Abstract: A Finite Element Method to Restore a Folded and Faulted Gridded Surface

Michael D. Ward, Donald D. Clarke, Herbert G. Adams

The computer program Flatten_Surface was written to restore to its predeformational state a folded and faulted gridded surface by best fitting of finite elements. The method treats the regular grid of a surface as a series of columns of quadrilateral finite elements. The surface can be intersected with gridded fault surfaces. Through a series of 3-D rotations each element is rotated into the horizontal plane. Each element is fit to two of its previously fit neighbors by a simple iterative rotation procedure that balances the area of overlap/underlap or distance between adjoining elements. The filling procedure takes into account the faulted elements. This process is repeated until the surface area has been conserved.

Flatten_Surface was tested by unfolding two hand created perfect grids, one unfaulted and one faulted, a faulted sine curve, and a data set from the Wilmington Oil Field, CA. The hand created data sets and the faulted sine curve are perfectly restored on the first fitting. The Wilmington data set was rapidly restored with and an error in the surface area of 0.0009%.

It is felt that this program has a large potential for use in the petroleum industry.

AAPG Search and Discovery Article #90958©1995 AAPG Pacific Section Meeting, San Francisco, California