Page 355 - Geology and Geochemistry of Oil and Gas

316 APPENDIX C

of the distribution and abundance of isotopes,
including problems of nuclear frequency and stability
in the universe.
Geologic system ‘‘A well-organized natural assembly of interconnected
and interacting elements of lithosphere having
common development history and comprising a single
natural unit with properties that are not inherent in
its individual elements.’’ (Buryakovsky, 1992,
pp. 273–295).
Geomathematics Mathematics as applied to geology; ‘‘the closely
interrelated system involving mathematical and
applied statistics, experimental design, and associated
computer techniques as applied to geological
sciences’’ (Osborne, 1969, in: Vistelius, 1980). See
also: Mathematical geology.
Geophone Microphone placed near the Earth’s surface to detect
seismic waves.
Gilsonite A black, shiny asphaltite with conchoidal fracture
and black streak, which is soluble in turpentine. Syn:
Uintahite.
Grainstone Grain-supported carbonate rock textural type,
generally mud-free. Syn: Sparite.
Gravity drainage Gravity force results in movement of oil downward as
the gas migrates upward. This force is strong in
steeply dipping reservoirs.
Gum Naturally occurring or synthetic hydrophylic colloids
used to control various properties of drilling fluids.
Gypsum A naturally occurring crystalline form of calcium
sulfate (CaSO 4 2H 2 O).

H
Hardground General term for a surficial or near-surficial layer of
sediment that is cemented syndepositionally, close to
or at the sediment–water interface.
Hard water Water containing more than 60 mg/l (60 ppm) of
hardness-forming constituents (calcium and
magnesium) expressed as CaCO 3 equivalent. Cf:
Alkaline (soft) water.
Heater-treater A vessel that heats an emulsion and removes water
and gas from the oil to raise it to a quality acceptable
for a pipeline or other means of transport. Syn: Oil
treater.
Hemipelagic Deep-sea sediments composed of the remains of
pelagic organisms and small amount of terrigenous
material.