Petroleum Geology

Petroleum Geology

the study and application of geology to the exploration and production of petroleum products

petroleum

a thick, flammable accumulation pf hydrocarbons that appears yellow to black and occurs naturally beneath the Earth's surface

Sulfur

an undesired by-product in petroleum that generates sulfur oxides when burned

crude oil

the liquid form of petroleum

sweet crude oil

crude oil that contains little amounts of sulfur

sour crude oil

crude oil that contains high amounts of crude oil

tar and bitumen

the solid form of petroleum

natural gas

the gaseous form of petroleum

carbon cycle

a cycle that describes the interaction and movement of carbon atoms and molecules through the Earth's spheres of physical environments

organic theory

a theory regarding the origin of petroleum that declares hydrocarbons to be derived from organic matter, and material being geochemically converted to petroleum

plankton

main source of petroleum

black shale

a sedimentary rock that contains >5% organic matter

Lipid

biomolecule combination of fatty acids with glycerol that are mostly fats, oil, and waxes , and have the greatest potential to be the HC sources

protein

giant biomolecule that make up the solid of animal tissues and plant cells, and are rich in carbon, but contain substantial amounts of N, S, O

carbohydrates

common biomolecules in plant tissues that are based on sugars and their polymers, cellulose, starch, and chitin

Lignin

Polymer biomolecule consisting of numerous aromatic rings and is a major component in land plants that can be converted to coal through deoxygenation

Source rock

a fine-grained rock containing organic material that generated high amounts of hydrocarbons

Total Organic Content

The measure of the potential of a source rock to generate hydrocarbons and represent the amount of carbon, oxygen, and hydrogen within the source rock

Bitumen

The fraction of TOC with high molecular weight and soluble in organic solvents

Kerogen

The insoluble, non-extractable residue fraction of the TOC that forms in the transformation from OM into a complex mixture with a general composition of large HC molecules that breakdown with continuous exposure to high temperature

Paleothermometer

indicates that measure the maximum temperature the source rock had been subjected to

production index

a parameter that measures the ability of a reservoir to deliver fluids to the wellbore

hydrogen index

a parameter that characterizes the origin of organic matters

Maturation

The process of a source rock becoming capable of generating petroleum by being exposed to temperature pressures in time

Diagenesis

the maturation phase that occurs in low T and P near shallow subsurface reduces the oxygen in the organic matter, leaving the HC ratio unchanged

Catagenesis

occurs in deeper subsurface levels as burial continues and T and P increases; HC ratio declining as the petroleum is released from kerogen first than oil and then the gas

Metagenesis

The stage closest to metamorphism, having higher T and P, completely expelled the remaining HC, methane, with carbon being left as the H:C ratio declines

oxygen index

a parameter that correlates with the ratio of O to C

Biomarkers

organic compounds that act as chemical tracer of certain ancient organisms

Time-Temperature Index

An index integrating the increase of temperature in a period of time as a rock is buried

Vitrinite reflectance (Ro)

a maturation indicator that measures the reflectance of vitrinite in oil

Level of organic maturation

a maturation indicator based on coal ranks and adjusted to give linear scale

Type I: Liptinite

primarily algae from freshwater, brackish, hypersaline, lagoonal, or lacustrine environments; oil-prone

Type II: Exinite

originated from either phytoplanktons and bacterial microorganisms in marine sediments, soft parts of terrestrial plants; oil and gas prone

Type III: Vitrinite

hard or structural parts of terrestrial plants or higher plant debris; dominant type for SE Asia (tertiary in age); mainly derived from terrestrial plants rich in resins and waxes, and may have deposited in coal swamps and paralic settings; gas-prone

Type IV: Inertinite

oxidized residue, reworked material; or fossil charcoal

I-S

algae from sulfate-rich, anoxic lakes

II-S

kerogen rich in sulfur that deposited in anoxic marine environments with normal to elevated salinity

Crude Oil

Petroleum in liquid form that is composed of hydrocarbons that originated as liquid and remained as a liquid once extracted and is mostly lighter than water

Paraffin

saturated hydrocarbons with a general chemical formula of CnH2n+2, which includes methane, ethane, propane, and butane

Naphthene

hydrocarbons that remains liquid at normal temperatures and pressures, expressed with a general formula of CnH2n, which includes cyclopentane and cyclohexane

aromatic

unsaturated hydrocarbons commonly found in petroleum that is liquid at normal temperatures and pressures, generally expressed with a formula of CnHn, and includes benzene, toluene, and xylene

asphalthene

under heterocompounds; heavy compounds of crude oil, and the major components in many natural tars and asphalts

natural gas

lighter, gaseous fraction of hydrocarbons that is found free or dissolved in crude oil in natural underground reservoir

dissolved gas

natural gas dissolved in crude oil at the subsurface but may be physically removed during refining

associated gas

or gas cap; the free gas residing on top of crude oil in the reservoir

Hydrogen sulfide

an undesirable free gas in the subruface that can damage well equipment and reduces the alue of hydrocarbon deposits

Non-associated gas

trapped free gas found without any significant amounts of crude oil

natural gas liquids

liquefied gas that include wet gases, natural gasoline, and condensate

dry gas

natural gas that contains less than 0.1 gal/1000 ft^3 of condensate that is largely methane

wet gas

natural gas that contains more than 0.3 gal/1000 ft^3 of condensate that is largely methane

methane

the largest component of natural gas that is known as the marsh gas at the surface

mantle methane

derived from the primordial methane in tha mantle

microbial methane

a by-product of the bacterial decay of organic matter

thermogenic methane

product of the thermal breakdown of heavier hydrocarbons

gas hydrates

ice crystals with structured atomic latices that contain molecules of methane and other gases

condensates

petroleum that are found to be gaseous in the subsurface but condenses to liquid as it cools when it nears the surface

asphalt, tar, pitch

the heavy, solid, or semisolid forms of hydrocarbon

Pour point

the lowest temperature at which the crude oil will be able to flow under specific controlling conditions

migration

the process of the movement of petroleum from its source rock to its reservoir, until its expulsion unto the Earth's surface, and is not exactly defined how the process occurs

primary migration

expulsion of petroleum from the source rocks into the permeable carrier beds

secondary migration

migration from carrier beds into the reservoir and traps

Tertiary migration

migration through leakage and extraction of petroleum unto the Earth's surface

micelle

colloidal organic surfactants whose molecules possess hydrophobic and hydrophilic ends

surfactants

compounds that lower the surface or interfacial tension between two liquids or between a liquid and a solid

reservoir

a rock mass with enough porosity and permeability that has accumulated an economically viable amount of petroleum

effective porosity

the ratio of interconnected pore volume to the total volume

Catenary pore

completely permable pore that permits flushing of natural or artificial fluids

Cul-de-sac pore

pores unaffected by flushing but is permable enough to yield petroleum

closed pore

impermeable pores that are unable to yield petroleum

gross pay

the total vertical interval from the top of the reservoir down to the petroleum-water boundary

net pay

the portion of the reservoir that can produce economically viable amounts of petroleum with a specific production method

Non-pay

The portion of the reservoir that cannot produce economic amounts of petroleum

traps

a geometric arrangement of strata that permits the accumulation of petroleum but prevents any further migration

seal

also cap rock; a fine-grained or crystalline, impermeable rock that is relatively ductile, laterally continuous and acts as a barrier, preventing further migration of petroleum to the surface

sealing capacity

a measure of the weakest part of the seal that can be greatly weakened by faults and fractures

sealing fault

impermeable faults that serve as seals for petroleum

Catchment area

The total area in prospect where petroleum will migrate to

Pre-concession round

Concession work

Exploration

Appraisal and development planning

Project Execution

Production and maintenance execution

Abandonment

stages of petroleum production

RA. No 7638

Department of Energy Act of 1992

Philippine National Oil Company; PD No. 334

a government-owned company created on November 9, 1973 which provides and maintains adequate and stable supply of oil

Forearc basin

limited petroleum potential; low geothermal gradient; scarcity of good clastic behavior

Ilocos Basin

Central Luzon Basin

Cagayan Valley Basin

Bicol Shelf

West Masbate-Iloilo Basin

West Luzon Basin

East Palawan Basin

Examples of forearc basin in the Philippines

Backarc basin

moderate to high geothermal gradient; typically has volcano-clastic reservoirs

Visayas Sea Basin

Southeast Luzon Basin

Cotabato Basin

Sulu Sea Basin

Examples of back-arc basin in the Ph

Rift Basin

insufficient trap size; high geothermal gradient; inadequate development of source rock

Mindoro-Cuyo Basin

Northwest Palawan Basin

Southwest Palawan Basin

Reed Bank Basin

Examples of Rift Basin in PH

Play

A geographically and stratigraphically delimited area where common geological factors exist in order that petroleum accumulation can occur

Lead

Potentially containing an economic amount of petroleum but lacks sufficient data to prove it

Play fairway

area within the basin where the specific geological attributes necessary for the existence of petroleum accumulation exist

Rotary drilling

a form of drilling used for onshore or offshore drilling that utilizes a rotating bit at the end of a hollow steel tube with teeth that gouge or chip the rock at the bottom of the borehole

Kelly

a square section steel where a drill pipe is attached to

Formation evaluation

a method of determining a borehole's ability to produce petroleum

Coring

The acquisition of cylindrical drill cores to determine lithologies and structures in the subsurface

stank tank in oil originally in place (STOOIP)

The total amount of oil present before production

rock. vol x net to gross factor x oil/gas saturation/ (oil formation volume factor)

formula of STOOIP

1896

The year of first exploratory drilling in Toledo-1 in Cebu

1985

Enactment of the PD 87 Oil Exploration and Developnment act of 1972

Coal (C135H96O9NS)

the sedimentary rock dominantly composed of altered remains of vegetation

Vitrain

Bright, shiny, black coal that is mostly composed of wood tissue and can break into cubic pieces