Abstract: At least some of method and system embodiments extrapolate any given set of horizons to cover a specified area of interest in such a manner that the horizons are conformable to each other. An automated dual-extrapolation approach is employed, beginning with horizon extrapolations using a proportional method where possible, and following that with a horizon extrapolations using a thickness-based method. With proper selection of the extrapolation order, the set of horizons remains fully conformable. The process of deriving a structural 3D model from partial horizons in fields lacking field-wide reference horizons is facilitated, making it more feasible to fully model complex fields and correct errors in such models.