Fossil water

Land L.S. (1970) Phreatic vs vadose meteoric diagenesis of limestones Evidence from a fossil water table. Sedimentology 14,175-185. 

It is known that only a small amount of the extracted groundwater originates from recent groundwater resources (Table 36). The rest is extracted from a reservoir of fossil water that has been formed 20.000 years ago when temperatures were considerably lower in that area than they are today. 

The fossil water is characterised by high total mineralization as a result of long residence times in the subsurface as well as by lower 2H and 180 isotope values as a result of the lower temperatures during formation (Table 37). The different amounts of 13C can be explained by the establishment of equilibrium of the fossil groundwater with marine limestones with higher amounts of 13C than recent groundwater, which reflects the lower concentrations of 13C in the atmosphere. 

If the amount of fossil water in the extracted groundwater is known an estimation can be given on how long it will take to completely exploit the approximately 5 m high, 1 km wide and 10 km long reservoir assuming a constant rate of production of 5 L/s. 

However, this simple picture is complicated by a large number of factors other than site temperature that can affect or 5D of fossil waters. In aggregate, the effect of these additional factors may be small, or may exceed the effect of temperature. For this reason, much recent work has moved away from paleothermometry based on or 5D. Instead, or 5D are increasingly being used as hydrologic tracers. Much of the power of these analyses results from coupling of interpretations of or 5D of water with temperature reconstructions based on other techniques, which often use multiple parameters and which often exploit simpler systems. 

Recovery of Deep Pore Water that may be Fossil Water... 

Petroleum is a mixture of liquid hydrocarbons of variable composition depending on its origin alkanes, cyclic hydrocarbons (cyclopentane, cyclohexane), and aromatic hydrocarbons. Crude oil always contains light gases (methane, ethane), particles in suspension, more or less brackish fossil water, and sulphur compounds. The sulphur content ranges from 0.5 to 3 %, depending on its origin. 

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