Difference between revisions of "Normal hydrostatic pressure"
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==Fluids== | ==Fluids== | ||
− | A fluid is “a substance (as a liquid or gas) tending to flow or conform to the outline of its | + | A fluid is “a substance (as a liquid or gas) tending to flow or conform to the outline of its container.”<ref name=Webster_1979>Webster's New Twentieth Century Dictionary, Unabridged, 2nd ed., 1979: New York, Simon and Schuster, 2129 p.</ref> Thus, the explorationist should think of oil, gas, and water as fluids to understand their behavior in the subsurface. In this article, where the fluid state (liquid or gaseous) is important, the state (or phase) is specified. |
==Fluid pressure== | ==Fluid pressure== | ||
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==Properties of hydrostatic pressure== | ==Properties of hydrostatic pressure== | ||
− | Normal hydrostatic pressure has the following properties:<ref name=ch05r5>Dahlberg, E., C., 1994, Applied Hydrodynamics in Petroleum Exploration, 2nd ed.: New York, Springer-Verlag, 295 p | + | Normal hydrostatic pressure has the following properties:<ref name=ch05r5>Dahlberg, E., C., 1994, Applied Hydrodynamics in Petroleum Exploration, 2nd ed.: New York, Springer-Verlag, 295 p.</ref> |
* Amount of pressure increases with depth. | * Amount of pressure increases with depth. | ||
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==See also== | ==See also== | ||
− | |||
* [[Geostatic and lithostatic pressure]] | * [[Geostatic and lithostatic pressure]] | ||
* [[Normal hydrostatic pressure gradients]] | * [[Normal hydrostatic pressure gradients]] |
Revision as of 16:32, 11 March 2014
Exploring for Oil and Gas Traps | |
Series | Treatise in Petroleum Geology |
---|---|
Part | Critical elements of the petroleum system |
Chapter | Formation fluid pressure and its application |
Author | Edward A. Beaumont, Forrest Fiedler |
Link | Web page |
Store | AAPG Store |
Fluids[edit]
A fluid is “a substance (as a liquid or gas) tending to flow or conform to the outline of its container.”[1] Thus, the explorationist should think of oil, gas, and water as fluids to understand their behavior in the subsurface. In this article, where the fluid state (liquid or gaseous) is important, the state (or phase) is specified.
Fluid pressure[edit]
Fluid pressure is that pressure exerted at a given point in a body of fluid.
Hydrostatic pressure[edit]
Normal hydrostatic pressure is the sum of the accumulated weight of a column of water that rises uninterrupted directly to the surface of the earth. Normally pressured fluids have a great degree of continuity in the subsurface through interconnected pore systems. Abnormally pressured fluids can occur where fluids are completely isolated in containers (compartments) that are sealed on all sides.
Hydrostatic mud pressure[edit]
The geological definition of “hydrostatic” differs from the engineering definition. Engineers use “hydrostatic” to refer to the pressure exerted by the mud column in a borehole at a given depth. Hydrostatic mud pressures are found on DST (drill-stem test) reports and on scout ticket reports of DSTs.
Properties of hydrostatic pressure[edit]
Normal hydrostatic pressure has the following properties:[2]
- Amount of pressure increases with depth.
- Rate of pressure change depends only on water density.
- Vector representing the direction of maximum rate of pressure increase is vertical (i.e., the fluid is not flowing laterally).
- The pressure-depth relationship is completely independent of the shape of the fluid container.
Static vs. dynamic fluids[edit]
Fluid pressure is nondirectional if the fluid is static. If a pressure imbalance exists in any direction, the fluid moves in the direction of lower fluid pressure. The diagrams in Figure 1 illustrate balanced and unbalanced pressures.
See also[edit]
- Geostatic and lithostatic pressure
- Normal hydrostatic pressure gradients
- Abnormal hydrostatic pressure
- Causes of overpressure
- Causes of underpressure