Oilfield Glossary
Oilfield Glossary
Search by Discipline
Terms beginning with:
# A B C D E F

Formation Evaluation

516 result(s) found.

 formation evaluation Ascertaining the location and properties of subsurface lithological layers requires acquisition and interpretation of well logs. Logs can be drawn by hand to reflect lithology as cuttings are pumped to surface; or they can be acquired by wireline logging tools lowered into the well, or while drilling, using specially instrumented drill collars that make up part of the drilling assembly. Interpretation can be carried out by hand, using established log analysis formulae, or by sophisticated computer routines. Formation evaluation is the key to determining whether a well has struck pay, or is just a dry hole. Terms in this discipline range from Archie equation to logging, and from permeability to Z/A effect. All definitions have been reviewed by formation-evaluation experts, and many are accompanied by high-quality photographs or illustrations.

Variables and Numbers

Sor m Sw 6FF40
a n


a activation log API unit array sonic
accelerator source adjacent bed apparent matrix attenuation
accuracy Alford rotation Archie equation attenuation resistivity
acid effect alpha processing Archie rock azimuthal
acoustic log altered zone armor azimuthal density
acoustic mode aluminum activation log array induction azimuthal laterolog
acoustic transducer annulus array laterolog azimuthal resolution
acquisition log antisqueeze array propagation resistivity


backup curve bit resistivity bottomhole temperature broadside array
bad hole borehole compensation bound fluid bucking coil
balanced array borehole correction bound water bucking current
base exchange borehole gravity bound-fluid log bulk relaxation
base log borehole gravity meter Boyle's Law buoyancy method
BHT borehole televiewer Boyle's Law Double Cell butterfly chart
bimetallism Born method Boyle's Law Single Cell button resistivity
Biot theory bottom log interval bridle


cable centralizer Compton scattering corrected gamma ray
cake centrifuge computed tomography correlate
calibration channeling conductive invasion correlation log
camera chemical neutron source conductive rock matrix model CPMG
capillary pressure curve clay bound water conductivity cross dipole
carbon density clay-bound water conductometric titration cross section
carbonate gamma ray coding core crossplot porosity
cartridge compatible scales core analysis crosswell electromagnetic tomography
cation exchange capacity compensated density log core gamma log crosswell reflection tomography
cation-exchange capacity compensated neutron log core image crosswell seismic tomography
cave effect compensated-density log core plug crosswell tomography
cement bond log composite log corkscrew hole curve
cementation exponent compressibility


data rate depth correlation detail log diffusion relaxation
Dean-Stark extraction depth datum diameter of invasion dip correction
deconvolution depth derived diameter of investigation direct hydrocarbon typing
deep induction depth mark dielectric constant dispersed clay
delta rho depth matched dielectric permittivity distillation extraction
delta t depth of invasion dielectric propagation log drainage
delta t stretch depth of investigation dielectric resistivity drained test
delta-t stretch depth reference differential SP drillpipe conveyed
density measurement depth wheel differential spectrum dual induction
departure curve depth-derived diffusion dual water


eccentralizer electrical double layer electromagnetic propagation epithermal neutron porosity measurement
echo spacing electrical log electromagnetic propagation measurement equivalent conductance
effective porosity electrical survey elemental capture spectroscopy equivalent water resistivity
effective water saturation electrode device endfire array estimated ultimate recovery
elastic neutron scattering electrode resistivity enhanced diffusion excavation effect
electrical anisotropy electrokinetic potential environmental corrections


far water filtrate slump flushed-zone water saturation free fluid
fast diffusion first reading formation free induction decay
fast formation fish formation evaluation free water
fast formation arrival fishing bell formation exposure time free-induction decay
fast neutron reaction flexural mode formation factor fresh core
fast-formation arrival fluoroscopy formation water fresh water
fast-neutron reaction flushed zone forward modeling FTIR
filtrate flushed zone water saturation Fourier transform infrared spectroscopy full waveform


Gal gamma-gamma log GR guard electrode
gamma ray interactions geochemical log grain density guard log
gamma ray log geometrical factor gravity units


head heading housing hybrid scale
head wave horizontal resistivity Humble formula hydrogen index


ID induced gamma ray spectroscopy insert inverse
IM induction in-situ fluid analysis inverse filter
imbibition induction electrical survey interwell tomography irreducible water
in situ fluid analysis inelastic neutron scattering invaded zone isolated porosity
in situ viscosity evaluation inertial resistance invasion iterative forward modeling


J factor


K coefficient


lag leaky mode liquid-junction potential logging tool
laminated sand limestone compatible scale log logging unit
laser diffraction limestone porosity unit logarithmic mean long spacing sonic log
last reading limestone-compatible scale logging longitudinal relaxation
lateral liquid saturation method logging run long-spacing sonic log


m measurement error microlaterolog monopole
magnetic mud measurement range microlog moveable hydrocarbons
magnetic resonance medium induction microporosity moved hydrocarbons
maximum recorded temperature membrane potential microresistivity mud filtrate
measure point mercury displacement method microspherical log mudcake
measurement after drilling microcylindrical log minute mark multiple salinity


n neutron generator neutron porosity normal mode
native state core neutron interactions NMR nuclear magnetic resonance
natural gamma ray spectroscopy neutron log normal nuclear magnetic resonance measurement
neutron capture


oil wet oil-wet oxide closure model oxide-closure model
oilfield battery


pad phase shift resistivity pore throat propagation time
pair production phase-shift resistivity porosimeter proximity log
parallel resistivity photoelectric effect porosity exponent pseudogeometrical factor
pass Pickett plot porosity unit pseudostatic spontaneous potential
PEF pickup porous plate technique PSP
permanent datum pick-up potassium pulse echo
permeameter play back precision pulsed neutron spectroscopy log
permittivity playback preserved core pulsed neutron spectroscopy measurement
perpendicular resistivity polarization horn propagation resistivity pulse-echo
phase shift polarization time propagation resistivity measurement


quadrant density quick look quicklook


R signal real-time data reproducibility restored state core
Rh recorded data reservoir quality (RQ) retort method
Rv recorder residual oil ring resistivity
Rwa reference point residual oil saturation ROS
radial processing relative dielectric constant resistive invasion routine core analysis
radial resolution relative dielectric permittivity resistivity R-signal
radial response relaxation time resistivity index rugose
radius of investigation remaining oil saturation resistivity log rugosity
random error repeat section resolution matched run
real time data repeatability response matched


sampling error sidewall sonde error standoff
sampling interval sidewall core sonic measurement static spontaneous potential
sandstone compatible scale sieve analysis SOR steady state
sandstone porosity unit sigma Soxhlet extractor step profile
sandstone-compatible scale skin effect SP stick and slip
saturation equation slow formation specific permeability Stoneley permeability
saturation exponent slowing-down length spectrum stress induced anisotropy
saturation unit slowing-down time spherical focusing stress-induced anisotropy
scintillation detector slowness spine and ribs plot structural shale
secondary porosity index slowness time coherence spiral borehole summation of fluids method
secondary-porosity index slowness-time coherence spontaneous potential surrounding bed
shale baseline small pore water spreading loss survey
shifted spectrum small-pore water square log systematic error
shoulder bed sonde SSP


T1 thermal diffusion length time-lapse trace
T2 thermal neutron absorber tool string track
tail thermal neutron porosity measurement top log interval transition zone
tapered cutoff thorium tornado chart transmission tomography
telemetry tick mark torpedo transverse relaxation
terrain correction time after bit tortuosity true resistivity
thermal capture time lapse total porosity


UCS uncertainty undrained test unsteady state
ultra-long spaced electrical log unconfined compressive strength uniaxial compressive strength uranium
ultrasonic measurement undisturbed zone


variable-density log verification listing vertical resolution virgin zone
verification vertical resistivity vertical response volumetric cross section


wait time water wet well log whole core
wall cake water-filled resistivity wet clay porosity wireline
water filled resistivity water-wet wet-clay porosity wireline log
water saturation weak point wettability


X signal X-ray diffraction X-ray fluorescence (XRF) X-signal


Z/A effect