PETROLEUM GEOLOGY (BASIN STRATIGRAPHY) Flashcards
complex of igneous and met rocks in continental areas and have negative relief compared to their surroundings
Basement/Shield
Inccludes both the depression ad thick accumulation of seds
Basin
Areas with normal veneer of seds over the basement and has neutral relief
Shelf or Platform
Receive thinner than average sedment and have positive relief
Arches
Geometry of a basin
Area
Types of Basin
according to tectonic Settings in the Philippines
Geothermal Gradient
Back Arc (VSCCS)
Mod to High
Fore Arc (ICWWABE)
Low
Rift Basins (NMSR)
High Geotherm
BASINS in the PHILIPPINES
Ilocos Trough
Cagayan Valley Basin
W.Luzon Basin
C.Luzon Basin
SE Luzon Basin
Bicol Shelf
W.Masbate Iloilo Basin
Mindoro Cuyo Platform
Reed Bank Basin
NW Plwn Basi
SE Plwn Basin
E.Plwn Basin
Sulu Sea Basin
Visayan Sea Basin
Cotabato Basin
Agusan-Davao Basin
Deepest and Thickest
Agusan Davao
Largest in terms of Area
Visayan Sea Basin
Etymolyogy of Petroleum
Petro “Rock”
Oleum “Oil”
Forms of Petroleum at Normal Temp
Crude Oil (L)
Natural Gas (G)
Tar and Bitumen (S)
Color of Petroleum
Ylw, Grn, Brwn, Blk
Type of Crude Oil dependng on Sulfur Content
Sweet
Main By-product of Petroleum which often clogs wells
Sulfur
Theory which states that hydrocarbon where derived from geochem conversion of organic matter and material in time through agents of T and P
Organic Theory
A concept which encompasses all of the elements and processes of petroleum Geol
Petroleum System
Elements of Petroleum System
1) Source Rock
2) Migration
3) Reservoir Rock
4) Cap or Seal Rocks
5) Traps
6) Timing
A rock capable of generating oil and gas that is rich in Organic Matter that is matured enough to expel oil or gas
Source Rock
Material composed of organic molecule in monomeric or polymeric form derived directlly or indirectly from the organic part of organism
Organic Matter (OM)
are skeletal parts of organism included in generation of organic matter?
NO
the basic process that accomplishes mass production of organic matter on earth which converts light energy to chemical energy by the transfer of H from water to CO2 and produce Glucose and Oxygen
water+Co2+sunlight = glucose + oxgen
Photosynthesis
Primary OM producer during the Precambrian to Devonian
Marine Phytoplankton
Primary OM producer Devonian Onwards
terrestrial sources
Present OM producer
Equal
Four most important OM producer (PZHB)
Phytoplanktons (Algae)
Zooplanktons (Prostita)
Higher Plants
Bacteria
Controls of OM Production
Light
Temp
Chemical Comp. of SeaWater
Which depth or part of the water column in biological productivity concentrated?
60-80 merters
Most Biologically productive part of Aqueous Envir
Open Seas
Most Biologically productive part of Terrestrial Envi
Forests
Favorable envi for OM accumulation and preservatio
Lagoons
Estuaries
Deep Basin
A type of Organic Material in Seds that is insoluble in ordinary organic solvents
Kerogen
Type of Organic Material that is soluble in organic solvents and is the oil part of OM which is mobile
Partially converted kerogen due to high T and and time
Lower Molecular weight than Kerogen
Bitumen
What is of greatest interest for Pet Geologists?
Kerogen - because oil and gas comes from thermal maturity of Kerogen
Types of Keorgen (ALEXVITIN)
Kerogen
I
ALGINITE (Algal)
II
EXINITE (Herbaceous)
III
VITRINITE (Woody)
IV
INERTINITE (Eroded or Reworked)
Type II composed of Land Plant Cuticle
Cutinite
Type II composed of Land Plant Resin
Resinite
Type II composed of Land Plants Lipids and Marine Algae
Liptinite
First million years characterized by Microbial Activity and Compaction and is the most important stage because it is during this stage that the composition of the kerogen is determined
Diageneses
Characterized by Continuous burial and increas in temp which ceases microbial activity and in which kerogen undergo further chemical transformation and also the stage in which Oil , Gas and Methane is produced
Catagenesis
Occurs at much grater depths (15,000 feet) at which kerogen starts to crystallize and coal starts forming anthracite. Methane is mostly produced at this stage necause of cracking of hydrocarbons
Metagenesis
The extent of time-temp driven reactions that convert sed organic matter to oil, wet gas a
Thermal Maturity
Most common method to determine thermal maturity by assessing the refelctivity of coal associated with the source rock
Vitrinite Reflectance
Alteration of coal associated with source rock
Thermal Alteration Index
Major Source Rocks
Shale 65
Carbonates 21
Marl (Carbonate-rich mud) 12
Coal 2
The expulsion of generated hydrocarbons from the source rocks to the carrier beds or reservoir rock
Migration
Migration from source rock to carrier beds which is non reservoir rocks and is the longerst time
Primary Migration
Migration from carrier beds to the reservoir
Secondary Migration
Migration from one reservoir to another
Tertiary Migration
A process of enhancing Porosity and permeablity by injecting HCl thus dissolving the cement of the reservoir
Acidization
A process in which liquid sand is driven into the reservoir under HIGH Pressure
Fracturing or hydraulic fracturing
These are rocks that are sufficiently porous and permeable to store hydrocarbons expelled from the source rock
Reservoir Rocks
Common types of reservoir
Sandstones 60%
Limestone 39
Others 1
The most important reservoir rocks because majority of grains are hard, stable, insoluble without crystal characteristics in short inert
Sandstones
Provenance of Sandstones
quartz arenite
What are the depositional environments of most Sandstone Reservoirs
Deltaic Distributaries
Mouth Bars and Channel Sands
How much of the worlds’ oil reserve is hosted by Carbonate Reservoir?
40%
How much of the World’s Gas reserve is hosted by Carbonate Reservoir?
30%
Cabronate environment deposition
Shallow Warm marin TROPICAL environments
The commonest Carbonate Depositional Model in which carbonate are deposited on FLANKS of CRATONIC MASS, CONTINENTAL MARGINS or other tectonic depositional feature in VERY SHALLOW MARINE WATER and may accumulate up to sea level when Sedimentation exceeds subsidence
Carbonate Shelf model
Depositional model wherein there is NO PROMINENT BREAK in slope and facies belt tends to be broader and repreent Earliest depostional stage n the development of Carbonate Shelf model
Carbonate Ramp model
Homoclinal ramps distally steepened ramps
Carbonate Ramps
Depositional or acceretionary shelves, by mass marignes and erosional margins
Rimmed carbionate Shelves
These are non marine carbonates common in lakes and are most important source rocks
Lacustrine Carbonates
Lacustrine facies characterized by mostly VARVED lime muds and Terrestrial Clays occupying LAKE CENTERS and are rich source rocks for oild
Profundal (Gitna)
FRINGES(borders) the lake lower amounts of clays higher proportions of Skeletal Carbonates Debris
Littoral Carbonates
Formed in shallow lakes and marshes in shallow ponds developed o exposed carbonate platforms
Fresh-water marl
Terrestrial Carbonate settings composed of carbonate grains transported by ONSHORE WINDS ad is primarly coposed of ooids, pelets and froams, with Cross bedding dipping landward
Carbonate Dunes
Forms in ARID to SEMI ARID alkaline soil zone by recprecipitation of low Mg CaCO3. Evaporation is ivolved and occrus ass vertically zone profiles
Caliche
Terrestrial Carbonate which forms in Caves or Karst related and indicators of SEA LEVEL DROP
Cave Deposits/Speleothems
Lithologic unit which impedes the flow of hydrocarbons specfically a rock that has very small pore throats and poorly connected pores to allow the passage of hydrocarbon
Seal or Cap Rocks
Mjor types of seals
Shales 65%
Evaporites 33%
Carboates 2%
Most ductile to least ductile
Salt
Anhydrite
Shales-Keroge rich
Silt shales
Carbonate mudtsones
Cherts
TRAPS
please see separate tab
Why is timing important
Trap myst be formed before or during the migration of hydrocarbons
Why is fracture detrimental on a seal?
Because a single small fractures can leak off million barrels of oils in thousand of years which can drain the field
Rocks with reservoir qualities that ABUT the reservoir and will drain the reservoir of the hydrocarbon
Thief Beds
What is the effects of biodegration to oil
It will make the oil heavy
