− | [[file:applying-gravity-in-petroleum-exploration_fig15-12.png|left|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, 1975;,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|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, 1975;<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 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. |