First half echo inclusion in nuclear magnetic resonance data

A system comprising:

• a nuclear magnetic resonance (NMR) tool comprising a magnet and two or more antennas, the NMR tool configured to measure a sequence of NMR waveforms associated with a sample in a borehole, the sequence of NMR waveforms comprising a free induction decay (FID) waveform measured by a first antenna of the two or more antennas after an excitation pulse generated by a second antenna of the two or more antennas and a set of echo waveforms associated with refocusing pulses generated by at least one of the two or more antennas;
• and
• one or more processors coupled to a memory, the one or more processors configured to:
• determine a set of echo values based on the set of echo waveforms;
• determine an apparent time-zero echo value based on the FID waveform, the apparent time-zero echo value representing an echo at time zero of a time domain and the set of echo values representing echoes along a set of times after time zero of the time domain;
• apply a correction factor to the apparent time-zero echo value to yield a corrected time zero echo value;
• and
• determine a spectrum associated with a sample based on an inversion performed on the corrected echo value and the set of echo values before or after a conversion of the corrected time zero echo value and the set of echo values to porosity units, the conversion of the corrected time zero echo value and the set of echo values being based on one or more conversion factors.

A non-transitory computer-readable storage medium having stored thereon instructions which, when executed by a system, cause the system to:

• obtain a sequence of waveforms via a nuclear magnetic resonance (NMR) tool in a borehole, the sequence of waveforms comprising a set of echo waveforms associated with refocusing pulses generated by the NMR tool and a free induction decay (FID) waveform associated with an excitation pulse generated by the NMR tool;
• determine a set of echo values based on the set of echo waveforms;
• determine an apparent time-zero echo value based on the FID waveform, the apparent time-zero echo value representing an echo at time zero of a time domain and the set of echo values representing echoes along a set of times after time zero of the time domain;
• apply a correction factor to the apparent time-zero echo value to yield a corrected time zero echo value;
• and
• based on one or more conversion factors, convert the corrected time zero echo value and the set of echo values to porosity units to yield converted echo values in porosity units;
• and
• determine a spectrum associated with a sample based on an inversion performed on the corrected time zero echo values and the set of echo values before or after a conversion of the corrected time zero echo value and the set of echo values to porosity units, the conversion of the corrected time zero echo value and the set of echo values being based on one or more conversion factors.