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Line 14: − + − + − {| class = "wikitable"+ − |-+ − ! Step+ − ! Action+ − |-+ − | 1+ − | Plot measured fluid pressure on a hydrostatic pressure–depth plot.+ − |-+ − | 2+ − | Determine the hydrocarbon pressure gradient from one of two ways:+ − + − + − + − |-+ − | 3+ − | Determine the buoyancy pressure gradient: static water pressure gradient minus hydrocarbon pressure gradient. − |- − | 4 − | Determine a pressure above or below the measured depth point. The table below lists the steps for determining this number. − − * <table-wrap id="ch05utbl16a" position="float"> <table frame="hsides"> <colgroup> <col align="center"></col> <col align="left"></col> </colgroup> <thead> <tr> <th align="center"> Step </th> <th align="center"> Action </th> </tr> </thead> <tbody> <tr> <td align="center"> 1 Pick a depth above or below the measured point. </td></tr> <tr> 2 Multiply the difference in depth by the buoyancy pressure gradient. </tr> <tr> 3 Add the number from step 2 to the measured pressure if the depth is deeper; subtract if shallower. </tr> </tbody> </table> </table-wrap> − − |- − | <th align="center"> Step</th> − | <th align="center"> Action</th> − |- − | 1 − | Pick a depth above or below the measured point. − |- − | 2 − | Multiply the difference in depth by the buoyancy pressure gradient. − |- − | 3 − | Add the number from step 2 to the measured pressure if the depth is deeper; subtract if shallower. − |} − − − − − − − − − − − − − − <tr><td align="center">5</td><td align="left">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.</td></tr> Line 73:
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Hydrocarbon pressure gradient: plotting (view source)
Revision as of 17:54, 17 February 2022
, 17:54, 17 February 2022added Category:Treatise Handbook 3 using HotCat
| 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 = 5-1
| frompg = 5-26
| topg = 5-64
| 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
| isbn = 0-89181-602-X
| isbn = 0-89181-602-X
}}
}}
We can estimate the downdip free-water level from a valid fluid pressure measured within a reservoir.
We can estimate the [[Dip|downdip]] [[Free water level|free-water level]] from a valid [[Normal hydrostatic pressure#Fluid_pressure|fluid pressure]] measured within a reservoir.
==Plotting gradient==
==Plotting gradient==
The table below outlines the procedure for plotting a hydrocarbon pressure gradient on a hydrostatic pressure plot when a measured pressure is available from the reservoir.
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]]?
##*'''Solution:'''
* Measured hydrocarbon density * 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.
'''Example:'''
Measured pressure at [[depth::7607 ft]] is 3530 psi and buoyancy pressure gradient is 0.076 psi/ft. What is the hydrocarbon pressure at 7507 ft?
'''Solution:'''
7607 – 7507 = 100 ft
100 ft × 0.076 psi/ft = 7.6 psi
Hydrocarbon pressure at [[depth::7507 ft]] = 3530 psi – 7.6 psi = 3522.4 psi
==See also==
==See also==
* [[Estimating static oil pressure gradients]]
* [[Estimating static oil pressure gradients]]
* [[Estimating static gas pressure gradients]]
* [[Estimating static gas pressure gradients]]
* [[Finding free-water level using pressure]]
* [[Free water level determination using pressure]]
==External links==
==External links==
[[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]]