Page 357 - Geology and Geochemistry of Oil and Gas

318 APPENDIX C

Illite Very common and widely occurring group of clay
minerals; crystals form tiny flakes; formed by the
weathering decomposition or hydrothermal alteration
of muscovite or feldspar. Syn: Hydrous mica,
Hydromica.
Induction log Measurement of the formation resistivity response to
the induced current.
Inflow performance Plot of the flowing bottom-hole pressure versus the
relationship (IPR) flow rate, greatly influenced by the reservoir drive
mechanism.
Injection Placing fluids into the reservoir under pressure. See:
Carbon dioxide injection, Caustic injection.
In-situ combustion Enhanced recovery technique by starting a fire at the
injector to generate heat and gas to drive oil toward
the producing wells.
Interfacial tension The surface tension occurring at the interface between
two liquids that do not mix, such as oil and water.
Internal sediment Fine-grained sediment, including insoluble residue
that has collected in pores in sediments or rocks; such
sediment is generated syn-depositionally as a result of
organic boring and micritization, or partial
dissolution of soluble rocks.
Internal yield Minimum internal pressure to burst casing (pipe).
Interstitial Interparticle (either pore space, cement, or fluids).
Intrabasinal Said of sediments or rocks formed within or derived
from the basin of deposition. Cf: Terrigenous.
Intracratonic Geologic features found on cratons, e.g.,
intracratonic basins, intracratonic seas.
Intrastratal Formed or occurring within a given layer or layers.
Syn: Intra-formational.
Irreducible fluid saturation Equilibrium saturation of the wetting phase, which
cannot be lowered by flowing indefinitely a non-
wetting phase through a porous medium, providing
evaporation does not take place.
Isopachous Cement which completely lines the pores in a rock.
Syn: Circum-granular.
Isotropic medium A medium whose physical properties are the same in
all directions. Cf: Anisotropic medium.

J
Jackup drilling rig A mobile bottom-supported offshore drilling
structure with columnar or open-truss legs that
support the deck and hull.
Joint Single section of a pipe.