Changes

[[file:applying-gravity-in-petroleum-exploration_fig15-12.png|left|300px|thumb|{{figure number|1}}(left) The difference between the BHGM density measurements and the gamma-gamma log density measurements. (right) Density values measured by the BHGM (left line) and the gamma-gamma tools (right line). Copyright: Rasmussen;<ref name=Rasmussen>Rasmussen, N. F., 1975, The successful use of borehole gravity meter in northern Michigan: The Log Analyst, September-October, p. 1-10</ref> courtesy ''The Log Analyst''.]]

[[file:applying-gravity-in-petroleum-exploration_fig15-12.png|left|300px|thumb|{{figure number|1}}(left) The difference between the BHGM density measurements and the gamma-gamma log density measurements. (right) Density values measured by the BHGM (left line) and the gamma-gamma tools (right line). Copyright: Rasmussen;<ref name=Rasmussen>Rasmussen, N. F., 1975, The successful use of borehole gravity meter in northern Michigan: The Log Analyst, September-October, p. 1-10</ref> courtesy ''The Log Analyst''.]]

The broad departure between the BHGM and gamma-gamma density logs in this Michigan reef example reveals the edge of the reef complex is within a few hundred feet of the well. The overlying low-density zone near the top of the log is salt. The sharp difference in density at the arrow is caused by a remote higher [[porosity]] zone not detected by the gamma-gamma density log. The broader difference anomaly observed over the length of the interval is explained by the influence of the entire reef complex.

The broad departure between the BHGM and gamma-gamma [[density log]]s in this Michigan reef example reveals the edge of the reef complex is within a few hundred feet of the well. The overlying low-density zone near the top of the log is salt. The sharp difference in density at the arrow is caused by a remote higher [[porosity]] zone not detected by the gamma-gamma density log. The broader difference anomaly observed over the length of the interval is explained by the influence of the entire reef complex.

[[:file:applying-gravity-in-petroleum-exploration_fig15-12.png|Figure 1]] shows three logs. The log under the scale on the left is the difference between the BHGM density measurements and the gamma-gamma log density measurements. The logs under the scale on the right are the density values measured by the BHGM (left line) and the gamma-gamma tools (right line).

[[:file:applying-gravity-in-petroleum-exploration_fig15-12.png|Figure 1]] shows three logs. The log under the scale on the left is the difference between the BHGM density measurements and the gamma-gamma log density measurements. The logs under the scale on the right are the density values measured by the BHGM (left line) and the gamma-gamma tools (right line).