Changes

* Deviation is rarely constant in a well, even when that is the objective of drilling.

* Deviation is rarely constant in a well, even when that is the objective of drilling.

[[file:conversion-of-well-log-data-to-subsurface-stratigraphic-and-structural-information_fig1.png|thumb|{{figure number|1}}Surface projection of well course for a nominally vertical well. Copyright: Don Clarke, Dept. of OH Properties, City of Long Beach, CA).]]

[[file:conversion-of-well-log-data-to-subsurface-stratigraphic-and-structural-information_fig1.png|thumb|{{figure number|1}}Surface projection of well course for a nominally vertical well. © Don Clarke, Dept. of OH Properties, City of Long Beach, CA).]]

[[file:conversion-of-well-log-data-to-subsurface-stratigraphic-and-structural-information_fig2.png|thumb|{{figure number|2}}Well course of two types of deviated wells. True stratigraphic thickness and true vertical thickness of a dipping stratigraphic unit are shown in relation to the measured interval in a well penetrating the unit.]]

[[file:conversion-of-well-log-data-to-subsurface-stratigraphic-and-structural-information_fig2.png|thumb|{{figure number|2}}Well course of two types of deviated wells. True stratigraphic thickness and true vertical thickness of a dipping stratigraphic unit are shown in relation to the measured interval in a well penetrating the unit.]]