Method and apparatus for improving the vertical resolution of NMR logs

A system for increasing the resolution of NMR log data obtained using a multi-frequency NMR tool having N operating frequencies, comprising:

• means for providing a NMR pulse echo signal comprising components corresponding to at least two operating frequencies of the tool;
• means for separating the provided pulse echo signal into two or more data-flow paths, each data flow path corresponding to an operating frequency of the tool;
• means for processing the signal in each data flow path separately to remove coherent noise components;
• and
• means for combining output signals from the separately processed data flow paths to remove random noise components.

A method for increasing the resolution of NMR log data obtained using a multi-frequency NMR tool having N (N≧2) operating frequencies, comprising:

• (a) providing an NMR pulse echo signal having components corresponding to at least two operating frequencies of the tool;
• (b) separating the provided pulse echo signal into two or more data-flow paths, each data flow path corresponding to an operating frequency of the tool;
• (c) filtering the signal in each data flow path using a first filter designed to reduce the contribution of non-formation signal components;
• and
• (d) filtering the output signal from the first filter to achieve a predetermined signal-to-noise ratio (SNR) for a given resolution of the NMR log data.