Post on 12-Jan-2016
Stratigraphy and hydrocarbonsStratigraphy and hydrocarbons
ERTH 1010 & 1100
DepositionDeposition
This simple example shows how the deposited strata is both spatial and temporal changing.
With increasing time, deposits record these changes.
General rulesGeneral rules
• Sediments are largely associated with water• Supermarine - streams, rivers, lakes• Marine - Shore, shelf, basin• High energy - steep drainages and wave
action - sands or coarser• Low energy - ponded water: lakes, lagoons,
basins, shallow drainages - silts and clays• Relatively free from terrigenous (continental)
clastic particles - good for life - carbonates
Energy changesEnergy changes
Faster flow
Slower flow
Deposition changes with location in a stream
As a stream makes a bend, water flow increases on the outside of the curve - erodes.
Inside the curve, deposition.
Oxbow lakesOxbow lakes
Meandering rivers may change channels (during flooding). This may strand former channels.
Catskill deltaCatskill delta
General relationshipsGeneral relationships
In the shoreline environment
The source of clastic particles is dominated by the land (delivered by streamflow)
Wave-sediment energies are typically greatest nearshore
Organisms prefer less silty waters - are abundant in shelf waters.
Forces along shoreForces along shore
Sedimentary environments are complex. Water energy is in the driver’s seat, but fluid dynamics is difficult to constrain.
Courtenay, Vancouver Is., B.C.
Barrier IslandsBarrier Islands
Mustang Is., TXMustang Is., TX
Adjacent to Corpus Christi, Mustang Island is a condo-haven, sport fishing port, and petroleum service port.
Hurricane free for 25 years!
Barrier islandsBarrier islands
Barrier islands are nothing more than loose sand - transient on short time scales.
Deposits in sectionDeposits in section
Shallow seafloorShallow seafloor
Shallow water can be a boon to life - carbonate formation
Corals are example of autotrophic -hetrotrophic symbiosis.
Sunlight helps feed the organism.
Thatcher Park, NYThatcher Park, NY
South of Albany - one of the world’s best examples of the shallow sea environment.
Helderberg group (largely carbonates).
Deltas and timeDeltas and time
Deltas form from low energy distribution of stream-borne sediments. With continued deposition, deltas extend outward into the basin.
Hydrocarbon formationHydrocarbon formation
• Biogenic deposition• Soft parts versus hard parts• Soft parts made of carbohydrates, fats,
proteins (C-O-H with P and N)• Preservation requires low oxygen (reducing
environments) remove O to get C-H
• The environments that produce materials that will become hydrocarbons are those that offend the average nose!
Small amounts
Largely in clastic sediments and rocks
Largely organic
Yet greatly important in everyday life – oil is one of the biggest drivers of first world
economies.
Even if you don’t own a car – all of the clothes you wear and the food you eat was transported to you.
Small amounts
Largely in clastic sediments and rocks
Largely organic
Yet greatly important in everyday life – oil is one of the biggest drivers of first world
economies.
Even if you don’t own a car – all of the clothes you wear and the food you eat was transported to you.
CH (Hydrocarbon)CH (Hydrocarbon)
Largely organic material - piles of dead plants and animals.
Compressed and heated over time.
Reducing (no extra O) conditions (chemical or biochemical).
Largely organic material - piles of dead plants and animals.
Compressed and heated over time.
Reducing (no extra O) conditions (chemical or biochemical).
Q: what type of rocks are being formed in the above diagram?
The start…The start…
Oil’s originsOil’s origins
Oil and originsOil and origins
Hydrocarbon takes time to “cook”
But more importantly, it needs a way to accumulate - move from the source region into an area from which it can be economically extracted.
Hydrocarbon takes time to “cook”
But more importantly, it needs a way to accumulate - move from the source region into an area from which it can be economically extracted.
Organic material that may produce petroleum is called Kerogen.
For a given temperature, kerogens made of buried algae yield more petroleum than leafy, woody, or peat materials
Organic material that may produce petroleum is called Kerogen.
For a given temperature, kerogens made of buried algae yield more petroleum than leafy, woody, or peat materials
Q: which organic material yields the most petroleum?
Kerogen MaterialKerogen Material
CrackingCracking
The process of making hydrocarbon involves several steps – obviously not all organic matter becomes oil and gas.
Specific conditions with respect to heating and low oxygen levels are required.
The process of making hydrocarbon involves several steps – obviously not all organic matter becomes oil and gas.
Specific conditions with respect to heating and low oxygen levels are required.
What is being made?
C-H from C-H-O molecules.
Methane (CH4) to asphaltenes
Cn, n is 1 to 60, increasing n changes state.
In CH4, n is 1.
What is being made?
C-H from C-H-O molecules.
Methane (CH4) to asphaltenes
Cn, n is 1 to 60, increasing n changes state.
In CH4, n is 1.e.g. Straight-chain parafins
n = 1-4 gas
n = 5-16 liquid
n > 16 solid
e.g. Straight-chain parafins
n = 1-4 gas
n = 5-16 liquid
n > 16 solid
Hydrocarbon general usage names
Oil: predominantly liquid hydrocarbon
Natural gas: predominantly gas hydrocarbon
Coal: Hydrocarbon with substantial amounts of other material (e.g. oxygen-organics)
Hydrocarbon general usage names
Oil: predominantly liquid hydrocarbon
Natural gas: predominantly gas hydrocarbon
Coal: Hydrocarbon with substantial amounts of other material (e.g. oxygen-organics)
Paraffins (Arkanes) CnH2n+2
Cycloparaffins (Cycloalkanes) CnH2n
Aromatics (Arenes) CnH2n-6
Olefin (Alkenes) CnH2n-2
Asphalitics (N, S, and O)
Paraffins (Arkanes) CnH2n+2
Cycloparaffins (Cycloalkanes) CnH2n
Aromatics (Arenes) CnH2n-6
Olefin (Alkenes) CnH2n-2
Asphalitics (N, S, and O)
Q: which hydrocarbons burn more efficiently?
Petroleum nomenclaturePetroleum nomenclature
Oil is not very soluble in water (vice-versa) because of their different molecular structure.
Oil is not very soluble in water (vice-versa) because of their different molecular structure.
Water and oil are largely separate in nature – oil floats on water.
Water and oil are largely separate in nature – oil floats on water.
Q: why does oil float on water?
Seismic surveyingSeismic surveying
Reflection SeismologyReflection Seismology
Generating your own mini-earthquakes
Collect the reflected signal with a series of small seismometers (geophones).
Do the math to stack the data
Do the math to spatially distribute the raypaths as a time function
Do the math to convert travel time into depth
Make a geologically reasonable interpretation of significant reflectors
Seismic SurveyingSeismic Surveying
Offshore exploration requires most work be done at the surface (on floating vehicles)
The seismic waves travel through the water.
Seismic imagingSeismic imaging
North SeaNorth Sea
Production drilling requires ability to crush and remove rock using a drill. The bit is supported by large segments of pipe, extended sequentially with increasing depth. A highly specialized fluid (mud) is used to float out rock fragments and lubricate stem and bit.
Production drilling requires ability to crush and remove rock using a drill. The bit is supported by large segments of pipe, extended sequentially with increasing depth. A highly specialized fluid (mud) is used to float out rock fragments and lubricate stem and bit.
DrillingDrilling
Drilling offshoreDrilling offshore
When oil is finally encountered it may be under some pressure - however, this pressure is released over time. Eventually, the oil must be pumped out of the rock pores.
When oil is finally encountered it may be under some pressure - however, this pressure is released over time. Eventually, the oil must be pumped out of the rock pores.
Additional treatments, such as “hydrofracking” and gas injection may help to maintain production levels.
Additional treatments, such as “hydrofracking” and gas injection may help to maintain production levels.
From Hunt, 1979
Crude oil is a mixture of hydro carbons – some oxidize easier than others.
Distillation separates hydrocarbons into groups – from light hydrocarbons in gasoline to heavy in motor oil
Crude oil is a mixture of hydro carbons – some oxidize easier than others.
Distillation separates hydrocarbons into groups – from light hydrocarbons in gasoline to heavy in motor oil
RefiningRefining
HydrocarbonsHydrocarbons
We’ve previously seen viscosity increase in earth materials as a function of polymerization.
Note a similar effect in these refined materials based on crude oil.
Recall that some petroleum generation uses gas to “chase out” sluggish oil. That gas is CO2, typically removed from natural gas.
Recall that some petroleum generation uses gas to “chase out” sluggish oil. That gas is CO2, typically removed from natural gas.
We might be able to pump the CO2 released at power plants into these former oil reservoirs for long term storage.
We might be able to pump the CO2 released at power plants into these former oil reservoirs for long term storage.
BPBP
SequestrationSequestration
EnergyEnergy
SourcesSources
Oil is not everywhereOil is not everywhere
There is more gasThere is more gas
Natural gas is somewhat easier to find, particualrly in North America
However, gas is difficult to transport.
Gas wells generally have to be connected to a pipeline.
Compressing gas into a liquid is expensive and energy intensive
ANWRANWR
WhereWhere
How muchHow much
HydrocarbonsHydrocarbons
Coal and contentCoal and content
MiningMining
MiningMining
FossilsFossils
Coal in North AmericaCoal in North America