Hydrocarbon pressure gradient: plotting
Jump to navigation
Jump to search
| 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.
| |||
| Step | Action | |||
| 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. |
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
5Plot 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 |
|
|
|
|