Difference between revisions of "Hydrocarbon pressure gradient: plotting"
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##*'''Example:''' Measured pressure at [[depth::7607 ft]] is [[pressure::3530 psi]] and buoyancy pressure gradient is 0.076 psi/ft. What is the hydrocarbon pressure at [[depth::7507 ft]]? | ##*'''Example:''' Measured pressure at [[depth::7607 ft]] is [[pressure::3530 psi]] and buoyancy pressure gradient is 0.076 psi/ft. What is the hydrocarbon pressure at [[depth::7507 ft]]? | ||
##*'''Solution:''' | ##*'''Solution:''' | ||
− | ##** 7607 ft | + | ##** <math>7607 \text{ ft} - 7507 \text{ ft} = 100 \text{ ft} </math> |
− | ##** 100 ft | + | ##** <math>100 \text{ ft} \times 0.076 \text{ psi/ft} = 7.6 \text{ psi} </math> |
− | ##** Hydrocarbon pressure at | + | ##** <math>\text{Hydrocarbon pressure at 7507 ft } = 3530 \text{ psi} - 7.6 \text{ psi} = 3522.4 \text{ psi} </math> |
# Plot the pressure number from step 4 on the pressure–depth plot and draw a line between this point and the measured pressure point. This line is the hydrocarbon pressure gradient. | # Plot the pressure number from step 4 on the pressure–depth plot and draw a line between this point and the measured pressure point. This line is the hydrocarbon pressure gradient. | ||
Line 48: | Line 48: | ||
[[Category:Critical elements of the petroleum system]] | [[Category:Critical elements of the petroleum system]] | ||
[[Category:Formation fluid pressure and its application]] | [[Category:Formation fluid pressure and its application]] | ||
+ | [[Category:Treatise Handbook 3]] |
Latest revision as of 17:54, 17 February 2022
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 |
We can estimate the downdip free-water level from a valid fluid pressure measured within a reservoir.
Plotting gradient
The list below outlines the procedure for plotting a hydrocarbon pressure gradient on a hydrostatic pressure plot when a measured pressure is available from the reservoir.
- Plot measured fluid pressure on a hydrostatic pressure–depth plot.
- Determine the hydrocarbon pressure gradient from one of two ways:
- Measured hydrocarbon density
- Estimates of hydrocarbon density
- Determine the buoyancy pressure gradient: static water pressure gradient minus hydrocarbon pressure gradient.
- Determine a pressure above or below the measured depth point. The table below lists the steps for determining this number.
- Pick a depth above or below the measured point.
- Multiply the difference in depth by the buoyancy pressure gradient.
- Add the number from step 2 to the measured pressure if the depth is deeper; subtract if shallower.
- Example: Measured pressure at depth::7607 ft is pressure::3530 psi and buoyancy pressure gradient is 0.076 psi/ft. What is the hydrocarbon pressure at depth::7507 ft?
- Solution:
- Plot the pressure number from step 4 on the pressure–depth plot and draw a line between this point and the measured pressure point. This line is the hydrocarbon pressure gradient.
See also
- Static hydrocarbon pressure gradients
- Estimating static oil pressure gradients
- Estimating static gas pressure gradients
- Free water level determination using pressure