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Hydraulic Flow Units Page 1 sur 21
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Interactive Petrophysics Help
Hydraulic Flow Units
The module takes Porosity and Permeability data and div ides it up into Hy draulic f low units based on the f ollowing methods :
1. Rock Quality Index (RQI).
2. Winland R35 method.
3. Pittman methods. Includes the Pittman R10, R15, R20, R25, R30, R35, R40, R45, R50, R55, R60, R65, R70 and R75 equations.
4. Lucia Carbonate Rock Fabric Number (RFN).
Initial f low unit div ision boundaries can be made using cluster analy sis. The f low unit boundaries can be adjusted using an interactiv e histogram. A
Lorenz plot of Cumulativ e Storage Capacity against Cumulativ e Flow Capacity can also be used to pick f low boundaries.
Once the f low unit boundaries hav e been picked an output HFU curv e is created. Both a numerically and a Text curv e can be output.
The Lucia Carbonate Rock Class ty ping does not produce Hy draulic Flow units but is included with the other HFU methods since it is based on the
same ty pe of porosity permeability plots.
Discriminators and zones can be used to select the data f or the selection of the f low unit boundaries and also the creation of the result f low unit curv es.
The module works equally well with core or log porosity , permeability data. It is recommended not to mix log and core data due to up scaling resolution
problems.
Data Setup
Select the wells f rom the drop down box. Then select the porosity and permeability curv e f rom the curv e drop down boxes. Curv e units are
important and will be looked up f rom the curv e header and set if f ound, howev er it is important that the user v erif ies these are correct.
The ‘Output Set Name’ column is the curv e set where the output curv es will be written f or each well. This can be changed by well or
changed f or all wells by editing the box at the base of the grid and clicking the ‘Update Output Sets’. The check box ‘For Output set use input
set’ allows the user to automatically select the input set f or the porosity curv e as the output set. The user must click the ‘Update Output Sets’
button af ter selecting this option to apply it.
Clicking on the grid header line will do the f ollowing :
 Use Column : Turns all the well selection either on or of f .
 Well Name Column : Selects all wells not currently loaded.
 Porosity Curv e column : Takes the porosity curv e name f or the f irst row and tries to f ind the same curv e in all other wells.
 Permeability Curv e column : Takes the permeability curv e name f or the f irst row and tries to f ind the same curv e in all other wells.
Discriminators

The discriminator tab allows the user to set up a set of discriminators f or the selection of the data either f or use f or the creation of the HFU
boundaries or f or the creation of the HFU output curv es.
The discriminator setup works the same as in many other IP modules. Note that if any curv es are selected other than the Porosity or
Permeability curv e then these curv es must exist in all wells.
The ‘Select Data f rom Named Zones’ can be used to limit the data selection or data output to just these selected zones. If the ‘Use Zones’ is
turned on then the selected zones must exist in all wells.
Hydrauli c Flow Unit Typing
Three methods are prov ided f or Hy draulic Flow Unit Ty ping, Rock Quality Index (RQI), Winland R35 and Pittman. These methods are
independent of each other and all three methods can be run and the results compared.
The Lucia Rock Class Ty ping is used to create the major three rock ty pes f or Carbonate reserv oirs.
Rock Quality Index HFU
The analy sis is done in two parts, f irstly the selection of f low unit boundaries and secondly , using these f low units boundaries, the
creation of hy draulic f low units. The two stages are separate and dif f erent input data and discriminators can be used f or each stag

For example the f low unit boundaries could be selected using one group of wells and then applied to another group.
Selection of Flow Unit Boundaries - RQI method
The selection of the f low units using the RQI method is done f rom the Flow Zone Indicator (FZI) output curv e. The module creates
three new curv es f rom the input porosity and permeability data :
 Rock quality index RQI = 0.0314 x Sqrt( K / Phi )
 Pore-Grain v olume ratio PhiZ = Phi / (1 – Phi)
 Flow Zone Indicator FZI = RQI / PhiZ
The initial selection of the f low zone boundaries is done automatically . The user selects the ‘Number of f low Units’ then clicks the
‘Make RQI Curv es’ button. There are two options :
 The boundaries are selected f rom the maximum and minimum FZI v alues. They are equally spaced in logarithmic space.
 The boundaries are selected using cluster analy sis (Check the ‘Select f low unit boundaries using cluster analy sis´). The FZI
data is clustered into 25 nodes using K mean clustering. Then the cluster nodes are re-clustered into the number of selected
f low units using Hierarchical clustering. See Cluster analy sis module f or more details of these methods.
The low v alues of the f irst f low unit and the high v alue of the last f low units are extended to cov er data bey ond the dataset currentl
selected.
Once the boundaries are selected the Flow Unit Statistics are shown in the table.
The f irst f our column in the table are editable :
 HFU # : This is the number used to describe the f low unit and is written to the output HFU curv e.
 HFU Name : This is the text v alue describing the f low unit. Def ault to ‘HFU 1’, ‘HFU 2’ .... It is output to the HFU text curv e.
 Start, Stop : These columns are the boundaries f or the f low units. The ‘Stop’ v alue is normally the same as the ‘Start’ v alue f
the next f low unit. If these v alues are changed the curv e statistics are re-calculated.
Discriminators can be used to select the data that goes into making the initial f low unit boundaries. Check the ‘Use Discriminators f
f low unit selection’ and set up the discriminators on the discriminator tabs.
Flow Unit boundaries can be adjust using the interactiv e histogram (click the ‘Histogram’ button) or using a Lorenz crossplot (click
‘Lorenz’ plot).
If the ‘Auto Calculate HFU’s’ button is turned on then if the HFU boundaries are changed interactiv ely on the Histogram or Lorenz
the result HFU’s are recalculated and any crossplots updated. This allows the user to see instantly how changes to HFU boundari
look on the result crossplots.
Histogram

The histogram shows the f low unit boundary lines as v ertical red lines. These can be mov ed interactiv ely by clicking and dragging the
line to a new v alue.
Clicking on the ‘Format’ button in the menu will display the panel at the base of the histogram where the scales, number of histogram
div ision can be adjusted. Clicking the ‘Update’ button will apply any changes to the histogram.
By clicking on the ‘Output’ menu button the histogram can be output to the Clipboard, graphics f ile and the printer.
Lorenz Plot
The Lorenz plot is created f rom the porosity and permeability data f or the selected data sets. The data is rev erse sorting using the FZI
v alue associated with each Phi / Perm pair. The sorted data is then linearly accumulated and normalized to a giv e a maximum v alu of
1.0. The cumulated porosity (‘Cumulativ e Storage Capacity ’) is plotted of the X axis. The cumulativ e permeability (‘Cumulativ e F
Capacity ’) is plotted on the Y axis. The Z axis is the FZI and is plotted as a color scale.
The Lorenz plot can be used f or picking the f low unit boundaries at inf lection points on the Lorenz curv e. The option to ‘Draw Linear
Segments’ can help with the picking of the inf lection points.
The Lorenz plot shows the f low unit boundary lines as v ertical red lines with the v alue of each boundary printed at the base of each
line. These can be mov ed interactiv ely by clicking and dragging the line to a new v alue.
Clicking on the ‘Format’ button in the menu will display the panel at the base of the plot where the f ollowing f ormat options are
av ailable.
 Interactiv e Boundaries : This turns on of f the red interactiv e lines.
 Z Axis Logarithmic scale : This makes the Z axis color scale logarithmic.
 Draw Linear Segments : This draws a linear line between each boundary segment.
 Expand X axis scale : This plots the X axis scale f rom -0.1 to 1.0. This allows clear v iewing of data right on the 0.0 v alue X ax
 Expand Y axis scale : This plots the Y axis scale f rom 0.0 to 1.1. This allows clear v iewing of data right on the 1.0 v alue Y axi
 Draw Grid : This plots the horizontal and v ertical grid lines.

Boundary Re-Initialization
Once the HFU boundaries hav e been created either automatically or edited manually then the ‘Make RQI Curv es’ button no-longer
ef f ects the current set boundaries. This allows more wells to be added to the setup and the RQI curv es created f or these wells
without af f ecting the current boundaries. If the user requires the def ault boundaries to be recreated then click the ‘Re-initialize HFU
button.
Crossplot
The PhiZ v . RQI crossplot with a FZI Z axis can be created by clicking the ‘Crossplot’ button.
The FZI v alues appear as parallel stripes across the data with unit slope of 1 on a Log / Log plot.
Output Equations
When the output equation button is clicked the user can either output the HFU permeability equations to a IP multi-line f ormula
parameter set, or as a text f ile.
Text file output.

Output parameter file loaded into the multi-line formula.
The multi-line f ormula f ile can be used f or batch processing multiple wells where the HFU is known. The parameter f ile would hav e to
be adjusted to pick up the correct input porosity and HFU curv e names used in the wells.
Calculation of Flow Units - RQI method
The f low units are calculated using the boundaries set in the Flow Units Statistics table. The def ault is to output a numeric curv e
where each numeric v alue represents a f low unit. It a text description of the f low unit is also required then check the ‘Output HFU t
curv e’. Click the ‘Make HFU Curv es’ button to output the HFU curv es.
Both PhiZ v . Rqi and Phi v . Perm crossplots are av ailable to v iew the results. The Z axis is the HFU number. If the ‘Display HFU Lines
on crossplot’ option is on the mean HFU equation lines are display ed in the crossplot. The lines are crossplot user equations and the
labels are crossplot annotations and both can be edited inside the crossplot.

RQI Methodology
This methodology is described well in SPE paper 26436 “Enhanced Reserv oir Description: Using Core and Log Data to Identif y
Hy draulic (Flow) units and Predict Permeability in Uncored Interv als/Wells”
The basic Kozeny -Carmen relationship is giv en as
Arrange as
Where K = permeability in µm
Where K is in md
We can theref ore write
The theory say s that FZI will be a constant f or a f low unit. A log/log plot of RQI against Phiz will show data in the same f low unit as
v alues on a straight line with unit slope. The FZI of the f low unit will be the point on the line when Phiz equal 1.
Windland R35 HFU
The analy sis is done in two parts, f irstly the selection of f low unit boundaries and secondly using these f low units boundaries the
Selection of Flow Unit Boundaries - Winland method

The selection of the f low units using the Winland method is done f rom the Winland R35 output curv e this is calculated f rom the
f ollowing equation :
WinR35 = ALog( 0.732 + 0.588 Log(K) – 0.864 Log(Phi) ) where Phi is in percent.
‘Make WinR35 Curv e’ button. There are two options :
 The boundaries are selected f rom the maximum and minimum WinR35 v alues. They are equally spaced in logarithmic space
 The boundaries are selected using cluster analy sis (Check the ‘Select f low unit boundaries using cluster analy sis´). The Win
The low v alues of the f irst f low unit and the high v alue of the last f low units are extended to cov er data bey ond the dataset currently
selected.
 Start, Stop : These columns are the boundaries f or the f low units. The ‘Stop’ v alue is normally the same as the ‘Start’ v alue f or
Discriminators can be used to select the data that goes into making the initial f low unit boundaries. Check the ‘Use Discriminators f or
Flow Unit boundaries can be adjust using the interactiv e histogram (click the ‘Histogram’ button) or using a Lorenz crossplot (click the
‘Lorenz’ plot).
If the ‘Auto Calculate HFU’s’ button is turned on then if the HFU boundaries are changed interactiv ely on the Histogram or Lorenz plot
the result HFU’s are recalculated and any crossplots updated. This allows the user to see instantly how changes to HFU boundari look
on the result crossplots.
Histogram

Lorenz Plot
The Lorenz plot is created f rom the porosity and permeability data f or the selected data sets. The data is rev erse sorting using the
WinR35 v alue associated with each Phi / Perm pair. The sorted data is then linearly accumulated and normalized to a giv e a
maximum v alue of 1.0. The cumulated porosity (‘Cumulativ e Storage Capacity ’) is plotted of the X axis. The cumulativ e permeabilit
(‘Cumulativ e Flow Capacity ’) is plotted on the Y axis. The Z axis is the WinR35 curv e and is plotted as a color scale.
av ailable.
Once the HFU boundaries hav e been created either automatically or edited manually then the ‘Make WinR35 Curv es’ button no-
longer ef f ects the current set boundaries. This allows more wells to be added to the setup and the WinR35 curv e created f or these
wells without af f ecting the current boundaries. If the user requires the def ault boundaries to be recreated then click the ‘Re-initializ
HFU’s’ button.
Crossplot
The Phi v .Perm crossplot with a WinR35 Z axis can be created by clicking the ‘Crossplot’ button. The Winland R35 ov erlay is shown
on the crossplot.

Output Equations
Text file output.

be adjusted to pick up the correct input porosity and HFU curv e names used in the wells. Note that the Winland equations use
porosity in percent so the input porosity curv e may need multiply ing by 100 bef ore it can be used.
Calculation of Flow Units – Winland method
The Phi v . Perm crossplot is av ailable to v iew the results. The Z axis is the HFU number.
If the ‘Display HFU Lines on crossplot’ option is on the mean HFU equation lines are display ed in the crossplot. The lines are
crossplot user equations and the labels are crossplot annotations and both can be edited inside the crossplot. If the ‘Display HFU
Lines on crossplot’ is turned of f then the Winland R35 crossplot ov erlay will be display ed.
Winland Methodology
Log (R35) = 0.732 + 0.588 Log(Kair) – 0.864 Log(Phicore)
The Winland equation was created by Dale Winland of Amoco. It is an empirical equation where R35 is the pore aperture radius
corresponding to the 35th percentile of mercury saturation in a mercury porosimetry test, Kair is the uncorrected air permeability (in
md) and Phicore is porosity in %.
The equation was originally def ined f rom mercury porosimetry measurements on some 300 samples f rom the Spindle Field in
Colorado. Winland correlated porosity and permeability to pore throat radii corresponding to dif f erent mercury saturations and f oun
that the 35th percentile gav e the best correlation. The 35th percentile was taken to approximate the modal class of pore throat size
where the pore network becomes interconnected f orming a continuous f luid path through the sample. More accurately , the abov e i
only true at the pore throat size corresponding to the point of inf lexion of the pore throat size v ersus mercury saturation plot (as seen
on an “Apex” plot).
Winland used an R35 v alue of 0.5μm as the def inition of net pay f or the Spindle Field due to ev idence he had seen of dry wells
hav ing an R35 of <0.5μm and producing wells with R35>0.5μm. The v alue of 0.5μm has since been used in other reserv oirs to def
pay .
Pittman HFU

The analy sis is done in two parts, f irstly the selection of f low unit boundaries and secondly using these f low units boundaries the
Selection of Flow Unit Boundaries - Pittman method
Log(R10) = 0.459 + 0.500 Log(K) - 0.385 Log(Phi)
Log(R15) = 0.333 + 0.509 Log(K) - 0.344 Log(Phi)
Log(R20) = 0.218 + 0.519 Log(K) - 0.303 Log(Phi)
Log(R25) = 0.204 + 0.531 Log(K) - 0.350 Log(Phi)
Log(R30) = 0.215 + 0.547 Log(K) - 0.420 Log(Phi)
Log(R35) = 0.255 + 0.565 Log(K) - 0.523 Log(Phi)
Log(R40) = 0.360 + 0.582 Log(K) - 0.680 Log(Phi)
Log(R45) = 0.609 + 0.608 Log(K) - 0.974 Log(Phi)
Log(R50) = 0.778 + 0.626 Log(K) - 1.205 Log(Phi)
Log(R55) = 0.948 + 0.632 Log(K) - 1.426 Log(Phi)
Log(R60) = 1.096 + 0.648 Log(K) - 1.666 Log(Phi)
Log(R65) = 1.372 + 0.643 Log(K) - 1.979 Log(Phi)
Log(R70) = 1.664 + 0.627 Log(K) - 2.314 Log(Phi)
Log(R75) = 1.880 + 0.609 Log(K) - 2.626 Log(Phi)
The Pittman method has 14 dif f erent equations. The user must f irst select the appropriate equation f or the rock ty pe. The
appropriate equation can be determined f rom ‘Apex’ plots of mercury injection capillary pressure measurements (see Pittman
Methodology ).
‘Make Pittman Curv es’ button. There are two options :
 The boundaries are selected f rom the maximum and minimum Pittman v alues. They are equally spaced in logarithmic space.
 The boundaries are selected using cluster analy sis (Check the ‘Select f low unit boundaries using cluster analy sis´). The Pittm

The low v alues of the f irst f low unit and the high v alue of the last f low units are extended to cov er data bey ond the dataset currently
selected.
 Start, Stop : These columns are the boundaries f or the f low units. The ‘Stop’ v alue is normally the same as the ‘Start’ v alue f or
Discriminators can be used to select the data that goes into making the initial f low unit boundaries. Check the ‘Use Discriminators f or
Flow Unit boundaries can be adjust using the interactiv e histogram (click the ‘Histogram’ button) or using a Lorenz crossplot (click the
‘Lorenz’ plot).
If the ‘Auto Calculate HFU’s’ button is turned on then if the HFU boundaries are changed interactiv ely on the Histogram or Lorenz plot
the result HFU’s are recalculated and any crossplots updated. This allows the user to see instantly how changes to HFU boundari look
on the result crossplots.
Histogram
Lorenz Plot
The Lorenz plot is created f rom the porosity and permeability data f or the selected data sets. The data is rev erse sorting using the
Pittman v alue associated with each Phi / Perm pair. The sorted data is then linearly accumulated and normalized to a giv e a
maximum v alue of 1.0. The cumulated porosity (‘Cumulativ e Storage Capacity ’) is plotted of the X axis. The cumulativ e permeabilit
(‘Cumulativ e Flow Capacity ’) is plotted on the Y axis. The Z axis is the Pittman curv e and is plotted as a color scale.

av ailable.
Once the HFU boundaries hav e been created either automatically or edited manually then the ‘Make Pittman Curv es’ button no-
longer ef f ects the current set boundaries. This allows more wells to be added to the setup and the Pittman curv e created f or these
wells without af f ecting the current boundaries. If the user requires the def ault boundaries to be recreated then click the ‘Re-initializ
HFU’s’ button.
Crossplot
The Phi v .Perm crossplot with a Pittman Z axis can be created by clicking the ‘Crossplot’ button. The appropriate Pittman ov erlay is
shown on the crossplot.

Output Equations
Text file output.

be adjusted to pick up the correct input porosity and HFU curv e names used in the wells. Note that the Pittman equations use
porosity in percent so the input porosity curv e may need multiply ing by 100 bef ore it can be used.
Calculation of Flow Units – Pittman method
The Phi v . Perm crossplot is av ailable to v iew the results. The Z axis is the HFU number.
If the ‘Display HFU Lines on crossplot’ option is on the mean HFU equation lines are display ed in the crossplot. The lines are
crossplot user equations and the labels are crossplot annotations and both can be edited inside the crossplot. If the ‘Display HFU
Lines on crossplot’ is turned of f then the Pittman crossplot ov erlay will be display ed.
Pittman Methodology
Log(R10) = 0.459 + 0.500 Log(K) - 0.385 Log(Phi)
Log(R15) = 0.333 + 0.509 Log(K) - 0.344 Log(Phi)
Log(R20) = 0.218 + 0.519 Log(K) - 0.303 Log(Phi)
Log(R25) = 0.204 + 0.531 Log(K) - 0.350 Log(Phi)
Log(R30) = 0.215 + 0.547 Log(K) - 0.420 Log(Phi)
Log(R35) = 0.255 + 0.565 Log(K) - 0.523 Log(Phi)
Log(R40) = 0.360 + 0.582 Log(K) - 0.680 Log(Phi)
Log(R45) = 0.609 + 0.608 Log(K) - 0.974 Log(Phi)
Log(R50) = 0.778 + 0.626 Log(K) - 1.205 Log(Phi)
Log(R55) = 0.948 + 0.632 Log(K) - 1.426 Log(Phi)
Log(R60) = 1.096 + 0.648 Log(K) - 1.666 Log(Phi)
Log(R65) = 1.372 + 0.643 Log(K) - 1.979 Log(Phi)
Log(R70) = 1.664 + 0.627 Log(K) - 2.314 Log(Phi)
Log(R75) = 1.880 + 0.609 Log(K) - 2.626 Log(Phi)
The Pittman equations are based on correlation made on around 200 mercury injection PC curv es f rom sandstone plugs. The R v alue
corresponds to the aperture size at a certain mercury saturation (example R30 is the aperture size at 30% mercury saturation).
The PC plug pressures were turned into aperture sizes. Then f or each equation the aperture f or the equation saturation was
regressed along with the plugs porosity and permeability to f ind the f itting coef ficients.

The equation to use will be the one whose saturation represents the v alue where the mercury f luid path through the rock becomes
continuous. In the Pittman study a saturation of 36% was f ound to be the av erage f or these sandstones.
If a plot of mercury saturation (HgSat) v ersus HgSat/PC is made (“Apex” plot), then the HgSat at the maximum v alue on the Y axis
(threshold pressure) is the saturation where the Hg become continuous. An “Apex” plot can theref ore be used to determine the
correct equation to use. “Apex” plots can be output f rom the Saturation Height Setup module.
More Details can be f ound in the paper : Pittman, E.D.: "Relationship of Porosity and Permeability to Various Parameters Derived
from Mercury Injection-Capillary Pressure Curves for Sandstone," AAPG Bull., v. 76, no. 2 (1992b) 191-198.
Lucia Rock Class Typing
Lucia def ined three Carbonate rock classes def ined by their Rock Fabric Number (RFN).
 Class 1 : Grain-dominated Fabrics – Grainstone. RFN’s of 0.5 – 1.5
 Class 2 : Grain-dominated Fabrics – Packstone. RFN’s of 1.5 – 2.5
 Class 3 : Mud-dominated Fabrics – Packstone, Wackestone, Mudstone. RFN’s of 2.5 – 4.0.
The Rock Fabric number is calculated f rom :
Where porosity is in decimals and permeability is in milli-darcies.
The analy sis is done in two parts, f irstly the selection of Rock Class boundaries and secondly using these Rock Class boundaries the
creation of Rock Class curv es. The two stages are separate and dif f erent input data and discriminators can be used f or each stage For
example the Rock Class boundaries could be selected using one group of wells and then applied to another group.
Changing of the Rock Class boundaries is only necessary if y ou wish to dev iate f rom Lucia’s def inition of the Rock classes.
Selection of Rock Class Boundaries - Lucia method
The initial selections of the Rock Class boundaries are those def ined by Lucia. Click the ‘Make Lucia RFN Curv e’ button to calculate
the curv es. The statistics f or the classes will be display ed in the table.

 RC # : This is the number used to describe the rock class and is written to the output Rock Class curv e.
 RC Name : This is the text v alue describing the rock class. Def ault to ‘RC 1’, ‘RC 2’ and ‘RC 3’. It is output to the Rock Class
text curv e.
 Start, Stop : These columns are the boundaries f or the Rock Classes. The ‘Stop’ v alue is normally the same as the ‘Start’ v alue
f or the next Rock Class. If these values are changed the curv e statistics are re-calculated.
Clicking the ‘Set Def aults’ will return the boundaries to those specif ied by Lucia.
Rock Class boundaries can be adjusted using the interactiv e histogram (click the ‘Histogram’ button).
If the ‘Auto Calculate Rock Class’ check box is turned on then if the Rock Class boundaries are changed interactiv ely on the
Histogram the result Rock Class curv es are recalculated and any crossplots updated. This allows the user to see instantly how
changes to Rock Class boundaries look on the result crossplots.
Histogram
The histogram shows the Rock Class boundary lines as v ertical red lines. These can be mov ed interactiv ely by clicking and dragging
the line to a new v alue.
Crossplot
The Phi v .Perm crossplot with a RFN Z axis can be created by clicking the ‘Crossplot’ button. The appropriate Lucia ov erlay is shown
on the crossplot.

Output Equations
When the output equation button is clicked the user can either output the Rock Class permeability equations to a IP multi-line f ormula
Text file output
Output parameter file loaded into the multi-line formula
The multi-line f ormula f ile can be used f or batch processing multiple wells where the Rock Classes are known. The parameter f ile
would hav e to be adjusted to pick up the correct input porosity and Rock Class curv e names used in the wells. Note that the Lucia
equations use porosity in decimals so the input porosity curv e may need div iding by 100 bef ore it can be used.
Calculation of Rock Class – Lucia method
The Rock Classes are calculated using the boundaries set in the Rock Class Statistics table. The def ault is to output a numeric curv e
where each numeric v alue represents a Rock Class. If a text description of the f low unit is also required, then check the ‘Output Ro
Class text curv e’. Click the ‘Make Rock Class Curv es’ button to output the RC curv es.
The Phi v . Perm crossplot is av ailable to v iew the results. The Z axis is the RC number.
If the ‘Display Rock Class Lines on crossplot’ option is on, the mid Rock Class equation lines are display ed in the crossplot. These
lines will be positioned at the midpoint of each class not the av erage class v alue as is done f or the HFU methods. The lines are
crossplot user equations and the labels are crossplot annotations and both can be edited inside the crossplot. If the ‘Display Rock
Class Lines on crossplot’ is turned off then the Lucia crossplot ov erlay will be display ed.

Calculation of Swi – Lucia Method
If the ‘Output Rock Class Swi Curv e’ is checked then the Lucia Swi curv es will be calculated by Rock Class (see methodology below
f or equations). The Swi v alue is calculated f rom height abov e the f ree water lev el (in f eet) and porosity . The user must enter the f re
water lev el depth in well depth units (f eet or meters). The TVDSS depth, at each depth lev el, will be looked up in each well using the
inf ormation entered in the well header (Position tab). If this inf ormation is missing an error message will appear.
The height abov e the FWL will also be output as a curv e, in the depth units of the well.
The Swi v . Ht crossplot is av ailable to v iew the results. The Z axis is the RC number.
Lucia Methodology
Lucia studied many Carbonate reserv oirs and showed that 3 major petrophy sical classes of rocks showed similar porosity (non v uggy
porosity ) permeability relationships. He plotted the core data Porosity v . Permeability f or each class and f it the data using a RMA
regression. He combined the equations into a global transf orm using the boundaries of the petrophy sical rock classes.
Where
rf n : Rock Fabric Number
φip : Interpartical porosity
Rock classes were established with the f ollowing Rock Fabric Numbers.

 Class 1 : Grain-dominated Fabrics – Grainstones, dolograinstones, and large cry stalline dolostones. RFN’s of 0.5 – 1.5
 Class 2 : Grain-dominated Fabrics – Packstones. RFN’s of 1.5 – 2.5
 Class 3 : Mud-dominated Fabrics – Packstone, Wackestone, Mudstone. RFN’s of 2.5 – 4.0.
Lucia took the core Capillary Pressure data to establish av erage equations, by rock class, f or calculating irreducible water saturation.
Where
H : height abov e the FWL in f eet
φ : interparticle porosity in v /v
More Details can be f ound in Jerry Lucia book Carbonate Reserv oir Characterization, 2007 published by Springer. Also SPE paper
84942 Predicting Permeability from Well Logs in Carbonates With a Link to Geology for Interwell Permeability Mapping August 2003
by James W. Jennings Jr and F. Jerry Lucia.

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