CHAPTER 5

Question 1

Definition: Energy per unit surface area or force per unit length at interfaces between immiscible fluids or solids.

Answer 1

Interfacial Tension (IFT)

Question 2

Definition: Ability of a fluid to preferentially wet a solid surface in the presence of a second immiscible phase.

Answer 2

Wettability

Question 3

Relation to IFT: Linked to interfacial energies between solid and fluid phases.

Answer 3

Contact Angle

Question 4

Definition: Pressure difference across a curved interface in a capillary tube.

Answer 4

Capillary Pressure

Question 5

Definition: **Ratio **of effective permeability to viscosity for a fluid phase.

Answer 5

Mobility

Question 6

Definition: Effective permeability of a phase divided by absolute permeability.

Answer 6

Relative Permeability

Question 7

Definition: Ratio of water production rate to total production rate.

Answer 7

Fractional Flow

Question 8

Dependence: Depends on the composition of the two fluids at the interface.

Answer 8

nterfacial Tension (IFT)

Question 9

Measurement: Determined by contact angle, measured through the denser phase.

Answer 9

Wettability

Question 10

Equivalent Height: Estimates transition zone height between phases; inversely proportional to density differences.

Answer 10

Capillary Pressure

Question 11

Oil-Water System: Oil is nonwetting in water-wet reservoirs.

Gas-Oil System: Gas is nonwetting; oil is wetting.

Answer 11

Capillary Pressure

Question 12

Compares mobilities of different phases.

Answer 12

Mobility

Question 13

Simplified Equation: Neglects capillary pressure and gravity at high flow rates.

Answer 13

Fractional Flow

Question 14

Solution-gas ratio, formation volume factors (FVF), viscosity, density, compressibility, porosity, permeability.

Answer 14

Basic Requirements

Question 15

Factors: Pressure amount and free gas availability.

Answer 15

Repressurization

Question 16

Effects: Alters oil FVF, solution gas, and viscosity.

Answer 16

Repressurization

Question 17

Bubble Point Pressure:

Undersaturated Reservoir: Pressure where first gas bubble forms.

Saturated Reservoir: Pressure at gas-oil contact.

Answer 17

Repressurization

Question 18

Gas Injection: May not restore initial pressure due to produced solution gas.

Answer 18

Repressurization

Question 19

Data Integration: Plotted similarly to oil FVF curves.

Answer 19

Repressurization

Question 20

Purpose: Speeds up fluid property calculations in simulations.

Answer 20

Equal-Spacing of PVT Data

Question 21

Solutions for Issues:

Add dummy pressure entries.

Retain curve shape and extrapolate.

Manually equal-space data.

Answer 21

Equal-Spacing of PVT Data

Question 22

Ensures PVT data spans the entire pressure range to avoid simulation instability.

Answer 22

Smoothness

Question 23

Usage: For compositional effects or multiple reservoirs.

Tracking Methods:

Oil/Gas Tracking: Monitors fluid movement with mixing.

Tracer Tracking: Monitors movement without mixing.

Answer 23

Multiple PVT Tables

Question 24

-Oil is the **nonwetting phase** in a water-wet reservoir.

Answer 24

Oil-Water Capillary Pressure

Question 25

-In gas-oil systems, gas usually behaves as the nonwetting phase and oil is the wetting phase

Answer 25

Gas-Oil Capillary Pressure

Question 26

Basic PVT Data requirements:

Answer 26

solution-gas ratio formation volume factors viscosity density compressibility effective porosity permeability etc.

Question 27

Properties affected by repressurization:

Answer 27

oil formation volume factor solution gas oil viscosity

Question 28

How to define bubble point pressure: For_____________ , it is the pressure at which the first bubble of gas comes out of solution.

Answer 28

undersaturated reservoir

Question 29

How to define bubble point pressure: For____________, it is the **pressure at the gas oil contact.**

Answer 29

saturated reservoir

Question 30

when produced, the bubble point shall be defined as the pressure which all free gas **could be dissolved** or also called as the ______________

Answer 30

“saturation pressure”.

Question 31

retain the shape of the curve add values below the bubble point to reduce the spacing terminate the table at 2100 psi (in some models) extrapolate and add additional entries equally-space your PVT data

Answer 31

Solution to the problems

Question 32

*different fluid* properties but only in **one reservoir**, should be used instead of beta simulator

Answer 32

compositional

Question 33

– different fluid properties but signifies different reservoirs found

Answer 33

multiple reservoirs

Question 34

allows monitoring of fluids from one region to another and includes mixing of various fluids

Answer 34

oil (or gas) tracking feature

Question 35

also allows monitoring of fluids from one region to another but does **not include mixing of various fluids**

Answer 35

tracer tracking