/* DEFINITION OF SEGY TRACE HEADER FOR LARSE ONSHORE-OFFSHORE * AIRGUN DATA. * * 16Dec94 David Okaya install and update. * * * Lower case definitions are standard SEGY. * UPPER CASE ARE RE-DEFINITIONS FOR LARSE DATA. * Software which redefines or fills the SEGY values: * ESL = from Ewing shot list * R2S = ref2segy * SG = segygather * UTM = deg2utm (modification of trond/usc program) * LMO = usc_segylmo apply reduced traveltime * HFIX = usc_segyheadfix fixes trace headers * CAT = usc_segysmartcat cat disk files to one SEGY tape * UCC = usc_clockcor USC version of PASSCAL clockcor * UDB = usc_debias debias reftek amplitudes */ Sierra size SEGY bytes GCV type FIX ---- --------------- --- --- ------ -------------------------------- ---- long lineSeq 1- 4 none Sequence number within line long reelSeq 5- 8 none Sequence number within reel CAT long event_number 9- 12 kfldfn COMMON RECEIVER GATHER INDEX# HFIX [1-175] long channel_number 13- 16 kfldtn COMMON RECEIVER TRACE INDEX# HFIX [1-22,138] long energySourcePt 17- 20 kspct SP# FOR THIS LINE [101-N_EOL] ESL long cdpEns 21- 24 kcdp SHIP LINE # [1-16] HFIX long traceInEnsemble 25- 28 ktrace SHIP LINE TRACE # [1-EOL] HFIX short traceID 29- 30 ktrtyp SEGY Trace identification code: HFIX MAKE SURE IS SET TO "1" short vertSum 31- 32 kvsum No. vertically summed traces short horSum 33- 34 khsum No. horizontally summed traces short dataUse 35- 36 notuse 1 = production, 2 = test long sourceToRecDist 37- 40 range SOURCE-RECEIVER OFFSET (ABS) LMO long recElevation 41- 44 kgpel Receiver group elevation SG long sourceSurfElev 45- 48 kspel Source surface elevation SG long sourceDepth 49- 52 kspdp REFTEK AMPLITUDE BIAS REMOVED UDB long datumElevRec 53- 56 kgpdat UTM SOURCE X UTM long datumElemSource 57- 60 kspdat UTM SOURCE Y UTM long sourceWaterDepth 61- 64 kspwdp UTM RECEIVER X UTM long recWaterDepth 65- 68 kgpwdp UTM RECEIVER Y UTM short elevationScale 69- 70 - short coordScaler 71- 72 SHOULD BE 100,000; set to 1 HFIX long sourceLongOrX 73- 76 shotx DEC-DEG LONG SOURCE X (/3600.) SG long sourceLatOrY 77- 80 shoty DEC-DEG LAT SOURCE Y (/3600.) SG long recLongOrX 81- 84 rcvrx DEC-DEG LONG RECEIVER X (/3600.) SG long recLatOrY 85- 88 rcvry DEC-DEG LAT RECEIVER Y (/3600.) SG short coordUnits; 89- 90 kunits COORDINATE UNITS [CONSTANT AT 2] HFIX short weatheringVel 91- 92 kwtvel LMO REDUCING VELOCITY (M/S) LMO short subWeathingVel 93- 94 kswevel Sub-weathering vel. short sourceUpholeTime 95- 96 sptuh Uphole time at source in microsec short recUpholeTime 97- 98 gptuh Uphole time at rec. in microsec short sourceStaticCor 99-100 spst TIMING CORRECTION FROM CLOCKCOR UCC if =32767, uncorrectable short recStaticCor 101-102 gpst LMO REDUCING STATIC X/V (MSEC) LMO short totalStatic 103-104 static Total static applied *10,000 UCC short lagTimeA 105-106 kmslga Lag time A (msec) short lagTimeB 107-108 kmslgb Lag time B short delay 109-110 kmsfds TIME OF FIRST SAMPLE (msec) LMO short muteStart 111-112 fmute front mute time in sec short muteEnd 113-114 tmute end mute time in sec short sampleLength 115-116 knsamp #SAMPLES IF <2^16; ELSE =0 HFIX short deltaSample 117-118 sr SAMPLING INTERVAL IN MICROSEC HFIX short gainType 119-120 kgntyp Gain type: 1=fixed 2=binary 3=flat 4.. short gainConst 121-122 kinsgn instrument gain constant short initialGain 123-124 kgbn instrument inital gain in dB short correlated 125-126 kcorcd correlated trace? 1=no 2=yes short sweepStart 127-128 kswfrs sweep start frequency 129-132 cdpx CDP X coordinate 133-136 cdpy CDP Y coordinate 137-140 k3dste 3-D state (not used) short sweepLength sweep length in milliseconds short sweepType 1=lin 2=parab 3=exp 4... opt short sweepTaperAtStart short sweepTaperAtEnd short taperType short aliasFreq 141-142 kalhz alias filter frequency short aliasSlope 143-144 kaldbo alias filter slope short notchFreq 145-146 knthz notch filter frequency short notchSlope 147-148 kntdbo notch filter slope short lowCutFreq 149-150 klohz low-cutoff frequency short hiCutFreq 151-152 khihz hi-cutoff frequency short lowCutSlope 153-154 klodbo low-cutoff slope short hiCutSlope 155-156 khidbo hi-cutoff slope short year 157-158 kyear YEAR OF SHOT SG short day 159-160 kday DAY OF SHOT SG short hour 161-162 khour HOUR OF SHOT SG short minute 163-164 kminit MINUTE OF SHOT SG short second 165-166 ksecnd SECOND OF SHOT SG short timeBasisCode 167-168 ktmtyp TIME CODE [GMT=2] short traceWtingFactor 169-170 ktrwgt COMMON STATION GATHER# [1-172] HFIX short phoneRollPos1 171-172 kgprs1 LAND ARRAY # [1,2,3] HFIX short phoneFirstTrace 173-174 kgpbtr FIELD STAKE # R2S short phoneLastTrace 175-176 kgpetr C.S.G. THIS ARRAY [1-84,47,41] HFIX sum must = max of bytes 169-170 HFIX short gapSize 177-178 gpgap C.R.G. THIS ARRAY [1-86,48,41] HFIX sum must = max of bytes 9-12 short taperOvertravel 179-180 lntpr taper 181-184 --- not used 185-188 krcdp receiver CDP of trace 189-192 kscdp source CDP number of trace 193-196 -- scalar for datum at CDP 197-198 kfold number of traces in CDP 199-200 ksset subset number of subline PASSCAL SEGY ---------- 201-204 sid shotpoint ID number | 205-208 sidcdp shotpoint ID at CDP | 209-212 kgpcdp receiver # at CDP | 213-216 ksecdp shotpoint elev at CDP | 217-220 kgecdp group point elev at CDP | 221-224 kswcdp shotpoint water depth at CDP | 225-226 sstcdp shotpoint static at CDP *1000 | 227-228 gpsc receiver static at CDP in sec | 229-232 ksdcdp shotpoint depth at CDP | 233-234 kspidx sequential shot index | 235-236 kgpidx sequential receiver index \ / short extrash[10] 181-200 long samp_rate 201-204 short data_form 205-206 short m_secs 207-208 short trigyear 209-210 short trigday 211-212 short trighour 213-214 short trigminute 215-216 short trigsecond 217-218 short trigmills 219-220 float scale_fac 221-224 short inst_no 225-226 short not_to_be_used 227-228 long num_samps 229-232 char extra[8] 233-240 }; /* end of segy trace header */ ********************************************************************************* Detailed explanations of specific elements in this structure that were modified by USC (appear in all upper-case above): ********************************************************************************* Structure elem. Actual usage Range --------------- -------------------------------- ----------------- event_number COMMON RECEIVER GATHER INDEX# 1-175 channel_number COMMON RECEIVER TRACE INDEX# 1-22,138 energySourcePt SHOT POINT# FOR THIS LINE 101-N_EOL cdpEns SHIP LINE # 1-16 traceInEnsemble SHIP LINE TRACE # 1-EOL traceID SEGY Trace identification code: MAKE SURE IS SET TO "1" sourceToRecDist SOURCE-RECEIVER OFFSET (ABS) datumElevRec UTM SOURCE X datumElemSource UTM SOURCE Y sourceWaterDepth UTM RECEIVER X recWaterDepth UTM RECEIVER Y coordScaler SHOULD BE 100,000 set to 1 sourceLongOrX DEC-DEG LONG SOURCE X (x100000.) sourceLatOrY DEC-DEG LAT SOURCE Y (x100000.) recLongOrX DEC-DEG LONG RECEIVER X (x100000.) recLatOrY DEC-DEG LAT RECEIVER Y (x100000.) coordUnits COORDINATE UNITS [CONSTANT AT 2] weatheringVel LMO REDUCING VELOCITY (M/S) recStaticCor LMO REDUCING STATIC X/V (MSEC) delay TIME OF FIRST SAMPLE (msec) sampleLength #SAMPLES IF <2^16; ELSE =0 deltaSample SAMPLING INTERVAL IN MICROSEC year YEAR OF SHOT day DAY OF SHOT hour HOUR OF SHOT minute MINUTE OF SHOT second SECOND OF SHOT timeBasisCode TIME CODE [GMT=2] traceWtingFactor COMMON STATION GATHER# 1-172 phoneRollPos1 LAND ARRAY # 1-3 phoneLastTrace C.S.G. THIS ARRAY [1-84,47,41] gapSize C.R.G. THIS ARRAY [1-86,48,41] ********************************************************************************* Number of traces (airgun shots) in each line (there were 16 lines in the expt.) Due to redundant use of SP, the difference in end@ and start@ may be less than the total number of traces for each line. ********************************************************************************* BYTES: 21-24 (CDP) 25-28 (CDP TRC) 17-20 (SP) Line Name Ship Line # Traces (# of shots) start@ end@ ------ ------ ------------------- ------ ---- 01 1 653 101 753 01R 2 2310 105 2414 01X 3 848 101 935 01Y 4 968 101 1068 TR1 5 976 101 783 03 6 2446 101 2546 03R 7 2488 101 2587 TR2 8 394 101 494 02 9 3117 101 3215 02R 10 722 101 822 02X 11 1296 101 1369 02Y 12 1519 101 1619 02Z 13 783 101 883 TR3 14 1074 101 1174 01A 15 1227 101 1327 01B 16 1307 101 1407