Introduction Origin of Petroleum
to Oil & Gas 1. Rock cycle
Exploration
Cool below Earth’s surface: magma
Cool on Earth’s surface: lava
2. Sedimentary basins
• a low area in the Earth’s crust, of tectonic origin, in which sediments
accumulate
• provide both a source of sediment and a relatively low place for the
deposition of that sediment
• formed by plate tectonic activity
3. Conventional and unconventional reservoirs
Conventional Unconventional
• oil and gas is extracted by the • used due to increasing scarcity
natural pressure from the of retrieving oil and gas using
wells and pumping operation conventional methods
• use an artificial lift or water • allows to drill down, drill
and gas injections to help horizontally, and fracking
increase production occurs.
• if profit<expenses, production • allows oil and gas to be
stop flowing from tight sands that
we normally could not retrieve
with conventional methods of
drilling
,Petroleum system
1. Source rock
o Organic-rich rocks generate oil or gas when heated.
o Typical source rocks, like shales or limestones, have about 1% organic
matter and at least 0.5% total organic carbon.
o Rich source rocks can contain up to 10% organic matter.
o Marine rocks: produce oil, terrestrial rocks (like coal): produce gas.
o Under suitable conditions, source rocks can also act as reservoir
rocks, such as in shale gas reservoirs.
2. Reservoir rock
o where oil migrates and is held underground.
o Sandstones, limestones and dolostones, some from ancient coral
reefs, are also reservoir rocks.
o Reservoir rock under a magnifying lens: yellow objects are sand
grains, and purple areas are "pore spaces" where oil fits.
o In porous rocks, with many pore spaces, oil can move freely.
3. Seal rock/cap rock
o Impermeable
o Commonly shale, anhydrite or salt form barrier above reservoir rock
so the fluid cannot migrate beyond reservoir
4. Overburden rock
o section above the source rock
o thickness and age of overburden rock provides a history of the rate of
burial of a source rock toward and through the increasing
temperature domains of the basin
exploration techniques
• magnetic technique
used to estimate the thickness of the crust or to constrain
temperatures in the crust using the Curie isotherm
• gravimetric survey
uses accurate measurements of the Earth's gravitational field to
locate horizontal and vertical variations in the density of subsurface
rocks
Gravimetry applications include:
• Regional geological mapping;
• Detection of karsts and voids;
• The determination or improvement of terrestrial geoid;
• The oil and gas exploration
• Mineral exploration;
• Measurements of sediment thickness;
• The archaeological surveys.
, • Seismic method
Refraction -measures the shortest time for a seismic pulse
to travel from the source to receivers.
-helps calculate seismic velocities and layer
depths
-preferred method for accurately mapping
bedrock depth
Reflection -involves inducing a seismic wave into the earth
and recording the waves that are reflected from
sub-surface layers
-ideal for mapping geology at depths exceeding
50 m.
Multi-channel - used to evaluate the shear-wave velocities of
Analysis of subsurface materials
Surface Waves - through the analysis of the dispersion
(MASW) properties of Rayleigh surface waves ("ground
roll")
Resonance - based on the frequency analysis of seismic
records for high resolution seismic investigation
Borehole -Down-hole technique: consists of measuring the
arrival of seismic waves emitted from the surface
in increments down the borehole
- Cross-hole technique: uses a seismic source
located in an adjacent borehole
Exploration well
• a deep hole drilled to find new oil or natural gas sources
• Drilling is uncertain, and every new oil well starts as an exploration
well.
• Exploration relies on technology, like exploration geophysics, to
detect and quantify deposits.
Appraisal well
• assesses a hydrocarbon reservoir before starting commercial oil
production
• ensure discovered hydrocarbons are economically viable, providing
information on their extent, likely production rate, and fluid
properties
to Oil & Gas 1. Rock cycle
Exploration
Cool below Earth’s surface: magma
Cool on Earth’s surface: lava
2. Sedimentary basins
• a low area in the Earth’s crust, of tectonic origin, in which sediments
accumulate
• provide both a source of sediment and a relatively low place for the
deposition of that sediment
• formed by plate tectonic activity
3. Conventional and unconventional reservoirs
Conventional Unconventional
• oil and gas is extracted by the • used due to increasing scarcity
natural pressure from the of retrieving oil and gas using
wells and pumping operation conventional methods
• use an artificial lift or water • allows to drill down, drill
and gas injections to help horizontally, and fracking
increase production occurs.
• if profit<expenses, production • allows oil and gas to be
stop flowing from tight sands that
we normally could not retrieve
with conventional methods of
drilling
,Petroleum system
1. Source rock
o Organic-rich rocks generate oil or gas when heated.
o Typical source rocks, like shales or limestones, have about 1% organic
matter and at least 0.5% total organic carbon.
o Rich source rocks can contain up to 10% organic matter.
o Marine rocks: produce oil, terrestrial rocks (like coal): produce gas.
o Under suitable conditions, source rocks can also act as reservoir
rocks, such as in shale gas reservoirs.
2. Reservoir rock
o where oil migrates and is held underground.
o Sandstones, limestones and dolostones, some from ancient coral
reefs, are also reservoir rocks.
o Reservoir rock under a magnifying lens: yellow objects are sand
grains, and purple areas are "pore spaces" where oil fits.
o In porous rocks, with many pore spaces, oil can move freely.
3. Seal rock/cap rock
o Impermeable
o Commonly shale, anhydrite or salt form barrier above reservoir rock
so the fluid cannot migrate beyond reservoir
4. Overburden rock
o section above the source rock
o thickness and age of overburden rock provides a history of the rate of
burial of a source rock toward and through the increasing
temperature domains of the basin
exploration techniques
• magnetic technique
used to estimate the thickness of the crust or to constrain
temperatures in the crust using the Curie isotherm
• gravimetric survey
uses accurate measurements of the Earth's gravitational field to
locate horizontal and vertical variations in the density of subsurface
rocks
Gravimetry applications include:
• Regional geological mapping;
• Detection of karsts and voids;
• The determination or improvement of terrestrial geoid;
• The oil and gas exploration
• Mineral exploration;
• Measurements of sediment thickness;
• The archaeological surveys.
, • Seismic method
Refraction -measures the shortest time for a seismic pulse
to travel from the source to receivers.
-helps calculate seismic velocities and layer
depths
-preferred method for accurately mapping
bedrock depth
Reflection -involves inducing a seismic wave into the earth
and recording the waves that are reflected from
sub-surface layers
-ideal for mapping geology at depths exceeding
50 m.
Multi-channel - used to evaluate the shear-wave velocities of
Analysis of subsurface materials
Surface Waves - through the analysis of the dispersion
(MASW) properties of Rayleigh surface waves ("ground
roll")
Resonance - based on the frequency analysis of seismic
records for high resolution seismic investigation
Borehole -Down-hole technique: consists of measuring the
arrival of seismic waves emitted from the surface
in increments down the borehole
- Cross-hole technique: uses a seismic source
located in an adjacent borehole
Exploration well
• a deep hole drilled to find new oil or natural gas sources
• Drilling is uncertain, and every new oil well starts as an exploration
well.
• Exploration relies on technology, like exploration geophysics, to
detect and quantify deposits.
Appraisal well
• assesses a hydrocarbon reservoir before starting commercial oil
production
• ensure discovered hydrocarbons are economically viable, providing
information on their extent, likely production rate, and fluid
properties
