1. A method, implemented on a computer, for determining the uncertainty of soft-data debiasing of property distributions of spatially correlated reservoir data, comprising: inputting, into the computer, soft-data at a plurality of spatial locations on a grid and hard-data at a plurality of location along well paths that intersect the grid, wherein each location of the hard-data is collocated with soft-data values of one or more types; calculating, using the computer, a variogram of the hard-data and creating subsets of independent hard-data using the variogram and the soft-data values that are collocated with each of the hard-data location; applying, using the computer, a bootstrap process on each of the plurality of subsets of independent hard-data to obtain a plurality of bootstrap data sets from each of the plurality of subsets of independent hard-data; calculating soft-data debiased histograms for each of the obtained plurality of bootstrap data sets using a binary decision tree and the collocated soft-data; and characterizing the uncertainty of the soft-data debiased histograms.