NMR echo signal correction techniques

A method, comprising:

• performing, using an NMR tool, a Carr-Purcell-Meiboom-Gill (CPMG) measurement by transmitting a first excitation pulse and a first plurality of refocusing pulses, and obtaining a first set of NMR echo signals;
• performing, using the NMR tool, a modified CPMG measurement by transmitting a second excitation pulse and a second plurality of refocusing pulses and obtaining a second set of NMR echo signals, wherein;
• the second excitation pulse is shifted by 0 or π radians relative to the first excitation pulse;
• a first refocusing pulse of the second plurality of refocusing pulses is shifted by 0 or π radians relative to the second excitation pulse;
• a second refocusing pulse and subsequent refocusing pulses of the second plurality of refocusing pulses are shifted by π/2 or −π/2 radians relative to the second excitation pulse;
• and
• the first refocusing pulse of the second plurality of refocusing pulses is transmitted before the second refocusing pulse and the subsequent refocusing pulses of the second plurality of refocusing pulses;
• and
• determining a correction factor based on the CPMG measurement and the modified CPMG measurement.

A system, comprising:

• an NMR tool;
• a control system comprising a plurality of processors, wherein the control system is configured to:
• perform, using the NMR tool, a Carr-Purcell-Meiboom-Gill (CPMG) measurement by transmitting a first excitation pulse and a first plurality of refocusing pulses, and obtaining a first set of NMR echo signals;
• perform, using the NMR tool, a modified CPMG measurement by transmitting a second excitation pulse and a second plurality of refocusing pulses and obtaining a second set of NMR echo signals, wherein:
• the second excitation pulse is shifted by 0 or π radians relative to the first excitation pulse;
• a first refocusing pulse of the second plurality of refocusing pulses is shifted by 0 or π radians relative to the second excitation pulse;
• a second refocusing pulse and subsequent refocusing pulses of the second plurality of refocusing pulses are shifted by π/2 or −π/2 radians relative to the second excitation pulse;
• and
• the first refocusing pulse of the second plurality of refocusing pulses is transmitted before the second refocusing pulse and the subsequent refocusing pulses of the second plurality of refocusing pulses;
• and
• obtain a transient-corrected echo train based on the CPMG measurement and the modified CPMG measurement.