Page 373 - Geology and Geochemistry of Oil and Gas

334 APPENDIX C

arched so that they dip in all directions away from the
center of the dome.
Sample [geol] A representative unit of a rock, cuttings, fluid, ore,
fossil population, or other entity for analysis or
display.
Sample [stat] A set of items selected from the population; if
properly selected may be used to estimate parameters
of population.
Sampling [stat] The process of selecting items from the population.
Sapropel Material composed of plant remains, most commonly
algae, that is or has macerated and putrefied in an
anaerobic environment: source material for
petroleum and natural gas.
Saturation Percentage of a particular fluid in a porous medium,
expressed as the percent of the pore volume.
Scale inhibitor Chemicals introduced into the producing well to
prevent the buildup of scale, paraffin, etc. These
can block off the flow of fluids and gas into the
wellbore.
Schizohaline Said of a water body or environment of fluctuating
salinity.
Screen liner Perforated pipe or wire mesh screen placed at the
bottom of the well to prevent larger formation
particles from entering the wellbore.
Seal An impermeable bed that acts as a barrier to the
vertical or lateral migration of hydrocarbons.
Sea-marginal Environments close to the sea, such as lagoons, tidal
flats, beaches, or deposits in these environments. Syn:
Marine-transitional.
Secondary cementing Any cementing operation after the primary cementing
operation including a plug-back job.
Secondary recovery The production obtained by introducing a second
source of energy, i.e., waterflooding.
Sediment [geol] Solid fragmental material, or a mass of such material,
either inorganic or organic, that originates from
weathering of rocks and is suspended in, transported
by, and deposited by air, water, or ice. Sediment can
also form as a result of coagulation of clays, chemical
precipitation from solution, or secretion by
organisms. It forms in layers on the Earth’s surface at
ordinary temperatures in a loose, unconsolidated
form; e.g., sand, gravel, silt, mud, loess, alluvium.
Sediment [prod] Particulate material (clay, silt, etc.) that is carried
along with the produced fluids and settles to the
bottom of the tank.