Abstract: A method for identifying annular gas sources in a wellbore are disclosed. In one embodiment, the method comprises providing a set of parameters, wherein the set of parameters corresponds to depths in the wellbore. In addition, the method comprises analyzing annular gas in the wellbore to provide isotopic data of the annular gas. The method further comprises correlating the isotopic data to the set of parameters to identify the annular gas source.

Abstract: A method for measuring the infiltration of coring fluid into a core sample taken from a formation comprises a) providing a coring fluid containing cesium in a first concentration, b) using the coring fluid and a coring means to generate the core sample, c) determining the concentration of cesium present in the core sample; and d) comparing the core sample cesium concentration to the first concentration. A further preferred step comprises using the comparison in step d) to calculate the degree of infiltration of the coring fluid into the core sample.