the subsurface environment
DESCRIPTION
The Subsurface EnvironmentTRANSCRIPT
The Subsurface Environment
Revision:
1. Seal2. Structural trap3. Stratigraphic trap
Introduction
We shall discuss about subsurface waters
The effects of pressure and temperature on the
condensation and evaporation of gas and oil.
Fluid dynamics in sedimentary basins
Genetic ClassificationNormally, four types of subsurface water can be defined according to their genesis:
1. Meteoric waters: Occur near the earth surface. Involved in hydrogeological cycle.
2. Formation waters (connate waters): water trapped in the pore spaces or rocks in sedimentary basins, and have not recently been involved in the hydrogeological circle. These waters evolve with time as a result of water-rock interactions and gain high salinity.
3. Juvenile waters: These are igneous or metamorphic origin
4. Mixed water
Meteoric
Mixed
Connate
Juvenile
Settings of Earth’s Water Observe all the places where
water is present
Rivers
Oceans: 96.5% of near-surface water
Lakes: fresh or salty
Swamps and wetlands
Atmosphere
Glaciers: 69% of freshwater
Biological water
Groundwater: 30% of freshwater
Water in minerals: may be large amount
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How Does Water Move? Observe how water moves between settings
Air currents
Evaporation(oceans, lakes, rivers,…)
Condensation Precipitation(rain, snow, hail)
RunoffInfiltration:
water seeps
into ground
Groundwater flows
Groundwater flows onto surface
Most precipitationinto ocean; some evaporates on way down
Transpiration from plants
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Reduction potential (also known as redox potential, oxidation / reduction potential, ORP, pE or Eh) is a measure of the tendency of a chemical species to acquire electrons and thereby be reduced. Reduction potential is measured in volts (V), or millivolts (mV).
Each species has its own intrinsic reduction potential; the more positive the potential, the greater the species' affinity for electrons and tendency to be reduced. ORP is a common measurement for water quality
Note: Conductivity increases and gradient decreases with depth & declining porosity
Regional variations in heat flow affect petroleum generation. In areas of high heat flow & high geothermal gradient, the optimal tempt. Will be reached at shallower depth.
Questions?