clayshale

Clay / Shale Calculations

pypetrophysics.clayshale.gr_clay_shale_vol(minvalue, maxvalue, inputvalue, method='linear', limit_result=False, low_limit=0, high_limit=1)

Calculates a clay or shale volume from gamma ray log data.

Maxvalue can be set to represent 100% shale value when working with VShale, or it can be set to 100% clay when working with VClay.

Non-linear equations can be selected using the method argument:
larionov-young larionov-old steiber clavier
Parameters:
  • minvalue (float) – Value representing a 100% clean interval.
  • maxvalue (float) – Value representing either 100% clay or 100% shale.
  • inputvalue (float) – Gamma ray value from log measurements.
  • method (string) –
    Select method for calculating VClay or VShale:
    linear larionov-young larionov-old steiber clavier

    By default: linear

  • limit_result (bool, optional) – Apply limits to the result value. By default False
  • low_limit (int, optional) – Low limit. If value falls below this limit it will be set to this value. By default 0
  • high_limit (float, optional) – High limit. If value falls above this limit it will be set to this value. By default: 1
Returns:

Returns a VShale or VClay in decimal units.
Return type:

float

References

Larionov VV (1969) Borehole radiometry: Moscow, U.S.S.R., Nedra Steiber RG (1973) Optimization of shale volumes in open hole logs. J Petrol Technol 1973(31):147–162

Asquith and Krygowski (2004) Basic Well Log Analysis. Second Edition. Original paper reference cannot be found for Clavier (1971), however, the following discussion provides insight to its origins. https://www.researchgate.net/post/Volume_fraction_of_shale_full_reference_for_Clavier_1971

pypetrophysics.clayshale.sp_clay_shale_vol(minvalue, maxvalue, inputvalue, limit_result=False, low_limit=0, high_limit=1)

Calculates a clay or shale volume from SP log.

Maxvalue can be set to represent 100% shale value when working with VShale, or it can be set to 100% clay when working with VClay.

Parameters:minvalue (float) – Value representing a 100% clean interval.
maxvalue : float
Value representing either 100% clay or 100% shale.
inputvalue : float
Gamma ray value from log measurements.
limit_result : bool, optional
Apply limits to the result value. By default False
low_limit : int, optional
Low limit. If value falls below this limit it will be set to this value. By default 0
high_limit : float, optional
High limit. If value falls above this limit it will be set to this value. By default: 1
Returns:Returns a VShale or VClay in decimal units.
Return type:float