Automatic Seismic Reflection Picking

Abstract

A computational system is described that detects seismic reflections recorded digitally on magnetic tape, performs migration if desired, and plots the information in cross‐section form. The detection or “picking” philosophy is based on the selection of the time positions of either all peaks or all troughs in the set of traces which constitutes the seismic section of interest. A lateral continuity search “correlates” these peaks or troughs across the traces in order to define reflection segments. All reflection segments which span at least three consecutive traces are stored in digital format on magnetic tape. They are given a grade which is the product of their spatial span and mean amplitude. A time‐varying grading threshold is employed to limit the number of reflection segments which are output to an automatic plotter or carried for subsequent processing such as computer migration. Several examples of these automatically derived cross sections are shown and compared with the original variable‐area record sections. This system is readily extended to multiline or grid data. Thus it is feasible to generate and display automatically three‐dimensional interpretive aids such as isochrons and isopachs.

5. Refraction Surveys

“…This principle can be extended so that appropriate picked times from consecutive traces are joined together to form a refractor segment or event (e.g., Paulson and Merdler, 1968;Chun and Jacewitz, 1980, 1983. For example, a simple comparison of the refraction arrival times from one source to two consecutive receiver locations can be made to verify that the time difference is within an acceptable limit, after taking the refractor moveout into account.…”

Pointe Automatique*

“…Pour illustrer ce que nous venons de dire, nous reprenons l'étude de l'hyperbole de &ffraction de la figure g. Nous voulons mettre en évidence les branches La méthode utilisée pour élaborer ce programme présente des points communs avec celle décrite par Paulson et Merdler (1968 . 9).…”

“…II) en appliquant le troisième schkma constitué de trois éventails. L'éventail central a une ouverture 02 = 6 ms et les deux éventails latéraux ont la même ouverture WI = ws = 8 ms équidistants du milieu d'une distance II = IZ = IO ms.La méthode utilisée pour élaborer ce programme présente des points communs avec celle décrite parPaulson et Merdler (1968). L'usage dde souplesse au programme et les temps de calcul doivent être plus courts.Le second programme est conçu pour le traitement de structures géologiques complexes telles que l'étude de failles, de biseaux.…”

Pattern analysis of seismic records

“…They have been proposed by others (Paulson and Merdler, 1968;Schneider, 1971) for automated seismicsection analysis, but pattern recognition (Fu, 1974;Chen, 1984) provides an attractive alternative for the initial steps in seismic data analysis (Bois, 1980(Bois, , 1982Liu and Fu, 1982;Lu, 1982). Often in such approaches seismic traces become lists of elements that summarize the shapes of short segments of the trace.…”