast ‘concealed’ basins • Southwest Carboniferous basin

– Legislation and regulation

Competition for the subsurface Conclusions

Geology of Northern Ireland

Indigenous oil and gas resources Could • Enhance security of supply by reducing dependence on imported oil, gas and coal • Provide inward investment and create employment • Generate income through corporation tax (30%), ringfenced petroleum tax (32%) and royalties (7.5%) on petroleum production revenue

Potential for oil and gas resources in NI – limited exploration but no production to date

History of exploration • Petroleum legislation enacted in 1964 • First licence, in Fermanagh, in 1965 • Exploration activity modest – cycles driven by prices, discoveries in analogous settings and technological advances • 10 seismic surveys and 15 exploration wells • Some oil and gas shows but no production BUT Significant untested potential for both oil and gas

Petroleum prospectivity in Northern Ireland Southwest

Concealed Basins

Unconventional gas

Reservoir Permo-Triassic sandstones

Reservoir Carboniferous shales

Seal

& sandstones

Permo-Triassic mudstones

Seal Carboniferous shales

Source Carboniferous shales

Source Carboniferous coals & shales

Traps Structural Stratigraphic

Traps Non-essential

Secondary targets Carboniferous sandstones Unconventional gas

Elements of conventional petroleum exploration play Elements Organic-rich source rock Permeable reservoir rock Impermeable caprock Efficient trap Processes Source maturation Trap formation Hydrocarbon migration

Relative timing of processes is crucial!

Conventional and ‘unconventional’ gas resources Characterised by reservoir quality and production methods Conventional Porosity 10 – 30% Permeability 1mD – 1 Darcy Gas is present as free gas, trapped within the pore space between the grains of the reservoir rock Gas will usually flow from the reservoir up to the surface under its own pressure Unconventional Porosity