FUNDAMENTAL RESERVOIR FLUID PROPERTIESEkeh Modesty KelechukwuDept. of Chemical & Petroleum EngineeringUCSI University56000 Cheras , Kuala Lumpurekehmodesty@ucsi.edu.my

SyllabusFundamental 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 ReservoirGasOilwater

Hydrocarbon ReservoirFluids: oil, gas and waterReservoir fluid must flow to the surface for marketable oil and gasTypical Flow

Hydrocarbon Reserves1

Oil or Gas or Mixture of Both

Fluid flow in reservoirSaturated with oil, gas and water

Recovery optimizationseparatorOil reservoir

Sampling and analysis of reservoir fluids separator surface sampling

bottomhole sampling PVT analysisSampling 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 GasHydrocarbons

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 WellHydrocarbons

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 noneTypical 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, cokeTypical 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 hydrocarbonsHydrocarbon Homolog SeriesHydrocarbonsAlkenes-unsaturated H-olefin: 1 double bond-diolefin: 2 double bondsAlkanes (paraffin)-saturated HAliphaticAlkynes (acetylene)-unsaturated H-triple bonds

Compounds in Crude Oil (South Ponca Field, Oklahoma)

Alkanes, CnH2n+2 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 Physical properties:

AlkaneFormulaBoiling point [C]Melting point [C]Density [gcm3] (at 20C)MethaneCH4-162-183gasEthaneC2H6-89-172gasPropaneC3H8-42-188gasButaneC4H100-138gasPentaneC5H1236-1300.626(liquid)HexaneC6H1469-950.659(liquid)HeptaneC7H1698-910.684(liquid)OctaneC8H18126-570.703(liquid)NonaneC9H20151-540.718(liquid)DecaneC10H22174-300.730(liquid)UndecaneC11H24196-260.740(liquid)DodecaneC12H26216-100.749(liquid)IcosaneC20H4234337solidTriacontaneC30H6245066solidTetracontaneC40H8252582solidPentacontaneC50H10257591solid

Nomenclature of AlkanesBased 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.