Abstract: Methods and apparatus suitable for quickly and accurately measuring 13C levels and supporting data in an aqueous fluid reservoir. Interpreting the resulting data to indicate key factors regarding a reservoir and completion methods, including reservoir constraint, gas producibility, and completion success. A sensor and to a sensing method that evaluates the level of hydrologic constraint in aquifers occurring in unconventional reservoirs, such as shales and coals is disclosed. Specifically, Raman spectroscopy is disclosed as a sensor and a sensing method that measures the level of naturally-occurring 13C in an aqueous reservoir and compares the level of 13C to the levels typical for highly constrained and highly unconstrained reservoirs. The disclosed sensor and sensing method also monitors the level of naturally-occurring 13C in a reservoir. Also disclosed is a method of using ?13CDic to evaluate geographic areas of coal bed reservoir water having biologic methanogenic activity.

Abstract: Well fluids in coalbed natural gas reservoirs and other carbonaceous reservoirs are analyzed to determine production factors such as gas content, critical desorption pressure, and/or other reservoir and operational variables. In particular, the partial pressure of methane or a predictor substance, or a methane concentration, are measured and/or determined for the wells and production factors are determined therefrom.

Abstract: A measuring system for in-situ measurements down a well (1) by a spectrometer (4) is provided. The spectrometer (4) includes a radiation source (5) and a detector (6). A probe (15) optically connected to the spectrometer (4) and includes an optical pathway (7) for transmission of a radiation from the radiation source (5) and at least a second optical pathway for transmission of a characteristic radiation from a sample to the detector (6). A positioner is provided to position the probe (15) near a side surface (11) of the borehole (3) and to optically couple the optical pathways (7) to the side surface (11), wherein the probe (15) is traversable up and down the well (1) by way of a guide operatively connected to the probe (15) and to a fixed location at the wellhead. By use of the apparatus and method a concentration of methane or other substance of interest is obtained, and thereby, a potential production of a coal bed methane formation is obtained.