METHOD FOR MEASURING NUCLEAR-MAGNETIC PROPERTIES OF WELL ROCK Russian patent published in 2000 - IPC

FIELD: comprehensive measurements of nuclear- magnetic and magnetic properties of rock during well lodging. SUBSTANCE: nuclear induction signals are sequentially excited from hydrogen-containing material at each point of section and signal frequency is measured. Then surrounding rock is polarized, induction signal excited from free-fluid hydrogen nuclei is subjected to direct Fourier transforms, amplitude and width of spectral line of proton resonance are measured, and results obtained are used to determine free fluid index and reduced time of crosswise relaxation. Then nuclear induction signal is excited again from hydrogen-containing substance and its frequency is measured, frequencies of nuclear induction signals are compared, and magnetic field induction in well before and after polarization is judged from relations between first and third results of frequency measurement, their difference being used to determine residual magnetization of rock as well as real time of free fluid crosswise relaxation. All mentioned measurements are made at same point of space. Source signal is transferred due to Fourier transform from time to frequency representation. EFFECT: provision for using effective digital signal filtering and for measuring amplitude and width of proton resonance spectral line. 6 dwg