Apparatus and methods for J-edit nuclear magnetic resonance measurement

A nuclear magneticresonance instrument, comprising:

• a housing adapted to move in a wellbore;
• a magnet disposed in the housing adapted to induce a static magnetic field in a zone of interest, the static magnetic field being primarily inhomogeneous in the zone of interest;
• an antenna assembly disposed in the housing, the antenna assembly adapted to induce an oscillating magnetic field in the zone of interest and to receive nuclear magnetic resonance signals;
• and
• an electronic module including a memory to store instructions for performing a J-edit pulse sequence.

A method for obtaining nuclear magnetic resonance measurements in a wellbore, comprising:

• inducing a static magnetic field in a fluid sample, the static magnetic field being primarily inhomogeneous in the fluid sample;
• applying an oscillating magnetic field to the fluid sample according to a preparation pulse sequence that comprises a J-edit pulse sequence for developing J modulation;
• and
• acquiring the nuclear magnetic resonance measurements using a detection sequence, wherein the detection sequence comprises at least one 180-degree pulse.

A method for characterizing formation fluids, comprising:

• disposing a nuclear magnetic resonance instrument in a borehole;
• inducing a static magnetic field in a fluid sample in a region of interest, the static magnetic field being primarily inhomogeneous in the fluid sample;
• applying an oscillating magnetic field to the fluid sample according to a preparation pulse sequence that comprises a J-edit pulse sequence for developing J modulation;
• and
• acquiring nuclear magnetic resonance measurements using a detection sequence, wherein the detection sequence comprises at least one 180-degree pulse.