SEG Y Format

Scorpion and

System Four

SEG Y Format

November 2006 1018-010007B

Copyright

Copyright 2006 Input/Output, Inc. All rights reserved.

No part of this publication may be reproduced, transmitted, transcribed, stored in a retrieval system, or translated into any language or computer language in any format or by any means, electronic, mechanical, magnetic, optical, chemical, manual, or otherwise, without prior written permission of Input/Output, Inc.

Input/Output, Inc.12300 Parc Crest DriveStafford, Texas 77477-2416 USATel +1.281.552.3002Fax +1.281.879.3626 www.i-o.comCopyright violators also may be subject to civil penalties.

Disclaimer

Input/Output, Inc. makes no warranties as to the accuracy, validity, or fitness for use or application of the contents of this document. Input/Output, Inc. reserves the right to revise the information in this document at any time without notice.

Original publication date: November 2006

P/N: 1018-010007B

Contents

Chapter 1. History and Current Requirements............... 1-1History ......................................................................................................................................... 1-1Current Requirements.................................................................................................................. 1-1

Chapter 2. Blocks in Format .......................................... 2-1Reel Identification Header Format ........................................................................................................... 2-2

Text Block ................................................................................................................................... 2-2Binary Block................................................................................................................................ 2-3

Trace Data Block Format.......................................................................................................................... 2-6Trace Data Block ......................................................................................................................... 2-6Trace Identification Header ......................................................................................................... 2-8

Index ............................................................................... I-1i

Chapter 1. History and Current Requirements

History The SEG Y format was published in 1975 and reflects the state of seismic data recording at that time. The original format specified bit positions and signal patterns for 800 bpi NRZI (Non-Return to Zero Inverted) and 1600 bpi PE (Phase Encoded) recording formats. The original format also mentions IBM's proposed 6250 bpi GCR (Group Coded Recording) format. Currently, the type of media and recording technology used is not relevant to discussion of the application specific format of data written to sequential media.

Current Requirements

The SEG Y format allows for a collection of trace data of similar sample rate and trace length on one tape. It specifies that all the data on one reel be from one line. With 3D recording, it is not practical to have the restriction of all the data on a given tape being from one receiver line. Therefore, Input/Output Land Recording Systems do not restrict data to be from only one receiver line. The restrictions on sample rate and trace length are also unnecessary. However, I/Os RSR system (Transcriber 2) system currently pads or trun-cates traces to the same length.

I/Os Scorpion and System Four systems set the Binary Header values for Sample Interval and Number of Samples to zero (0), where zero means vari-able Sample Interval and variable Number of Samples. Each Trace Header contains the Sample Interval and the Number of Samples for that trace. This was done to allow different record lengths and different sample intervals per reel.

This document describes the differences between the I/O SEG Y specifica-tion and the original SEG Y specification, now referred to as SEG Y 1975 or Rev 0.

NOTEThis document does not make reference to the second SEG Y publication by the Society of Exploration Geophysicists: SEG Y rev 1 Data Exchange Format, SEG Technical Standards Committee, Release 1.0, May 2002.SEG Y Format 1-1

Chapter 1. History and Current Requirements1-2 SEG Y Format

Chapter 2. Blocks in Format

The tape consists of a Reel Identification header, consisting of a 3200-byte block of EBCDIC card image information and a 400-byte binary encoded block. The Reel Identification header is followed by blocks of demultiplexed trace data, consisting of a 240-byte Trace Identification header. The Trace Identification header is followed by the Trace Data samples. As designed, free areas were left in the both the EBCDIC and binary blocks of the Reel Identification header and in the Trace Identification header for future expansion.

Tables 2-1, 2-2, and 2-3 are from the original SEG Y specification. The data on tape appears in the following order:

Table 2-1. SEG Y Demultiplexed Format

Table 2-2. SEG Y Reel Identification Header

Table 2-3. SEG Y Trace Data Block

NOTEI/O systems write two EOF marks at the end of data instead of one.SEG Y Format 2-1

Chapter 2. Blocks in FormatReel Identification Header Format

Text Block The first part of the Reel Identification Header consists of 3200 bytes of EBCDIC data, which is the equivalent of 40 data cards. The original SEG Y specified format for this block is illustrated in Table 2-4:

Table 2-4. 3200 Byte EBCDIC Reel Header

Each card image contains the character C in the first column. By definition, card image numbers 23 through 39 are unassigned for optional use, so the text shown in Table 2-4 is in the specified format. Unused characters are EBCDIC Blank.

Proper system setup by the operator is required to ensure that all fields are populated. It is also possible to treat the entire 3200 bytes as a free form EBCDIC text block.2-2 SEG Y Format

Reel Identification Header FormatStarting with the RSR Transcriber 2 version 1.3.2, the EBCDIC block will be populated in one of three ways. If there is a segyhdr.txt file in the project directory, then the EBCDIC block will be filled with information from the segyhdr.txt file. If there is no segyhdr.txt file but there is XTM information, the first 6 lines of the EBCDIC block will be populated with the following information, which comes from the XTMs Job Text packet:

Client Prospect Contractor Crew ID Location ObserverIf there is no segyhdr.txt file and there is no XTM information available for the output data range, the EBCDIC block will be blank, except for a C in column 1 of all 40 lines. The data will be in EBCDIC format if the data sample format is IBM floating point or IEEE with EBCDIC option. The data will be in ASCII format if the IEEE ASCII option is selected. Column one in each line is uppercase C. Blank characters are used to fill the 80 character lines.

The Scorpion and System Four EBCDIC block will be populated by informa-tion from their respective databases.

Binary Block The binary coded section of the Reel Identification header consists of 400 bytes, of which the first 60 bytes have assigned definitions and the remaining 340 bytes are unassigned for optional use. I/O systems use 14 of the unassigned bytes as shown in Table 2-5.

It is strongly recommended that information on the following nine entries always be recorded:

Line number Reel number Number of data traces per record Number of auxiliary traces per record Sample interval this reel Number of samples per trace Data sample format CDP fold Measurement systemThese are denoted with an asterisk in column 2 of Table 2-5. I/O systems set many of these fields to 0 because the information is either unknown or more appropriately documented in the Trace Identification header.SEG Y Format 2-3

Chapter 2. Blocks in FormatTable 2-5. 400 Byte Binary Reel Header

400 Byte Binary Reel HeaderBytes SEG Y Specification I/O Specification

3201-3204 Job ID number 0

3205-3208 * Line number 0

3209-3212 * Reel number Same as SEG Y Specification

3213-3214 * Number of data traces per record 0

3215-3216 * Number of aux. traces per record 0

3217-3218 * Sample interval, this reel (in microseconds)

Same as SEG Y Specification,(for Scorpion and System Four = 0, meaning variable)

3219-3220 Sample interval, original record (in microseconds)

Same as SEG Y Specification,(for Scorpion and System Four = 0, meaning variable)

3221-3222 * Number of samples per data trace (this reel)

Number of samples per data trace. Traces are padded with zeros or truncated if necessary to match this length. (For Scorpion and System Four = 0, meaning variable)

3223-3224 Number of samples per data trace (original record)

Number of samples per data trace. Traces are padded with zeros or truncated if necessary to match this length. (For Scorpion and System Four = 0, meaning variable).

3225-3226 * Data sample format:1 - IBM floating point (4 bytes)2 - fixed point (4 bytes)3 - fixed point (2 bytes)4 - fixed point w/gain code (4 bytes)

Add:5 - IEEE floating point single precision (4 bytes)

Note: RSR Transcriber 2 only outputs formats: 1-IBM and 5 - IEEE.Scorpion and System Four only outputs format:5 - IEEE.

3227-3228 * CDP fold 0

3229-3230 Trace sorting code:1 - as recorded (no sorting)2 - CDP ensemble3 - single fold continuous profile4 - horizontally stacked

0

3231-3232 Vertical sum code:1 - no sum2 - two sum ....N - N sum (N = 32767)

0

3233-3234 Sweep frequency at start 0

3235-3236 Sweep frequency at end 0

3237-3238 Sweep length (in milliseconds) 0

3239-3240 Sweep type code:1 - linear 3 - exponential2 - parabolic 4 - other

0

3241-3242 Trace number of sweep channel 0

3243-3244 Sweep taper length at start (in msec)

0

3245-3246 Sweep taper length at end (in msec)

02-4 SEG Y Format

Reel Identification Header FormatBytes SEG Y Specification I/O Specification

3247-3248 Taper type:1 - linear 3 - other 2 - cosine squared

0

3249-3250 Correlated data traces:1 - no 2 - yes

0

3251-3252 Binary gain recovered:1 - yes 2 - no

0

3253-3254 Amplitude recovery method:1 - none2 - spherical divergence3 - AGC4 - other

0

3255-3256 * Measurement system: 1 - meters 2 - feet

Same as SEG Y Specification

3257-3268 Impulse signal polarity: Increase in pressure or upward case movement gives: 1 - negative number 2 - positive number

0

3259-3260 Vibratory polarity code:Seismic signal lags pilot signal by:1 - 337.5- 27.5 2 - 27.5- 67.5 3 - 67.5-112.5 4 - 112.5-157.5 5 - 157.5-202.56 - 202.5-247.57 - 247.5-292.58 - 292.5-337.5

0

3261-3262 Unassigned RSR Data Collection Unit (DCU) Serial Number if Tape from one DCU, 0 otherwise

3263-3264 Unassigned Manufacturers code = 18

3265-3266 Unassigned Format Version = 1

3267-3268 Unassigned Reel Header Revision = 1

3269-3270 Unassigned BigEndian or LittleEndian (headers and data)0 = BigEndian257 = LittleEndian (only a disk file option on RSR Transcriber 2, Scorpion and System Four is always BigEndian)

3271-3272 Unassigned Line spacing in tenths of measurement unit.

3273-3274 Unassigned Station spacing in tenths of measurement unit.

3275-3600 Unassigned UNUSED

400 Byte Binary Reel HeaderSEG Y Format 2-5

Chapter 2. Blocks in FormatTrace Data Block Format

Trace Data Block Each Trace Data block consists of a 240-byte Trace Identification header followed by the number of data samples specified in the Reel Identification header binary block, bytes 3221-3222. The original format allows four data sample formats. Of these four original data sample formats defined, only IBM 4-byte floating point is supported. I/O systems allow the use of a fifth data sample format, the IEEE floating point format. This IEEE format is also the recommended data sample format for the RSR Transcriber 2 and the only for-mat for Scorpion and System Four.

Data from RSR/VRSR and MRX (Miniaturized Remote Extender) boxes are normalized to their equivalent input voltage, expressed in millivolts (mV). The maximum millivolt value depends on the preamp K-gain used in the box. See Table 2-6 to relate the largest and smallest possible values on tape to a given K-gain. The preamp K-gain is stored in trace header bytes 121-122.

Table 2-6. RSR or MRX K-gain vs. Largest and Smallest Values Written to SEG Y Tape

Data recorded by VectorSeis receivers are in acceleration, with the Least Significant Bit (LSB) equal to 20, 40, or 160 nano (10e-9) units of Gravity (nG), depending on setting. For the RSR Transcriber 2, using a silver bullet version of VectorSeis, data is normalized to a maximum possible value of 1.0. A fixed multiplier is needed to convert the normalized values back to the 20, 40, or 160 nG LSB setting as shown in Table 2-7. See trace header byte 202 for the VectorSeis receiver sensor scaling code.

RSR or MRX K-gain vs. Largest and Smallest values written to SEG Y tape

RSR or MRX K-gain (dB), Bytes 121-122

Largest absolute value written to tape (mV)

Smallest absolute value written to tape, other than zero (only LSB on)

12 2048 0.000 244 140 625 000 000

24 512 0.000 061 035 156 250 000

36 128 0.000 015 258 789 062 500

48 32 0.000 003 814 697 265 6252-6 SEG Y Format

Trace Data Block FormatTable 2-7. RSR (Transcriber 2) with silver bullet VectorSeis Multipliers to Convert Values to Gs

RSR using the current version of VectorSeis receivers, and Scorpion and Sys-tem Four preserve the 20, 40, or 160 nG LSB values for VectorSeis data. No scaling is necessary to read the data. Largest and smallest values are shown in Table 2-8. See Trace Header byte 202 for the VectorSeis receiver scaling code.

Table 2-8. RSR (Transcriber 2) with current VectorSeis, Scorpion and System Four Largest and Smallest Values Written to SEG Y Tape

Analog data from Scorpion and System Four is normalized to their equivalent input voltage, expressed in millivolts (mV). The maximum millivolt value depends on the preamp scale factor used in the box. See Table 2-9 to relate the largest and smallest possible values on tape to a given gain factor. The preamp gain factor is stored in trace header byte 202.

RSR VectorSeis LSB Setting vs. Largest and Smallest values written to SEG Y tape and multiplier to apply to return values to Gs

Least Significant Bit (LSB) Setting - value in nanoGs

Largest absolute value written to tape


Multiplier to apply to data to get LSB setting

20 1.0 0.000 000 119 209 289 550 781 250 0.167 772 160

40 1.0 0.000 000 119 209 289 550 781 250 0.335 544 320

160 1.0 0.000 000 119 209 289 550 781 250 1.342 177 280

RSR VectorSeis (current version) Scorpion and System Four LSB Setting vs. Largest and Smallest values written to SEG Y tape

Least Significant Bit (LSB) Setting - value in nanoGs

Largest absolute value written to tape (Gs)


20 0.167 772 160 0.000 000 020

40 0.335 544 320 0.000 000 040

160 1.342 177 280 0.000 000 160SEG Y Format 2-7

Chapter 2. Blocks in FormatTable 2-9. Scorpion and System Four Analog Largest and Smallest Values Written to SEG Y Tape

Trace Identification Header

The original SEG Y binary coded trace header consists of 240 bytes, of which the first 180 bytes have assigned definitions and the remaining 60 bytes are unassigned. I/O systems use all of the remaining 60 bytes and redefine some obsolete bytes when recording VectorSeis data.

It is strongly recommended that information on the following six entries always be recorded:

Trace sequence number within line Original field record number Trace number within field record Trace identification code Number of samples this trace Sample interval in microseconds These fields are denoted with an asterisk in column two of Table 2-10 and are described in detail in the following paragraphs.

The trace sequence number within line entry (bytes 1-4) is used to count traces through an entire write process. A write process may span more than one tape. In this case, the first value of trace sequence number within line entry on Tape 2 would not start with 1 but rather with a number one greater than the last trace sequence number within line entry from Tape 1.

The original field record number entry (bytes 9-12) equals the file number set by the RSR Transcriber 2, Scorpion and System Four operator. The file number can also be taken from an IMAGE SEG-D tape when merged into a RSR Transcriber 2 project. The original field record number entry can also equal the Shot Id for unordered data that is made directly by reading an RSR Data Collector Unit (DCU).

The trace number within field record entry (bytes 13-16) equals the trace number within a record (an I/O Energy Point (EP)) starting with 1.

The trace identification code entry (bytes 29-30) is the same as the original

Scorpion and System Four Analog Gain Factor vs. Largest and Smallest values written to SEG Y tape

Gain Factor Largest absolute value written to tape (mV)


0 2500 0.000 310 462 589 257 994

2 625 0.000 077 615 647 314 499

4 156.25 0.000 019 403 911 828 625

6 39.0625 0.000 004 850 977 957 1562-8 SEG Y Format

Trace Data Block FormatSEG Y specification with the addition of code 9 as unknown Aux type and code 62 as GPS Aux/External data.

The number of samples this trace and the sample interval in microseconds entries (bytes 115-116 and 117-118, respectively) are the same as in the reel binary header block for RSR Transcriber 2. For Scorpion and System Four, only the trace header contains the correct values for each trace. The reel header values are set to zero (0) meaning that the trace length and interval can vary throughout the reel.

Table 2-10 shows the I/O 240 Byte Trace Header in comparison with the original SEG Y specification.Table 2-10. 240 Byte Trace Header Original SEG Y Spec. vs. I/O Spec.

240 Byte Trace Header Original SEG Y Specification vs. I/O Specification

Bytes SEG Y Specification I/O Specification

1-4 * Trace sequence number within line = Trace sequence number, counts through one write process. Starting with 1.

5-8 Trace sequence number within reel Starting with 1.

09-12 * Original field record number = File number for shot ordered data.Controlled by RSR Transcriber 2 operator or value taken from merged IMAGE SEG D file. = Shot Id for unordered data (e.g. SEG Y from an RSR DCU)

13-16 * Trace number within field record = Trace number within a record (an I/O EP). Starting with 1.

17-20 Energy source point number 1 for the first event at a shot point, 2 for the 2nd, and so on. (-1) for Stacked. For RSR Transcriber 2: (-64,-65, ) for Correlated File (I/Os EP number).

21-24 CDP ensemble number For Scorpion and System Four: Total number of traces within a record (an I/O EP).

25-28 Trace number within CDP ensemble For Scorpion and System Four: Reel/Volume number.

29-30 * Trace identification code:1 - seismic data 2 - dead 3 - dummy 4 - time break 5 - uphole6 - sweep7 - timing8 - water break9 - 32767 - optional use

9 - Unknown Aux Type10 - Killed (data zeroed) due to VLFF (Scorpion and System Four only)62 - GPS Aux / External Data63 - 32767 optional use

31-32 Number of vertically summed traces yielding this trace


33-34 Number of horizontally summed traces yielding this trace

0

35-36 Data use:1 production 2 - test


37-40 Distance from source pt to receiver 0

41-44 Receiver group elevation 0 if not known

45-48 Surface elevation at source 0 if not knownSEG Y Format 2-9

Chapter 2. Blocks in FormatBytes SEG Y Specification I/O Specification

49-52 Source depth below surface 0 if not known

53-56 Datum elevation at receiver group 0 if not known

57-60 Datum elevation at source 0 if not known

61-64 Water depth at source 0

65-68 Water depth at group 0

69-70 Scale factor for previous seven entries (power of 10 - i.e., 10^X)

0 if not known

71-72 Scale factor for next four entries (power of 10 - i.e., 10^X)

0 if not known

73-76 Source coordinate - X 0 if not known

77-80 Source coordinate - Y 0 if not known

81-84 Group coordinate - X 0 if not known

85-88 Group coordinate - Y 0 if not known

89-90 Coordinate units:1 - length (meters or feet) 2 - seconds of arc

0 if not known

91-92 Weathering velocity 0

93-94 Subweathering velocity 0

95-96 Uphole time at source 0 if not known or not applicable, in 0.1 msec

97-98 Uphole time at group 0

099-100 Source static correction 0

101-102 Group static correction 0

103-104 Total static applied 0

105-106 Lag time A. Time in msec between trace ID header and time break

For Scorpion and System Four: MS word of 4 byte Time shift for Asynchronous Time-break, in microseconds.

107-108 Lag time B. Time in msec between time break and initiation time of energy source

For Scorpion and System Four: LS word of 4 byte Time shift value from System time-break for Asynchronous time-break, units of microseconds.

109-110 Delay recording time. Time in msec between initiation time of energy source and time when recording of samples begins

0

111-112 Mute time - start 0

113-114 Mute time - end 0

115-116 * Number of samples this trace. Same as SEG Y Specification

117-118 * Sample interval in microseconds Same as SEG Y Specification

119-120 Instrument gain type:1 - fixed 2 - binary3 - floating point4 to N - optional use

1

121-122 Instrument gain constant Preamp K-gain, dB (For Scorpion and System Four Analog = 0).

123-124 Instrument early or initial gain (dB) 0

240 Byte Trace Header Original SEG Y Specification vs. I/O Specification2-10 SEG Y Format

Trace Data Block FormatBytes SEG Y Specification I/O Specification

125-126 Correlated: 1 - no 2 - yes Data Type: 0 - Raw1 - Stacked only,2 - Correlated before Stacked3 - Correlated after Stacked4 - Correlated only5 - Raw noise edit

127-128 Sweep frequency at start 0 if not known or not applicable, in 0.1 Hz

129-130 Sweep frequency at end 0 if not known or not applicable, in 0.1 Hz

131-132 Sweep length in milliseconds 0 if not known or not applicable

133-134 Sweep type:1 - linear 3 - exponential2 - parabolic 4 - other

0 if not known or not applicable

135-136 Sweep taper length at start in msec 0 if not known or not applicable

137-138 Sweep taper length at end in msec 0 if not known or not applicable

139-140 Taper type:1 - linear 2 - cosine squared 3 - other

0 if not known or not applicable

141-142 Alias filter frequency in Hertz

143-144 Alias filter slope in dB per octave. For VectorSeis: minimum phase anti-alias slope = 261 dB/octave, linear phase anti-alias slope = 260 dB/octave

145-146 Notch filter frequency Notch #1 (0.01Hz)

147-148 Notch filter slope Notch #1 bandwidth, % of the notch freq. in .1% units.

149-150 Low cut filter frequency Variable low cut freq. (0.1 Hz), 0 = off

151-152 High cut filter frequency 0

153-154 Low cut filter slope Variable low cut slope: 12 dB/octave, 0 = off

155-156 High cut filter slope 0

157-158 Year data recorded Year data recorded, 4 digits used. (For RSR Transcriber 2: Derived from SID)

159-160 Day of year Day of year. (For RSR Transcriber 2: Derived from SID)

161-162 Hour of day (24 hour clock) Hour of day (24 hour clock),(For RSR Transcriber 2: Derived from SID)

163-164 Minute of hour Minute of hour. (For RSR Transcriber 2: Derived from SID)

165-166 Second of minute Second of minute. (For RSR Transcriber 2: Derived from SID)

167-168 Time basis code:1 - local 2 - GMT 3 - other

2 - GMT

169-170 Trace weighting factor (defined as 2^-N volts for least significant bit)

0

171-172 Geophone group number of roll switch position 1

For RSR Transcriber 2 VectorSeis, Windowed Data Start Time, in sample counts

173-174 Geophone group number of trace number one in original record

For RSR Transcriber 2 VectorSeis, Windowed Data Length, in sample counts

240 Byte Trace Header Original SEG Y Specification vs. I/O SpecificationSEG Y Format 2-11


175-176 Geophone group number of last trace in original record

For RSR Transcriber 2 VectorSeis, Byte 175: MS byte andByte 176: Mid byte of the 3 byte Windowed Data RMS value (Offset value removed). (For units, see byte 202 and Table 2-7 or Table 2-8).

177-178 Gap size For RSR Transcriber 2 VectorSeis, Byte 177: LS byte of the 3 byte Windowed Data RMS value (Offset value removed).Byte 178: MS byte of the 3 byte Windowed Data Offset value. (For units, see byte 202 & Table 2-7 or Table 2-8).

179-180 Overtravel associated with taper1 - down 2 - up

For RSR Transcriber 2 VectorSeis, Byte 179: Mid byte andByte 180: LS byte of the 3 byte Windowed Data Offset value. (For units, see byte 202 & Table 2-7 or Table 2-8).

181-182 Unassigned Revision number of this trace header. Starting with RSR Tran-scriber 2 version 1.6.5, the Trace Header Revision Number will be the version number of the Transcriber 2 application software, e.g. 165. For Scorpion and System Four (release 1.0 and up), the Trace Header Revision number starts at 500.

183-186 Unassigned Shot ID (SID - unique number that identifies shot)

187 Unassigned Aux channel signal description (0 if seismic data)Also Aux channel order on tape. 08(h) Master Clock Timebreak09(h) Master Confirmation Timebreak0A(h) Slave Clock Timebreak0B(h) Slave Confirmation Timebreak0C(h) Analog Uphole0E(h) Digital Uphole10(h) Waterbreak14(h) User Specified #118(h) User Specified #21C(h) User Specified #320(h) Unfiltered Pilot24(h) Filtered Pilot28(h) User Specified #42C(h) User Specified #530(h) User Specified #631(h) Vibrator Reference32(h) Vibrator Out33(h) Vibrator User34(h) User Specified #738(h) User Specified #83C(h) User Specified #93D(h) Aux channel from I/O Image System3E(h) GPS Aux / External Data3F(h) unused channel

188 Unassigned Aux. channel ID from RSR (0-63). This number uniquely identifies an Auxiliary channel across the system. When used with a source, this number uniquely identifies this source within a source set controlled by one shooter ID. Zero value for seis-mic data.



189-192 Unassigned Shotpoint line in hundredths

193-196 Unassigned Shotpoint station in hundredths

197-198 Unassigned Receiver line

199-200 Unassigned Receiver station, or for RSR Transcriber 2: source EP number when trace is a correlated Aux.

201 Unassigned Vector Seis Receiver Type (VSMT): VSM (silver bullet version) = 18, SVSM (current version) = 21

202 Unassigned VSMT sensor scaling code in hex:2, 4, 5, 7, 16 or 17: 20 nG LSB0, 1, or 6: 40 nG LSB3: 160 nG LSB (Strong Motion Mode)128: Invalid for SVSM, (scaling set to 40 ng).For Scorpion and System Four Analog: gain factor.

203-204 Unassigned VSMT horizontal orientation angle, numbers are in 0.0001 radians.

205-206 Unassigned VSMT VOA - Vertical Orientation Angle, numbers are in 0.0001 radians.

207 Unassigned Source type: (from XTM)0: LatId1: DynamiteId2: VibratorId3: AirGunId4: WaterGunId5: WeightDropId6: OtherId7: MixedSourcesId8: NoSourceId (8 is used if unknown).9: TestOscId10: ImpulsiveId

208 Unassigned Sensor type: (SEG D Rev 2)0: Unknown Sensor type unknown 1: Hydrophone 2: Geo-Vertical Geophone, Marshphone or Z3: Geo-Horiz Inline Geophone - X 4: Geo-Horiz Cross-Line Geophone - Y 5: Geo-Horiz Other 6: Acc-Vert - Z 7: Acc-Horiz Inline - X 8: Acc-Horiz Cross-line - Y 9: Acc-Horiz Other



209 Unassigned Auxiliary Channel Set Type: 00(h) Unused channel02(h) Timebreak03(h) Uphole04(h) Waterbreak05(h) Time Counter06(h) External Data07(h) Other08(h) Unfiltered Pilot09(h) Filtered Pilot0A(h) Special #10B(h) Special #20D(h) Special #30E(h) Special #40F(h) Special #5FA(h) Reserved (Transcriber 2 only)

210 Unassigned Noise edit type: None = 0 Burst = 1 Diversity = 2 Both = 3

211-212 Unassigned Noise edit gate length in ms. Burst edit gate length if type 1, Diversity gate length if type 2 or type 3.

213 Unassigned Device type: MRX = 7, RSR = 9, VRSR (silver bullet ver-sion) = 17, VRSR (current version) = 20,AuxUNIT-1C = 23, DUNIT-3C = 25, Analog-1C = 29

214-216 Unassigned Device serial number

217 Unassigned Device channel number

218 Unassigned For RSR Transcriber 2: Auxiliary Channel Source set ID.For Scorpion and System Four: Sim Unit Vib ID (1-255).

219 Unassigned Device Status Bits: Bit 0 = Analog A/D OverscaleBit 1 = Analog A/D Overflow, for VectorSeis with Scorpion or System Four: set when VOA could not be calculated due to errorBit 2 = Analog Preamp Overscale or SVSM Sensor OverscaleBit 3 = VectorSeis VLFF errorBit 4 = Invalid Receiver Line/Station (RSR Transcriber 2 only)Bit 5 = Trace was Zero filled (RSR Transcriber 2 only)Bit 6 = Battery improperly removed (RSR Transcriber 2 only)Bit 7 = For Scorpion and System Four & RSR Transcriber 2 VectorSeis: Dynamic Offset Filter mode, 0 = Static



220 Unassigned LAT test type and codes: 1 Calibrate K-Gain 2 SEG Pulse 3 User Pulse 4 Box Common Mode Rejection 5 Box Crossfeed 6 HPE Performance 7 Dynamic Range 8 Shot Noise 9 Long Noise10 Signal Level Dist.11 Attenuator Accuracy12 Signal Dep. Noise13 Harmonic Dist.14 Cable Comm. Mode Rejection15 Cable Crossfeed16 Ohming Seis Group17 Geophone Response18 Spread Noise 19 Geophone Pulse20 Amplifier Accuracy21 Sine Wave Internal22 Vertical Orientation23 Digital Telemetry Test24 VSMT sensor Loop-Back Test25 Seismic Channel DC Offset26 Reserved27 Common Mode Imbalance Leakage

221-222 Unassigned Fixed low cut frequency: on = 3.0 Hz (units = 0.1 Hz), 0 = off

223 Unassigned Fixed low cut slope: on = 12 dB (units = dB/octave), 0 = off

224 Unassigned Box function: 0 - Seis1 - Auxiliary 2 - Aux source (Aux-D)6 - Aux pilot (Aux-P)

225-226 Unassigned For RSR, Notch #2 frequency (0.01Hz). For VRSR, Byte 225: MS byte &Byte 226: Mid byte, of the 3 byte Maximum Absolute Ampli-tude value in trace. (For units, see byte 202 & Table 2-7 or Table 2-8).

227-228 Unassigned For RSR, Notch #2 bandwidth, % of the notch freq in .1% units. For VRSR, Byte 227: LS byte of Maximum Absolute Amplitude. Byte 228: MS byte of the 3 byte Filter Offset value. (For units, see byte 202 & Table 2-7 or Table 2-8).

229-230 Unassigned For RSR, Notch #3 frequency (0.01Hz). For VRSR, Byte 229: Mid byte &Byte 230: LS byte of Filter Offset value. (For units, see byte 202 & Table 2-7 or Table 2-8).



231-232 Unassigned For RSR, Notch #3 bandwidth, % of the notch freq in .1% units. For VRSR, VSMT ASIC Build Date, Week/Year. Year 0 = 1999, 1 = 2000, 2 = 2001...

233 Unassigned Event type:00(h) for a zeroed or truncated trace40(h) LAT data Raw Trace80(h) Seis Data normal, Raw88(h) Seis Data normal, Stack90(h) Seis Data normal, CorrelatedA0(h) Seis Data test, RawA8(h) Seis Data test, StackB0(h) Seis Data test, Correlated

234 Unassigned Sensor type ID 00(h) No sensor defined.01(h) Geophone 1 component vertical 02(h) Marshphone03(h) Hydrophone04(h) Aux.05(h) Geophone - 3C Horizontal, X - In-line06(h) Geophone - 3C Horizontal, Y - Cross-line07(h) Geophone - 3C Vertical, Z08(h) 0B(h) reserved0C(h) Accelerometer - 3C Horizontal, X - In-line0D(h) Accelerometer - 3C Horizontal, Y - Cross-line0E(h) Accelerometer - 3C Vertical, Z

235-237 Unassigned VSMT serial number

238 Unassigned VSMT version number

239 Unassigned VSMT revision number

240 Unassigned Data Modified flags Bit 0 = VRSR static offset removed Bit 1 = VOR AppliedBit 2 = RSR Phase Adjusted Pilot (to match VectorSeis data), or Correlated Seis or Correlated Aux produced from RSR Phase Adjusted PilotBit 3 = Reserved Bit 4 = All data zeroed due to VLFF (Scorpion and System Four VectorSeis only) or partial data zeroed due to missing packets (Scorpion and System Four only)Bit 5 = Time shift applied for Asynchronous Time-break (Scorpion and System Four only)Bit 6 = Reserved Bit 7 = Reserved


Index

Numerics240 byte Trace Header 2-93200 byte EBCDIC Reel Header 2-23D recording 1-1400 byte Binary Reel Header 2-4

AAnalog-1C Gain Factor 2-8

Bbit positions 1-1

DData Collector Unit (DCU) 2-8

EEBCDIC

Blank 2-2block 2-3data 2-2format 2-3text block 2-2

Energy Point (EP) 2-8

GGCR (Group Coded Recording) format 1-1GPS Aux/External data 2-9

IIBM

4-byte floating point 2-6floating point 2-3

IEEEASCII 2-3floating point 2-6with EBCDIC 2-3

JJob Text packet 2-3

KK-gain 2-6

LLeast Significant Bit (LSB) 2-6

MMRX (Miniaturized Remote Extender) boxes 2-6MRX K-gain 2-6

NNRZI (Non-Return to Zero Inverted) recording format 1-1number of samples

this trace 2-9SEG Y Format I-1

Ooriginal field record number 2-8

PPE (Phase Encoded) recording format 1-1

RReel Header

400 byte Binary 2-4Reel Identification header 2-1, 2-6Rev 0 1-1RSR 1-1, 2-6RSR (Remote Seismic Recorder) boxes 2-6

Ssample interval

in microseconds 2-9SEG Y

1975 1-1Current Requirements 1-1current requirements 1-1differences with original 1-1History 1-1published 1-1specification 1-1

SEG Y format 1-1SEG Y Specification vs. I/O Specification 2-9segyhdr.txt file 2-3sensor scaling code 2-6signal patterns 1-1Society of Exploration Geophysicists 1-1

TText Block 2-2Trace

Data Block 2-6Identification code 2-8Identification header 2-1, 2-3, 2-6number within field record 2-8sequence number within line 2-8

Trace Header240 byte 2-9

Transcriber 2 1-1, 2-3, 2-6

VVectorSeis 2-6, 2-7, 2-8, 2-11, 2-12VRSR 2-7VRSR LSB Setting 2-7

XXTM information 2-3I-2 SEG Y Format

12300 Parc Crest DriveStafford, TX 77477

USA

Tel +1.281.552.3002 Fax +1.281.879.3626

www.i-o.com

SEG Y FormatContentsChapter 1. History and Current RequirementsHistoryCurrent Requirements

Chapter 2. Blocks in FormatReel Identification Header FormatText BlockBinary Block

Trace Data Block FormatTrace Data BlockTrace Identification Header

Index

/ColorImageDict > /JPEG2000ColorACSImageDict > /JPEG2000ColorImageDict > /AntiAliasGrayImages false /CropGrayImages true /GrayImageMinResolution 300 /GrayImageMinResolutionPolicy /OK /DownsampleGrayImages true /GrayImageDownsampleType /Bicubic /GrayImageResolution 300 /GrayImageDepth -1 /GrayImageMinDownsampleDepth 2 /GrayImageDownsampleThreshold 1.50000 /EncodeGrayImages true /GrayImageFilter /DCTEncode /AutoFilterGrayImages true /GrayImageAutoFilterStrategy /JPEG /GrayACSImageDict > /GrayImageDict > /JPEG2000GrayACSImageDict > /JPEG2000GrayImageDict > /AntiAliasMonoImages false /CropMonoImages true /MonoImageMinResolution 1200 /MonoImageMinResolutionPolicy /OK /DownsampleMonoImages true /MonoImageDownsampleType /Bicubic /MonoImageResolution 1200 /MonoImageDepth -1 /MonoImageDownsampleThreshold 1.50000 /EncodeMonoImages true /MonoImageFilter /CCITTFaxEncode /MonoImageDict > /AllowPSXObjects false /CheckCompliance [ /None ] /PDFX1aCheck false /PDFX3Check false /PDFXCompliantPDFOnly false /PDFXNoTrimBoxError true /PDFXTrimBoxToMediaBoxOffset [ 0.00000 0.00000 0.00000 0.00000 ] /PDFXSetBleedBoxToMediaBox true /PDFXBleedBoxToTrimBoxOffset [ 0.00000 0.00000 0.00000 0.00000 ] /PDFXOutputIntentProfile () /PDFXOutputConditionIdentifier () /PDFXOutputCondition () /PDFXRegistryName () /PDFXTrapped /False

/Description > /Namespace [ (Adobe) (Common) (1.0) ] /OtherNamespaces [ > /FormElements false /GenerateStructure true /IncludeBookmarks false /IncludeHyperlinks false /IncludeInteractive false /IncludeLayers false /IncludeProfiles true /MultimediaHandling /UseObjectSettings /Namespace [ (Adobe) (CreativeSuite) (2.0) ] /PDFXOutputIntentProfileSelector /NA /PreserveEditing true /UntaggedCMYKHandling /LeaveUntagged /UntaggedRGBHandling /LeaveUntagged /UseDocumentBleed false >> ]>> setdistillerparams> setpagedevice

Documents

SEG Y Format