Page 353 - Geology and Geochemistry of Oil and Gas

314 APPENDIX C

Formation resistivity F ¼ R 0 =R w , where R 0 is the electrical resistivity of a
factor formation 100% saturated with formation water and
R w is the formation water resistivity. F ¼ a f m ,
where f is the porosity, a is the empirical constant,
and m is the cementation factor (varies from 1.3 for
unconsolidated sands and oolitic limestones to 2.2 for
dense sandstones and dolomites). F embodies the
effects of grain size, shape, distribution, sorting, and
packing.
0
Formation resistivity F ¼ R t =R 0 , where R t is the true resistivity of a
index formation saturated with formation fluids (oil,
gas, water) in different proportions and R 0 is the
resistivity of a formation 100% saturated with
0
n
formation water. F ¼ aðS w Þ , where S w is the
water saturation, a is the empirical constant, and n
is the saturation exponent (varies from 1.6 for clayey
sands to 2 for clean, non-clayey sands and
limestones).
Formation testing The gathering of pressure data and fluid samples
from a formation to determine its production
potential before choosing a completion method. Syn:
Flow test.
Formation Volume Factor The volume of oil (and the solution gas dissolved in it)
(FVF or B) at reservoir pressure, p, and temperature, T, per unit
volume of stock-tank oil (at surface, T ¼ 601F and
p ¼ 1 atm).
Fossil Any remains, trace, or imprints of a plant or animal
that has been preserved, by natural processes, in the
Earth’s crust since some past geologic time; any
evidence of past life.
Fraction Percentage or fraction of a separate component of the
crude oil having a certain boiling point range.
Fracture acidizing Acid solution is injected into the formation at a high
enough pressure to fracture the formation. The acid
etches the new fracture.
Fracturing Artificial opening up (fracturing) of a formation, by
pumping fluids under high pressure, to increase
permeability and flow of oil to the well. See also:
Hydraulic fracturing, Fracture acidizing.
Framebuilder Organisms capable of creating massive, generally
wave-resistant buildups.
Framestone Reef rock that has formed as a result of the
accumulation of large, in-place fossils that formed the
actual framework of the deposits.