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83 Cards in this Set
- Front
- Back
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What is Petroleum Geology?
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It is the application of geology to petroleum Exploration and Production
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What are Hydrocarbons?
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Complex molecules of hydrogen and carbon
Organic matter is chemically transformed into HC's |
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What is Petroleum?
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Naturally Occurring HCs in the subsurface
-oil -gas -Heavy tar- asphalt - bitumen -unrefined = crude |
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4 Ways a geoscientist things
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a) Temporal thinkings
b) earth as a complex syste c) learning in the field d) spatial thinking |
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Current Energy obtained by Hydrocarbons in the US
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85%
40% oil 22% natgas 23% coal |
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Order of sedimentary rocks by % quantity
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Siltstone/shale ~75%
Limestone/dolostone~14% sandstone/Conglomerate~11% |
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Petroleum Reserves by rock type
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Carbonate >60%
Siliciclastic <30% Volcanic ~10% |
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Recovery Factors for Reservoirs
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Carbonate - <4% to 25%
Sandstones ~ 30 to 35% Unconventional <4% to 8% |
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5 Layers of the Earth
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1.Solid Inner Core
2.Liquid External Core 3.Lower Mantel 4.Upper Mantel 5.Lithosphere |
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Types of plate Margins
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1. Divergent
2. Convergent 3. Transform |
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Wilson Cycle
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1. Continental Rifting
2. Rift Basin creation 3. Seafloor spreading - old basin 4. Ocean closing/ Subduction 5. Arc-Continent collisions (foreland basin creation) 6. Continent-Continent Collisions |
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Continental Rifting and hydrocarbon creation
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Sediment deposited in Grabens could create a source of hydrocarbons.
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2 types of Melting Processes
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1. Decompression
2. Hydration |
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What is Decompression Melting
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Hot rock moving into an area of lower pressure without losing heat
occurs in upper mantle below spreading centers and in hotspots |
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What is Hydration Melting
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Water added to subducting slab lowers melting point of mantel material
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Oceanic Crust is made of
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silicates with FE, MG, CA
Majority basalt and Olivine |
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Continental Crust is made of
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silicates with K, AL, CA, NA
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Name the 4 Mineral Groups
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1. Silicates
2. Carbonates 3, Sulfates 4 Halides |
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Example of Silicate Mineral
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Quarts, Olivine, Feldspar, Mica, Clay minerals
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Examples of Carbonates
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Calcite, Dolomite
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Example of a Sulfate
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Gypsum
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Example of Halide
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Salt
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Clastic Sedimentary rocks
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transported and deposited as mineral grains and rock fragments
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Chemical Sedimentary Rocks
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Biochemical - Precipitated organicallu from solution
Evaporites - Precipitated inorganicaly from solution |
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Sedimentary Process
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Weathering
Transportation Deposition Compaction / Diagenesis |
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Energy Environments for clastic deposition - What are the grain sizes?
1. High energy 2. Med energy 3. Low Energy |
1. large/coarse
2. medium 3. fine/clay sized |
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Energy environments for Carbonate deposition - what is the possible location?
1.High wave 2. Medium Wave 3. Low energy |
1. Platform edge
2 Protected area behind reefs 3. Lagoon, Platform slop |
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What causes ductile Deformation?
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High Temperatures and Pressures
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Location where brittle structures give way to ductile deformation in the crust
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15-20km deep
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Name the 3 Types of Deformation
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1. Folds
2. Faults 3. Fractures |
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Name 3 types of folds
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Anticline - Apex up
Syncline - Apex down Monocline - unidirectional |
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What is the hanging wall
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the hanging wal is the side above the dipping fault plane
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What is the footwall
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the side below the dipping fault plane
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What is the bearing of a fault
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The compass direction of the fault plane (strike)
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Name the types of faults
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1. normal fault
2. reverse fault 3. trust fault 4. listric fault 5. strike slip fault |
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What is a normal fault?
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Hanging wall moves down relative to the footwall - caused from tension
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What is a reverse fault?
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Hanging wall moves up relative to the footwall - caused by compressional stress
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What is a trust fault?
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A reverse fault at a low angle
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What is a Listric fault
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Curved faults that become closer to horizontal with depth
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What is a Strike-Slip Fault?
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Horizontal movement along the strike of a fault - transform fault boundary
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What is a structural cross section?
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Uses present sea level as datum and reveal the true vertical depth of formations.
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What is a stratigraphic cross section?
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Uses subsurface marker beds as datum, shows beds as they were deposited.
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What is a Contour Map?
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an accurate 2D drawing of a 3D land surface (topography) or Subsurface (depth) features
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What is a structural contour Map
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Defines the shape of the subsurface and defines anatomy of a trap.
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What are Isopach maps
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Records the thickness of particular formations and illustrated the shape of the bed at time of deposition of mapped interval.
Data shows True Stratigraphic Thickness |
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What are Isochore Maps
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Similar to Isopach maps but they show True Vertical Thickness instead of True stratigraphic thickness
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What is a Reservoir Quality map?
Also known as Net Sand map. |
Contors sand:shale ratio of a formation
Indicates the source of the sane and areas where good reservoirs may be found. |
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What is a net pay map?
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Contours Ratio of Gross pay to Net Pay
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What is Gross Pay
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Total vertical interval from the top of the reservoir to the GOC, OWC, or GWC
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What is net Pay?
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The cumulative vertical thickness from which petroleum may actually be produced.
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What are the stipulations on Net pay?
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Lower limit of Porosity
Lower Limit of Permeability Upper Limit of Water Saturation |
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What are the 3 Drilling systems?
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Hoisting System
Rotary System Fluid circulating system |
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What does mud Logging record?
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Cutting depths, oil, gas, and other lithological and engineering data made onsite while drilling.
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What are the 4 important Zones in the borehole environment?
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1.mudcake
2. Flushed zone (invaded zone) 3. Transitional zone 4. Uninvaded zone |
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What does Spontaneous potential Distinguish?
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Lithology
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If the mud salinity > formation salinity what does the SP log read?
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Reversed SP response
Sand will be high Shale will be low |
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If the mud salinity < formation salinity what does the SP log read?
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Normal SP response
Sand will be Low Shale will be high |
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If the mud salinity = formation salinity what does the SP log read?
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SP response is suppressed
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Resistivity Logs help distinguish?
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Lithology
Hydrocarbons Fluid Saturations |
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Resistivity of Common materials.
Minerals - Petroleum- Distilled water - Salt water- |
Minerals - 10^7
Petroleum- 10^14 Distilled water -10^3 Salt water- <10 |
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Gravity Measurements respond to?
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Density of Rock
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Magnetic Measurements respond to?
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Iron content of the rock.
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Gamma Ray logs measure?
And what do readings mean? |
Potassium, Thorium, and Uranium elements which are present in the formations.
Low Reading - carbonate High Reading - usually shale |
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2 Density Devices
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Compton Scattering
Photoelectic effect |
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Neutron Devices readings
high or low mean? |
The more hydrogen in the formation the fewer the counts at the detectors. The fewer the counts the higher the porosity or higher the HC content.
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Neutron / Density log Crossover shows?
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Cross overs tend to show Gas in reservoir rocks.
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Sonic logs measure?
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The compressibility and flexibility of the formation.
The more compressible the formation, the slower the sound wave travels, and so the possibility of more porous or more gas or more fractures. |
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What is Free Water?
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Free water is free to move in and out of pore spaces
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What is Interstitial water?
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Water that is bonded to mineral grains, it cannot be removed during production or oil and gas from reservoirs,
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Meteoric water
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ground and near surface waters
Including seawater |
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Connate water
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Sealed water in basins, this water cannot leave the basin and has a high PH
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The closer you are to hydrocarbon reservoirs....
What happens to the salinity of connate water? |
The higher the salinity of connate water
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What is petroleum?
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a thick flammable, yellow to black mixture of gaseous liquid, and solid hydrocarbons that occur in the earths surface.
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Sweet and sour gas is bassed on the presence and absence of what?
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H2S
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What is the Oil Window
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From 60 to 175 C
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What is the Gas Window
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From 100 to 315 C
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What is the Wet gas window
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100 to 175C
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What is the Dry gas window?
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225 to 315c
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What are the 4 levels of a petroleum system?
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1. Sedimentary Basin
2. Petroleum System 3. Play 4. Prospect |
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What is a petroleum System?
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a natural system that encompasses a pod of activ sourse rock and all related oil and gas and which includes all the geologic elements and processes that are essential if a hydrocarbon accumulation is to exist.
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Keys to a petroleum system
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Must contain a petroleum source rock, a reservoir rock, a seal, and plenty of over burden. Along with a trap, hydrocarbon generation, migration, and accumulation as well as timing.
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What is the critical moment in a burial history?
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The point in time that best shows the generation- migration - accumulation, age and essential elements at a specified location.
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Definition of a Play-
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a play is a group of reservoirs genetically related by depositional origin, structural style or trap type, and nature of source rocks or seals.
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