LEC SEMINAR - "Characterizing Crustal Fluid Systems Using Noble Gases"
Dr Zheng Zhou, University of Manchester
Friday 01 February 2013, 0945-1030
LEC Training Room 1
Crustal fluids, including groundwater, natural gases and oil, play an important role within the Earth. They are also key resources critical to human society. Understanding the processes occurring within crustal fluid systems will provide us with knowledge to enhance energy production (such as shale gas and oil), tackle climate change (such as geological storage of CO2) and control groundwater pollution.
Noble gases have proven to be a versatile tool in the investigation of crustal fluid systems. They are chemically inert and occur in small enough quantities for noble gas production from natural sources to significantly alter their isotopic signature, providing fluid source and age information. Due to the unique noble gas isotopic signatures associated with each potential source it is possible to resolve all inputs to any given crustal fluid system. Within the system their inert, trace nature provides us with a unique opportunity for determining the physical processes controlling the fluid systems. Indeed, the processes controlling noble gases dissolution in water at recharge are understood well enough to derive the temperature of water recharge and past climate information to better than ±0.5oC.
While the principles of noble gas tracing of crustal fluid interactions are long established, it is only recently that developments in analytical techniques have enabled these properties to be fully exploited. Several case studies will be presented to illustrate the application of noble gas isotopes in quantifying fluid interactions: (1) The San Juan Basin coalbed methane gas field in New Mexico and Colorado; (2) The Jackson Dome natural CO2 gas deposit in Mississippi; (3) The New Albany shale gas field in the Illinois Basin; (4) The large tight gas sand reservoirs in Utah and Colorado; (5) The Salt Creek oil field in Wyoming. These case studies highlight the powerful potential noble gases have for:
Developing physical models to describe interactions among crustal fluid systems
Quantifying the role of groundwater associated with natural gas and oil systems
Quantifying the rate of biogenic methane production
Dating the groundwater residence time
Tracing the origin of CO2 and identifying the natural mechanisms responsible for CO2 sequestration
Describing gas migration and communication mechanisms in tight gas/shale gas reservoirs
Developing techniques for monitoring fracking projects