Fundamental Reservoir Fluid Behaviour

FUNDAMENTAL RESERVOIR FLUID PROPERTIES

Ekeh Modesty KelechukwuDept. of Chemical & Petroleum Engineering

UCSI University56000 Cheras , Kuala Lumpur

[email protected]

Syllabus

Fundamental of Reservoir Fluid Behaviours

Sampling and analysis of reservoir fluids Basic classification of hydrocarbons Hydrocarbon phase behaviours (single, double, multi- components) Classification of reservoir fluids Gas properties Liquid properties Formation water properties

Typical Reservoir

Gas

Oil

water

Hydrocarbon Reservoir

Fluids: oil, gas and water

Reservoir fluid must flow to the surface for marketable oil and gas

Typical Flow

Hydrocarbon Reserves

Np A h Sw Swi 1

B oi

1

Bo

Gp A h 1 Swi Bgi Bg

1

gi g

1 1

B B

Oil or Gas or Mixture of Both

Pre

ssur

e

Temperature

oil

gas

Oil + Gas

Bubble point

Fluid flow in reservoir

qw kw A

p

L

qo ko A

p

L

qg kg A

p

L

Saturated with oil, gas and water

Recovery optimization

separator

Oil reservoir

Sampling and analysis of reservoir fluids

separator surface sampling

bottomhole sampling

PVT analysis

Sampling Methods:

Analysis Methods:

To obtain good equilibrium and representative reservoir fluid sample. Temperature and pressure changes influence equilibrium composition of the gas and liquid phases.

HPHT Compositional analysis up to C70 Constant composition expension Viscosity Differential liberation Compressibility

General properties of hydrocarbon fluids

Formation volume factor, Bg, Bo, Bw: volres/volsc

Density, specific gravity

Isothermal Compressibility

Viscosity

Solution Gas-Oil Ratio

Ideal gas law: pV = nRT

Real gas law: pV = znRT

Typical composition of Petroleum Gases

Natural Gas

Hydrocarbons

Methane 70-98%Ethane 1-10%Propane trace - 5%Butane trace - 2%Pentane trace - 1%Hexane trace - 0.5%Heptane+ trace - 0.5%

Non-hydrocarbons

Nitrogen trace - 15%Carbon dioxide trace - 5%Hydrogen Sulfide trace - 3%Helium up to 5%, normally traces or none

Gas from Oil Well

Hydrocarbons

Methane 45-92%Ethane 4-21%Propane 1 - 15%Butane 0.5 - 7%Pentane v. little - 3%Hexane v. little - 2%Heptane+ v. little - 1.5%

Non-hydrocarbons

Nitrogen v. little – up to 10%Carbon dioxide v. little - 4%Hydrogen Sulfide v. little - 6%Helium none

Typical composition of Petroleum Gases

Crude oil fractions Boiling Chemical Point, oF Composition Usages

Gas hydrocarbon C1 – C2 Fuel gas up to 100 C3 – C6 Bottled fuel gas, solvent

Gasoline 100 – 500 C5 – C10 Motor fuel, solvent

Kerosene 350 – 480 C11 – C13 Jet fuel, cracking stock

Light Gas Oil 450 – 480 C13 – C17 Diesel fuel, furnace fuel

Heavy Gas Oil 580 – 750 C18 – C25 Lubricating oil, bunker fuel

Lubricant and Wax 750 – 950 C26 – C38 Lubricating oil, paraffin wax, petroleum jelly

Residual Oil 950+ C38+ Tar, roof compound, asphalt, coke

Typical Crude Oil Fractions

Typical composition analysis of crude oils

Carbon 84 - 87%

Hydrogen 11 - 14%

Sulfur 0.06 – 2%

Nitrogen 0.1 – 2%

Oxygen 0.1 – 2%

Basic classification of hydrocarbons

Hydrocarbon Homolog Series

Hydrocarbons

Alkenes-unsaturated H-olefin: 1 double bond-diolefin: 2 double bonds

Alkanes (paraffin)-saturated H

Aliphatic

Alkynes (acetylene)-unsaturated H-triple bonds

Cyclic aliphaticNaphthalene

Aromatics(Benzene)

Compounds in Crude Oil (South Ponca Field, Oklahoma)

Alkanes, CnH2n+2

1 Methane2 Ethane3 Propane4 Butane5 Pentane6 Hexane7 Heptane8 Octane9 Nonane10 Decane20 Eicosane30 Triacontane

No. of Carbon Name

Covalent bond: sharing electrons Isomerism - same molecular formula but different structure, different physical and chemical properties Prefix isomers – n-, iso-, neo-, etc.

Heptane C5 H12

n-heptane iso-heptane neo-heptane

Alkanes, CnH2n+2

Alkane FormulaBoiling point [°C]

Melting point [°C]

Density [g·cm3] (at 20°C)

Methane CH4 -162 -183 gas

Ethane C2H6 -89 -172 gas

Propane C3H8 -42 -188 gas

Butane C4H10 0 -138 gas

Pentane C5H12 36 -130 0.626(liquid)

Hexane C6H14 69 -95 0.659(liquid)

Heptane C7H16 98 -91 0.684(liquid)

Octane C8H18 126 -57 0.703(liquid)

Nonane C9H20 151 -54 0.718(liquid)

Decane C10H22 174 -30 0.730(liquid)

Undecane C11H24 196 -26 0.740(liquid)

Dodecane C12H26 216 -10 0.749(liquid)

Icosane C20H42 343 37 solid

Triacontane C30H62 450 66 solid

Tetracontane C40H82 525 82 solid

Pentacontane C50H102 575 91 solid

Physical properties:

Nomenclature of Alkanes

Based on IUPAC (International Union of Pure and Applied Chemistry) rules:

Alkyl groups (missing one hydrocarbon atom): methyl group, ethyl group, prophyl group

The largest continuous chain of carbon atoms is taken as the framework on which the various alkyl groups are considered to be substituted. Thus the following hydrocarbon is a pentane.

The parent hydrocarbon is then numbered starting from the end of the chain and the substituent groups are assigned numbers corresponding to their positions on the chain. The direction of numbering is chosen to give the lowest sum for the numbers of the side chain substituents. Thus, thehydrocarbon is 2,3-dimethylpentane. .

These rules are as follows:

Nomenclature of Alkanes

Where there are two identical substituents in one position as in the compound below numbers are supplied for each.

Branched-chain substituent groups are given appropriate names by a simple extension of the system used for branched chain hydrocarbons. The longest chain of the substituent is numbered starting with the carbon attached directly to the parent hydrocarbon chain. Parentheses are used to separate the numbering of the substituent and the main hydrocarbon chain.

When there are two or more different substituents present, the common method is to list the substituents in alphabetical order, although the substituents are sometimes listed in order of increasing complexity.