Difference between revisions of "Hydrocarbon pressure gradient: plotting"
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| Determine the hydrocarbon pressure gradient from one of two ways: | | Determine the hydrocarbon pressure gradient from one of two ways: | ||
| − | + | * Measured hydrocarbon density | |
| − | * Measured hydrocarbon density | + | * Estimates of hydrocarbon density |
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| Determine a pressure above or below the measured depth point. The table below lists the steps for determining this number. | | 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]] | ||
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| − | | | + | | 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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==See also== | ==See also== | ||
Revision as of 15:54, 30 January 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 |
We can estimate the downdip free-water level from a valid fluid pressure measured within a reservoir.
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.
| 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.
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:
|
| 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
- Static hydrocarbon pressure gradients
- Estimating static oil pressure gradients
- Estimating static gas pressure gradients
- Finding free-water level using pressure
External links
| find literature about Hydrocarbon pressure gradient: plotting |
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