Depth Extent - A Practical Example in Magnetic Depth Estimation

Corrections for depth extent, or the thickness of the assumed magnetic body, are critical in obtaining accurate magnetic depth to basement estimates in common exploration environments. However, determination of the correct thickness to depth (T/D) ratio would seem to require a pre-supposition of the approximate depth to basement and magnetic layer thickness. We show by application to the "Bishop" model that significant improvements in depth to magnetic basement can be made by incorporating a thickness to depth (T/D) ratio in our depth calculations by making reasonable geologic assumptions even when no a-priori knowledge exists as to the appropriate T/D to use. Using basic assumptions of isostasy combined with known geologic information gained through integration with seismic, gravity and well control yields even better results with limited additional effort. Better magnetic depth to basement estimates can have a direct impact in improving regional structural and basin models resulting in an improved understanding of the regional tectonic elements and play characteristics.