Oil Reservoir Pressure Reduction and Gas Liberation

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary reason for taking samples early in the life of a reservoir?

To minimize errors caused by differences in relative movement of oil and gas after solution gas has been liberated (correct)

To reduce the cost of sampling

To ensure the sample is representative of the reservoir

To obtain a more accurate PVT study

What is the minimum pressure required for sub-surface sampling to be representative?

At or above the bubble point

Below the saturation pressure

At or above the saturation pressure (correct)

At or below the dew point

What is the main limitation of wellhead sampling?

It is only possible for very undersaturated systems (correct)

It is not representative of the reservoir fluid

It requires a separator

It is expensive

What is the primary concern when sampling wet gas and gas condensate fluids?

Alteration of the sample conditions Signup and view all the answers

What is the purpose of a phase diagram in PVT studies?

To predict the phase behavior of the reservoir fluid Signup and view all the answers

What is the term for the pressure at which the oil and gas phases separate?

Saturation pressure Signup and view all the answers

What is the purpose of recombining fluids in the laboratory?

To recreate the original reservoir fluid composition Signup and view all the answers

What is the main advantage of downhole fluid sampling?

It provides a more representative sample of the reservoir fluid Signup and view all the answers

What is the primary objective of PVT analysis in reservoir fluid evaluation?

To establish the correlation between pressure and volume at reservoir temperature Signup and view all the answers

What type of diagram illustrates the evolution of hydrocarbon phases during production?

Phase diagram Signup and view all the answers

In a gas condensate system, what is the critical pressure below which liquid dropout occurs?

Dew point pressure Signup and view all the answers

Which of the following is NOT a key parameter measured in PVT analysis for dry gas?

Bo Signup and view all the answers

What is the primary consideration in sampling reservoir fluids?

Representativeness of the reservoir contents Signup and view all the answers

What is the purpose of Constant Composition Expansion (CCE) test?

To simulate the flash vaporization process Signup and view all the answers

Which of the following PVT tests is used to evaluate the effect of separator conditions on Bo and GOR?

Multistage Separation (MSS) Signup and view all the answers

What is the main application of PVT analysis in the petroleum industry?

All of the above Signup and view all the answers

What is the purpose of the PVT tests?

To determine Bo, Bg, and Rs that reflect actual production Signup and view all the answers

What happens to the gas when the reservoir pressure drops below the bubble point?

The gas comes out of solution and initially remains in the pores in contact with the oil Signup and view all the answers

What is the term for the liberation of gas from oil in the tubing?

Flash liberation Signup and view all the answers

What is the classification of reservoir fluids in increasing order of chemical complexity?

Dry gas, wet gas, gas condensate, volatile oil, black oil Signup and view all the answers

What is the purpose of understanding phase behavior in reservoir fluids?

To design the surface facilities and determine depletion and production strategies Signup and view all the answers

What is the term for the type of phase diagram that shows the behavior of a single compound hydrocarbon?

Hydrocarbon phase diagram Signup and view all the answers

What is the term for the point at which gas starts to flow?

Critical gas saturation Signup and view all the answers

What is the type of reservoir fluid that is characterized by a high gas content?

Volatile oil Signup and view all the answers

Study Notes

Pressure and Volume Measurements

After 4-8 pressure reduction, the cell contains only residual oil at reservoir temperature, which is then cooled to standard temperature and has its volume measured.

Liberation of Gas from Oil

When reservoir pressure drops below the bubble point, flash liberation dominates.
Gas comes out of solution and initially remains in the pores in contact with the oil.
Single-phase oil continues to flow into the well, although it has a slightly different composition than that of the original reservoir fluid.
When enough gas accumulates to reach the critical gas saturation, it begins to flow.
Gas liberation occurs in the tubing, considered flash liberation, keeping the two phases in contact with each other.
Flash liberation also dominates in the separator, where a sudden pressure drop releases more gas.

Petroleum Reservoir Fluids

Petroleum reservoir fluids can be divided into five general categories in increasing order of chemical complexity:
- Dry gas
- Wet gas
- Gas condensate
- Volatile oil
- Black oils
The phase behaviors of gas condensates and volatile oils are considerably more complex than those of black oils.

Phase Behavior

Understanding phase behavior is crucial as oil and gas are produced from the reservoir, subjected to pressure, temperature, and compositional changes.
These changes affect the volumetric and transport behavior of reservoir fluids and the produced oil and gas volumes.
The type of reservoir fluid determines depletion and production strategies and the design of the surface facilities.
Except for polymer flooding, all EOR methods rely on the phase behavior of reservoir fluids and fluids injected into the reservoir.

Reservoir Fluids

Schematic phase diagrams include:
- Generic (single and multi-component cases)
- Black Oil
- Solution-Gas Drive
- Dry Gas
Black oil (P>Pb):
- Properties: Bo, µo, Co (assumed constant)
Solution-gas drive (P

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

This quiz assesses understanding of the process of pressure reduction in oil reservoirs, resulting in gas liberation and its measurement. It covers the concepts of bubble point, flash liberation, and residual oil.