Changes

==Depth of investigation==

==Depth of investigation==

[[file:applying-gravity-in-petroleum-exploration_fig15-11.png|300px|thumb|{{figure number|2}}Depth of investigation is tunable by means of varying the separation between two gravity measurements, Δ''z''. After McCulloh et al.<ref name=ch15r9>McCulloh, T., H., Kandle, J., R., Schoellhamer, J., E., 1968, Application of gravity measurements in wells to problems of reservoir evaluation: Transactions of the 9th Annual SPWLA Logging Symposium. Fundamental work describing the distance of sources seen by the borehole gravity meter.</ref> Copyright: SPWLA.]]

[[file:applying-gravity-in-petroleum-exploration_fig15-11.png|300px|thumb|{{figure number|2}}Depth of investigation is tunable by means of varying the separation between two gravity measurements, Δ''z''. After McCulloh et al.<ref name=ch15r9>McCulloh, T. H., J> R. Kandle, J. E. Schoellhamer, 1968, Application of gravity measurements in wells to problems of reservoir evaluation: Transactions of the 9th Annual SPWLA Logging Symposium. Fundamental work describing the distance of sources seen by the borehole gravity meter.</ref> Copyright: SPWLA.]]

[[:file:applying-gravity-in-petroleum-exploration_fig15-11.png|Figure 2]] shows how the depth of investigation is tunable by means of varying the separation between two gravity measurements, Δ''z''. The rule of thumb is that 90% of the gravity effect can be imaged at a distance away from the borehole within five times Δ''z''.

[[:file:applying-gravity-in-petroleum-exploration_fig15-11.png|Figure 2]] shows how the depth of investigation is tunable by means of varying the separation between two gravity measurements, Δ''z''. The rule of thumb is that 90% of the gravity effect can be imaged at a distance away from the borehole within five times Δ''z''.