Estimating formation parameters. At least some of the illustrative embodiments are methods including: combining a first plurality of actual logs from a first plurality of actual boreholes, at least one actual log associated with each actual borehole, and thereby creating a first equivalent log along a first equivalent path; combining a second plurality of actual logs from a second plurality of actual boreholes, at least one actual log of the second plurality of actual logs associated with each actual borehole of the second plurality of actual boreholes, and thereby creating a second equivalent log along a second equivalent path; and estimating a plurality of values of a parameter of one or more formations along a proposed borehole path, each value associated with a distinct depth along the proposed borehole path, the estimating using the equivalent logs.