Real time petrophysical evaluation system

Apparatus for petrophysically evaluating a subsurface formation comprising:

• a spectroscopy device,
• a density device,
• a neutron device,
• a resistivity device,
• means for determining formation porosity, permeability, hydrocarbon/water saturation, and irreducible water saturation using measurements from said spectroscopy, density, neutron, and resistivity devices.

A subsurface formation petrophysical evaluation method comprising:

• making a plurality of different measurements on a subsurface formation;
• said measurements including indicators of a plurality of absolute or relative formation elemental concentrations;
• processing said measurements to determine a plurality of parameters associated with said subsurface formation;
• and
• determining subsurface formation net pay intervals based on said determined parameters and interval acceptance criteria.

A subsurface formation petrophysical evaluation method comprising:

• making a plurality of different measurements on a subsurface formation while drilling;
• said measurements including indicators of a plurality of absolute or relative formation elemental concentrations;
• processing said measurements to determine a plurality of parameters associated with said subsurface formation;
• and
• determining drilling parameters based on said determined parameters and desired wellbore criteria.