Abstract

A recent log evaluation technique has been made possible by the use of Compatible Logging. The Dual Induction Log measures the formation resistivities as they actually exist. While logging a Formation Density, Sonic or Epithermal Neutron Log, we simultaneously measure a different parameter to use with the Dual Induction Log. With the use of a computer device, we will change the readings of the porosity tool into an equivalent resistivity reading. This computer curve will show what the formation would read if all the pore space were filled with water. By having the computer curve on a similar scale as the Dual Induction Log, we can make a comparison of the curves by overlaying them on top of each other. Then, in the clean zones where the curves are matching will be water and the anomalies that separate will be oil or gas.

Another technique allows the Formation Density, Sonic and Epithermal Neutron Logs to be recorded on identical apparent limestone porosity scales. Overlay of one on the other provides, at a glance, a continuous interpretation of lithology, complex or variable lithology is readily solved and the formation porosity is determined with greater accuracy and reliability than before.

Synergetic Log Systems are engineered to complement one another and to give more information about formations and their fluid content than the sum of information obtained from the individual logs.