The McCully gas field is located approximately 10 km from the town of Sussex in southern New Brunswick, Canada. There are currently 32 active natural gas production wells which produce dry gas and condensates from the low-permeability Hiram Brook sandstone and Frederick Brook shale members of the Carboniferous Albert formation. The wells range from inclined to vertical, and have been hydraulically fractured in order to stimulate production. This study provides new geochemical data that allows for characterization of deep fluids in the McCully field and the porewaters in four shallow cores from fractured sandstone and siltstone units drilled adjacent to gas wells. Deep formation fluids of the Hiram Brook and Frederick Brook reservoirs were characterized by sampling production gas and produced water from the wellheads of production wells. Chemical and stable isotope compositions of the gas samples were determined by gas chromatography (GC) and gas-chromatography isotope-ratio-mass-spectroscopy (GC-IRMS), and compositions of the water samples were determined by inductively-coupled-plasma mass spectroscopy (ICP-MS), optical-emission spectroscopy (ICP-OES), and isotope-ratio mass spectroscopy (IRMS). Results indicate that gas compositions differ significantly between the two reservoirs, with the deeper Frederick Brook displaying greater maturity and evidence of isotope reversal. Results from the production water samples indicate that the salinity of formation water is as high as 53,600 mg/kgw (milligrams per kilogram water), and that salinity of the formation water was likely derived from a marine source. However, the strength of conclusions about the formation water composition is limited because the produced water was affected by refluxing in the wellhead, and by the formation of precipitates after sampling. Porewater from low-permeability drill-core samples was extracted using the ‘paper-absorption’ method. Vertical composition profiles were prepared for four observation wells, and the data indicate that porewater composition in these rocks is strongly controlled by lithology, redox conditions, and proximity to fractures that act as conduits for meteoric water.
| Identifer | oai:union.ndltd.org:uottawa.ca/oai:ruor.uottawa.ca:10393/37348 |
| Date | 29 March 2018 |
| Creators | Barton, David |
| Contributors | Al, Tom |
| Publisher | Université d'Ottawa / University of Ottawa |
| Source Sets | Université d’Ottawa |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf |
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