More Resources Flashcards
The value chain
Acquire
- acquire the acreage (land)
Explore
- find petroleum
Appraise
- determine size/complexity
Develop
- drill wells and build facility
Produce
- get the petroleum out
Abandon
- remove facility
“The petroleum system”
Source
Reservoir
Seal
Trap
(Migration and timing)
Reservoir =
In the subsurface
Filled with water
Petroleum displaces
POROSITY - storage
Net:gross
PERMEABILITY - flow
Formation volume factors
Oil shrinks at the surface
- gases exsolved in the subsurface
Gas expands at the surface (due to lower pressure)
> > > how much actually there?
> > > how much left in the subsurface?
- oil ~65%
Tools for exploration and production
Satellite images
Seismic
Core and cuttings
Outcrop data
Gravity and magnetic
Wire line logs
Fluid samples
Petroleum seepage
Source =
Organic material preserved in sediments
Bury and heat
Crack
Wireline logs
Tools run into well on a wireline, measure
Rock/fluid/void properties
P, T
Fluid flow
Gamma log
Sandstones and limestones have a low natural radioactivity
Mudstones have a high natural reactivity due to clay minerals and feldspars…
- K!!!
- U
- Th
What does petroleum play require?
Mature source rock (buried deep enough to convert solid phase organic material to oil and gas)
Reservoir
Regional seal
Plays =
Reservoirs/seal combinations
Prospect =
Petroleum target ready to be drilled
- trap is mapped
- size/key risks defined
Salt withdrawal =
Less dense = can rise and create a gap
Appraisal =
Determine if it can be developed economically
- how big
- reservoir architecture
- reservoir quality
- compartmentalised?
- fluid contacts?
- what are the petroleum fluids?
Baffles and barriers =
Low permeability rocks
Baffle = small, oil can flow around
Think about vertical/horizontal drilling
Stabilisation wedges =
7 25 Gt wedges in order to halt CO2 and find alternatives
Stabilisation wedges - examples
1) increase fuel economy of 2 billion cars 30-60mpg
2) reduce electricity use in homes/offices/stores by 25%
Replace coal…
3) double nuclear power
4) x40 wind power
5) x700 solar power
6) stop deforestation
7) CCS at 800 large coal fired power plants
How does CCS work?
Capture
A) compress - transport - inject/store in fluid state
B) sequester = react to form an inert material
What can you react CO2 with to form an inert material?
Fly ash/combustion residues
Peridotite
C-Fix carbon concrete
Novacem
Types of carbon capture
Pre combustion
Oxyfuel
Post combustion
Pre combustion carbon capture
Separate CO2 from the H/CO2 mixture obtained from fossil fuels
Oxyfuel carbon capture
Burn in pure oxygen = CO2 and steam
Condense and isolate
Post combustion carbon capture (MOST)
Use solvents to remove CO2 from dilute, low pressure exhaust gases
CO2 storage - limiting technology
i.e. difficulties with the technology
Data density - difficult to compare sites
Site capacity
Site injectivity (?fracture if too fast)
Reservoir and seal reactivity (alters water chemistry)
Site integrity
Site monitoring
CO2 storage options
Depleted oil/gas reservoirs
Enhanced Oil Recovery
Deep unused saline aquifers*
Enhanced CBM recovery
Saline aquifers =
Geological formations with water too brackish for potable purposes
Goaf =
Void space due to coal mining/underground coal gasification - up to 2000 x more permeable than deep saline aquifers
Trapping mechanisms
Structural and stratigraphic
Residual CO2 in pore spaces
Solubility
Mineral
Residual CO2 trapping
Brine = wetting fluid
Adheres to pore sides due to surface tension
Brine moves upwards = CO2 displaced BUT passes through pore throat = some trapped
Solubility trapping
CONVECTION ENHANCED DISSOLUTION
Increase [CO2] = increase brine density = convection
Cosmic Ray Muon Tomography
Dense minerals (high atomic number) deflect charged, very penetrating particles created by cosmic radiation striking in the atmosphere
Sensors in subsurface to see how many have come through
See where CO2 is moving above of sensors are underneath
Types of geothermal energy
Ground source heat (shallow)
Hydrothermal systems
Engineered geothermal systems
Ground source heat pumps
Earth = source in winter, sink in summer
Absorbs/rejects heat from/to the ground
6m ~constant depth
Energy efficient heating/cooling device
Hydrothermal systems
Deep convection cells
Engineered geothermal systems =
Fracture stimulation of hot, dry rock e.g. granite
Currently rely on natural hydrothermal systems and high heat flow on plate boundaries
Ways to extract heat in geothermal power generation
DRY STEAM
FLASH STEAM
BINARY CYCLE
Dry steam
Hydrothermal fluids used directly
> 210 degrees
~20-100 MWe
Binary cycle
Lower T fields
Separate hydrothermal from “binary” e.g. butane/pentane
Then vaporise binary fluid in a heat exchanger to drive a turbine
What does coal formation need?
Abundant land plants - therefore <465Ma (before then was limited, need to have evolved and grown)
Anaerobic decomposition - near surface water table!
Rapid basin subsidence/sediment accumulation = economically thick deposits
Intermittent high clastic input (burial)
Ideal conditions for coal formation
DELTAS
- esp elongate/birdsfoot; weak marine currents/waves
Valley bogs
Blanket bogs e.g. UK Quarternary Peat deposits
What happens to coal’s properties with increasing rank?
Increase calorific value
Decrease volatile components
Rank order of coal
Peat
Lignite (soft brown coal)
Sub-bituminous (hard brown coal)
Bituminous
Anthracite
Graphite
How does the distribution of sands affect whether coal is deposited?
Differential compaction
- mud compacts more than sandstone
- sandstone “blocks” coal formation
SEAM SPLITS
SEAM THINNING/ABSENCE
WASHOUTS
- coal eroded away and then filled with sand
Coalfields of Britain and Ireland
Between Caledonian and Variscan orogeny = basin = sediment accumulation
(“PALAEOGEOGRAPHY”)
Region of rifted continental crust between Highlands massif and marie Cornwall-Rhenish basin
Post-Carboniferous coal is minor
Peat = NW Britain
- Ireland 25% electricity
History of coal exploitation in the UK
12TH-14TH C
- Bishops of Durham charged people for transporting coal over their land in the NE
17TH C
- long wall mining = long and not deep
- 40% recovery
DEMAND INCREASED
18TH C
- deep mining
- 1913 = peak production
1947
- NCB standardised operating procedures
1984
- Miners Strike
- offset with oil/gas
- cost $7 billion
2015
- last deep pit closes, some opencast remain
UK operations 2010
11 producing underground mines
33 producing surface mines
UK Major Producers 2010
UK Coal Mining Ltd Scottish Coal Mining Company Ltd ATH Resources Ltd Celtic Energy Hargreaves Services Powerfuel
UK operation 2016
0 producing underground mines
33 producing surface mines
Fewer applications and many refused
What do reserves-to-production graphs indicate?
Longevity
Types of reserve
TECHNICAL
- using available technology
PROVEN
- extant economic/operating conditions
PROBABLE
- most likely recoverable
POSSIBLE
- P10 reserve/equivalent
What happens as the size of a reserve increases?
The likelihood to be able to distract diminishes
Ways to extract coal
Mine
CBM + ECBM
UCG
Gas in coal
Free gas in micropores and cleats
Methane dissolved in water
Adsorbed gas
- coating around edge of matrix grains
- semi fluid
- increase pressure = gas
CBM production profile
Dewatering stage
- permeability increases as pressure reduces
Stable production stage
Decline stage
Methane and water plotted on same graph
CBM characteristics
Low permeability Cleat dominated Peak 0.3mmscf/d Many wells Co-produces water
Conventional gas characteristics
Low to high permeability Matrix dominated Min. 20mmscf/d Few wells No water production
Enhanced Coal Bed Methane
Carbon dioxide preferentially adsorbed and methane desorbed
N.B. Process self limiting b/c CO2 adsorption reduces permeability
Underground Coal Gasification
Coal to gas while underground
2 wells interconnected
Oxygen injected = reaction
= syngas (H/CO/CH4/CO2)
Examples of UCG
Hett Hill, Durham 1912 (trialled)
Yerostigaz, Russia 1961 (operating)
Pilot schemes in Australia and N America
Interest in China/India
Risks associated with CCS
CO2 and CH4 leakage
SEISMICITY
GROUND MOVEMENT AND DISPLACEMENT OF BRINE
CCS Risks - CO2 and CH4 storage
Due to well/cap rock failure
- chances unknown
CO2 leakage generally lowest for coal seams and highest for deep saline aquifers
= HEALTH HAZARD
= ECOSYSTEM IMPACT
= SOIL/GROUNDWATER QUALITY
CCS Risks - Seismicity
Frequency can be reduced by controlling injection pressure
= INFRASTRUCTURE/BUILDING DAMAGE
= CAP ROCK DAMAGE AND SUBSEQUENT CO2 LEAKAGE
CCS Risks - Ground movement and displacement of brine
= BUILDINGS AND INFRASTRUCTURE
= SEISMICITY
= WATER TABLE RISE
= INCREASE OF SALINITY IN DRINKING WATER RESOURCES
Flash steam
Brine and steam separated
- at high pressures steam produces more energy
MOST POWER PLANTS USE
> 210 degrees
~20-100MWe
Transmissivity =
Permeability x thickness
Hydraulic properties of aquifers
TRANSMISSIVITY
POROSITY
PERMEABILITY
- primary = interconnected pores
- secondary = fracturing
Porosity calculation
Vol voids/total vol
Geophysical logs/lab measurements
Permeability calculation
Estimate from porosity
OR (more reliable)
Pumping test = direct borehole measurement
Formation resource evaluation
Geological model of aquifer (reservoir)
T field maps
Hydraulic properties
