Abstract: Using Computer for Time-to-Depth Conversion and Structure Mapping in Complexly Faulted Areas

D. Szumilas

A computerized method of converting a time map on a structural horizon to depth, and generating structure and isopach maps has been of assistance in interpretation of geophysical data. The method was designed for use in complexly faulted areas to minimize hand calculations, thus facilitating the evaluation of large volumes of data.

Two manual operations are required to prepare data for the computer. First, the explorationist connects all significant fault traces on his time map to define fault blocks or "fault polygons." Second, the fault polygons and time contours are digitized as separate sets of data.

The computer then is used to perform all subsequent calculations. A computer program first converts the digitized time-contour data to depth using a time-sliced or depth-sliced velocity file or a selected conversion function. The final structure map then is generated by another program which uses the depth data to calculate a grid of depth values representing the structural surface within each fault polygon. These gridded depth values are contoured within the fault-polygon outlines. In addition, if structural surfaces of multiple horizons are available, isopach maps can be generated. Only those gridded structural values within a fault block are subtracted when creating the isopachs.

If the original digitized data are saved, this method, in addition to facilitating the evaluation of large volumes of data, provides the capability for quick regeneration of structure maps whenever a change is made in the velocity file.

AAPG Search and Discovery Article #90968©1977 AAPG-SEPM Annual Convention and Exhibition, Washington, DC