
Publication History:
This article is based on
"Crain's Seismic Petrophysics" by E. R. (Ross) Crain, P.Eng., first
published in 2003, and updated annually until 2016.
This
webpage version is the copyrighted intellectual
property of the author.
Do not copy or distribute in any form without explicit
permission. 
SEISMIC
CURVE and PARAMETER MNEMONICS The log curve names and parameter names used in the
equations on this website have been chosen to be easily
recognized and to be "computerready". The names do not
reflect any particular service company's nomenclature.
Three simple rules were used: input parameters and input log
curves are always UPPER case; output curves or output result
values are MIXed case. There are no subscripts or
superscripts, and Greek symbols are spelled ponetically
As for all rules, there are exceptions, especially for
output result values where commonly used abbreviations are
well established, such as OOIP for original oil in place.
Output curves from one calculation step are often input
curves for a succeeding calculation, but the inout curve
does not become upper case, because it is still an output
curve from the prior step.
For example: DENS or PHID or RESD are input log curves DENSMA or CPERM are an input analysis parameters DENSma or PHIe are output log curves and could be inputs to another
calculation Reserves or OOIP are output result values
Computer software needs to distinguish between a log curve
and a parameter value. Each software package does this in
different ways. For example, the distinction is declared in
some packages, or a special symbol may be used to define a
loog cure, such as [ ] after the curve name.
See Also:
Log Curve Alias Table
Abbreviations for Log Analysis
THE LIST
Nomenclature  Log Analysis Calculations
BVWSH = bulk volume of water bound to 100 % shale
(fractional) DTC = sonic log reading (usec/ft or usec/m) DTCc = sonic log reading corrected for shale (usec/ft or
usec/m) DTCMA = sonic log reading in 100% matrix rock (usec/ft or
usec/m) DTCSH = sonic log reading in 100% shale (usec/ft or usec/m) DTCW = sonic log reading in 100% water (usec/ft or usec/m) DENS = density log reading (gm/cc or Kg/m3) DENSc = density log reading corrected for shale (gm/cc or
Kg/m3) DENSMA = density log reading in 100% matrix rock (gm/cc or
Kg/m3) DENSma = calculated matrix density (gm/cc or Kg/m3) DENSSH = density log reading in 100% shale (gm/cc or Kg/m3) DENSW = density log reading in 100% water (gm/cc or Kg/m3) DENS1 = density log reading in 1st mineral (gm/cc or Kg/m3) DENS2 = density log reading in 2nd mineral (gm/cc or Kg/m3) DEPTH = formation depth (ft or m) GR = gamma ray log reading (API units) GR0 = gamma ray log reading in 100% clean zone (API units) GR100 = gamma ray log reading in 100% shale (API units) KBUCKL = Buckles number (porosity saturation product 
fractional) KCP = sonic log compaction factor (fractional) Min1
= bulk volume of 1st mineral (fractional) Min2
= bulk volume of 2nd mineral (fractional) PE = effective photoelectric cross section (barns/cm3) PE1 = PE log reading in 1st mineral (barns/cm3) PE2 = PE log reading in 2nd mineral (barns/cm3) PESH = photoelectric log reading in 100% shale
(barns/electron) PHIbvw = effective porosity from BVW method (fractional) PHID = density log reading (fractional)PHIdc = porosity from
density log corrected for shale (fractional) PHIDSH = density log reading in 100% shale (fractional) PHIe = effective porosity (fractional) PHIMAX = maximum expected porosity in clean rock
(fractional) PHIN = neutron porosity log reading (fractional) PHInc = neutron porosity corrected for shale (fractional) PHIs = total porosity from sonic log (fractional) PHIsc = porosity from sonic log corrected for shale
(fractional) PHISSH = sonic porosity of 100% shale (fractional) PHIt = total porosity (fractional) PHIxnd = porosity from density neutron crossplot
(fractional) RESD = deep resistivity log reading (ohmm) Rwa = apparent water resistivity (ohmm) RWSH = water resistivity of water bound to shale (ohmm) SP = spontaneous potential log reading in zone of interest (mv) SP0 = spontaneous potential log reading in 100% clean zone (mv) SP100 = spontaneous potential log reading in 100% shale (mv) Sw = calculated water saturation from any method
(fractional) Vsh = shale volume from any method (fractional) Vshg = shale volume from gamma ray log (fractional) Vshs = shale volume from spontaneous potential log
(fractional) Vshx = shale volume from density neutron crossplot method
(fractional)
Nomenclature  Seismic Calculations
AcImp = acoustic impedance (g/sec/cm2) AcImp1 = acoustic impedance above boundary (g/sec/cm2) AcImp2 = acoustic impedance below boundary (g/sec/cm2) ALPHA = Biot's elastic constant (frac) ANGLE = incidence angle measured from vertical (degrees) Atten = acoustic attenuation (db/ft or db/m) AZM = azimuth of hydrophone from surface location of well minus the
azimuth of the geophone from the surface location of the well (degrees) C
= drift correction constant for each data point (fractional) C
= correction factor for offset (frac) D
= total drift between integrated sonic and seismic checkshot data (msec) DTC = sonic travel time of compressional wave (us/m) DTCmod = corrected sonic log reading (usec/ft or usec/m) DTCHY = sonic travel time of hydrocarbon (usec/ft or usec/m) DTCi = sonic travel time of ith component of matrix rock (usec/ft or
usec/m) DTCMA = matrix travel time for compressional wave (us/m) DTS_MA = matrix travel time for shear wave (us/m) DTCmod = sonic travel time of composite material (usec/ft or usec/m) DTS = sonic travel time of shear wave (us/m) DTst = sonic travel time of Stoneley wave (us/m) DTCSH = sonic travel time of shale (usec/ft or usec/m) DTCW = sonic travel time of water (usec/ft or usec/m) DENS = density log reading in a rock/fluid mixture (gm/cc or Kg/m3) DENSHY = density log reading in 100% hydrocarbon (gm/cc or Kg/m3) DENSi = density log reading in 100% of the ith component of matrix
rock (gm/cc or Kg/m3) DENSMA = matrix density (Kg/m3) DENSmod = calculated density log reading (gm/cc or Kg/m3) DENSSH = density log reading in 100% shale (gm/cc or Kg/m3) DENSW = density log reading in 100% water (gm/cc or Kg/m3) DEPTH = true depth (ft or m) Dhg = depth below hydrophone to geophone (ft or m) Dhy = depth of hydrophone below seismic reference datum (ft or m) Dkbg = depth below kelly bushing to geophone (ft or m) Dsrd = depth below seismic reference datum to geophone (ft or m) Drat = density contrast (ratio lower to upper layer density) Dstr = calculated straight ray depth (ft or m) Dtrue = calculated true depth (ft or m) Ekb = elevation of kelly bushing relative to sea level (ft or m) H1 = depth at bottom knee of drift curve segment (ft or m) H2 = depth at top knee of drift curve segment (ft or m) Hg = horizontal offset of geophone from surface location of well (ft
or m) Hhg = horizontal distance from hydrophone to geophone in deviated
well (ft or m) Hi = rock layer thickness (ft or m) INCR = sonic log data increment (ft or m) K
= acceleration parameter in average velocity equation (ft/sec or
m/sec) L
= distance between receivers (meters) NMO = normal moveout measured on seismic record (sec) NMOc = calculated normal moveout (sec) PHID = total porosity from density log (fractional) PHIe = effective porosity (fractional) PHIS = total porosity from sonic log (fractional) PHIsc = effective porosity from sonic log (fractional) PHItrue = true porosity of the reservoir (fractional) PHIvug = porosity in vugs (fractional) PHIx = effective porosity derived from density neutron crossplot
method (shale corrected) Refl = reflection coefficient (fractional) Refl1 = reflection coefficient of upper layer (fractional) Sw = water saturation in undisturbed zone (fractional) Sxo = water saturation in invaded zone (fractional) T1 = two way seismic time at top of layer (sec) T2 = two way seismic time at bottom of layer (sec) Tc = time at first arrival of compressional wave (usec) Ti = two way interval time through layer (sec) To = near trace (vertical) two way travel time (sec) To = time at onset of sound impulse (usec) Ts = slant path time (sec) Ts = time at first arrival of shear wave (usec) Tv = vertical time (sec) Tx = far trace (slant path) two way travel time (sec) Vavg = average velocity (ft/sec or m/sec) Vc = compressional velocity (m/sec) Vint = rock layer interval velocity (ft/sec or m/sec) Vinv1 = interval velocity of upper layer (ft/sec or m/sec) Vinv2 = interval velocity of lower layer (ft/sec or m/sec) Vo = initial velocity near surface (ft/sec or m/sec) Vp = compressional wave velocity (ft/sec or m/sec) Vrat = velocity contrast (ratio lower to upper layer velocity) Vs = shear velocity (ft/src or m/sec) Vst = Stoneley velocity (ft/sec or m/sec) Vstk = stacking velocity (ft/sec or m/sec) Vstk1 = root mean square velocity at top of layer (ft/sec or m/sec) Vstk2 = root mean square velocity at bottom of layer (ft/sec or
m/sec) X
= horizontal spread length (ft or m)
