DUG Insight trends define depth-dependent relationships between key elastic properties of lithologies. Trends can be generated using DUG Rock, but can also be estimated using other software and spreadsheets.
The depth-dependent trends define the relationship between Depth and Vp, Vp to Vs, Vp to Rho and, for reservoir lithologies, Vp to porosity. The trend equation for each relationship is a linear function, except for Vp - Rho (non-reservoir) which is defined by a power law.
Each trend function also includes an error parameter to describe the uncertainty or scatter inherent to the lithology.
where terms A and B are constant.
Trends can be imported into Insight using the Import menu from the Control Panel.
Fluid parameters define values for Vp and Rho with standard deviation values.
Lines or sections of lines starting with the "#" character are comments and are not read or processed.
The "Reference Fluid" parameters describe the fluid in place for the reservoir trends.
Because different picks and log sections will have different in-situ fluids, Gassmann fluid substitution must be performed on inputs to trends to ensure they are consistent and are not affected by local hydrocarbon or fluid effects.
In Dug Rock, this is performed by enabling the "Gassmann" checkbox.
Three additional parameters can be specified for trends, but are not required. These values account for the covariance between the various pairs of errors (i.e. Vp-Vs, Vp-Rho and Vs-Rho).