home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
ASME's Mechanical Engine…ing Toolkit 1997 December
/
ASME's Mechanical Engineering Toolkit 1997 December.iso
/
thermo
/
petindsw.exe
/
lha
/
READLOGS.DOC
< prev
next >
Wrap
Text File
|
1990-12-10
|
23KB
|
529 lines
ELOGANAL
Copyright (c) 1990 H L Hendrick, all rights reserved.
ELOGANAL is a shareware microcomputer program which allows
the user to perform the calculations involved in analyzing
electric logs run on prospective oil and gas wells. The program
was written in the "C" language for reduced code size, speed and
mathematical accuracy.
If this program is useful to you, please register the
program with the author by sending a check for $100.00 to H L
Hendrick P.O. Box 79530 Houston TX 77279. Program support and up-
date information will be furnished to registered users.
This package contains computer software and printed material
copyrighted by H L Hendrick. You should carefully read the fol-
lowing terms and conditions before using the software. Use of
the software indicates your acceptance of the software and all
terms and conditions.
This software product is licensed to one user for use on one
machine only.
Under international copyright laws there are penalties for
making unauthorized copies. You may make and distribute copies
of the program to others for their consideration. Any copy that
you make must include reproduction of the copyright notice and
warranty disclaimer. You may not sell any copy that you make.
H L Hendrick makes no express or implied warranty for the
software which is provided solely on an "as is" basis. H L
Hendrick disclaims all conditions and warranties, whether express
or implied with regard to the software, including all implied
conditions or warranties of fitness for a particular purpose. H
L Hendrick shall not have any liability or responsibility of any
kind including special, indirect or consequential damages, aris-
ing out of or resulting from such software or the use or
modification thereof.
H L Hendrick is a member of the Association of Shareware
Professionals (ASP). ASP wants to make sure that the shareware
principle works for you. If you are unable to resolve a
shareware-related problem with an ASP member by contacting the
member directly, ASP may be able to help. The ASP Ombudsman can
help, but does not provide technical support for members'
products. Please write to the ASP Ombudsman at P.O. Box 5786
Bellevue, WA 98006 or send a CompuServe message via easyplex to
ASP Ombudsman 70007,3536
1
The design goals of the program were to create a program
which would be of use to the log analyst in working old type logs
as well as the new more modern type logs. Empirical routines are
included to estimate the oil or gas content of the flushed zone
with an option to change it. Porosity estimates using the old
short normal technique are included with an option to re-enter if
the value is not deemed in an acceptable range. Rw can be calcu-
lated from the SP curve or from an API water analysis as well as
the Rwa method or by direct input of ppm of Cl or NaCl. The
program uses standard oil field analysis methods, formula and al-
gorithms. The statistical and empirical routines used were
recommended in publications by Douglas Hilchie and Jim Brock.
These publications are available from the Society of Petroleum
Engineers. Chart books from Schlumberger, Dresser and GO were
also used in designing and testing the program.
Estimates of critical water can be made from a list of for-
mation options or by entering core permeability. Relative per-
meability is calculated for all reservoir fluids regardless of
their presence. Water cut is estimated using Reservoir Engineer-
ing techniques utilizing relative permeability. The critical
water is estimated from statistical data for the type of forma-
tion selected and may not be correlative with the calculated
water cut.
The author of the program assumes the user is aware of the
uses and limitations of electric logs run on drilled wells and
does not intend to present a tutorial in log analysis. Petroleum
oriented literature should be reviewed for instructions regarding
the correct application of logging techniques. Standard logging
symbols are used in the screen presentation and printout.
HARDWARE REQUIREMENTS
Minimum requirements are a 128K, one disk drive, 8086/8088,
MS or PC DOS 2.xx or greater microcomputer or compatible.
If a co-processor is present it will be used. If a co-
processor is not present, the program will emulate the co-
processor using an internal 7K emulator.
In order to use the program, format a new disk and install
your operating system. Copy ELOGANAL.EXE to the new disk. Use the
new program disk you created and boot up. Enter ELOGANAL and run
the program. If you prefer, Copy the program to your hard disk.
Follow the menu prompts. Screen displays will be presented
and remain on screen until you enter a requested key.
2
The program can create and maintain a data file for each log
analysis. Provisions to display to screen or print the file are
included. The file name selected should relate to the name of
the well or operator. These files are stored in an ASCll format
and can be incorporated in a report prepared with a word proces-
sor.
After the initial run through the program, the UP ARROW and
DOWN ARROW keys will toggle the Main (underlined heading) menus.
A new depth can be input by entering a RIGHT ARROW or LEFT ARROW.
When a Main (underlined heading) menu is displayed, a re-
calculation can be made by entering <RETURN>. If the shale volume
or the type of shale changes, a new porosity will be calculated
and corrections made based on the shale changes. To exit the
program from a Main menu (underlined heading) enter END key.
Data entry begins with input from the log heading and
proceeds in a logical manner to set flags and constants used in
the calculations for the specific log being analyzed.
Entered log heading data will be displayed to screen with an
option to change a value. Most pre-1958 logs did not record the
Rmf and Rmc. If this is the case, you will be prompted to enter
a zero. The program will estimate both from Rm and the tempera-
ture will be set to the temperature of the mud.
TYPE OF MUD
1-Light weight fresh water muds sets density
of fluid to 1.0 and travel time to 189.
2-Heavy weight fresh water muds sets density
of fluid to 1.01 and travel time to 189.
3-Salt water base mud sets density of fluid to
1.1 and travel time to 185.
The log matrix lithology flag must be set for all log types
requested even though a Density, Neutron or Sonic log is not
available. If one or all of these logs is not available, setting
these flags will not affect the program.
LOG MATRIX LITHOLOGY
~~~~~~~~~~~~~~~~~~~~
1-Sand, sets matrix flags for density log to
2.65, Sonic log to 55.5 and neutron response
to a correction algorithm.
2-Lime, sets matrix flags for density log to
2.71, Sonic log to 47.5
3-Dolomite, sets matrix flags for density log to
3
2.87, Sonic log to 43.5 and neutron response
to a correction algorithm.
4-User input allows the user to input the desired
factor.
FORMATION OPTIONS
~~~~~~~~~~~~~~~~~
1- Soft Formations, sets MXP to 2.15,COER
to .62 and SXP to 2. (Humble).
2-Hard formations, sets MXP to 2, COER to 1
and SXP to 2. (Archie).
3-Low porosity carbonates, uses the Shell
developed method and sets SXP to 2, COER
to 1 with MXP being set based on porosity.
4-User input allows the user to input the
desired factors.
Rw OPTIONS
~~~~~~~~~~
1- Input Rw, allows direct input of known
water resistivity and temperature.
2-Compute from salinity, allows computation
of water resistivity from known ppm of NACL or CL.
3-Compute from Rwa, uses the method recommended
by the major logging companies for computation
of Rw from log data.
4-Compute from SSP, uses the method recommended
by the major logging companies for computation
of Rw from the SP curve.
5-Compute from analysis, allows computation
of Rw from a known API water analysis.
Factors used in the computation are set
for a water with a total solids content of
70000 ppm NACL. The user has the option
to change the factors to the correct values
for the water being used. These factors are
available in all logging company chart books.
SHALE CONTENT OPTIONS
~~~~~~~~~~~~~~~~~~~~~
4
Seven options are available for calculating VOLSH. Selection
of any option other than no correction, requires a selection of
the type of shale.
1-No corrections
Sets VOLSH to zero.
2-Direct input
VOLSH must be entered in a decimal fraction.
3-Gamma or SP index
Calculates VOLSH from the gamma or SP.
4-Tertiary age rocks
Calculates VOLSH using gamma index as proposed
by Larinov.
5-Older age rocks
Calculates VOLSH using gamma index as proposed
by Larinov.
6-Density-Neutron
7-Density-Sonic
8-Sonic-Neutron
Calculates VOLSH using a ratio of porosity
technique.
Five options are available for calculating porosity. If
x-plot is selected, four combinations of x-plots are available.
If direct input is selected, the porosity input will not be cor-
rected for fluid or shale content; however, the correction flag
must be set in order to output the water cut in the final dis-
play.
POROSITY OPTIONS
~~~~~~~~~~~~~~~~
1-Direct input
2-Sonic
3-Density
4-X-plots
5-Short Normal
If the x-plots option is selected, the x-plot menu will ap-
pear as follows:
1-CDL & CNL
2-Sonic & CNL
5
3-CDL & SNP
4-Sonic & SNP
The Short Normal option should be used only when no other
option is available. It is an empirical estimate and only ap-
plies where specific conditions of invasion exist.
ENTER SOURCE OF RESISTIVITY
~~~~~~~~~~~~~~~~~~~~~~~~~~~
1-Direct input, must be entered in decimal
fraction.
2-Induction Electrical Log, This option requires
input of the Induction and 16 inch normal. An
empirical correction is made as suggested by
Hilchie in his book "Old Electrical Log
Interpretation".
3-Dual Induction logs with SFL, this option requires
input of deep, medium and shallow resistivity.
A "Tornado Chart" correction is made mathematically.
4-Dual Induction logs with laterolog, this option
requires input of deep, medium and shallow
resistivity. A "Tornado Chart" correction is made
mathematically.
5-Dual Laterolog (20' Sequential), correction made
on tool type.
6-Dual Laterolog (28' Simultaneous), correction made
on tool type.
A 16 inch normal will corrected for hole size. If a
caliper survey is not available, the correction will
be made assuming a gauge hole.
SELECTION FOR CRITICAL WATER
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Option selection for several formations on which empirical
data is available can be made. If the logged formation is not on
the list of options or the formation is not known or if one
prefers to enter a known core permeability, option o should be
selected. If the logged formation is not on the list of options
and a core permeability is not known, options o must be selected
and when the prompt ask for entry, a zero must be entered. If
this is the case, the critical water cannot be estimated and the
permeabilities and water cut cannot be estimated.
After all data is entered, the program calculations are
made. All calculations are corrected for depth, shale volume,
fluid content and temperature. Resistivity is corrected as stated
6
above. An empirical estimate is made of critical water, absolute
permeability, relative permeability, effective permeability and
water cut. Water cut for oil is reported in a fraction. Water to
gas ratio is reported as bbls. per mcf.
Printer output is optional.
After entering log data and calculating factors for a zone,
recalculation of other zones of interest can be made without en-
tering all new data. The log heading data and type of mud does
not change. Use the arrow and entry key for rapid calculation of
additional zones of interest.
PLAYING "WHAT IF"
In order to play "what if", after the initial run through
the program, use the arrow keys to toggle the main menus. When
changes are made in the log matrix option or shale volume or type
of shale, porosity calculations made from Density, Neutron or
Sonic logs or x-plots are recalculated.
Each time the depth is changed, the temperature of the for-
mation and the Rw is automatically recalculated. Any parameter
that changes with depth i.e.,resistivity, shale volume, porosity
must be recalculated.
To exit the program:
1-Enter the END key or
2-Enter control C or
3-Enter control break.
MISCELLANEOUS HINTS
Names of logs used in the program are based on Schlumberger
trade marks. Logs from other companies which are compatible may
be used in the program.
Neutron logs from each logging company are not compatible.
The program requires the log matrix for these logs to be set to
lime and the charts from the logging company used to correct the
log reading to lime before using the cross-plot option. The CNL
is corrected for mud weight and temperature. The SNP is corrected
for hole size. If a caliper survey is not available, the correc-
tion will be made assuming a gauge hole.
The gamma ray log entry will be corrected for mud weight and
hole size. If a caliper survey is not available, the correction
will be made assuming a gauge hole.
When entering data from the log heading, operator name, well
name, location, county and state will accept 60 characters each.
7
Direct entry of porosity and shale content must be en-
tered in decimal fractions NOT per-cent. In other words a
porosity of 30% must be entered as .30 not 30.
When entering data from a density log, the entry may be made
in either a decimal fraction or the entry may be made in gm/cc.
The mathematics involved requires that the entries be
consistent. In other words, if a shale correction is made and
the formation density is entered in gm/cc, the shale density
must also be entered in gm/cc. If the formation density porosity
is entered in decimal fraction, the shale density porosity must
also be entered in decimal fraction. Neutron porosity must be
entered in decimal fraction.
Porosity crossplots for density and neutron logs are made by
a crossplot algorithm , after correcting for fluid and shale
content. Porosity crossplots using a sonic log are made by
converting all data to lime matrix and averaging, after
correcting for fluid and shale content.
Factors used to correct porosity for fluid content are
calculated assuming a normal pressure gradient and a natural gas
gravity of 0.65. The residual oil saturation in the flushed zone
is estimated based on empirical data and API gravity. The low
gravity cut off is 10 degrees API and the high gravity cut off is
50 degrees API. In other words, if one enters an API gravity of
less than 10, the value for 10 will be used. If one enters a
gravity greater than 50, The value for 50 will be used.
If the Induction Electric log option is selected and the 16
inch normal is greater than 10 times the mud resistivity, an in-
termediate evaluation is made for Sw, Porosity and Ro using the
Rocky Mountain method. If a shale option is selected, the Sw is
reduced by 10 per-cent and the porosity is adjusted to reflect
the decrease in Sw. This information will be displayed to the
screen but will not be printed on the final print out.
In order to maintain maximum versatility and range of data
input methods and allow the user to play "what if" , error trap-
ping is kept at a minimum. It is possible to enter data which
will cause math errors (divide by zero , etc). Care should be
used when entering data and the menu prompts should be followed.
If one enters data which causes a math error, the program will
notify the user and abort to the operating system.
Support for registered users is provided by mail to H L
Hendrick at P.O. Box 79530, Houston, TX 77279 or by telephone at
713-932-9408 or through CompuServe at address 76217,1171.
8
