Reservoir Petrophysics with Hydrocarbon Phase Analysis | Midterm Exam

Porosity

a measure of the storage capacity

Absolute porosity

 

ratio of the total pore space

Effective porosity

percentage of interconnected pore space

Saturation

\- fraction or percent of the pore volume

Capillary forces

\- forces retaining the water

Critical oil saturation

\- the saturation of the oil must exceed a certain value

Residual oil saturation

\- remaining oil left

Movable oil saturation

\- fraction of pore volume occupied by movable oil

Critical gas saturation

\- gas phase remains immobile until its saturation exceeds a certain saturation

Critical water saturation

- maximum water saturation

Wettability

\- tendency of one fluid

Surface tension

\- forces acting on the interface

Interfacial tension

\- when the interface is between two liquids

Capillary pressure

\- when two immiscible fluids are in contact

Capillary Hysteresis

\- pore spaces of reservoir rocks were originally filled with water

Drainage process -

process of generating the capillary pressure

Imbibition process

\- reversing the drainage process by displacing the nonwetting phase

Capillary hysteresis

\- process of saturating and desaturating a core

Transition zone

– vertical thickness

Zero capillary pressure

\- free water level

Leverett J-Function

\- dimensionless function of saturation

Permeability

\- property of the porous medium

Darcy’s Law

\- equation that defines permeability in terms of measurable quantities

Darcy

– he developed a fluid flow equation

1000 md

1 Darcy =

Dry gas

\- usually used in permeability determination because of its convenience, availability, and to minimize fluid-rock reaction

Klinkenberg

\- discovered that permeability measurements made with air

Mean pressure

\- defined as upstream flowing

Jones (1972)

\- studied the gas slip phenomena

Weighted-Average Permeability

\- averaging method is used to determine the average permeability of layered-parallel beds

Warren and Price (1961)

\- illustrated experimentally that the most probable behavior of a heterogeneous formation

Calhoun (1976)

\- suggested that in an ideal pore configuration

Effective permeability

\- as the saturation of a particular phase decreases, the permeability to that phase also decreases

Effective overburden pressure

\- pressure difference between overburden and internal pore pressure

Rock-matrix compressibility

\- defined as the fractional change in volume of the solid rock

Rock-bulk compressibility

\- defined as the fractional change in volume of the bulk volume

Pore compressibility coefficient

\- defined as the fractional change in pore volume of the rock

Formation compressibility

\- total compressibility

Geertsma

\- stated that in a reservoir only the vertical component

Formation compressibility

\- same order of magnitude

Newman (1973)

\- used 79 samples

Reservoir heterogeneity

\- variation in reservoir Properties

Degree of homogeneity

\- a number that characterizes the departure

Dykstra and Parsons (1950)

\- introduced the concept of the permeability variation coefficient

Relative permeability

\- the ratio of effective permeability

Stone (1970)

\- developed a probability model to estimate three-phase relative permeability

Minimum oil saturation

\- a nonzero residual oil saturation

specific gravity

RESERVOIR FLUID PROPERTIES

\- the ratio of the gas density

specific volume

RESERVOIR FLUID PROPERTIES

\- volume occupied by a unit mass

density

RESERVOIR FLUID PROPERTIES

\- ideal gas mixture

gas

RESERVOIR FLUID PROPERTIES

- homogeneous fluid

Gas viscosity

RESERVOIR FLUID PROPERTIES

- measure of the internal fluid friction

Petroleum reservoirs

the result of sedimentary processes

Nonassociated Gas

\- reservoirs that contain almost entirely natural gas

Dry gas

\- if the fluid at the surface still remains gas

Wet gas

\- if the surface pressures cause some liquid hydrocarbons to evolve

Associated Gas

\- almost all oil reservoirs except those classified as extra heavy or tars will produce some natural gas at the surface

Unconventional Gas

- geological setting and rock type

Tight gas

\- formed in sandstones

Coalbed methane (CBM)

\- methane gas that is found adsorbed in many buried coalbed deposits

Shale gas

\- found in organic shale rocks

Natural gas phase behavior

\- function of pressure, temperature, and volume

Bubble Point Curve

\- the curve that separates the pure liquid phase from the two-phase

Dew Point Curve - the curve that separates the pure gas phase from the two-phase

Critical Point

\- the point on the phase envelope where the bubble point curve meets the dew point curve

Cricondentherm

\- the highest temperature at which liquid and vapor can coexist

 

Cricondenbar

\- the highest pressure at which a liquid and vapor can coexist

Retrograde condensate systems and reservoirs

\- unique phenomenon that appears only among hydrocarbon mixtures.

Gas specific gravity

\- the ratio of the molecular weight

Viscosity

\- a measure of a fluid’s internal resistance to flow.