Page 109 - Petrophysics

82 PETROPHYSICS: RESERVOIR ROCK PROPERTIES

of continents and basins in response to rising and descending
convection currents in the mantle.
2. Calculate the seismic velocities through sandstone from the
following data and compare them to the velocities in limestone. Why
are the velocities different?

B = 3.4 x iolo Pa; S = 3.1 x 10” Pa; p = 2.64 g/cm 3

3. Explain the initial formation of the Appalachian mountain range.
What were the geologic periods and estimated time when this began
and reached its climax?
4. If the relative radiocarbon content of the remains of a plant is 1/7,
how long ago did the plant live? What geologic period and epoch
was this?
5. Define “craton.” Where are cratons located?
6. Discuss transgressive and regressive periods of sedimentary
deposition. Which period leads principally to the formation of
hydrocarbon source rocks? Why?
7. What are “clastics,” “granite wash,” “arkose,” and “graywacke”?
What are some general locations of these types of rocks?
8. Well logs of an area show that the temperature at the bottom of a
3,140 meter deep well is 92°C. If the mean surface temperature is
27”C, what is the geothermal gradient?
9. The composition of a brine sample from a geopressured zone
2,929 meters deep is listed below. Compare the brine sample analysis
to that of seawater (Table 2.3) and give a reasonable explanation
for the differences. What is the TDS of the brine?

Ion Concentration, ppm
Naf 29,400
Ca2+ 2,662
Mg2+ 1,011
K+ 172
Ba2+ 5
c1- 46,618
HCO- 714
so- 60
Br- 40
1- 23

10. The Saybolt viscosity of an oil is 117 seconds at 100OC. What is the
viscosity in centipoises if the oil density is 0.885 g/cm3?