Baseline studies of surface gas exchange and soil-gas composition in preparation for CO_2 sequestration research:Teapot Dome,Wyoming

摘要

A baseline determination of CO_2 and CH_4 fluxes and soil-gas concentrations of CO_2 and CH4 was made over the Teapot Dome oil field in the Naval Petroleum Reserve 3 in Natrona County,Wyoming,United States.This was done in anticipation of the experimentation with CO_2 sequestration in the Pennsylvanian Tensleep Sandstone underlying the field at a depth of 5500 ft [1680 m).The measurements were made in January 2004 to capture the system with minimum biological activity in the soils,resulting in a minimum CO_2 flux and a maximum CH_4 flux.The CO_2 fluxes were measured in the field with an infrared spectroscopic method.The CH_4 fluxes were determined from gas-chromatographic measurements on discrete samples from under the flux chambers.The CO_2 and CH_4 were determined at 30-,60-,and 100-cm (11 -,23-,and 39-in.) depths in soil gas by gas chromatography.A total of 40 locations had triplicate flux measurements using 1.00-m~2 (10.763-ft~2) chambers,and soil gas was sampled at single points at each of the 40 locations.Carbon dioxide fluxes averaged 227.1 mg CO_2 m~(-2) day~(-1),a standard deviation of 186.9 mg m~(-2) day~(-1),and a range of -281.7 to 732.9 mg m~(-2) day~(-1) not including one location with subsurface infrastructure contamination.Methane fluxes averaged 0.137 mg CH_4 m~(-2) day~(-1) standard deviation of 0.326 mg m~(-2) day~(-1) and a range of -0.481 to 1.14 mg m~(-2) day~(-1),not including the same contaminated location.