SEGZ地震数据格式资料

关于拟议中SEGZ地震数据交换格式若干资料说明
2008年7月,来自EnCana(世界最大的石油天然气公司之一)、Claritas (从事地震数据处理及软件开发的公司)和休斯敦咨询公司一些人提出了新的地震数据交换格式——SEG-Z格式标准建议。这个建议吸收了来自Divestco 、CGGVERITAS、Paradigm、BP、C&C Systems等公司的意见,建议的新格式具有若干技术突破,具有良好的实用性、灵活性和可扩展性(附录A)。此外,还有人提出了标准的道头命名方案的意见(附录B)。这些资料供参考。
王宏琳
2008-8-3
附录A 拟议中的SEGZ格式基本概念
以往国内外地震数据交换格式均采用类—SEGY格式。SEGY格式定义于1975年,地球物理界一直要求增强SEGY:
(1)用标准方法读任何类似SEGY格式,包含描述性文本头、二进制文件头、道头和数据。头可以是单独分开的,提供对磁盘数
据集快速存取,或与数据交接一起(interleaved with)(目前
SEGY标准)。
(2)变长度、动态道头。随着野外仪器更精密,需要增加道头空间。
你只需要定义使用什么,而不需要利用道头中空间位置。
(3)增加数据类型,在线和道头中存储无符号整数、IEEE浮点数。
创建定制的格式处理数字压缩。能够处理64位(例如,能够精
确指定UTM XY’)。
(4)建立映射或关键字文件,称为DESCRIPTOR(描述符),支持数据自动加载到工作站。这个想法是道头实体不再只用字节位置
和描述定义,而是用名字定义。这个重要性在能够定义每个道
国培计划2012头名字在道头中的位置,不再依靠字节位置定义头实体,所以
需要确定的名字集合成为必不可少!
SEG-Z格式可以看成在SEGY对象前面加一个描述数据和头格式的导文(preamble):
(1)增加关键字映射文件(DESCRIPTOR)在每个SEGY前面,描述信息名称和位置。
(2)提供新的格式容易扩充应付将来需要,即,变长度、动态字段定义、道头存储在单独的索引文件用于快速存取。
注意:
●DESCRIPTOR包含一个ASCII描述数据组织,可以容易分析。
●DESCRIPTOR描述后面数据,可以附加在数据文件开始处,也可以是单独
文件。如果是单独文件,文件后缀为".sgxtxt"。
●关于是否采用XML或Yaml有争论。由于不需要太灵活,不如有些固定
的,容易语法分析。
●信息动态存储,可以变长度。
以下是DESCRIPTOR 一般样子:
SEGZ-Format-Definition-V1
# The preceding line is a mandatory identifier since this can be in a standalone file.
# It "has" to be the first line of the file or the file is not valid.
SECTION SEGZ-parameters
# SECTION is the keyword identifier for the beginning of a section
情天欲海
#Comment - This header defines a normal SEGY file
Name,              Length, Description
Textual-header,      3200, SEGY Rev(0) Default, length of character line header (bytes)
File-header,          400, Length of binary line header (bytes)
Trace-header,        240, Length of trace header (bytes)
Trace-trailer,          0, Length of trace trailer, Normally not used
铸炉之主派伦迪乌斯Name,                Type, Description
Trace_Samp_format,  IBM4, Format 1 in the binary header (overides the File header)
Endianess,            BIG, Big Endian, data suitable for SUN type computers  Endianess,        LITTLE, Little Endian, data suitable for PC type computers ENDSECTION
# ENDSECTION is the keyword identifier for the end of the section
SECTION File-header-definition
Name,          Byte,Type,Vector,Scalar,Addend,Description
FILE_SAMP_RATE,  17,INT2,1,1,0,Sample Interval
FILE_SAMP_NUM,    21,INT2,1,1,0,Maximum number of data samples per trace
TRACE_SAMP_FORMAT,25,INT2,1,1,0,Data sample format code
ENDSECTION
SECTION Trace-header-definition
Name,Byte,Type,Vector,Scalar,Addend,Description
ITRACE_LINE,1,INT4,1,1,0,Trace sequence no within line
ITRACE_FILE,5,INT4,1,1,0,Trace sequence no within this file
CDP,21,INT4,1,1,0,Ensemble no. (CDP CMP CRP etc)
HORI_NSUM,33,INT2,1,1,0,No of horizontally summed traces in this trace
SOURCE_HT,41,INT4,1,1,0,Surface elevation at source point
CDP_X,73,INT4,1,1,0,X-coordinate of ensemble (CDP) for this trace
CDP_Y,77,INT4,1,1,0,CPD coordinate (Y)
SOURCE_POINT,53,IEEE4,1,1,0,Energy source point number (shot peg)
SAMP_NUM,115,INT2,1,1,0,Number samples, this trace, good for marine data ENDSECTION
#
ENDFILE
注:
●ENDFILE为文件结束关键字标识符。这是需要的,因为你需要知道文件
何时结束。如果不存在ENDFILE,我们则认为文件被污染!
●曾经对于描述SEGZ格式有争议。有人相信应该用XML或YAML,其他人
认为应该用简单的key=value句法规则。上面描述的数据法更简单,演
变自segy格式,在1990年前由Photon (SeisX)首先使用过。这个句法
有其基础,已经用了二十多年。
●有人提出了两种道头方案列表见附录B (SEGZ_validnames)。
附录B 道头命名(SEGZ_validnames)
海空在召唤SEGZ道头命名方案A
Possible Byte Location Proposed Name Description
(1)Trace Header
(2)  1 ITRACE_LINE Trace sequence no within line
(3)  5 ITRACE_FILE Trace sequence no within this file
(4)9 INLINE The in-line number for 3D poststack data
(5)9 FIELD_SHOTID Original field record number
(6)13 CROSSLINE The cross-line number for 3D poststack data
(7)13 FIELD_CHANNEL Trace number within original field record
(8)17 SOURCE_POINT Energy source point number (shot peg)
(9)21 CDP Ensemble no. (CDP CMP CRP etc)
(10)25 CDPTRACE Trace no. within the (eg CDP) ensemble
(11)29 TRTYPE 1=data 2=dead 3=dummy 4=time break 5=uphole (etc
(12)31 VERT_NSUM No of vertically summed traces in this trace
(13)33 HORI_NSUM No of horizontally summed traces in this trace
(14)35 DATA_USE Data use. 1=production 2=test
(15)37 OFFSET Distance from source point to receiver group
SULPHER
(16)41 REC_HT Elevation at receiver group
(17)45 SOURCE_HT Surface elevation at source point
(18)49 SOURCE_DEPTH Depth of source below surface (+ve)
(19)53 REC_DATUM Datum elevation at receiver
(20)57 SOURCE_DATUM Datum elevation at source
(21)61 SOURCE_WATERDEPTH Water depth at source point
(22)65 REC_WATERDEPTH Water depth at receiver group
(23)69 HEIGHT_SCALAR Scalar to be applied to heights (REC_HT to REC_WATERDEPTH) (24)71 COORD_SCALAR Scalar for spatial coordinates (SOURCE_X to REC_Y)
(25)73 SOURCE_X_LOCATION Source coordinate - X (East)
(26)77 SOURCE_Y_LOCATION Y-coordinate of ensemble
(27)81 CDP_X X-coordinate of ensemble (CDP) for this trace
(28)85 CDP_Y CPD coordinate (Y)
(29)89 RECEIVER_X_LOCATION Receiver group coordinate - X
(30)89 COORD_UNITS 1=length (metres/feet) 2=lat/Lon 3=Decimal degrees 4=DMS (31)91 WEATH_VEL Weathering velocity
(32)93 RECEIVER_Y_LOCATION Receiver group coordinate - Y
(33)93 SUBWEATH_VEL Subweathering velocity
(34)95 SOURCE_UPHOLE_TIME Uphole time at source [ms]
(35)97 REC_UPHOLE_TIME Uphole time at receiver [ms]
(36)99 SOURCE_STATIC Source static correction [ms]
(37)101 REC_STATIC Receiver group static correction [ms]
(38)103 TOTAL_STATIC Total static applied [ms]
(39)105 LAG_TIME_A Time between end of 240-byte header and time break [ms]
(40)107 LAG_TIME_B Time between time break and initiation time of energy source [ms] (41)109 DELAY Time between initiation of energy source and start of recording. (42)111 MUTE_START Start time of mute [ms]
(43)113 MUTE_STOP Mute end-time [ms]
(44)115 SAMP_NUM No of samples in this trace
(45)117 SAMP_RATE Sample rate in microseconds for this trace
(46)119 FIELD_GAIN_TYPE Gain-type of field instruments : 1=fixed 2=binary 3=floating (47)121 FIELD_GAIN_CONSTANT Instrument gain constant [dB]
(48)123 FIELD_INIT_GAIN Instrument early or initial gain
(49)125 CORRELATED Correlated : 1=no 2=yes
(50)127 SWEEP_START Vibroseis sweep frequency at start [Hz]
(51)129 SWEEP_END Vibroseis sweep frequency at end [Hz]
小鸡对话
(52)131 SWEEP_LENGTH Vibroseis sweep length [ms]
(53)135 SWEEP_TAPER_START Sweep trace taper length at start [ms]
(54)137 SWEEP_TAPER_END Sweep trace taper length at end [ms]
(55)139 SWEEP_TAPER_TYPE Sweep type : 1=linear 2=parabolic 3=expoential 4=other (56)141 ALIAS_FREQ Alias filter frequency [Hz]
(57)143 ALIAS_SLOPE Alias filter slope [dB/octave]
(58)145 NOTCH_FREQ Notch filter frequency [Hz]
(59)147 NOTCH_SLOPE Noteh filter slope [dB/octave]
(60)149 LOW_CUT_FREQ Low-cut frequency if used [Hz]
(61)151 HIGH_CUT_FREQ High-cut frequency if used [Hz]
(62)153 LOW_CUT_SLOPE Low-cut slope if used [Hz]
(63)155 HIGH_CUT_SLOPE High-cut slope if used [Hz]
(64)157 YEAR The year the data was recorded
(65)159 JULIAN_DAY Day of year
(66)161 PEAK_VAL Maximum value for trace
(67)161 COORDINATE_SYSTEM  EPSG (Survey) code
(68)161 HOUR Hour of day
(69)163 MINUTE Minute of hour
(70)165 AVG_VAL Average value for trace
(71)165 SECOND Second of minute
(72)167 TIME_BASE Time basis code : 1=local 2=GMT 3=other 4=UTC
(73)169 WEIGHTING_FACTOR Trace weighting factor (2 exp (-N) volts
(74)169 RMS_VAL RMS value for trace
(75)171 REC_NUM_POS1 REC_NUM_POS1
(76)173 REC_FIRST_TRACE Geophone group ID of first trace in original field record (77)175 REC_LAST_TRACE Geophone group ID of last trace in original field record (78)177 GAP_SIZE Total no of groups dropped
(79)179 OVERTRAVEL Taper overtravel 1=down/behind 2=up/ahead
(80)181 CDP_LATITUDE Latitude of CDP bin
(81)185 CDP_LONGITUDE Longitude of CDP bin
(82)189 ORIG_RECNUM Original field record number unique add 10k if duplicates
(83)193 ORIG_TRNUM Original field trace number (channel number)

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