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PStack PEP-клиент.
The program is intended for a stacking (addition) of several traces obtained
at one cable depth. As a result of addition uncorrelated the noise present
in each of traces, decreases.
The program can be used in the following cases:
- Repeated explosions at a motionless sonde. The points of supervision are
not imposed against each other at different situations of a sonde. In this case
traces obtained from identical channels of recording seismostation are added up.
- The points of supervision are imposed against each other at different situations
of a sonde. In this case traces obtained on one cable depth and
having one type (of a field TYPE and COMP) are added up.
If the combined case takes place, it is recommended twice to process the data:
at first as for a case 1, then result - as for a case 2.
In the program two algorithms of a stacking are realized:
The program is intended for usage at early stages of data processing. For work of
algorithm "POLICOR" it is required first break hodograph. It can be calculated
with the help of the program FBD and must be
saved in LDB.
The program is the PEP-client, that is, it is started from under the shell of
batch start pktexec, giving service under
setting of parameters, management of carrying out and viewing of the protocol of
work of the program.
The setting of parameters and start of the program occurs from under the
shell of batch start pktexec. The typical
session consists of the following steps:
- Start of the program from the menu of VSP package.
- The setting of the project, in the data catalogue of which the initial
modification is (menu item File - > Project...).
- Selection of initial (subjected to a stacking) of seismic traces modification
(parameter Non-stacked data modification).
- The setting of resulting modification of the stacked seismic traces.
(parameter Stacked resulting data modification).
- Selection of the first breaks hodograph from the list
(parameter First break hodograph). The hodograph must be designed on
initial modification of traces. The hodograph is used in algorithm "POLICOR" and
in a mode of elimination a difference energy at the left and to the right of the first breaks. In algorithm of direct summation the hodograph is not necessary and it can not be specified.
- The setting of a summation mode: Policor - "POLICOR" or
Direct sum - direct summation. The variant "POLICPOR" is steadier
against noises in initial traces.
- The setting of numerical parameters described in the item
3.2.1.
- Start of the program on carrying out (button Start in a toolbar or
menu itemPStack - > Start).
- The user can watch for a course of work of the program on the progress -
indicator on the panel of carrying out.
- After successful end of the program in the panel of results the name
of result modification and some numerical parameters describing work, done by
the program, (see item 3.2.3) should be given.
- For viewing the protocol of program passage the it is necessary to
press the button View log in a toolbar or to select the menu itemPStack - > View log.
- For an output from medium of batch start it is necessary to press the
button Exit in a toolbar or to select the menu itemFile - > Exit.
- Non-stacked data modification
- Traces modification requiring of stacking.
- Stacked resulting data modification
- The stacked traces modifications.
- First break hodograph
- Data base tables with first breaks hodograph. It is required to specify
only for algorithm of a stacking "POLICOR".
- Method of stacking
- Used method of traces stacking:
- Policor - weighed sum of traces, built on correlation maximum,
of traces after the elimination;
- Direct sum - direct sum of traces.
- Mode of stacking
- Used mode of summation (way of assembly of traces packs):
- Multiple records
- Stacking of repeated influences;
- Overlapped geophones
- Summation of traces from overlapped points of sonde.
- Offset of the left boundary analysis band, ms
- Displacement from a hodograph of the left border of area of the analysis
of mutual shifts and similarities. Positive number. Is used only in a mode "POLICOR".
- Width of analysis band, ms
- Width of analysis area of mutual shifts and similarities. Positive number.
Is used only in a mode "POLICOR".
- The most allowed shift, ms
- The greatest allowable shift of a trace concerning all others in a
selection of stacked traces. Positive number, not the greater half of width of
analysis area. Is used only in a mode "POLICOR".
- ACF computation base, ms
- Step of displacement of a sliding interval of ACF computation.
- Count of ACF computation bases, > 1
- Quantity of steps of ACF computation. The greater value increases time of
calculations and their accuracy. The positive number is more 1. Is used only in
a mode "POLICOR".
- Energy influence coefficient, 0.. 1
- Coefficient coefficient of the account of weightes on similarity and energy in cumulative weight
function. Coefficient is regulater, not giving ??????? to traces with small
amplitude strongly to underestimate amplitudes of good traces. The value equal
0 designates the absence of individual influence energy of traces on elimination
(average energy coefficient) is used. Positive number from 0 up to 1. Is used only
in a mode "POLICOR".
- The multiplier of standard deviation of energies ratio\nin 100
samples after and before Tfb for setting low allowed\nlevel of this ratio at
elimination of traces, >=0, 0 - elimination is disabled
- To eliminate of traces, by criterion of a ratio of energy 100 samples to
the right of hodograph to energy 100 samples to the left of hodograph. Trace is
eliminated, if the value of the indicated ratio is less 10 and less difference
of average median value obtained on all conditional summarized traces, and
standard deviation multiplied on given factor. For traces made a noise strong in
the first breaks field. The value 0 disconnects of elimination. Positive number. Is used only in a mode "POLICOR".
- Count of processed input traces
- Visually shows a share of the processed input traces.
- Current cable depth, m
- The current cable depth.
- Count of all input traces
- Count of all traces, sent on an input.
- Count of all input traces
- Count of all traces, sent on an input.
- Count of actual input traces
- Quantity of actual traces sent on an input of the program.
- Count of traces considered bad
- Quantity of the traces, eliminated by various attributes.
The reasons of elimination of each trace contain in the protocol of the
program passage.
- Count of output stacked traces
- Each stacked trace corresponds to the block (pack) of the not stacked traces.
For detailed acquaintance with the user interface of the shell of batch start,
see the description of the program pktexec.
An example of a shell window with the active panel of input of parameters
is resulted below:
For set of stacked traces ACF matrix by each from traces is calculated in interval
of the analysis with others traces.
For everyone series the sum of maxima ACF is determined. The range of ACF series
is made on value of the sum of their maxima. ACF from ACF is determined and the
stacking of ACF series from ACF in ranged order is made. For this
purpose the shift of summary ACF maximum of each series concerning
of series with maximal rank is determined and input of this shift in ACF traces.
On traces of the sum ACF with shift the primary shifts of initial traces rather ACF traces
with maximal rank are determined. The sum of maxima ACF of everyone trace concerning
others traces is calculated. By parabolic interpolation the amplitude in a point
of a maximum extremun is specified.
Median estimation of primary shifts is made by 20 % elimination of values.
The sum of ACF maxima in view of number traces is translated in similarity coefficient
of trace concerning set of other traces.
On the basis of similarity coefficients the table of quality of traces representing
the information on usage of traces is formed at the further processing. The
median estimation of similarity coefficients is made median. The trace, for which
the deviation of similarity coefficient is more than the deviation of median estimation
from 1, is eliminated. The traces, at which similarity coefficients are less than 0.1,
are eliminated also. The final shifts are formed according to the quality table.
In everyone initial uneliminated trace the shift is entered. Thus
traces are combined on form of recording of direct wave before weight
summation. By the amplitudes table of the same extremum of direct wave the median
estimation is made. The values of each traces are multiplied at median
estimation coefficient normalized on trace amplitude. Thus traces are equalized
on amplitude and their unidentity on exitation energy are removed.
The weight coefficients on similarity and energy are calculated by sliding interval methode.
The length of sliding interval is taken by equal of product KLE parameter
at elementary base LE length. A step of interval displacement is equal LE also.
The matrix of ACF values without the relative shift is calculated at each
elementary base for set traces.
The similarity coefficients are formed from values of this matrix as the ratio
of sum of products of traces values K,j at KLE elementary bases to square root
of product of sum of roots K and j-th traces, it is known that k not equal to j.
The obtained ratio is standartized.
The weights sum by similarity at interval is reduced to unit. The negative
values of similarity weights are reduced to zero preliminary.
The weight coefficients by energy are obtained by summing up of energy (ACF at k=j) by KLE
elementary bases for each trace. Then sum of inversely proportional values of energy
is reduced to unit.
The calculated values of similarity coefficients and energy coefficients
are related to interval centre. Linear interpolations these coefficients
is carried out between interals centres. The obtained values of coefficients
are spread accordingly before the beginning and of trace at extreme situations of interval.
Resulted summtrace is obtained by weight summing up of all traces in view
of coefficients on similarity and on energy. PE parameter defines the influence the coefficient
by energy. PE is connected with regulater, not giving by noisy traces with
small amplitude to lower strongly the good traces amplitudes. At PE=1 in
calculation of energy coefficient the power of each trace is taken into account,
individually, at PE<0 the power of a trace is taken into accounnt in comparison
with the average power of traces set.
The program accepts on an input the modification of the not stasked traces.
If the algorithm "POLICOR" is used, for each pack of traces of the
first breaks time must be determined which is searched in the table of a hodograph
on cable depth and number of the channel (HCAB, NTR). In consideration the
actual traces are accepted only.
The program uses the first breaks hodograph for correlation of traces on a
method "POLICOR". The hodograph can be determined with the help of the program
FBD.
The program creates the modification of stasked traces. The traces are written on
decrease of cable depths (from below upwards) without dependence from the order
of traces in an input file. For each pack of input traces one output is formed.
The program obtaines a name of the working projec througt variable medium PROJECT.
In case of start of the program from under the shell, this condition is carried
out by selection of the working project.
The program defines a site of system files of a package from variable VSPHOME,
determined in a structure of the user or in a file setup in a home
directory of the user of a package. In file setup given variable can act
also under a VSP name.
The program searches for the description of parameters in files $VSPHOME/etc/PStack.pep and $VSPHOME/etc/vsp.pep.
At a home directory of the file setup user there should be, containing
ways to the data catalogues given, settings and protocols of the projects passage,
and also way to system files of VSP package.
The other requirements are imposed by the shell of batch start
pktexec.
All messages are deduced in a standard flow of errors. In case of start of the
program from under the interactive shell the messages are saved in a file of
the protocol of passage of the setting LOG/$PROJECT/PStack-#.log. The
messages of classes of seriousli EL_FATAL and EL_ERROR are located after end of
work of the program in area of the messages of the interactive shell.
The program creates the detailed protocol of the work allowing at desire to
find out the steps of algorithm "POLICOR" and the accepted decisions on elimination
of traces.
Example of the protocol of passage with the comments is resulted below.
-
INFO: Job number is 35. INFO: Developer's level of the session is 1. INFO:
Start of PStack application. INFO: Version: unknown. INFO: Project: Gu648 INFO:
Moment: 2001/01/09 17:32:49
- Beginning of program work - standard header of the protocol of work.
-
INFO: Policor method of stacking. INFO: Repeated observation stacking mode.
- The modes, selected by the user, of a stacking and assembly of traces in
packs.
-
INFO: First break for HCAB=1500 NTR=3 is 962.734 ms. INFO: Trace HCAB=1500
NMGL=3 NTR=3 COMP ='Z ' TYPE ='D ' is stacked. INFO: Trace HCAB=1500 NMGL=54
NTR=3 COMP ='Z ' TYPE ='D ' is stacked.
- The messages about traces of a pack and time on a hodograph for them.
-
EL_WARNING: Can't stack by POLICOR due to first break isn't found: HCAB=1300
NTR=5
- The message about error in a case if for any pack the recording with
the first breaks time in a hodograph is not found.
-
INFO: HCAB=3090 m, channel NTR=9, first break TFB=1140.4 ms, traces 2
- The message about the beginning of summing up of 2 traces with number 9 on cable
depth 3090 and with the specified the first breaks time read from the table
of a hodograph.
-
INFO: Shifts determination (zero traces: 0, short window: 0, error code 0):
INFO: No. Shift, ms Amplitude Quality INFO: 1: -0.4490 4.581e+00 - > good
INFO: 2: +0.4490 4.433e+00 - > good
- The message with the information on the mutual shifts of traces on ACF, determined by the
program. The quality of both traces is appreciated as good.
-
INFO: Energy difference: INFO: No. Left energy Right energy Proportion Quality
INFO: 1: 2.446e-01 2.022e+01 82.6488 - > good INFO: 2: 5.533e-01 3.867e+01
69.9 - > good INFO: 2 good traces for summation on HCAB=3090 NTR=9
- The elimination table on energy. Both traces are recognized by good.
-
INFO: Append the only trace: HCAB=1540 NMGL=52 NTR=6
- The recording of summtrace in a resulting file if a pack consists of a
unique trace.
-
INFO: Append stacked trace: HCAB=1520 NMGL=3 NTR=3
- Recording of summtrace in a resulting file.
- " ERROR: Can not open ' %s modification due to %s. "
- Error at opening initial modification (see list
of errors).
- " ERROR: Can not create ' %s modification due to %s. "
- Error at creation of resulting modification (see
list of errors).
- " ERROR: Can not open ' %s db table due to %s. "
- Error at opening the table of a hodograph (see list of errors).
- " ERROR: Bad offset of the left boundary analysis band. "
- Invalid option value Offset of the left boundary analysis band, ms
- " ERROR: Bad width of analysis band. "
- Invalid option value Width of analysis band, ms
- " ERROR: Bad the most allowed shift. "
- Invalid option value The most allowed shift (up to half of analysis
band width), ms
- " ERROR: Bad computation base. "
- Invalid option value Computation base, ms
- " ERROR: Bad count of computation base. "
- Invalid option value Count of computation bases, > 1
- " ERROR: Bad energy influence coefficient. "
- Invalid option value Energy influence coefficient, 0.. 1
- " ERROR: Bad minimum of allowed energy difference. "
- Invalid option value Minimum of allowed energy difference in 100
samples around Tfb, > =0
- " ERROR: Bad method of trace stacking. "
- Errors of the setting of parameter of staking method of.
A error at a complete set of a package.
- " ERROR: Bad mode of trace stacking. "
- Error of the setting of parameter of a mode of the tax of traces in a
pack. A error at a complete set of a package.
- The interactive shell of batch start pktexec.
- The program of determination of the first breaks hodograph FBD.
