NML-The Hope for Production Prediction

Abstract

The nuclear magnetism log (NML) has recently been upgraded to a workable and reasonably trouble-free service. Although the first NML was run commercially in 1960 by Perforating Guns Atlas Corp., the service did not become routinely adequate until 1987. The NML has been one of the great hopes for significant improvement in log interpretation and should now provide the next significant improvement in log interpretation. The NML instrument measures the nuclear magnetism of protons. The proton is a particle identical to the nucleus of the hydrogen atom. The proton is like a magnet; when placed in a magnetic field, it tends to align with the magnetic field like a compass needle. The NML instrument in its simplest form has a large coil that produces a magnetic field when electrical current is passed through this coil. The protons in the formations around the wellbore are aligned by this magnetic field. The borehole (mud) is ''doped'' with something like magnetite to eliminate the borehole influence. When the magnetic field is released by stopping current flow in the coil, the protons tend to realign with the earth's magnetic field. During the process of realigning, the protons give back the energy that it tookmore » to align them. This energy induces a signal in the same coil used to create the magnetic field. The process is very inefficient.« less