Patent ID: 7523002

Claim:
A method of evaluating changes for a wellbore interval, comprising: obtaining first log data acquired by a logging sensor during a first pass over the wellbore interval; obtaining second log data at a time later than the first log data, said second log data being acquired by the logging sensor during a second pass over the wellbore interval; calculating a plurality of delta values between the first log data and the second log data, each delta value being calculated by taking a difference between a parameter of said first and second log data; deriving an observed effect using the plurality of the delta values; and identifying a correlation between the observed effect and a causal event; displaying said correlation on a display device so that changes for the wellbore interval can be evaluated as to the probable causal event responsible for the changes, wherein said correlation displaying comprises displaying a matrix comprising a header row defining possible causes in order to determine whether there has been a significant change in the parameter, and a header column defining the major formation parameter made by the logging sensors, a cell existing for every possible correlation identified between the observed effect and the probable causal event; and analyzing the causal event and changes for the wellbore interval based on the displayed matrix.