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116 PETROLEUM GEOLOGY
6.6.2 True/False
6.1 The K–T boundary is the boundary between the Earth’s crust and mantle.
6.2 A hydrocarbon reservoir must be able to trap fluids.
6.3 Formation volume factor is the ratio of surface volume to reservoir volume.
6.4 Capillary pressure must be a positive value.
6.5 Porosity is the fraction of void space in rock.
6.6 The Paleocene epoch is part of the Mesozoic era.
6.7 Mountain ranges can be formed by the collision of tectonic plates.
6.8 Reservoirs are found in sedimentary basins.
6.9 Volumetric analysis depends on dynamic information.
6.10 A microdarcy is greater than a nanodarcy.
6.6.3 Exercises
6.1 The temperature in some parts of the Earth’s crust increases by about 1 °F for
every 100 ft of depth. Estimate the temperature of the Earth at a depth of 2 mi.
Assume the temperature at the surface is 60 °F. Express your answer in °C.
6.2 A. A formation contains 10 ft of impermeable shale, 30 ft of impermeable
mudstone, and 60 ft of permeable sandstone. What is the gross thickness of
the formation?
B. What is the net‐to‐gross ratio of the formation?
6.3 A. Suppose a reservoir is 3 mi long by 6 mi wide and has an average gross
thickness of 40 ft, a net‐to‐gross ratio of 0.7, and a porosity of 0.18. Well
logs show an average water saturation of 0.30. An oil sample has a
formation volume factor of 1.4 RB/STB. We can calculate original oil in
place (in STB) using the following procedure.
B. What is the bulk volume of the reservoir (in RB)?
C. Calculate the pore volume of pay in the reservoir (in RB) if porosity is
0.18 and net‐to‐gross ratio is 0.7.
D. If the reservoir has an oil saturation of 0.7, what is the volume of oil in the
reservoir (in RB)?
E. Calculate original oil in place (in STB).
6.4 Radiometric dating is accomplished using the age equation
t D
t = half ln 1 +
ln2 P
where t is the age of the rock or mineral specimen, t is the half‐life in years
half
of the parent isotope, P is the current number of atoms of the parent isotope,
