Difference between revisions of "Free water level determination using pressure"

From AAPG Wiki
Jump to navigation Jump to search
Line 28: Line 28:
 
# Determine buoyancy pressure gradient (''P''<sub>bg</sub> ):
 
# Determine buoyancy pressure gradient (''P''<sub>bg</sub> ):
 
#*:<math>P_{\rm bg} = P_{\rm hydrostatic\ pressure\ gradient} - P_{\rm hydrocarbon\ pressure\ gradient}</math>
 
#*:<math>P_{\rm bg} = P_{\rm hydrostatic\ pressure\ gradient} - P_{\rm hydrocarbon\ pressure\ gradient}</math>
# Calculate downdip length of hydrocarbon column (''h''):
+
# Calculate downdip length of [[hydrocarbon column]] (''h''):
 
#*:<math>h = \frac{P_{\rm b}}{P_{\rm bg}}</math>
 
#*:<math>h = \frac{P_{\rm b}}{P_{\rm bg}}</math>
  

Revision as of 20:18, 3 March 2016

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

The free water level occurs where buoyancy pressure is zero in the reservoir-aquifer system. It defines the downdip limits of an accumulation. Pressure data reliability affects the resolution; however, resolution improves when it is supplemented with other petrophysical information.

Procedure: using repeat formation tester (RFT) data[edit]

Figure 1 Easy method for determining free-water level (FWL) by projecting RFT pressure data downward from a reservoir to the aquifer.

An easy method for determining free water level (FWL) is projecting RFT pressure data downward from a reservoir to the aquifer. Figure 1 illustrates the procedure.

Procedure using a single measurement[edit]

The list below outlines the procedure for determining the free water level using a single pressure buildup point in the reservoir.

  1. Determine buoyancy pressure (Pb ) at the depth of the measured pressure (Pm ) from the measured pressure:
  2. Determine buoyancy pressure gradient (Pbg ):
  3. Calculate downdip length of hydrocarbon column (h):

As an example, let's determine the downdip length of a 30°API oil column with the following givens:

Answer (tied back to steps above):

Therefore, the free water level is at depth::8167 ft.

See also[edit]

External links[edit]

find literature about
Free water level determination using pressure
Datapages button.png GeoScienceWorld button.png OnePetro button.png Google button.png