Two methods that extract automatically geological information from a dip file, are described and applied to field examples. The first method is devoted to extract automatically structural information from any dip file in order to facilitate cross-sections and 3-D modeling of the structures. This method relies on the basic idea that each structure such as fold, drag or rollover can be described in first approximation as part of a cylindrical or conical surface corresponding respectively to a great or small circle on a stereoplot. The processing of this method provides the user with the main structural parameters: the number of structures, their axes, their location in the well, and the structural dip at any depth of the well where dip information is available. This method is divided into three steps:
filtering the raw data both on quality and continuity, in order to keep dips with a structural significance;
grouping inside a file the dips whose poles are compatible with a same structure, i. e. the dips fitting a same great or small circle;
smoothing these dips according to structural trends.
The advantages and the limits of such single-well methods will be discussed from actual examples coming from different structural environments. The second method concerns a structural Dip-Removal based on stereoplot analysis of the layer curvatures. This method is based on two observations: first, most of sedimentary features or microstructures can be described locally as being parts of a cylindrical surface. Secondly most of the axes of these cylinders were initially horizontal, i. e. each local curvature axes corresponds to a line initially horizontal. Starting from these observations, the computation of the "structural dip" consists in determining the plane best fitting the local curvature axes, provided they are sufficiently varied. Applied to dip files obtained through different processing, this method provides both the actual structural dip and the "removed" sedimentary dips that can be used to figure out the sedimentary features, their orientations and to draw their cross-sections.
