A dean-stark extraction is performed on the North Sea chalk core plug
sample, which extracted 5.77 cm3 of water. The core plug has a
porosity of 36.1 % and bulk volume of 24.5 cm3. The wet and dry
weights of the sample are 50.64 and 42.33 g, respectively. The gas, oil
and water densities are 0.001, 0.85 and 1.035 g/cm3, respectively.
Calculate the gas, oil, and water saturations in the core plug sample.
Calculate the oil and gas pore volume.
Solution:
Pore Volume (PV) = Bulk Volume (BV) X Porosity (φ)
= 24.5 X 36.1 cm3
= 8.8445 cm3
Now ,
WW – DW = Mo + Mg + Mw
50.64 – 42.33 = Voρo + Vgρg + Vwρw
8.31 = 0.85Vo + 0.001Vg + 1.035 X 5.77
8.31 = 0.85Vo + 0.001Vg + 5.979
2.331=0.85Vo + 0.001Vg --------------------------(1)
Now,
PV = Vo + Vg + Vg
8.8445 = Vo + Vg + 5.77
Or, Vo + Vg = 3.0745 -----------------------------------(2)
Solving equation 1 and 2,
Vo = 2.742, Vg = 0.3325
Hence,
So = 100 X (2.742/8.8445) = 31 %
Sg = 100 X (0.3325/8.8445) = 3.76 %
Sw = 100 X (5.77/8.8445) = 65.24