[[:file:applying-gravity-in-petroleum-exploration_fig15-10.png|Figure 1]] illustrates the fundamentals of measuring density using a [[borehole gravity]] sensor. Two gravity measurements, ''g''<sub>1</sub> and ''g''<sub>2</sub>, are made downhole, separated in depth by Δ''z''. The value ''G'' is the universal gravity constant. Thus, the gravity gradient, Δ''g''/Δ''z'', is related directly to the density of the intervening layer. The result is a direct computation of the bulk density of that layer. | [[:file:applying-gravity-in-petroleum-exploration_fig15-10.png|Figure 1]] illustrates the fundamentals of measuring density using a [[borehole gravity]] sensor. Two gravity measurements, ''g''<sub>1</sub> and ''g''<sub>2</sub>, are made downhole, separated in depth by Δ''z''. The value ''G'' is the universal gravity constant. Thus, the gravity gradient, Δ''g''/Δ''z'', is related directly to the density of the intervening layer. The result is a direct computation of the bulk density of that layer. |