Dip profiles are graphs that show apparent dip as a function of distance along selected horizontal, vertical, or inclined lines on cross sections. Such profiles can be derived from dip-related data of any kind—surface data, subsurface data from maps and cross sections, seismic data, or dipmeter data, singly or combined. Their advantages for petroleum exploration are that (1) they organize dip-related structural and stratigraphic control into a single numerical package that can be evaluated on a "statistical" basis; (2) they often provide subtle clues to structural or stratigraphic conditions that are either missing, or not readily discernible, from other modes of data display; and, (3) they often provide surprisingly effective procedures for predicting deep structure, including drastic change of shape with depth, from shallow data.
The geometric basis for these capabilities is that the slope of a dip profile is directly related to the curvature of the bedding, as seen on a (transverse) cross section. Bedding curvature, however, is a conservative property of subsurface space and is characterized by various regularities that limit the range of permissible shapes that a dip profile may display. A dip profile accordingly, may show either zero slope, progressively increasing slope, progressively decreasing slope, or slope that is marked by the appearance of one or more of 10 possible "special points."
Figures & Tables
The Deliberate Search for the Subtle Trap
The papers included in this volume reflect both the geological and geophysical rationale used in searching for the subtle trap. The scope of the papers ranges from the general appraisal papers of new concepts and methods, to those relating to specific fields in the United States, Nigeria, China, Australia, Canada, Oman, offshore Spain, and the North Sea. The 21 chapters are sourced from a 1981 AAPG Annual Meeting session, dedicated to providing explorationists with the information needed to search for and discover the stratigraphic, paleogeomorphic, and unconformity-oriented subtle-trap accumulations of oil and gas.