Petrophysics lab report

Experiment 1: Density and porosity

In order to find the density of each of the three samples, first we measured the samples with a caliper. Because of the shape of the samples (cylindrical), we defined it by two dimensions, length and diameter. This dimensions are written in the table which contains all the measurements and results.

Density of the sample is calculated with the formula:

ρ = mVFor the volume we used this formula :

V= r ²π4

∗l

We also weighed the dry and the saturated samples with a electronic scale ; buoyancy was also accounted for .

To calculate the porosity of the samples we had to use an equation that is directly dependent on the Archimedes principle.

ϕ = ms , a−mdms ,a−ms ,w

ms,a.................. saturated mass

md.................... dry mass

ms,w.................. mass in water

We used the helium pycnometer to determine the volume and the density of the solid matrix (grains) . Out of the values that we got from the pycnometer, we calculate the porosity.

ϕ = 1 – (ρgesρ¿¿

) * 100

ρges................... density of the whole sample ( massvolume )

ρmatrix.............. density of the matrix

Experiment 2: Permeability

In our second experiment we have determined the permeability using a permeameter. We loaded the core samples in the apparatus and used, set the pressure of the gas (nitrogen) at 20 psi and then used the following settings:

Carbonate: high pressure and low flow rate Sandstone : low pressure and high flow rate

After that, we waited until the flow rate had a constant value. The software will determine the permeability using the average value of a certain amount of tests.

The results are presented in the table at the end of this document.

From this measurements we can see that the Φ-Archimedes and the Φ-volume are very similar and that means that our calculations are correct.

Experiment 3: Electrical Properties

For the third experiment of the porosity we need to find the electrical properties of our samples. We needed to saturate our samples with brine.

The samples were wraped on the sides with teflon isolating tape in order to conduct the current trough the inside of the sample (pores). Then we inserted the samples, one by one in the the instrument and measured their specific resistivity R0 , by applying a 10000 nA current between the anode and the cathode of the instrument.

The sample resistivity and the specific resitivity were calculated using the following formulas :

R = UI

R0 = k * UI

k....................... geometric factor (cross−section surfacelengthof sample )

U...................... voltage

I........................ current intensity

The specific resistivity was calculated by using the conductivity parameter Cw = 33.5 ms/cm :

Rw = 1K

The final step is to calculate the porosity by using the formation factor of the samples.

Φ = m√ 1F

F = R0

Rw

F....................... formation factor

m......................Archie parameter=2