Line 17: |
Line 17: |
| | | |
| ==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]]. |
| | | |
− | {| class = "wikitable"
| + | # Plot measured fluid pressure on a hydrostatic pressure–depth plot. |
− | |-
| + | # Determine the hydrocarbon pressure gradient from one of two ways: |
− | ! Step
| + | #* Measured hydrocarbon [[Wikipedia:Density|density]] |
− | ! Action
| + | #* Estimates of hydrocarbon density |
− | |-
| + | # Determine the [[buoyancy pressure]] gradient: [[Normal hydrostatic pressure gradients|static water pressure gradient]] minus hydrocarbon pressure gradient. |
− | | 1
| + | # Determine a pressure above or below the measured depth point. The table below lists the steps for determining this number. |
− | | Plot measured fluid pressure on a hydrostatic pressure–depth plot.
| + | ## Pick a depth above or below the measured point. |
− | |-
| + | ## Multiply the difference in depth by the buoyancy pressure gradient. |
− | | 2
| + | ## Add the number from step 2 to the measured pressure if the depth is deeper; subtract if shallower. |
− | | Determine the hydrocarbon pressure gradient from one of two ways:
| + | ##*'''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 [[Wikipedia:Density|density]] | + | ##*'''Solution:''' |
− | * Estimates of hydrocarbon density | + | ##** 7607 ft – 7507 ft = 100 ft |
− | |-
| + | ##** 100 ft × 0.076 psi/ft = 7.6 psi |
− | | 3
| + | ##** Hydrocarbon pressure at [[depth::7507 ft]] = [[pressure::3530 psi]] – [[pressure::7.6 psi]] = [[pressure::3522.4 psi]] |
− | | Determine the [[buoyancy pressure]] gradient: [[Normal hydrostatic pressure gradients|static water pressure gradient]] minus 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. |
− | |-
| |
− | | 4
| |
− | | 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:''' | |
− | * 7607 ft – 7507 ft = 100 ft | |
− | * 100 ft × 0.076 psi/ft = 7.6 psi | |
− | * Hydrocarbon pressure at [[depth::7507 ft]] = [[pressure::3530 psi]] – [[pressure::7.6 psi]] = [[pressure::3522.4 psi]] | |
− | |-
| |
− | | 5
| |
− | | 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== | | ==See also== |