The Subsurface Environment

1. The Subsurface Environment

2. Revision:
1. Seal
2. Structural trap
3. Stratigraphic trap

3. 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

5. Genetic Classification
Normally, 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
Juvenile Connate

6. Settings of Earth’s
Water Observe all the places where
water is present
Oceans: 96.5% of
near-surface water
Rivers
Lakes: fresh or
salty
Swamps
and wetlands
Atmosphere
Glaciers: 69% of
freshwater
Biological water
Water in minerals:
may be large
amount
Groundwater: 30% of freshwater
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7. How Does Water Move? Observe how water moves
between settings
Air currents
Evaporation
(oceans, lakes,
rivers,…)
Condensation Precipitation
(rain, snow, hail)
Runoff
Infiltration:
water seeps
into
ground
Groundwater flows
Groundwater flows onto
surface
Most precipitation
into ocean; some
evaporates on way down
Transpiration
from plants
17.01.b1

9.  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

22. Note: Conductivity increases
and gradient decreases with
depth & declining porosity

25. 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.

26. Questions?