Seismology intro lecture information Flashcards
What does siesmic well data allow the mapping of?
The trap on a scale of km to 10’s km
What does bore/ well data allow for?
Mapping of a small horizontal area (~10cm) but gives deth and geological information
What does the creation of geological wells allow for?
The drawing out or placing of materials
What is the energy transition?
The phasing out of hydrocarbon based energy sources due to high ghg emissions and move towards lower carbon emission sources (renewable and nuclear)
What is is hard to tell fro seismic imaging?
WHat fluid a trap holds (most water but some might hold oil or gas)
How is imaging of oil filled traps being produced?
By comparing the compressibility of the hydrocarbons and water
What is CCS?
Carbon Capture Storage
WHat does CCS do?
Capture excess carbon dioxide and placing back in the geological traps
What is an example of an early CCS plant?
Sleipner in the NOrwegian north sea
WHat is produced at Sleipner?
Methane from relatively deep geological traps but 10% CO2 with methane and CO2 emission not allowed into atmo so pumped back undeground to shallower trap
What is a crucial issue of any CCS scheme?
Monitoring to make sure that CO2 trap is not breached (as would eneter ocean and atmosphere)
How are CO2 traps monitored?
Time Lapse siesmic monitoring
How do we know the seal of CCS hasnt been breached?
When the amount of CO2 injected matches the amount stored
How can CCS help battle intermittent renewables?
By producing and storing hydrogen gas underground
What type of temperature is being looked for for ultra deep geothermal?
150c which is much higher then current production areas
WHat are the 4 basic things all seismic techniques have in common?
Source (siesmic waves)
Reciever (pick up vibrations)
Processing (into image)
INterpret (image in terms of geology)
What are seismic sources at sea made up of?
Air guns which build up in pressure then release an air buble which when it collpases produces a bang which is seismic source
How can layers be interpreted from seismic reflection data?
Whenever a change in layer occurs a small amount of the wave will be reflected back (density/ property changes)
What are the seismic recivers called in a marine survey?
Hydrophones
WHat is the systems of multiple hydrophones called?
multi-channel streamer
What is turned into a seismic image?
Amplitude over time
How are faults shown in seismic reflection?
Indicated by a loss of reflection
Why is depth halve the distance travelled by the seismic ray?
As it is 2 way time (time to hit the layer and bounce back)
What are the 3 steps of ccs?
Capture
TRansport
Storage
How much co2 has currenlty been sotred underground?
300 million tonnes
What is deep geological storage also known as?
geo-sequestration
what 3 things are needed for a deep geological stroage site? (co2)
Reservoir
topseal
trap
WHat characteristic is wanted from the reservoir rock for ccs?
Needs to be both porous (fraction of rock that can hold co2) and permeable (higher permeability to allow co2 migration into the reservoir)
WHat are the 2 main groups of resevoir rock?
Sandstones
Carbonates
WHat are the characteritics of a good seal?
Non-porous
Non-permeable
WHat is the top seal?
Wont let gas or liquid through
WHat qualities are needed for seal rocks?
Impermeable
Ductile
Located immeditely above the resevoir rock
Laterally persistent.
What is a geological trap?
structure that contains both a resevoir rock and a seal arranged so that buoyant pore fluid in the resevoir is trapped y the seal
WHat is a key thing a successful trap needs?
4 way closure
What is needed in 3d for a trap to be sucessful?
Needs to form a dome
