Transcript Document

Organics to petroleum
What are the major differences in the general organic chemistry of
terrestrial vs. marine organic matter?
What are the important steps in the maturation of marine organic matter
to form petroleum? Under what conditions of burial do these step occur?
What are the major groups of organic compounds present in
petroleum? What is the relationship between molecular weight and
behavior of petroleum hydrocarbons?
What is a ‘petroleum system’?
How does the geothermal gradient influence petroleum maturation?
What are petroleum ‘traps’? How do we locate them?
What methods are used to define the extent of petroleum reservoirs?
What is overpressure?
What is a Hubbert Curve?
terrestrial
marine/lacustrine
marine/lacustrine organics:
phytoplankton,
zooplankton; “sapropel”;
fats, resinous, waxy
terrestrial organics:
vascular plants: “humic”;
cellulose, lignin,
carbohydrates
marine
organic
matter
H:C ratio
20oC
carbon
dioxide
evolved
(decarboxlyation)
kerogen
methane
evolved
km
buried
1.0
60oC
2.0
90oC
petroleum
liquids
3.0
120oC
4.0
asphalt,
bitumen
200oC
5.0
alkanes – paraffin, straight – chain hydrocarbons
aromatics – more soluble in water, smelly, toxic
cycloparaffins - napthenes
Burial depth
and local geotherm
determine
the maturation
of petroleum
hydrocarbons.
The hydrocarbon
systems in
central NY
reached temps of
140 +, so most of
the local rocks
yield natural gas.
Finding oil: the first oil wells were located in the vicinity
of natural oil seeps. Natural oil seeps were used for millennia
as sources of tar and lubricating oils.
Some types of petroleum traps.
Cuttings
Rotary drill bit
A rotary drill is attached to a
drill stem. The rotation of the bit
is driven by drilling mud pumped down the drill stem. The
returning mud lifts cuttings from the well and cools the drill bit.
Coring of the well during drilling
is expensive – note the diamonds.
Cores provide information about the
details of rock structure and
composition.
Well ‘development’ – improving
the permeability of the reservoir.
Many oil and gas
reservoirs are
1000’s of feet beneath
the surface, and in
offshore settings, under
100’s to 1000’s of
feet of water.
Finding petroleum
reservoirs requires
very precise location
and definition of
subsurface rock
masses.
Numerous,
stacked oilbearing
reservoirs.
These may be
interconnected
and thus
require
sequential
development.
Well logs are representations of the rock and fluid properties
in a well. Lateral correlations of well logs help to define
the structure and stratigraphy of source beds, reservoir beds
and cap rocks.
Maps of porosity and permeability help define future drilling sites.
Isopach maps define the thickness of reservoir beds.
Past productivity trends help define future development of a
reservoir.
Reflection seismic data is critical to subsurface exploration.
Wellhead pressure
is provided by gas
and water in the
subsurface.
Post-extraction
treatment removes
water and separates gas from oil.
Secondary treatment involves pumping of water or gas into
wells that force oil into the extraction wells.
The circled well is the Mary Sudik #1, drilled by the Indian Territory Illuminating Oil Company in Oklahoma.
On March 26, 1930, this well blew out at 6,470 feet. The force blew 20 pieces of heavy 30-foot drill pipe out of the hole!
The "Wild Mary Sudik" was finally plugged off 11 days after blowing out, through the heroic efforts of dozens of people.
Six years later, theSudik lease had produced five million barrels of oil !
Overpressure may
result in well ‘blow-outs’
‘Christmas tree’ valve
systems control
well head pressure.
The Hubbert curves
for petroleum discovery
and production.
Historical influences on crude oil prices.
marine organics:
phytoplankton,
zooplankton
terrestrial organics:
vascular plants
Coal Rank
H2 O
Peat
20oC
Lignite
50oC
Sub-bituminous
oC
80
Bituminous
Anthracite
160oC
Graphite
240oC
H:C ratio
Methane
evolved