بنك الاسئلة EPS 1ST 2010 342

Part Two: Define the following terms:                                                                  (10 Marks)

1) Kerogen

2) Secondary dolomites

3) Atypical reservoir

4) Source rocks

5) Cap rocks

Model Answer:

1)Kerogen

The disseminated organic matter of sedimentary rocks that is insoluble in non-oxidizing acids, bases, and organic solvents. When heated, saporpelic kerogens yield oil and gas, and humic kerogen  yield mainly gas. Kerogen includes both marine and land derived organic matter.

2)Secondary dolomites: form by dolomitization, the replacement of a pre-existing calcium carbonate deposit. They are often coarsely crystalline, with porosity that may exceed 30%.

3) Atypical reservoir: Any rock can seve as a reservoir, providing that it has the two properties, porosity and permeability. Atypical reservoir include:

Shales, granites, and other igneous and metamorphic rocks. Generally, porosity that occurs in these is due to fracturing.

4) Source rocks

- Organic matter rich rock unit which under the influence of time and temperature has generated and expelled hydrocarbons (effective source rock).

-Potential source rock: is one which has not yet generated significant amounts of hydrocarbons due to immaturity.

5) Cap rocks

An impermeable rock layer that forms the seal on top of an oil or gas reservoir.

Part Three:                                                                                                                    (10 Marks)

1) Methane is lightest natural gas and has a formula of CH₄. What are the next 3 heavier

hydrocarbon gases, and what are their formulas?                                                

2) Circle one

Paraffins                         are/are not            pure hydrocarbons.                                              

Resins/Asphaltenes        are/are not            Non-hydrocarbons.

Aromatics                      are/are not             pure hydrocarbons. 

Naphthenes                    are/are not             Non-hydrocarbons.  

3) Match each of the “Gas” terms above with its definition below by placing the correct letter in the space provided.                                                                  

A. Free Gas       B. Dissolved Gas         C. Associated Gas          D. Dry Gas

E. Wet Gas        F. NGL                        G. LPG                           H. LNG

1- _____ is hydrocarbon gas (usually methane) which is compressed into liquid for storage

               and transportation.

2- _____ is in a gaseous phase in the subsurface reservoir and remains in a gaseous phase    

               when produced.

3- _____  are the hydrocarbon liquids which are separated from the produced-gas stream.

4- _____ is in solution within crude oil in the subsurface reservoir, but bubbles out of

               solution when pressure and temperature drops.

Model Answer:

Part Three:                                                                                                                    (10 Marks)

1) Ehane (C₂H₆,) Propane (C₃H₈) and Butane (C₄H10₁₀).

2) Circle one

Paraffins                         are/are not            pure hydrocarbons.                                              

Resins/Asphaltenes        are/are not            Non-hydrocarbons.

Aromatics                      are/are not             pure hydrocarbons. 

Naphthenes                    are/are not             Non-hydrocarbons.  

A. Free Gas       B. Dissolved Gas         C. Associated Gas          D. Dry Gas

E. Wet Gas        F. NGL                        G. LPG                           H. LNG

1- LNG (H) is hydrocarbon gas (usually methane) which is compressed into liquid for storage

    and transporation.

2- Free Gas (A) is in a gaseous phase in the subsurface reservoir and remains in a gaseous phase    

     when produced.

3- NGL (F)  are the hydrocarbon liquids which are separated from the produced-gas stream.

4- Dissolved Gas (B) is in solution within crude oil in the subsurface reservoir, but bubbles out of

     solution when pressure and temperature drops.