Difference between revisions of "Hydrocarbon pressure gradient: plotting"
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| part = Critical elements of the petroleum system | | part = Critical elements of the petroleum system | ||
| chapter = Formation fluid pressure and its application | | chapter = Formation fluid pressure and its application | ||
− | | frompg = 5- | + | | frompg = 5-26 |
− | | topg = 5- | + | | topg = 5-26 |
| author = Edward A. Beaumont, Forrest Fiedler | | author = Edward A. Beaumont, Forrest Fiedler | ||
| link = http://archives.datapages.com/data/specpubs/beaumont/ch05/ch05.htm | | link = http://archives.datapages.com/data/specpubs/beaumont/ch05/ch05.htm | ||
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==Plotting gradient== | ==Plotting gradient== | ||
− | The | + | 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 [[Wikipedia:Density|density]] | |
− | + | #* Estimates of hydrocarbon density | |
− | + | # Determine the [[buoyancy pressure]] gradient: [[Normal hydrostatic pressure gradients|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]]? | |
− | * Measured hydrocarbon [[density]] | + | ##*'''Solution:''' |
− | * Estimates of hydrocarbon density | + | ##** <math>7607 \text{ ft} - 7507 \text{ ft} = 100 \text{ ft} </math> |
− | + | ##** <math>100 \text{ ft} \times 0.076 \text{ psi/ft} = 7.6 \text{ psi} </math> | |
− | + | ##** <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. | |
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− | # 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:''' | ||
− | * 7607 ft | ||
− | * 100 ft | ||
− | * Hydrocarbon pressure at | ||
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− | |||
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− | |||
==See also== | ==See also== | ||
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* [[Estimating static oil pressure gradients]] | * [[Estimating static oil pressure gradients]] | ||
* [[Estimating static gas pressure gradients]] | * [[Estimating static gas pressure gradients]] | ||
− | * [[ | + | * [[Free water level determination using pressure]] |
==External links== | ==External links== | ||
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[[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
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.