the measure of void space in a rock

Φ=pore volume/bulk volume = V_p/V_b = (V_b-V_g)/V_b 

where Vg= grain volume

ρ=m/v

bulk density, ρ_b

grain density, ρ_g

grams/cm^3

quarts=2.65

calcite=2.71

clay (avg)=2.57

1. measure the bulk volume (V_b)
2. crush the sample to measure the grain volume 
3. use formulate V_p=V_b-V_g to estimate pore volume
4. divide pore volume by bulk volume

1. inject a gas or liquid into the rock after measuring bulk volume
2. the gas or liquid only goes where teh porosity is connected
3. dreain the gas or liquid, then measure the volume of it, and that equals pore volume

the largest inscribed circle within a pore space

free porosity<porosity

grain size

grain shape

grain packing and distribution

cementation

compaction

1. measurement of bulk and grain volume
2. optical method: use of petrographic thin section analysis
3. imbibition method: imbibing fluid into the pore space
4. mercury injection method: forcing non wetting liquid into porespace
5. gas expansion method: (He or N₂)
6. density method
7. NMR (proton density)

• formation factor
• micro resistivity logs
• neutron logs
• gamma-gamme logs
• acoustic logs
• NMR logs

average thermal gradient

average surgace temperature

(land and bottom of ocean)

surface temp: 68ºF

ocean bottom: 32ºF

lithostatic=overburden=confining

fluid=reservoir=pore=formation

fraction of the water in the pore space which cannot be produced

'bound water'

the capacity of a rock to transmit a fluid

all factors that control effective porosity also control permeability

is affected by the type of clay present

1. single fluid
2. no rock fluid interaction
3. incompressible fluid
4. laminar flow

a porous materal has k=1 if a pressure difference of 1 atm will produce a flow rate of 1cm^3/sec of a fluid with 1 cP viscosity through a cube having sides 1cm in length

k = permeability (darcy)

calculated in darcy's equation

when the rock is 100% saturated with a single phase (water, oil, or gas)

when two or more fluids coexist in a rock

the sum of the effective permeabilittes of all the phases will always be <= the absolute permeability