Changes

* ''i'' = next survey point below the marker depth

* ''i'' = next survey point below the marker depth

More sophisticated approaches to well-depth correction are the radius of curvature method ([[:file:conversion-of-well-log-data-to-subsurface-stratigraphic-and-structural-information_fig5.png|Figure 5a]]) and the minimum curvature method ([[:file:conversion-of-well-log-data-to-subsurface-stratigraphic-and-structural-information_fig5.png|Figure 5b]]). The ''radius of curvature method'' approximates the well path as a circular arc in the vertical plane, which is then wrapped around a vertical cylinder. The equations in the method (from <ref name=pt06r20 />) are as follows:

More sophisticated approaches to well-depth correction are the radius of curvature method ([[:file:conversion-of-well-log-data-to-subsurface-stratigraphic-and-structural-information_fig5.png|Figure 5a]]) and the minimum curvature method ([[:file:conversion-of-well-log-data-to-subsurface-stratigraphic-and-structural-information_fig5.png|Figure 5b]]). The ''radius of curvature method'' approximates the well path as a circular arc in the vertical plane, which is then wrapped around a vertical cylinder. The equations in the method (from Dailey<ref name=pt06r20 />) are as follows:

:<math>\mbox{TVD}  = (180/\pi)\sum (\mbox{MD}_{i} - \mbox{MD}_{i-1}) \times (\sin \alpha_{i} - \sin \alpha_{i-1}) /(\alpha_{i} - \alpha_{i-1})</math>

:<math>\mbox{TVD}  = (180/\pi)\sum (\mbox{MD}_{i} - \mbox{MD}_{i-1}) \times (\sin \alpha_{i} - \sin \alpha_{i-1}) /(\alpha_{i} - \alpha_{i-1})</math>