Noble Gas Tracing of Fluid Transport in Shale Reservoirs

The figure below on the right shows mole fractions for the noble gases tested as part of this sampling (isotopes of He, Ar, Ne, Kr, and Xe), at two separate horizontal hydraulically fractured shale gas wells The figure on the left shows several key ratios of noble gases, and horizontal lines indicating typical values of the ratios associated with atmospheric air The two figures below show production data (gas, water, and oil production rates, bottomhole pressure, and gas pseudo‐ pressure in the top panels. The bottom panels show some select data from preliminary sampling results (early data only) for the same wells and time scales as the production data. These data show that the 3H/4H ratio (red data) for the remaining uncontaminated samples is quite different from atmospheric data (red line), but the 40Ar/36Ar ratio (blue data) is quite similar to atmospheric data (blue line). Most of the ratios are relatively stable in time, but the 84Kr/20Ne ratio changes several orders of magnitude during early production. The mole fraction totals show the XKr increases dramatically during early sampling in well 1. The production data show the well was mostly producing water during this early period (i.e., hydraulic fracture flowback water), and once significant gas production began, the mole fraction of Kr increased several orders of magnitude. Likely contaminated samples (high O2 and other atmospheric gases) are overprinted with an “X”. Collected, but un‐analyzed samples are marked with a vertical gray line in the lower portion of these figures