petrophysical crossplots

I recently developed a computer program that generates some petrophysical and elastic parameters from well logs such as water saturation and hydrocarbon saturation, bulk volume, irreducible water saturation, porosity, permeability, shear impedance, acoustic impedance, and poisson ratio. I would like to know which parameters to cross-plot. For example, can you use a cross-plot of depth versus acoustic impedance for detection of hydrocarbons? My analysis is aimed at reservoir characterization.

• Neutron-density is often useful, if you have access to that data. What do you mean by generate? Is it a synthetic model? – Tactopoda Aug 15 '15 at 20:31
• thanks a lot for the help, Neutron-density cross-plot is for differentiating the phase of the hydrocarbon(i.e either oil and gas), and i meant compute(to calculate) instead of generate. – Taiwo Aug 18 '15 at 9:21

1. Condition all your data. Compute any 'missing' data you need or want (e.g. porosity $\phi$, lithofacies, saturation $S_\mathrm{W}$, S-wave velocity $V_\mathrm{S}$).
2. Inspect crossplots of relevant properties like velocity vs porosity, acoustic impedance vs elastic impedance (or maybe Poisson's ratio or ${V_\mathrm{P}}/{V_\mathrm{S}}$), and so on, colouring points by depth, $S_\mathrm{W}$ or lithofacies, say. Look for helpful discrimination.
Here are some nice $V_\mathrm{P}/V_\mathrm{S}$ vs acoustic impedance $I_\mathrm{P}$ crossplots from Amato's second tutorial to inspire you: