Studied by 32 people
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.
