PGE 424
Home Work 3
Due: March 6
1.
Attached is the mercury capillary pressure data in the spreadsheet HW3. The
cos
for mercury/air is 372 dyne/cm. Calculate the cumulative pore throat size
distribution, assuming a bundle of tubes model.
Answer:
Pc = 2
cos
/r . Therefore r = 2
cos
/Pc. In the spreadsheet, calculate a radius for
each capillary pressure value using
cos
=372 dyne/cm.
Radius (micron) = (2x372x10000)/ (Pc in psi x 68947.5 dyne/cm2/psi)
The saturation given in the spreadsheet is Snw.
Sw = 1Snw.
Cumulative pore size distribution, Cv = Sw = fraction of pores smaller than radius r.
Plot r vs. Cv, as shown below.
Hg Porosimetry
0.000
0.100
0.200
0.300
0.400
0.500
0.600
0.700
0.800
0.900
1.000
0.01
0.1
1
10
Throat Radius (micron)
Cumulative Fraction
Cum. Frac.
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Consider an oil reservoir of the porous medium studied in the last problem. The
cos
for oil/water is 24 dyne/cm. Assume the rock to be waterwet. Find the
initial oil saturation in the reservoir at 5m, 10 m, 20 m, 30 m, 40 m, and 50 m
above the water/oil contact. Oil density is 0.7 gm/ml and water density is 0.9
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 Spring '09
 SHARMA
 Orders of magnitude, capillary pressure, Amott test

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