4.Source & Migrasi

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CAP, Source rock MIGRATION

Demi matahari dan cahayanya di pagi hari

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a hydrocarbon is an organic compound 

consisting entirely of hydrogen and

carbon. Methane [1C] and ethane [2C]

are gaseous at ambient temperaturesand cannot be readily liquified by

pressure alone. Propane [3C] is

however easily liquified, and exists in

'propane bottles' mostly as a liquid.

Butane [4C] is so easily liquified that it

provides a safe, volatile fuel for small

pocket lighters. Pentane [5C] is a clear

liquid at room temperature,

commonly used in chemistry and

industry as a powerful nearly odorless

solvent of waxes and high molecular

weight organic compounds, including

greases. Hexane [6C] is also a widely

used non-polar, non-aromatic solvent,

as well as a significant fraction of

common gasoline 

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Facts to Consider

Basin

Location, Size, Maximum Depth, Age ( From Basement to Outcrop

+ max subsidence), Stratigraphy

Other item; eg Structure (extentional, compressional)

Petroleum System

Source rocks: Name(s), Kerogen type(s), TOC, depth to top oil

window, kitchen location

Migration Pathway: Carrier bed(s), faults, distance (vertical and

horizontal)Traps: Structural, stratigraphics, Combination (dominant type)

Reservoirs: Names, Rock types (both reservoir and seal)

Representative Fields (The biggest ones) OOIP,OGIP, RF, Cum Prod

Other (History, technology, etc)

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Petroleum System Elements

(Impermeable)

(Porous/Permeable)PotentialMigration Route

24803

Source RockSource Rock

Top Seal RockTop Seal Rock

Reservoir RockReservoir Rock

Anticlinal TrapAnticlinal Trap

(Organic Rich(Organic RichMigration

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Petroleum System Elements

• Source Rock - A rock with abundant hydrocarbon-prone organic matter

• Reservoir Rock - A rock in which oil and gas Acumulates:

- Porosity - space between rock grains in which oilaccumulates

- Permeability - passage-ways between poresthrough which oil and gas moves

• Seal Rock - A rock through which oil and gas cannot move effectively (such asmudstone and claystone)

• Migration Route - Avenues in rock through which oil and gas moves fromsource rock to trap

• Trap - The structural and stratigraphic configuration that focuses oil andgas into an accumulation

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Shale is a fine-grained, clastic sedimentaryrock composed of mud, which is a mix of

flakes of clay minerals and tiny fragments

(silt-sized particles) of other minerals,

especially quartz and calcite. The ratio of

clay to other minerals is variable.[1] Shale is

characterized by breaks along thin laminaeor parallel layering or bedding less than

one centimeter in thickness, called

fissility.[1] Mudstones, on the other hand,

are similar in composition but do not show

the fissility.

Cap & Source Rock

caprock   is generally referred to as any

nonpermeable formation that may trap oil,

gas or water, preventing it from migrating to

the surface

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SOURCE MATERIAL

Non Biogenic Origins

Biogenic (Kerogen)  – Host Rock ( Shales and Coals)

Kerogen Types

Types I  – Algal (oil prone) sapropelic

Types II  – Mixed

Types III  – Woody ( gas prone) humic

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SOURCE MATERIAL

Non Biogenic Origins

Biogenic (Kerogen)

Types I  – Algal (oil prone) sapropelic

Types II  – Mixed

Types III –

 Woody ( gas prone) humic

Host Rock ( Shales and Coals) 

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A rock rich in organic matter which,

if heated sufficiently, will generate

oil or gas. Typical source rocks,

usually shales or limestones,

contain about 1% organic matter

and at least 0.5% total organiccarbon (TOC), although a rich

source rock might have as much as

10% organic matter. Rocks of

marine origin tend to be oil-prone,

whereas terrestrial source rocks

(such as coal) tend to be gas-prone 

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Types of Petroleum

Oil and Gas are formed by the thermal cracking of

Organic compounds buried in fine grain rocks

Algae =

Wood =

Hydrogen Rich = Oil prone 

Hydrogen Poor = Gas prone 

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KEROGEN TYPES

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Source Rocks

Hydrocarbon originates from

minute organisms in seas and lakes.

When they die, they sink to the

bottom where they form organic-

rich "muds" in fine sediments.

These "muds" are in a reducing

environment or "kitchen", whichstrips oxygen from the sediments

leaving hydrogen and carbon.

The sediments are compacted to

form organic-rich rocks with very

low permeability.The hydrocarbon can migrate very

slowly to nearby porous rocks,

displacing the original formation

water.

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SOURCE MATERIAL

Non Biogenic Origins

Biogenic (Kerogen)

Types I  – Algal (oil prone) sapropelic

Types II  – Mixed

Types III –

 Woody ( gas prone) humic

Host Rock ( Shales and Coals)

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The Origin of Petroleum

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Oil shale, an organic-rich fine-

grained sedimentary rock, contains

significant amounts of kerogen (a

solid mixture of organic chemical

compounds) from whichtechnology can be used to extract

liquid hydrocarbons. The name oil

shale is a misnomer as geologists

would not necessarily classify the

rock as a shale, and its kerogendiffers from crude oil 

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Source Rock of Petroleum

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A type of woody kerogen that is

relatively uniform in composition.Since vitrinite changes predictably

and consistently upon heating, its

reflectance is a useful

measurement of source rock 

maturity. Strictly speaking, the

plant material that forms vitrinite

did not occur prior to Ordovician

time. Also, because vitrinite

originated in wood, its occurrence

in marine rocks might be limited

by the depositional processes that

act in a given depositional

environment.

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A measurement of the

maturity of organic matter

with respect to whether it hasgenerated hydrocarbons or

could be an effective source

rock. The reflectivity of at least

30 individual grains of vitrinite

from a rock sample is

measured under a microscope.

The measurement is given in

units of reflectance, % Ro, with

typical values ranging from 0%

Ro to 3% Ro. Generally, the

onset of oil generation iscorrelated with a reflectance of

0.5-0.6% and the termination

of oil generation with

reflectance of 0.85-1.1%.

Vitrinite reflectance

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Source Rock Kerogen Can Be Correlated to

oil/gas found in carrier beds and reservoir

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An area of the subsurface

where source rock has reached

appropriate conditions of

pressure and temperature to

generate hydrocarbons; also

known as source kitchen, oil

kitchen or gas kitchen.

Bitumen includes

hydrocarbons such as asphaltand mineral wax. Typically

solid or nearly so, brown or

black, bitumen has a

distinctive petroliferous odor.

Laboratory dissolution withorganic solvents allows

determination of the amount

of bitumen in samples, an

assessment of source rock

richness.

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The Petroleum Kitchen

Temperature-Pressure-Time

Geothermal Garadient : (Thermogenic Hydrocarbons)

Range : <1 to 11 degrees F per 100’ 

Typical Sedimentary Basins : 1.0 – 1.7 degrees F per 100’ 

Good Average : 1.2

Oil Window of ~ 120 – 300F (50-150 C) or about 5000-20000’ 

In Practice, oil below 15000’ rare 

Gas~ no practical limit to stable depth

Cracking of oil to gas controlled by source kerogen and temperatureDeep basin mostly gas

Practical limits related to maturity of source-not reservoir

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The naturally occurring, solid,

insoluble organic matter that occurs in

source rocks and can yield oil uponheating. Typical organic constituents of

kerogen are algae and woody plant

material. Kerogens have a high

molecular weight relative to bitumen,

or soluble organic matter. Bitumen

forms from kerogen during petroleum

generation. Kerogens are described as

Type I, consisting of mainly algal and

amorphous (but presumably algal)

kerogen and highly likely to generate

oil; Type II, mixed tterrestrial and

marine source material that can

generate waxy oil; and Type III, woody

terrestrial source material that

typically generates gas.

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Proses diagenesis material

organik yang diakibatkan oleh

proses biologis lebih dominan

terjadi dalam sedimen yang baruterendapkan (recently deposited )

dan biasa terjadi pada kedalaman

hingga 2 km serta temperatur

maksimal 75oC.

Pada proses diagenesis, yang terjadi

adalah proses kondesasi

pembentukan makromolekul yang

kompleks (kerogen) dari bahan

pembentuknya yang lebih

sederhana. Sebaliknya pada proses

katagenesis ini makromolekul yang

kompleks terurai menjadi molekul

yang lebih sederhana yang lebih

kaya akan hidrogen.

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Fasa yang kaya akan hidrogen ini

bersifat mobile dan dapat bermigrasi

keluar dari batuan sumber.

Katagenesis terjadi pada rentang

kedalaman 3-4 km dengan kisaran

temperatur sekitar 50-150oC dan

tekanan sebesar 300 sampai 1500 bar

Pada akhir proses katagenesis (transisi

ke metagenesis), yaitu pada

temperatur sekitar 150-180oC proses

pemutusan berjalan lebih lanjut

menghasilkan hidrokarbon dengan

rantai yang lebih pendek (£ C5) yang

dapat berupa gas dan sedikit

hidrokarbon dengan rantai > C5 yang

disebut kondensat sehingga sering juga

disebut sebagai zona gas basah (wet

gas).

Temperature Window

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Hydrocarbon Occurence & Thermal Maturity

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