Properties of Petroleum Fluids

Course Objectives

At the end of this course, you should have acquired the following skills:

Hydrocarbon Chemistry

1. Be able to name various hydrocarbon compounds given their molecular structure.
2. Be able to draw the molecular structures of various hydrocarbon compounds.
3. Be able to draw the pressure-temperature phase diagrams characteristic of pure substances, of 2—component mixtures, and of 3-component mixtures (ternary diagrams).
4. Be able to use ternary diagrams to read the compositions and quantities of the equilibrium gas and liquid.
5. Be able to draw the pressure-temperature phase diagrams for the 5 reservoir fluids, namely; dry gas, wet gas, condensate gas, black oil and volatile oil.

Physical Properties of dry gases

1. Given the mole composition of a dry gas, to be able to use it to calculate the following physical properties:

(i) the apparent molecular weight (ii) the specific gravity, (iii) gas compressibility factor (z-factor) and use it to calculate the gas density and formation volume factor, (iv) coefficient of isothermal compressibility and (v) coefficient of viscosity.

2. If Given the specific gravity of the dry gas instead, to be able to use it to calculate:

(i) z-factor, (ii) density, (iii) formation volume factor, (iv) coefficient of isothermal compressibility and (v) coefficient of viscosity

Properties of wet gases

1. Be able to take surface gas and liquid productions as well as their mole fractions and recombine them to calculate reservoir gas mole fractions for wet gases and condensate gases above the dew point. Use this recombined reservoir gas mole fractions to calculate the properties listed above.

Properties of condensate gases-PVT analysis

1. Be able to describe the experimental procedures (flash and differential) utilized for oil and gas PVT analysis.

2. Given a PVT report for a condensate gas, to be able to use it to calculate the physical properties of the wet gas.

Properties of Black oils

1. Given a PVT report for black oil, to be able to use it to calculate the physical properties of the black oil.

2. Be able to calculate the density and specific gravity (or API gravity) of crude oil at atmospheric temperature and pressure given its mole composition at atmospheric conditions.

3. Be able to calculate the density of crude oil at reservoir temperature and pressure given the reservoir oil composition.
4. Be able to calculate the density of crude oil at reservoir temperature and pressure given the stock tank gas composition, the stock tank oil gravity and the solution gas-oil ratio by:

• Calculating the pseudo-liquid density at STP
• Adjusting it to reservoir temperature and saturated pressure
• Adjusting it to reservoir temperature and reservoir pressure if it is greater than the bubble point pressure

5. Be able to calculate the density of crude oil at reservoir temperature and pressure given the stock tank gas gravity, the stock tank oil gravity and the solution gas-oil ratio by:

• Calculating the pseudo-liquid density at STP
• Adjusting it to reservoir temperature and saturated pressure
• Adjusting it to reservoir temperature and reservoir pressure if it is greater than the bubble point pressure

6. Be able to calculate oil formation volume factor given its densities at the surface and at reservoir conditions, surface gas gravity, and solution gas-oil ratio.

7. Be able to estimate oil formation volume factor, oil viscosity, and coefficient of isothermal compressibility from graphical correlations.

Properties of Gas-Oil mixtures- Separator calculations

Given the composition of well fluid (oil), be able to make separator calculations to obtain the compositions and quantities of the separator and stock tank fluids that will result.

Properties of Oil field Brines

Be able to calculate the physical properties (density, viscosity, isothermal compressibility, formation volume factor) for oil field waters from empirical or graphical correlations.

Properties of Gas-hydrates

Be able to predict the conditions for hydrate formation in the oilfield.