Petroleum Geology - Địa chất dầu khí pot

• CÁC TẠP CHÍ ĐỊA CHẤT DẦU– Tạp chí dầu khí, Tổng công ty dầu khí Việt Nam; – American Association of petroleum geologist AAPG; – Journal of petroleum geology England – The Australian pe

PETROLEUM GEOLOGY (ĐỊA CHẤT DẦU KHÍ)

• Chương 5: Sự hình thành và di cư của HC

• Chương 6: Môi trường ngầm

• Chương 7: Bản đồ và mặt cắt tầng ngầm

• Chươing 8: Cư trú của HC trong các bồn trầm tích

• Chương 9: Công nghệ khoan-hoàn tất giếng và khai thác DK

• Chương 10: Các phương pháp tìm kiếm thẩm lượng DK

TÀI LIỆU THAM KHẢO

1 Bài giảng địa chất dầu khí (Tiếng Anh), nguồn từ bộ

56 đĩa CD về dầu khí-IHRDC, Houston, USA

2 Basic petroleum geology, Peter K Link, OGCI

publications (Oil and Gas Consultants International, Inc.), 1987, Tulsa, Oklahoma, USA

3 Petroleum Geology, F K North, 1990, Unwin

Hyman Inc., London, UK

4 Geochemistry in petroleum exploration, 1985, D

W Waples, International Human Resources Development Coporation, Boston, USA

• CÁC TẠP CHÍ ĐỊA CHẤT DẦU

– Tạp chí dầu khí, Tổng công ty dầu khí Việt Nam; – American Association of petroleum geologist (AAPG);

– Journal of petroleum geology (England) – The Australian petroleum exploration association (APEA)

• CÁC TẠP CHÍ LIÊN QUAN ĐẾN ĐỊA CHẤT DẦU

– Tạp chí địa chất – Sedimentology (Trầm tích học) – Sedimentary geology (Địa chất trầm tích) – Journal of sedimentary petrology (Tạp chí thạch học TT)

PHƯƠNG PHÁP TRUYỀN ĐẠT &

– Tài liệu tham khảo: Sách, CD

3 Giáo viên trình bày các nội dung cốt lõi

4 Sinh viên tự nghiên cứu tài liệu, giải bài tập

chương & các vấn đề cụ thể

PHƯƠNG PHÁP TRUYỀN ĐẠT &

ĐÁNH GIÁ

• Bài tập, câu hỏi trên lớp (cuối mỗi chương)

• Bài tập-thảo luận nhóm

• Bài kiểm tra giữa kỳ

• Thi cuối kỳ

YÊU CẦU

1 Danh sách ban cán sự, ĐC-ĐT liên hệ

2 Phân nhóm: 04-05, nhóm trưởng

3 Khuyến khích mỗi người có E mail address riêng

4 Điểm danh (Ban CS lớp thực hiện)

5 Liên hệ:

– Trần Văn Xuân- BM ĐCDK – ĐT: 0903 70 07 70

– E.mail: tvxuan@geopet.hcmut.edu.vn ,

xuangeopet@vnn.vn

BEGINNING

• Petroleum products have been used for at least

8000 years

• Herodotus 450 BC – natural seeps

• Egyptians – mummification/ Victorian medication

• Ancient Greece everlasting flame in the sacred Oracle (thánh địa) at Delphi

• Persian Temples built around natural gas sources

Historical (cont)

• Early uses:

– medication, waterproofing, warfare

• Up to mid 19th century: all oil produced from seeps, shallow pits and hand dug shafts

• James Young: extracted oil from carboniferous shales, Scotland 1847: “oil-shales”

• 1st Natural gas: Sichuan Province -China several

thousand years ago

– Bamboo tools and pipes – salt production

• 1st oil-seeking well = Pechelbronn, France, 1745

• 1st well to produce oil: Oil creek, Pennsylvania by

“Colonel” Drake

The Demand for Oil Products

• Increased greatly by WWI (1914-18)

• By 1920 the oil industry dominated by the

“seven sisters”

• Post WWII, oil companies began to risk profits

from one productive area to explore for another.

• 1960: Organization of Petroleum Exporting

Countries (OPEC) formed in Baghdad (Iraq)

– Objective: control the power of the

independent oil companies by price control & appropriation of company assets

MAIN ACTIVITIES

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The science of petroleum geology

• Pore-fluid chemistry – reservoir degradation/ enhancement

• Organic geochemistry: biomarkers, fingerprinting

The science of petroleum geology

(cont)

• Physics

– Geophysics contribute to

• Understanding the earth’s crust

• Understanding the structures involved in trapping: folds, faults

• Identifying the position of such traps: magnetics, gravity, seismics

• Understanding the wells: wireline logs, lithology, porosity

The science of petroleum geology

(cont)

• Biology

– Study of fossil life: Palaeontology contributes

• Dating/ stratigraphic characterization

• Environmental characterization (fossil environments, palaeoecology)

• Biochemistry: transformation of plant and animal tissues into kerogen and through to oil and gas.

CHAPTER 1

ORIGIN & PROPERTIES OF HYDROCARBON

• THE ORIGIN OF PETROLEUM HYDROCARBON

• REQUIREMENTS FOR PETROLEUM

• ALTERATION OF CRUDE OIL

• GAS PROPERTIES AND CLASSIFICATION

THE ORIGIN OF PETROLEUM HYDROCARBON

• THEORIES OF INORGANIC ORIGIN

– Hypothesis of Dimitri Mendeleev

– Hypothesis of Sokoloff

• THEORY OF ORGANIC ORIGIN

• Analogy with organic matter

• Biomarker

• The present of porphyrins

• The polarization of ray-light

• Evidence of carbon isotopes

EVIDENCE OF CARBON ISOTOPES

• Carbon of mantle derivation -2 to -20

(Magmatic rocks, volganic gas, diamonds, and carbon in precambrian rocks or in meteorites)

• Carbon in organism or organic matter -15 to -30

• Marine plants and invertebrates (no bone) -12 to -30

• Land plants, coal and soil humus -23 to -28

• Associated petroleum gas -35 to -55

• Nonassociated petroleum gas -45 to –65

Requirements for Petroleum Accumulation

The task of finding a petroleum field is not a simple one.

• First, there must be a rock containing original organic matter-a

source rock Usually this is a mudrock or shale, which is a very

common rock type and makes up about 80% of the world's

sedimentary rock volume However, even an average shale contains only about 1% to 2% organic matter, and this number can vary

widely Many shales have very low organic content and make poor source rocks.

• Then, the source rock must be buried deeply so that temperature

and time can cause the organic matter to mature into petroleum This

usually requires deposition into sedimentary basins, depressed areas thickly filled by sediments Our search for petroleum is further

limited, since over half of the world's continental areas and adjacent marine shelves have sediment covers either too thin or absent.

Requirements for Petroleum Accumulation (cont)

• Even where the organic matter can become

mature, not all of it becomes petroleum In a

typical example ( Figure 1 ) a normal marine shale with only 1% original organic matter will have

less than a third of it converted to the

hydrocarbon molecules that make up oil and

natural gas (Waples, 1981) The rest remains

behind as an insoluble organic residue.

Figure 1

Requirements for Petroleum Accumulation

• Five factors, therefore, are the critical risks to petroleum accumulation ( Figure 2 ): (1) a mature source rock, (2) a migration path connecting source rock to reservoir rock, (3) a reservoir rock that is both porous and permeable, (4)

a trap, and (5) an impermeable seal

• If any one of these factors is missing or inadequate, the prospect will be dry and the exploration effort will be

unrewarded Not surprisingly then, less than half of the world's explored sedimentary basins have proved

productive, (Huff, 1980) and typically only a fraction of 1% of the petroleum basin's area, and at most 5% to 10%,

is actually prospective (Weeks, 1975).

Figure 2

PETROLEUM CHEMISTRY (self reading

in Petroleum geochemistry)

• Strictly speaking, hydrocarbons are compounds that contain only two elements, hydrogen and

carbon Consequently, petroleum is quite

simple in its elemental composition It contains relatively few impurities, mainly atoms of

nitrogen, sulfur, and oxygen Table 1, shows

the average composition of petroleum in all

three of its natural states of matter, as natural

gas, liquid crude oil and solid or semi-solid

asphalt

AVERAGE COMPARISION OF CRUDE OIL,

NATURAL GAS, ASPHALT

• “A mixture of hydrocarbons that existed in the liquid

phase in natural underground reservoirs and remains

liquid at atmospheric pressure after passing through

surface separating facilities”

• primary hydrocarbon molecules with a C/H ratio usually 6 – 8;

• Crude oil varies in chemical composition and physical

properties;

• Crude oil ranges in color from transparent through colors

of greenish – yellow, reddish, and brown to typical black

PHYSICAL AND CHEMICAL PROPERTIES OF CRUDE OIL

• Oil at the surface tends to be more viscous, most oils are less dense than water: generally measured as the difference

between its density and that of water

• The specific gravity of crude oil generally ranges from 0.780 (50 0 API) to 1.000 (10 0 API);

Thus light oils have API < 10° (!!!)

°API =

141.5

SG 60/60°F

- 131.5

PHYSICAL AND CHEMICAL PROPERTIES OF

The physical and chemical properties

of oil and gas

Hydrocarbon: composed of H and C

Oil, Crude

Plastic Asphalts, Coals, Kerogen

Wet

ethane, propane

Dry

methane

SPECIFIC GRAVITY OF OILS

• European Beaume’ scale;

• API scale (American Petroleum Institute)

API gravity

> 40 Light crude oils

25 – 40 Medium crude oils

< 25 Heavy crude oils

• The relation between API gravity and density

0.876 0.860 0.845 0.570

• Unit Measurement CSG – Centipoises, cP

• A drilling mud has a viscosity of about 15 cp., water

at 200C has a viscosity of 1,005 cp., crude oil has a viscosity of 1 to 3 cP At reservoir conditions

The chemistry of petroleum determines the types and

amounts of refined HCs produced

Table 01

• Although the elemental composition of hydrocarbons

is relatively simple, there are a vast number of ways

in which the atoms can be arranged

• Types of hydrocarbon molecules in crude oil are

paraffins, naphthenes, aromatics, and asphaltics;

(Table 2)

• Crude oil are divided into sweet and sour crudes

based on their sulfur content

• The smell ranges from gasoline (normal, sweet crude)

to foul (normal, sour crude) to fruity (aromatic

crude);

• Crude oil often contains significant amount of

dissolved natural gas;

CLASSIFICATION AND OCCURENCIES OF

CRUDE OIL

Crude Oil Classifications

• Crude oils may be classified by their relative enrichment in the four primary hydrocarbon groups One method, proposed by Tissot and Welte (1978) plots paraffins, naphthenes and the combination of aromatic and NSO

compounds as three axes of a triangular graph and divides the graph into fields that represent six crude oil classes (Figure 1)

• Most normal crude oils fall within only three of these fields

(1) rich in paraffins (paraffinic oil);

(2) they can have nearly equal amounts of paraffins and naphthenes which together make up more than 50% of the crude (paraffinic-naphthenic oil); or

(3) they can have subequal amounts of paraffins and naphthenes, which total less than 50%, and the

composition is dominated by the aromatics, resins and asphaltenes (aromatic intermediate oil).

• Oil may degrade into heavy oil and tar as a result of bacterial action and of flushing by fresh meteoric

waters of surface origin

• This oil falls into one of two classes

(aromatic-asphaltic or aromatic-naphthenic), both of which are enriched in aromatics

oil) but the paraffin content is always very low Deep burial, however, usually has the opposite effect in

altering crude oil It tends to make an oil less dense

and more paraffinic, through processes involving both thermal maturation and the precipitation and removal

of asphaltic molecules

Four important HC series in petroleum chemistry —the paraffins, naphthenes, aromatics, and resins and

asphaltenes

Table 02

THE NONHYDROCARBON CONSTITUENTS

OF OIL AND NATURAL GAS

• Sulfur and its compounds

SULFUR AND ITS COMPOUNDS

• Crude oil containing detectable amount of H2S are

called “sour crudes” If the sulfur is in other form than

H2S, the oil should be called a high sulfur crude and not a sour crude

Sulfur content (%)

< 0.2 Very sweet crudes0.2 – 0.6 Low sulfur crudes0.6 – 1.7 Intermediate

> 1.7 High sulfur crudes

ALTERATION OF CRUDE OIL

• DEASPHALTING

• DEGRADATION BY WATER WASHING

• DEGRADATION BY BACTERAL ACTION

(BIODEGARADATION)

(Figure 04)

THERMAL MATURATION

• Alteration of crude oil by thermal maturation takes

place with increasing depth of burial and increasing

time Crude oils become lighter and more paraffinic

due to the cracking of their heavier components and

increases in their gas content

• Old shallow oils, because of their maturity, are

comparable to young deep crudes both in density,

viscosity and paraffin content Like young shallow oils, however, they may have relatively high sulfur,

depending on source environment Deep old oils tend

to have the lowest viscosity, the lowest density and the lowest sulfur content

DEGRADATION BY WATER WASHING and

BIODEGARADATION

• Groundwater flushing causes various degrees of degradation

of oils, since flushing removes the lighter and more mobile

components of the oils

• In addition, oil at the surface and at very shallow depths may

be degraded due to the action of aerobic bacteria, a process

termed "biodegradation".

• Although groundwater flushing and biodegradation may act independently, they apparently act together in producing

degradation ( Figure 3 ) , by means of gas chromatographs,

illustrates how the lighter hydrocarbon compounds in crude oil are broken down by bacterial oxidation over a 21-day period

Figure 03

Figure 04

NATURAL GAS

Natural gases are classified according to their

hydrocarbon composition

• Gas composed of almost methane is dry gas

• If the proportion of ethane (C2H6) and heavier

molecules propane, and butane exceeds some of

arbitral values (4 or 5%), the gas is called wet gas.Natural gases consisting largely of methane may have any one of three distinct origins

– Petroleum gas

– Coal gas

– Bacteria gas

HYDROCARBON GASES

Defined based on their occurrence

• Free gas is a hydrocarbon gas that exists in the gaseous phase in a reservoir and remains in the gaseous phase when produced

• Dissolved gas is defined as natural gas in solution in

crude oil in a reservoir The reduction in pressure when oil is produced from a reservoir often results in

dissolved gas being emitted from oil as free gas

• Associated gas is natural gas which occurs as a gas cap which overlies and is in contact with crude oil within a reservoir Nonassociated gas is natural gas in reservoirs that do not contain crude oil (Figure 05)

Figure 05

LIQUIFIED GASES

• NGL, natural gas liquids , are hydrocarbon liquids

separated from the produced gas stream

Condensates are an important type of natural gas

liquid.

• LPG, liquified petroleum gas, is comprised of

heavier hydrocarbon gases, usually propane and

butane, stored under pressure in a liquid form.

• LNG, liquified natural gas, is natural gas, commonly methane, which is compressed into liquid for storage and transportation.

Natural Gas Liquid (NGL)

Classified into

Hydrocarbon Gases

Methane (dry) Ethane (wet) Propane Butane

ORGANIC ORIGIN Inert Gases

Helium Argon Krypton Radon Nitrogen Also Carbon dioxide Hydrogen sulfide

INORGANIC ORIGIN

Exercise chapter 1

CHAPTER 02

RESERVOIR

CONDITION FOR AN ACCUMULATION OF

OIL AND GAS

° A mature source rock

° A reservoir rock

° A migration route (betw Source & Res.)

° An impermeable seal

° A trap

° A single continuous deposit of gas and/or oil in the pores of a reservoir rock A reservoir has a single pressure system and don’t communicate with other reservoirs.

° The portion of the trap that contains petroleum, including the reservoir rock, pores, and fluids.

° A pond, lake or environment that is used store liquids.