ABSTRACT

Growth structures form as sediments are deposited near active faults, mobile salt or in subsiding basins. The law of superpostion requires that the growth section be deposited in a systematic manner. The growth section obeys non-random processes and records the history of deposition along with the dynamic processes that affect the deposition of sediments. Accordingly, correlations obtained from the growth section record the progressive history of structures. In order to study the growth history using Dd/d, the correlations are usually presented in the form of a graph. Surprisingly, on the plots of Dd/d the correlations often plot along monotonic or linear curves. Although growth plots confirm that sediments are deposited systematically, growth typically changes abruptly across sequence boundaries, disconformities, and active faults. Abrupt changes in growth on the plots indicate abrupt tectonic or stratigraphic changes. Correlation data points that deviate from the general linear trends may represent stratigraphic miscorrelations. The Dd/d Growth Plot Analysis is a powerful technique. Growth plots are used to rapidly distinguish faults from unconformites in areas of high bed dip and poorly imaged 3-D seismic data; to locate sequence boundaries and subtle stratigraphic traps; to identify and solve correlation problems in areas of rapidly changing lithology; to identify high growth or potentially thick sand rich intervals on seismic profiles; to determine the time of structural growth and fault timing; to check interpretations for consistency; and to rapidly identify problems that may go unrecognized using standard interpretation techniques. The high-resolution Dd/d technique graphically displays the growth history of an area in a manner that is readily interpreted. The technique is applied to several correlation problems that were encountered while mapping around salt. On one diapir the well logs could not be confidently correlated due to rapid stratigraphic thinning onto salt, and the 3-D seismic data set did not image the high bed dips. The initial interpretation resulted in two horizons that crossed each other. Growth plots may resolve mapping problems where problems exist in correlating the well logs or 3-D seismic data.