1. A computer-implemented method of interpreting well log data indicative of physical attributes of a portion of a subterranean formation comprising: partitioning, via computer, the well log data into i segments, each ith segment representing a respective contiguous portion of the extent of the logged well; defining, via computer, a membership function for each segment, the membership function defining a degree to which each segment belongs to a defined set; and determining, via computer, based on attribute values derived from previously interpreted depositional units, and the membership functions, a depositional type for each segment, converting, via computer, the well log data to shale volume data, wherein the shale volume data are represented as a series of numerical values V sh =s 1 , s 2 , . . . , s i , where s i is an average of the shale volume data within the ith segment.
1. A computer-implemented method of interpreting well log data indicative of physical attributes of a portion of a subterranean formation comprising: partitioning, via computer, the well log data into i segments, each ith segment representing a respective contiguous portion of the extent of the logged well; defining, via computer, a membership function for each segment, the membership function defining a degree to which each segment belongs to a defined set; and determining, via computer, based on attribute values derived from previously interpreted depositional units, and the membership functions, a depositional type for each segment, converting, via computer, the well log data to shale volume data, wherein the shale volume data are represented as a series of numerical values V sh =s 1 , s 2 , . . . , s i , where s i is an average of the shale volume data within the ith segment. 2. The computer-implemented method as in claim 1 , wherein the partitioning further comprises applying at least one variation criterion to the well log data such that each segment represents data varying from neighboring data by an amount less than the variation criterion.