BANDWIDTH EXTENSION TOOL
PLUG-IN FOR PETREL 2014
USER MANUAL
LARSEN AND TOUBRO INFOTECH LTD.
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©2014 Larsen and Toubro Infotech Ltd. All rights reserved.
ABOUT THIS DOCUMENT
This document provides instructions for the use of ‘Bandwidth extension tool’ for Petrel 2014.1,
including operation of the plug-in.
COPYRIGHT NOTICES AND DISCLAIMERS
'Bandwidth extension tool' for Petrel is Copyright of Larsen and Toubro Infotech Ltd. All rights
reserved.
© All rights including Copyrights and rights of translation, reproduction etc. reserved and vested
exclusively with Larsen & Toubro Infotech Ltd. No part of this user documentation may be reproduced,
transmitted in any form or by any means or otherwise stored in a retrieval system of any nature without
prior written permission of copyright owner.
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©2014 Larsen and Toubro Infotech Ltd. All rights reserved.
TABLE OF CONTENTS
1
Introduction .......................................................................................................................................... 4
2
Overview ............................................................................................................................................... 4
3
Algorithms ............................................................................................................................................. 5
4
5
6
3.1
Gabor Wavelet Deconvolution...................................................................................................... 5
3.2
Time Variant Spectral Whitening (TVSW) ..................................................................................... 5
3.3
Cosmetic Enhancement by Loop Re-convolution ......................................................................... 6
Utility ..................................................................................................................................................... 7
4.1
Resampling .................................................................................................................................... 7
4.2
Spectrum ....................................................................................................................................... 7
Tutorial .................................................................................................................................................. 8
5.1
Stepwise procedure for “Gabor Deconvolution” .......................................................................... 8
5.2
Stepwise procedure for “Time Variant Spectral Whitening” ...................................................... 14
5.3
Stepwise procedure for “Seismic Resampling” ........................................................................... 17
5.4
Stepwise procedure for “Cosmetic Enhancement” .................................................................... 19
5.5
Spectrum Tab .............................................................................................................................. 22
Input Tree Structure............................................................................................................................ 24
6.1
Algorithms ................................................................................................................................... 24
6.2
Spectrum ..................................................................................................................................... 25
7
References .......................................................................................................................................... 26
8
Help and Support Information ............................................................................................................ 27
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©2014 Larsen and Toubro Infotech Ltd. All rights reserved.
1 Introduction
Resolution is the ability to identify individual features or details in a given image. By the 3D nature of
seismic data, seismic resolution involves both vertical (temporal) and horizontal (spatial) resolution. The
horizontal or spatial resolution is concerned with the ability to distinguish and recognize two laterally
displaced features as two distinct adjacent events. The vertical resolution refers the ability to distinguish
two close seismic events corresponding to different depth levels.
Enhancing the frequency bandwidth of surface seismic data has always been a quest for geophysicists.
In fact, seismic resolution is the key to the extraction of stratigraphic details from seismic data and this
has become more important over the last decade.
Conventionally processed post-stack seismic data has a comparatively narrow frequency spectrum with
the signal utilizing only a fraction of the available bandwidth. High-frequency enhancements aim to
sharpen the data, ostensibly defining structures and pinch-outs more clearly. Irrespective of whether
these techniques actually recover any missing or hidden information from the data, they can help with
the interpretation because events can appear more sharply defined and are less swamped by the low
frequency ringing that characterizes conventional seismic data.
2 Overview
The ‘Bandwidth extension tool’ Plug-in is developed using Ocean SDK. This is a plug-in that gives the user
a way to enhance the resolution of seismic image by widening the frequency bandwidth. Main features
of the plug-in are

The plug-in ventures towards reshaping the spectra and increasing high and low frequency ends.

It helps in identifying reflectors and horizons at the deepest of available data-set.

It provides the capability of targeting high frequency resolution for enhancing and delineating
thin beds buried in the seismic data.
The ‘Bandwidth extension tool’ plug-in allows the user to perform enhancement by three different
algorithms.

Gabor Wavelet De-convolution
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
Time Variant Spectral Whitening (TVSW)

Cosmetic Enhancement of Seismic Data by Loop Re-convolution
3 Algorithms
3.1 Gabor Wavelet Deconvolution
Gabor deconvolution is a time-varying deconvolution whose operator adapts to the characteristics of
the particular data captured by a time-overlapped set of windows. Gabor deconvolution makes the use
of time-shifted Gaussian windows as in the original. A deconvolution operator is constructed by
smoothing the magnitudes of the Gabor Transform of a seismic trace, and computing the corresponding
phase. A Gabor operator array can be constructed for each trace and applied to that trace or
constructed from the summed Gabor magnitudes of a trace ensemble and applied to each trace in that
ensemble. Gabor deconvolution is an experimental procedure, with several parameters which may be
varied to attempt to optimize performance.
Usage

Gabor deconvolution is intended for use on ensembles of traces in the form of inline, xline or
seismic volumes.

The traces must be post-stack traces for this version.

Data most suited to this application are those on which time-varying phenomena are
superimposed (various types of noise), or which show visible non-stationary (isolated "bright"
events, loss of bandwidth with time, etc.).

As there are many parameters to select, the default values have been chosen to allow
reasonable results to be obtained from Gabor deconvolution with no intervention by the user.

However, the performance can usually be considerably enhanced by experimenting with the
parameters.
3.2 Time Variant Spectral Whitening (TVSW)
In the user-specified frequency band, TVSW time-variantly adjusts the amplitude spectrum of the input
trace and suppresses the amplitude of the frequency out of the band. This process is called “time5
©2014 Larsen and Toubro Infotech Ltd. All rights reserved.
variant spectral whitening” or “time-variant amplitude compensation”. TVSW either does the fine
processing or the general processing, depending on the amount of frequency increment defined by the
user and the latter can also obtain a reasonably good result. This method functions as the single trace
time-variant deconvolution and is a process usually applied post-migration to improve the resolution
and appearance of seismic data and is a crude attempt to correct for frequency attenuation.
Usage
TVSW should ideally be used to correct the amplitude spectrum for the specific frequency spectrums
with respect to the corresponding time windows.
3.3 Cosmetic Enhancement by Loop Re-convolution
An innovative method of cosmetic enhancement of seismic data has been described by Young (Young,
2005) which is based on loop re-convolution principle. This procedure generates a sparse spike
reflectivity from seismic, weighted by interpolated amplitude at all maxima and minima. Then a suitable
broad band wavelet can be convolved with the resulting series followed by spatial filtering for smoother
appearance. Irrespective of whether this technique actually recovers any missing or hidden information
from the data, it can help in interpretation because events can appear more sharply defined and less
affected by low frequency, typical characteristic of conventional seismic data.
General Workflow
The basic idea is to first create a sparse-spike representation of the seismic data and then convolve with
a high-frequency wavelet. The algorithm is as follows:
1) Calculating the first derivative of the seismic trace
2) Identify the zero-crossings (which correlate to the maxima & minima on the seismic) and
3) Convolve the spikes with a higher-frequency wavelet. An alternate to this approach
implemented here is to smooth the spike series to imitate the behavior of wavelet convolution.
Note: Ideal data input is a cube resampled at a smaller sampling interval for this algorithm.
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Usage
Using loop re-convolution principle it interpolates the amplitude values to enhance the continuity of
events by generating sparse spikes.
4 Utility
4.1 Resampling
This utility resamples the input seismic cube for smaller sampling interval using spline interpolation. It is
provided to fulfill the requirement of Cosmetic Enhancement workflow. However, the technique is less
effective for the re-sampling at greater sampling intervals.
4.2 Spectrum
This utility will generate the amplitude spectrum (plot of amplitude VS frequency) of the seismic cube
for the given inline, xline or inline/Xline range. The spectrum will facilitate the understanding of
Amplitude /Frequency content of the input volume/inline/Xline.
Note: If further smoothening of the spectrum is required, user may go to Process Actions tool bar of
the Function Window and click on Smooth Function tool
to achieve the desired smoothening.
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5 Tutorial
This section describes how to use ‘Bandwidth extension tool’ for resolution enhancement.
Note:
Users can work on their own dataset or test dataset provided along with this plug-in.
5.1 Stepwise procedure for “Gabor Deconvolution”
1. Open Petrel.
2. Load the Petrel Project.
3. Select Processes Pane > Plug-ins > Bandwidth extension tool
Screen 1: Petrel Process Pane
Also, User has an option to open Bandwidth extension tool from the ribbon.
Select Seismic Interpretation tab > Interpretation plugins > Bandwidth extension tool
Screen 2: Petrel Ribbon Mode
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5.1.1
Input Tab
1. Select Input Tab
2
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Screen 3: Input Tab with all Algorithms
2. Select “Algorithm” using drop down menu.
3. Select “Cube”, “Inline” or “Xline” as input type.
Note:
Only one option is allowed to select among “Cube”, “Inline” or “Xline”. For E.g. If “Cube” is selected
then Input boxes for the “Inline” and “Xline” will be disabled.
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1
2
3
Screen 4: Input Tab for Gabor Deconvolution
1. Input “Cube”, “Inline” or “Xline” using
button.
2. The plug-in gives the user an option to run the processes of ‘Bandwidth extension tool’ in
background i.e. while the process for ‘Bandwidth extension tool’ is running, user will be able to
use all other functionalities of Petrel and to run another process of Petrel except rest of the
algorithms of ‘Bandwidth extension tool’.
3. The plug-in generates a new cube after processing the algorithm. User can choose to place the
processed cube either in the same seismic collection as the input cube, by selecting the option
here. If this is not selected, the processed cube will be placed in a new seismic collection named
‘Bandwidth extension tool’. This option is available only for cube.
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5.1.2
Parameters Tab
Parameter values are user defined and data dependent. Processed results fully depend on the
parameter values provided. Wrong parameter values may lead to an improper output. Therefore it is
advised to provide relevant parameter values according to the input seismic data.
2(a)
Screen 5: Parameter tab for Gabor Deconvolution
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2(g)
Screen 6: "Filter" section in Parameter tab for Gabor Deconvolution
1. Select Parameter Tab
2. Input parameters
a) Spectral ordering: If user wants to reshape the Fourier spectrum then this checkbox
needs to be checked. This option is available only when spectral balancing is required.
b) Window Size: Size of Gaussian temporal window in seconds. This value takes care of
number of samples in a trace to be analysed at a time. Default value is populated when
the seismic data is provided.
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c) Increment value: Temporal increment between windows (sec). If the window size is small
then processing will be time consuming but the quality of the processing will be thorough.
Default value is populated when the seismic data is provided.
d) Stability Factor: A small positive value for stabilizing the spectrum of the propagating
wavelet.
e) Time Smoother: It is the size of the temporal smoother (sec) and it automatically gets
populated according to the Seismic data that is provided in input tab. If user wants, the
value can also be edited.
f) Frequency Smoother: It is the size of the smoothing window in frequency (Hz). It is
recommended to use smaller frequency window for realistic results.
Note:
The maximum value for Time Smoother is populated for the provided data. It is advisable not
to change this value beyond the maximum.
If Filter option is checked, provide following parameters:
g) Maximum Attenuation: Provide maximum attenuation of input cube in decibels.
h) Tapering percentage: Provide tapering percentage.Tapering is applied during design of
window prior to auto-correlation. It is specified as the percentage of window length
with respect to maximum record time of input data.
i) Scalar: Enter the value of scalar to be multiplied to output seismic cube in order to
boost the amplitudes.
j) Corner Frequencies: Provide corner frequencies of the Gaussian filter (Hz).
Corner frequency1: 3db down point of filter on low end.
Corner frequency2: Gaussian width on low end
Corner frequency3: 3db down point of filter on high end.
Corner frequency4: Gaussian width on high end.
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k) Phase Filtering: There are two different options of selecting the phase filtering. Filters
using Minimum phase wavelet have short time duration and a concentration of energy
at the start of the wavelet. Filters using Maximum phase wavelet have the phase greater
for maximum than the minimum at every point. It is the time reverse of the minimum
phase.
3. Window: The Gabor deconvolution uses two types of windows for forward and reverse
construction. The analysis window is for decomposing a seismic trace into its Gabor transform,
and a synthesis window to recreate a seismic trace from its (modified) Gabor components.
4. Click “Apply” button after providing all the parameters to start the processing. This will generate
the processed cube which will be placed in the input tree either in the existing seismic collection
or in the separate folder as specified by the user.
5. “OK” button have the save functionality as “Apply” but it closes the window after processing.
Note:

Gabor Deconvolution may be tried on inline/xline first to validate the parameters and then it can
be tried on the whole cube with properly identified parameters.

The time consumption for the processing with “Gabor Deconvolution” depends upon the
hardware configuration of the user’s machine.
5.2 Stepwise procedure for “Time Variant Spectral Whitening”
5.2.1
Input Tab
1. Select Input Tab
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2
4
Screen 7: Input Tab for Time Variant Spectral Whitening
2. Select “Time Variant Spectral Whitening” using drop down list.
3. Select “Cube”, “Inline” or “Xline” as input type.
4. Provide data for the selected type (Cube/Inline/Xline).
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5.2.2
Parameters Tab
1. Select Parameter Tab
Screen 8: Parameters Tab for Time Variant Spectral Whitening
2. Input parameters
a) Number of Filters: Number of Gaussian filters slices to reconstruct the spectrum of the
seismic. Large value will be effective but will slow down the process.
b) Minimum Frequency: Lowest frequency to be whitened.
c) Maximum Frequency: Highest frequency to be whitened.
d) Automatic Envelope Correction Length: This is the length of filter for, correcting the
envelope of the seismic data and makes it smooth.
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Note:
The value of the “Automatic Envelope Correction Length” should be less than the half of the
trace length.
3. Click “Apply” button after providing all the parameters to start the processing. This will generate
the processed cube which will be placed in the input tree either in the existing seismic collection
or in the separate folder as specified by the user.
4. “OK” button have the save functionality as “Apply” but it closes the window after processing.
5.3 Stepwise procedure for “Seismic Resampling”
5.3.1
Input Tab
1. Select Input Tab
Screen 9: Input Tab for Seismic Resampling
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2. Select “Seismic Resampling” using drop down menu.
3. Provide data for the “Cube”.
5.3.2
Parameters Tab
1. Select Parameter Tab
Screen 10: Parameters Tab for Seismic Resampling
2. Filter: Check this option for simultaneous band pass filtering with Resampling.
3. Provide value for “Sampling Interval”. This is in Milliseconds. It should be less than the “Existing
Sampling Interval”.
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4. Click “Apply” button after providing all the parameters to start the processing. This will generate
the processed cube which will be placed in the input tree either in the existing seismic collection
or in the separate folder as specified by the user.
5. “OK” button have the save functionality as “Apply” but it closes the window after processing.
Note:
Value for “Existing Sampling Interval” gets populated automatically according to the data.
5.4 Stepwise procedure for “Cosmetic Enhancement”
5.4.1
Input Tab
1. Select Input Tab
2
3
4
Screen 11: Input Tab for Cosmetic Enhancement
2. Select “Cosmetic Enhancement” using drop down menu.
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3. Input “Resampled Seismic Cube”.
4. Input “First Derivative of the Resampled Seismic Cube”.
Note:
 It is not mandatory to provide only resampled cube as input.
 The “Derived Cube” could be obtained by “Geophysics > Volume Attributes”.
5.4.2
Parameters Tab
1. Select Parameters Tab
Screen 12: Parameters Tab for Cosmetic Enhancement
2. Input Parameters
a) Apply Filter: This Algorithm provides two options. First one if user wants to retain just the
spike series and perform their own convolution and filtering steps. The second option
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enables user to apply an ormsby band pass filter to adjust spike series to realistic seismic
volume.
b) Corner Frequencies (Corner frequency 1, Corner frequency 2, Corner frequency 3,
Corner frequency 4) : These are the four corner frequencies for ormsby band pass filter,
low cut, low pass and high cut high pass.
3. Click “Apply” button after providing all the parameters to start the processing. This will generate
the processed cube which will be placed in the input tree either in the existing seismic collection
or in the separate folder as specified by the user.
4. “OK” button have the save functionality as “Apply” but it closes the window after processing.
5.4.3
Guidelines
The behavior of seismic amplitude spectrum changes with time/depth. At the shallower level most of
the frequency content is preserved, so generally resolution is good but with increasing time/depth, due
to multiple attenuation processes, the data loses the high frequency content.
Cosmetic Enhancement algorithm generates a sparse spike reflectivity from seismic, weighted by
interpolated amplitude at all maxima and minima. Then a suitable broad band wavelet can be convolved
with the resulting series followed by spatial filtering for smoother appearance. The operation is
implemented at phase zero therefore the data at the shallower and deeper level is treated similarly.
As the purpose of resolution enhancement is primarily to focus on the recovery of high frequency
content at the deeper level therefore the cosmetic enhancement algorithm is logically more applicable
and relevant for the seismic data at the deeper level or higher depth.
Note:
The log file for petrel needs to be flushed regularly for consistent performance.
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5.5 Spectrum Tab
1. Select Spectrum Tab.
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Screen 23: Spectrum Tab
2. Provide data for the “Cube”.
3. Once the cube is inserted, first and last inline and xline number will be populated in the disabled
boxes, as shown in the above screen.
4. Select an option among “Range”, “Inline number” or “Xline number”.
a. Range: - This option is to generate the amplitude spectrum within a specific inline/ xline
range. Provide the number of the start and end, inline/ xline to specify the sub volume of
a larger volume for which the spectrum has to be generated.
Note:
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If user inputs Inline/ Xline number beyond the minimum/ maximum range of the cube, it will
automatically set the values to the minimum/ maximum of Inline/ Xline number for the
selected cube.
b. Inline number: - Provide the number of the inline for which the spectrum has to be
generated.
c. Xline number: - Provide the number of the xline for which the spectrum has to be
generated.
5. Click on “View amplitude spectrum” to generate and view the amplitude spectrum of the
selected volume, inline or xline, in the functional window.
6. Amplitude spectrum generated by this utility can be viewed in the “Function Window” of Petrel
as shown in the below screen.
Screen 14: Spectrum in Function Window of Petrel
Note:
Spectrum Tab is independent of the other functionality of ‘Bandwidth extension tool’. This utility
doesn’t have any relevance to the processing of all other algorithms in the plug-in.
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6 Input Tree Structure
6.1 Algorithms
User has the option to place the processed cube in the same seismic collection as the input cube or the
processed cube can be placed in a different survey folder named ‘Bandwidth extension tool’
Screen 15: Placing of processed cube in existing survey collection or
New survey folder as specified by the user
In the new survey folder there will be two sub-folders, one for processed seismic cubes and another for
the processed seismic lines (inline/Xline).
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Screen 16: Two sub-folders for processed seismic cube and lines (Inline/Xline)
6.2 Spectrum
The spectrum will be placed in the new collection named “Bandwidth Extension Tool - Spectrum” as
shown in the below screen.
Screen 17: Input tree structure for "Spectrum"
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7 References

Robinson, E. A., 1967, Predictive decomposition of time series with application to
seismic exploration: GEOPHYSICS, Soc. of Expl. Geophys., 32, 418-484.

Margrave, G. F., Lamoureux, M. P., Grossman, J. P., and Iliescu, V., 2002, Gabor
deconvolution of seismic data for source waveform and Q correction: Expanded
Abstracts 72nd Ann. Internat. Mtg. Soc. of Expl. Geophys. 2190-2193.

Aki, K., and Richards, P. G., 2002, Quantitative Seismology (second edition), University
Science Books.

Cary, P. W. and Lorentz, G. A., 1993, Four-component surface-consistent deconvolution:
Geophysics 58, 383-392.

Montana, C. A., and Margrave, G. F., 2005, Phase correction in Gabor deconvolution:
75th Ann. Internat. Mtg: Soc. of Expl. Geophys., Expanded Abstracts, 4 pages.

Margrave, G. F., and Lamoureux, M. P., 2002, Gabor Deconvolution: 2002 CSEG Annual
Convention, Calgary, Alberta.

Margrave, G. F., Dong, L., Gibson, P. C., Grossman, J. P., Henley, D. C., and Lamoureux,
M. P., 2003, Gabor Deconvolution: extending Wiener’s method to non-stationarity: The
CSEG RECORDER, 28, no 12 (December).

Margrave, G. F., Gibson, P. C., Grossman, J. P., Henley, D. C., Iliescu, V., and
Lamoureux, M. P., 2004, The Gabor Transform, pseudodifferential operators, and
seismic deconvolution, Integrated Computer-Aided Engineering, 9, 1-13.

O’Doherty, R. F., and Anstey, N. A., 1971, Reflections on amplitudes: Geophys. Prosp.,
19, 430-58.

Peacock, K. L., and Treitel, S., 1969, Predictive deconvolution: Theory and practice:
Geophysics, 34,155-169.

Perz, M. and Margrave, G. F., 2005, Assessing the Impact of Robinson’s First
Deconvolution Paper: The CSEG RECORDER, 30, no. 2, 37-40.
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
Perz, M, Mewhort, L., Margrave, G. F., and Ross, L., 2005a, Gabor Deconvolution: real
and synthetic data experiences: 2005a CSEG Annual Convention, Calgary, Alberta.

Perz, M, Mewhort, L., Margrave, G. F., and Ross, L., 2005b, Gabor Deconvolution: real
and synthetic data experiences: SEG expanded abstracts, 24, 494-497.

Robinson, E. A. and Treitel, S., 1967, Principles of digital Wiener filtering: Geophys.
Prosp., 15, 311-333.

Schoepp, A. R., and Margrave, G. F., 1998, Merging inverse Q-filtering and deconvolu tion: CSEG National Convention (Geo-Triad), Calgary, Alberta.
Link:

http://www.cseg.ca/publications/recorder/2006/2006special/2006special-gabordeconvolution.pdf

http://www.crewes.org/ForOurSponsors/ConferenceAbstracts/2004/EAGE/Margrave_E
AGE_2004.pdf

http://www.cseg.ca/conventions/abstracts/2005/2005abstracts/036S0131Young_P_Cosmetic_Enhancement_of_Seismic_Data.pdf
8 Help and Support Information
‘Bandwidth extension tool’ is provided by © L&T Infotech. For support information contact Larsen and
Toubro Infotech Ltd. e- mail: [email protected];
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©2014 Larsen and Toubro Infotech Ltd. All rights reserved.