A METHOD FOR OBTAINING MULTI-DIMENSIONAL PROTON DENSITY DISTRIBUTIONS FROM A SYSTEM OF NUCLEAR SPINS

摘要

La method for obtaining a multi-dimensional proton density distribution from a system of nuclear spins. A plurality of nuclear magnetic resonance (NMR) data is acquired from a fluid containing porous medium having a system of nuclear spins. A multi-dimensional inversion is performed on the plurality of NMR data using an inversion algorithm employing a Fredholm integral of the first kind, wherein two or more kernels are reduced to a single composite kernel to obtain the multi-dimensional proton density distribution. A series of conventional CPMG pulse sequences, from a conventional NMR tool, excites the system of nuclear spins. A regression method which reduces computational efforts and retains only those grid points, and preferably their neighboring grid points, which have non-zero values, during subsequent iterations of solving for the multi-dimensional proton density distribution is applied. This regression process is repeated until the density distribution is satisfactorily smooth.