Chapter 3- More Insight Flashcards
What is bubble point pressure ?
This is the pressure at which the first sign of gas formation is detected.
What is dew point pressure ?
This is the pressure in which the first drop of liquid condenses out of gas .
Classification of a petroleum reservoir is based on ?
Reservoir and reservoir fluid
Classify a petroleum reservoir based on reservoir?
1) initial pressure Pi
2) temperature
Classify a petroleum reservoir based on reservoir fluid ?
1) critical pressure and temperature. Pc and Tc
2) composition x
Reservoirs can be classified into two types namely ?
Oil reservoir
Gas reservoir
How do we identify an oil reservoir?
If the reservoir temperature Tres is less than the critical temperature Tc of the reservoir fluid , the reservoir is classified as an oil reservoir
How do we identify a gas reservoir?
If the reservoir temperature is greater than the critical temperature of the reservoir fluid , the reservoir is considered a gas reservoir.
What are the 3 major state variables ?
Pressure
Volume
Temperature
Depending on the initial pressure of the reservoir, oil reservoirs can be sub-classified into the following categories.
Under saturated oil reservoir
Saturated oil reservoir
Gas cap reservoir
When do we have an under saturated oil reservoir ?
If the initial reservoir pressure is greater than bubble point pressure of the reservoir fluid .
Pi,res>Pb
When do we have a saturated oil reservoir?
If the initial reservoir pressure is equal to the bubble point pressure
Pi, res= Pb
When do we have a gas cap reservoir?
If the initial reservoir pressure is below the bubble point pressure of the reservoir fluid .
Pi,res
What is another term for gas cap reservoir
Two phase reservoir because it’s in the two phase region
Based on physical properties composition gas oil ratio, appearance and P-T phase diagram of reservoir fluid , crude oils are commonly classified into ?
Black oil BO
Low shrinkage LS
High shrinkage HS
Near critical NC
When produced , black oils usually yield gas-oil ratios between ?
200-700 scf/STB
What is the oil gravities of black oils?
15-40 degree API
What is the color of the stock tank oil ?
Brown to dark green in color
According to Ahmed tarek ( reservoir engineering handbook second edition )
According to Oscar , it’s color is black
How are the quality lines for black oils ?
They are approximately equally spaced
How is the liquid shrinkage curve prepared?
It is prepared by plotting the liquid volume percent as a function of pressure.
How is the liquid shrinkage curve for black oils ?
It is approximately a straight line except at very low pressures .
How are the quality lines for low shrinkage oil ?
They are closely spaced near the dew point curve
What is the function of liquid shrinkage curve ?
They show the shrinkage characteristics of the various categories of crude oils
What are the other associated properties of low shrinkage oil ?
Oil formation volume factor less than 1.2 bbl/STB
Gas-Oil ratio less than 200scf/STB
Oil gravity less than 35 degree API
Black or deeply colored
What is another name for high shrinkage Oil?
Volatile oil
How are the quality lines for high shrinkage
They are close together near the bubble point and are more widely spaced at lower pressures.
What is the major characteristic of high shrinkage ?
It is commonly characterized by a high liquid shrinkage immediately below bubble point
What are the other characteristic properties of high shrinkage oil ?
Oil FVF less than 2 bbl/STB
GOR between 2000-3000 scf/STB
Oil gravities between 45-55 degree API
Greenish to orange in color
Lower liquid recovery of separator conditions
What happens to the API gravity of the stock tank liquid in the later life of the high shrinkage oil reservoir?
The API gravity of the Stock Tank liquid will increase in the later life of the reservoir.
When do we have a near critical reservoir?
This is when the reservoir temperature is near the critical temperature Tc of the hydrocarbon system
How else can we identify a near critical oil without comparing the temperature of the reservoir to the critical temperature ?
We can do this by looking at the quality lines , because all the quality lines converge at the critical point .
What are the other characteristic properties of the high shrinkage oil ?
High GOR of 3000 scf/STB
Oil FVF 2.0 bbl/STB or higher
