United States Patent [191
`Gallagher
`
`[11] Patent Number:
`[45] Date of Patent:
`
`4,933,912
`Jun. 12, 1990
`
`[73] A ,
`ssigneez
`
`[54] THREE DIMENSIONAL SEISMIC
`PRQSPECHNG METHOD
`[75] Inventor: Joseph G. Gallagher, Bartlesville,
`Okla.
`C
`PM P l
`' 'ps etro eum ompany,
`Bartlesville, 0km.
`[21] APPL Nod 393,430
`4
`Aug- 11’ 1989
`[22] F?ed‘
`[51] Int. Cl.5 ............................................. .. G01V 1/28
`[52] US. Cl. .............. .
`.' .... .. 367/59; 367/56
`[58] Field of Search ..................... .. 367/56, 58, 59, 60,
`367/37, 73; 364/421
`
`[56]
`
`_
`References Clted
`US. PATENT DOCUMENTS
`
`.. 367/60
`.
`4,330,873 5/1982 Peterson ..... ..
`367/56
`4,476,552 10/1984 Waters et a1.
`.. 367/47
`4,573,148 2/1986 Herkenhoff et al.
`4,672,545 6/1987 Lin et al. ........................... .. 364/421
`
`364/421
`4,727,488 2/1988 Flinchbaugh ........... ..
`4,742,497 5/1988 Beasley et a1. ...................... .. 367/52
`Prima'? Exami'_1e"—Th°ma$ H- Tafcla
`Assistant Exammer—-Ian J. Lobo
`Attorney, Agent, or Firm-William R. Sharp
`[57]
`ABSTRACT
`A 3-D seismic prospecting method is provided which
`employs an areal array of sources and receivers by
`which seismic traces are generated. The areal array is
`Segregated into a plurality of Shells and angulafly 59'
`parted Sections from whlch a preselected number III of
`Source-‘receiver pairs are selected for a particular com
`mon midpoint. By means of the shells and sections, the
`source-receiver pairs so selected have associated there
`with a wide range of offsets and azimuth angles for the
`preselected fold m. The seismic traces corresponding to
`the selected source-receiver pairs are summed to give a
`stacked trace corresponding to the common midpoint.
`
`8 Claims, 8 Drawing Sheets
`
`STATION
`
`000000000000 H 000000000000
`20 0000000000000
`0000000000000
`
`000000000000
`0000000000000
`
`U) E
`
`00000000000001000000000000
`000013‘ 0000000000000|000000000000
`
`
`00000000000 111
`000000000
`
`/
`
`,
`
`LINE
`
`NE
`
`_
`
`/
`/
`
`8 000000
`
`0000~0000\Q0000000006000000 00000000000000000/00000000
`oooloooyooolooo 000000/000 [O0 000 /000000
`0060000000009 \0\00000000000/000/o
`/60000 oroooooooooo/oo
`00000000000 060000000000 000000000000 00000\Q000\o0 \ 000000 0000\0000000\0 6000000000000
`
`000 000000\000\000
`000000\Q090/000000 0000
`00000000000000/00/0000 OOO\OOOb\OOOOO
`000 000
`
`s §"Q9§\PP§LOEQU®1QAQQ
`F). 00\000
`00<l0|0 000000000p006l
`0000000000000 0000000000000 000000
`6000/0655 00/000,0000/0000 00000000/ , 00000000000/00 0/000/000/000000 @‘QM'OQQIQQQJQQ
`{e 0010 001 \000\000\000000 0000
`0001000
`000000000
`00\0000000
`
`0 0
`
`WesternGeco Ex. 1005, pg. 1
`
`

`

`US. Patent Jun. 12, 1990
`
`Sheet 1 of 8
`
`4,933,912
`
`
`
`:PECEIVEP POSITION
`
`
`
`I SOURCE POSITION
`
`
`
`I CMP POSITION
`
`é O x
`
`SE
`
`l
`
`/
`/
`/
`/
`/
`
`/
`
`00 000000 000,00
`00/000/0/0000001000
`0 0 06 0 0 0/ ,Mo 0 0 0 0
`0/000 00000/0/60|000\0
`0/000,000000 00|0 000\0
`0 O_O_LO’_O/O/O’O'O'O 00
`
`8 0000000/0 0 0001000000
`
`0 0'0 00 0 0 0 000
`0
`0 0 0 0 0 0 0 0 0 0/0 6|0 0\0 0 0 0
`0/000/0000 00|000000\0 00
`0
`I0_0 0!00 0/000l000\00 010004
`00I000T000\005?000/000;000;
`000b0000 0'000000/000/
`04L
`00
`00 0 00\0_gl90/0000 0000
`00
`000 0 0 00 0000|0000 0/000o0 0
`0\000<>000\0\0000 0 00/0000/000/
`00000\000000%9p0/0000/000d0
`
`25 0 000 00 0 0 00 0 0 00 00|0 0000 00 00
`0\0000\0 0 00001000 000/0000/0
`0000\00000|0 0 000000000
`0000000QQJL0900/000 0000
`O
`000 0 0 0000100 00 000 00
`000\Q00000|00 0 000600 0
`O
`O O O O O O O O O O
`000000\0\0_0L|0~0/0/0r600 0
`00
`O
`O O O O O O O O O O O O O O O O O/O/
`1 0 0 0 0 0 0 0 0 0 0
`000 000 000T00000 0 000
`O
`0
`00 0000000100 00000000 0
`0000000 00'00000000000
`00 0 000000100000 000000
`
`096 0 0
`
`0 0 0|0 0 0 0
`
`l
`
`1
`
`SW
`
`NE
`
`LINE
`
`NW
`
`5 10
`
`9.9
`
`_ _ _ _ _ _
`
`_ _ _ _ _ __
`
`NOIIVIS
`
`WesternGeco Ex. 1005, pg. 2
`
`

`

`US. Patent Jun. 12,1990 ‘
`
`Sheet 2 of 8
`
`4,933,912
`
`SELECTING AN ARRAY OF SEISMIC SOURCE
`POSITIONS AND RECEIVER POSITIONS
`
`I
`
`PRODUCING A PLURALITY OF SEISMIC
`TRACES CORRESPONDING TO A PLURALITY
`OF SOURCE-RECEIVER PAIRS OF THE ARRAY
`
`I
`
`SELECTING A FOLD NUMBER n1 WHERE
`n1 IS AN INTEGER OF AT LEAST 2
`
`I
`
`SELECTING COMMON MIDPOINT ( CMP)
`OF A SET OF AT LEAST A PORTION
`OF THE SOURCE-RECEIVER PAIRS, HEREAFTER
`DENOTED AS S-R SET, WHERE THE NUMBER
`OF PAIRS IN THE S-R SET IS
`GREATER THAN n1
`
`'
`
`I
`
`SEGREGATING THE ARRAY INTO n2 SECTIONS,
`WHERE n2 IS AN INTEGER
`AND WHERE 2Sng$n1
`
`I
`
`SEGREGATING THE ARRAY INTO n3 SHELLS
`WHERE n3 IS AN INTEGER AND 2Sn3$n1
`AND WHERE EACH SHELL HAS n2 PORTIONS,
`EACH PORTION LYING IN A DIFFERENT SECTION
`
`I
`
`SELECTING n1 SOURCE POSITIONS OR n1
`RECEIVER POSITIONS IN THE ARRAY WHICH
`CORRESPOND TO n1 SOURCE'RECEIVER PAIRS
`OF THE S~R SET, SUCH THAT EACH SHELL
`PORTION OF EACH SHELL INCLUDES AT LEAST
`ONE SELECTED SOURCE POSITION OR RECEIVER
`POSTION THEREIN TO THE EXTENT THAT EACH
`SUCH SHELL PORTION HAS AT LEAST ONE SOURCE
`POSITION OR RECEIVER POSITION
`CORRESPONDING TO A SOURCE—RECEIVER
`PAIR OF THE S-R SET
`
`I
`
`SUMMING THE SEISMIC TRACES WHICH
`CORRESPOND TO THE n1 SOURCE-RECEIVER
`PAIRS TO YEILD A STACKED TRACE
`
`FIG. 2
`
`REPEATING THE CMP
`SELECTION THROUGH
`SEISMIC TRACE
`SUMMING STEPS
`WITH RESPECT TO
`ADDI;%E)§gLI_N$gMMON
`
`A
`
`WesternGeco Ex. 1005, pg. 3
`
`

`

`US. Patent Jun. 12, 1990
`
`Sheet 3 of 8
`
`4,933,912
`
`zOHEqHm
`
`LINE
`2O
`15
`10
`1 O ® <8 O ® O O ® O O O O ® O O O O O 8 O ® ® ®
`O 8 ® O O ® O O O O O Q? O O ® O O ® O O O O ®
`O O O O O O O O O O O O O O O O O O O O O O O
`O O O O O O O O O O O O O O O O O O O O O O O
`5 O ® ® O O '8 O O ® O O ® O O O O 0 ® O O ® O ®
`O O O O O O O O O O O O O O O O O O O O O O O
`0 O O O O O O O O O O O O O O O O O O O O O ®
`0 ® ® O O O O O ® O O ® O O ® 0 O O O O ® O O
`O O O O O O O O O O O O O O O O. O O O O O O O
`10 O ® O O O O O O O O O O O O O O O O O O O O ®
`O ® ® 0 O ® O O ® O O 69 O O ® O O ® O O ® O 8
`O O O O O O O O O O O O O O O O O O O O O O O
`O ® O O O O O O O O O O O O O O O O O O O O ®
`0 ® 8 O O ® O O O O O ® O O ® O O ® 0 O ® O O
`15 O O O O O O O O O O O O O O O O O O O O O O O
`O ® O O O O O O O O O O O O O O O O O O O O ®
`O ® ® O O ® O O ® O O ‘8 O O ® O O ® O O ® O ®
`0 8) O O O O O O O O O O O O O O O O O O O O O
`O O O O O O O O O O O O O O O O O O O O O O O
`20 O ® ® O O ® O 0 ® O 0 ® 0 O @ O O ® O O ® O 48
`O O O O O O O O O O O O O O O O O O O O O O O
`O ® O O O O O O O O O O O O O O O O O O O O ®
`O 8) ® O O O O O ® O O ® O O O O O ® O O ®U O ®
`O O O O O O O O O O O O O O O O O O O O O O O
`25 O O O O O O O O O O O O O O O O O O O O O O ®
`O ® ® O O ® O O ® O O O O O O O O ® O O ® O ®
`O ® O O O O O O O O O O O O O O O O O O O O O
`O O O O O O O O O O O O O O O O O O O O O O O
`O ® 18) O O O O O ‘8 O O ® O O ® O O ® O O ® O ®
`30 O ® O O O O O O O O O O O O O O O O O O O O ®
`O O O O O O O O O O O O O O O O O O O O O O O
`‘O ® ® 0 O ® O 0 ‘8 O O 8 O O ® O O ® O O 8 O ®
`O ® O O O O O O O O O O O O O O O O O O O O ®
`O O O O O O O O O O O O O O O O O O O O O O O
`35 O ® ® O O ® O O 18 O O ‘8 O O ® O O ® O O 8) O ®
`O ® O O O O O O O O O O O O O O O O O O O O ®
`O O O O O O O O O O O O O O O O O O O O O O O
`O ® O O O ® O O ® 0 O 81 O O ® O O ® O O ® O ®
`O ® O O O O O O O O O O O O O O O O O O O O ®
`40 O O O-O O O O O O O O O O O O O O O O O O O O
`O ® ® O O ® O O O O O ® O O ® O O ® O O ® O O
`O O O O O O O O O O O O O O O O O O O O O O O
`O O O O O O O ® O O O O ® O O ® O O ® O O ® ®
`O ® O O O O O O ® O O ® O O ® O O ® O O ® ® ®
`
`O
`
`=RECEIVER POSITION
`
`X = SOURCE POSITION
`
`FIG.
`
`WesternGeco Ex. 1005, pg. 4
`
`

`

`US. Patent Jun. 12, 1990
`
`Sheet 4 of 8
`
`4,933,912
`
`2052.5
`
`LINE
`20
`15
`1O
`l O ® ® ® ® O O O O O ® O 8) ® O O O O ® O ® ® 8
`O ® ® O O ® O O O O O 81 O O ® O O O O O ® O ®
`O ® O O O O O O O O O O O O O O O O O O O O O
`O O ® O O O O O O O O O O O O O O O O O O O O
`5 O O O O O O O O ® O O O O 0 ® O O ® 0 O O ® ®
`O O O O O O O O O O O O O O O O O O O O O O O
`O O O O O O O O O O O O O O O O O O O O O O ®
`O O O O 0 ® 0 O ® O O ® O O ® 0 O ® 0 O ® 0 ®
`0 O ® ® O O O O O O O O O O O O O O O O O O O
`10 O ® O O O O O O O O O O O O O O O O O O O O ®
`O ® ® O O (8) O O O O O ® O O ® O O ® O O O O 69
`O O O O O O O O O 0 ® O O O O O O O O O O O O
`O O O O O O O O O O O O O O O O O O O O O O ®
`O ® ® O O ® O O ® O O O O O ® O O 69 O O ® O ®
`15 O O O O O O O O O O O O O O O O O O O O O O O
`O O O O O O O O O O O O O O O O O O O O O O O
`O 8 ® O O O O O ® 0 O 81 O O 8) O O O O 0 ® O ®
`O 8) O O O O O O O O O O O O O O O O O O O O O
`O O O O O O O O O O O O O O O O O O O O O O O
`20 O ® 69 O O ® O O O O O ® O O O O O ® O O ® O ®
`O O O O O O O O ® O O O O O O O O O O O O O O
`O 8) O O O O O O O 0 ® 0 O O O O O O O O O O ®
`O ® O O O O O O ® 0 O O O O ® 0 0 O O O O O ®
`O O O O O O O O O O O O O O O O O O O O O O O
`25 O O 69 O O O O O O O O O O O O O O O O O O O O
`O ® ® O O ® O O 18 O O ® O O ® O O ® O O ® O ®
`0 83 O O O O O O O O O O O O O O O O O O O 0 ®
`O O O O O O O O O O O O O O O O O O O O O O O
`O 8 ® O O O O O ® O O O O O ® O O ® O O 81 O ®
`30 0 ® O O O O O O O O O O O O O O O O O O O O ®
`O O O O O O O O O O O O O O O O O O O O O -O O
`O ® 8 O O 8) O O ® O ® O O O ® O O ® O O ® 0 ®
`0 O O O O O O O O O O O O O O O O O O O O O O
`O O O O O O O O O O O O O O O O O O O O O O O
`35 O ® ® O O ® 0 O ® O O O O 0 ® O O ® O O ® O O
`O ® O O O O O O O O O O O O O O O O O O O O ®
`O O O O O O O O O O O O O O O O O O O O O O O
`O O 8 O O ® O O ® O O O O O O O O 69 O O ® O ®
`0 ® O O ‘O O O O O O O O O O O O O O O O O 0 ®
`40 O ® O O O O O O O O O O O O O O O O O O O O O
`O ® O O O ® O O ® O O O O 83 O O O ® O O ® O O
`O O O ® O O O O O O O O O O O O O O O O O O O
`O ® 8) O ® O O ® O O O O ® ® O O O O ® O O ® ®
`O ® ® O O ‘8 O 0 ® O O ® O O O O O O O O ® ® ®
`
`O =RECEIVER POSITION
`FIG.
`
`X = SOURCE POSITION
`
`WesternGeco Ex. 1005, pg. 5
`
`

`

`g NOILVLS dWO
`o+o+o+o+0+.Ago+o+o+o+o+o+e——o+o+o+o+o+o+o+o+o——o
`
`
` +++++++++++++++++++++++++++++++++++++++++++—-+o+o+o+o+o+o——o+o+o+o+o+o+o~o+o+o+o+o+o+o+o+oggo+++++++++++——+++++++++++++++++++++++++++++++++ +++++++++++++++++++++++++++++++++++++++++++——+
`
`
` + +
`
`
`
`+o+a+o+o-—0
`
`. + .+ U + C %
`
`_
`4.
`
`+++++++++++++++++——+
`
`
`
`SOURCE-RECEIVERARRAYPOSITIONANDALSOCMPPOSITION
`
`
`
`
`
`
`
`
`
`CMPPOSITIONONLY
`
`l <
`
`.
`_F
`C’
`4.
`‘U
`4_
`Ci
`4.
`C'
`
`+ .
`
`’
`NOILVLS AVUHV
`
`US. Patent
`
`Jun. 12, 1990
`
`Sheet 5 of 8
`
`4,933,912
`
`C + '
`
`U 4
`
`.
`I’
`_F
`I.
`-F
`‘I
`_F
`‘.
`4.
`‘.
`
`+ rA
`
`+++++++++++~++++++++
`
`. C + C + . + . + C + C+ U + . + C + C + . + . + . + C + . + . . + . + C + . + . + C
`
`LL]
`2
`LLIH
`Z_IH
`_l>-
`<
`(101
`ED:
`O<
`
`40
`
`WesternGeco Ex. 1005, pg. 6
`
`

`

`US. Patent
`
`Jun. 12, 1990
`
`Sheet 6 of 8
`
`4,933,912
`
`1
`
`10
`
`’ LINE
`20
`
`30
`
`40 -.
`
`8 T AT I ON
`
`O . 6
`
`8 C)
`
`FIG. 6
`
`WesternGeco Ex. 1005, pg. 7
`
`

`

`Sheet 7 of8
`
`4,933,912
`
`FIG.
`
`US. Patent
`
`Jun. 12,1990
`
`STATION
`
`LINE
`4O
`30
`20
`10
`1
`-1236fi664655677777889AIIA98777777665646Q45321
`-2456777889ABCDDDEFFHIKKIGFEDDDCCIA9877765532
`‘556788899A3CDEEEFGGIJLLIGFEDDDCCBA9877765532
`-3678999AABCDEFFFGMHJKHHJGFEDDDCCBA9877765532
`-5678AAACCDEFGIIIKLLNOOOOHLKIIIGGFEDCAAA87753
`~3678AAACCDEFGIIIKLLNDDODNLKIIIGGFEDCAAA87753
`-3678AAACCDEFGIIIKLLNOOODMLKIIIGGFEDCAAA37753
`-3678!llEEFHIJMMHDDDDDDODODDDDDLLKIHGDDDA9964
`-579ADDDGGHJKLUDOODUDUOODOOODDOLLKIHGDDDA9964
`l O -379ADDDGGHJKLODDDDODODDDDOODDOLLKIHGDDDA9964
`-49ICGGGKKLNDOODDUUUDOUUUDOODODOUUMLKGGGCBB75
`-49ICGGGKKLDDDDODODDDODDDDDDDDDDODNMLHHHDCCBG
`-¢9BCGGGKKLODD00000000000OUOOUUDUONMLHHHDCC86
`-5!DEJJJ000000DDDO0000000ODOOOODUOOOUKKKFEE97
`-5|DEJJJODOOOOODDDODDOODDBDUDDDDUDDDDKKKFEE97
`-SIDEJJJODD000DOOODDODODDDDDDDDDDODDDKKKFEE97
`-SBDEJJJDUOUDUDDUDDDOUDOODDOOODDODODDKKKFEE97
`-5)DEJJJ00000000UDDDDUUOUDDOUDDDDDDDOKKKFEE97
`-6CEFKKKOOOOODDDOODODOOODBDDODUDBUOODLLLGFFA3
`-GcEFKKKDOOOUDDOUOODOODODDDODOOOOOOUDlLLGFFAS
`-7EGHHHMDUOOODDflDD0000000DODDOOOOODODDDDIHHl9
`-7EGHNNNODOOUDDODD0000000DDOOOUDODDOOODDIHHI9
`-7EGHNNNUOOUOODODOODDUODODOODDODDODOOODOIHHI9
`-7EGHNNNOODUUDDDDUDDUDDUDODDUOODODOODDDDXHHI9
`-9HJKDD00000000030DD0000000UUOUUDUUOOODDLKKDB
`-9HJK00000000000DD000000000OUDODOUOUODDDLKKDI
`~AIKLDD000000000DOODUOOOEODDDDDDDDDOODDDMLLEC
`-9GHMODDD0000000000000BUDDOOUDODDDDDDUDDIIICI
`-8EFFLLLU0000000000000DOUOOOUOODODODOHHHFGGIA
`-7CEEKKKDUOODOODDOOOODODOOODDOOOODUOOHHHGGGIA
`-3DEEKKKDOODOUDDOOODO0DDDOOOUOOODDOOONNNHHHCB
`-9FGGHHHDDDDUDOUUUO0DODDOOOOOODOODOOONNNGHHII
`-9FGGMHHDOODOUOUDODDDDDDDDODOODDDOOOONNNHHHBI
`-AHII000000000000000OOODODODDDDODOODDDDOIJJDD
`-BIJJODDO00000000000000DODUDDOOOOODODHHHMHHCC
`-IHHHMMMODODDDDOOUDD000OOOOOOODOOOOOOMHHHHHCC
`-IHHflMNMD00000000000ODODEUDDDODOODODOMMHHHHCC
`-IHHHMHMU09000000000DOODDUOODODODOOOOHHflHHHCC
`-IHHHMHMOUUOUDOOODDODOOOOOOOODUDODDDDLLLGGGII
`-lHHHHHMDODUODDUODDODDDOUDOOOOUOODUDULLLGGGIB
`-AFFFJJJLHMOODDUDDOUBOOUODOUOOOOOOLLLIIIEEEAA
`-AFFFJJJLLHOOOODOOODDDODDDUUUUDUDDLLLIIIEEEAA
`-AFFFJJJNMMOUOOUODDODDOOODDOODDDUOLLMIIIEEEAA
`-AFFFJJJNMHOOODUOOOOUOOOUDOODDOUUOMHHIIIEEEAA
`-CIIIMMNOOOOOOUDOOOODODOODOOODOOOOUODMHHHHHCC
`-IHHHNMMOODBODDDDOODDODODUOUUDODDOUDOLlLGGGII
`-IHHHMHMOOOOUODDUUODDDDDDDODODDUDOOOOLlLGGGII
`-AFFFKKKNNOOUOODDOODDDDDODDUODDDUEMMHIIIEEEAA
`-IHHHHHHOUUDUUDDDOODDDBDOOUUOUOODODOULLLGGGII
`‘IHHHMHHOUDDOODDOUODDDODDDDOOODODOODDLLLGGGIB
`'CIIINMNOUOODDUDDOODDDODUUDUOOODUODOOHHHHHHCC
`-IHHHMMMOODODDUDODODDDDOUDDUDUUDDOODDLLLGGGBI
`-BHNHMMMOOODDOUDOOOOOOOODOUOUODODOOUOLLLGGGBI
`-AGGGLLL00000000000DDOUDOODDODDDDOOUDKKKFFFAI
`-AHHHNNNDOOODODOODUOODDDOODDDDODDDDODNNNMHHll
`-AHHHNNNOODOUDOOOUOODDOOODDDOOODOODOONNNHHHII
`-IIIIOOUDODDDOUDOUGOODUODOOUOODUOODOUNNNHHHII
`-lJJJD000000000000DDDDDDDDDDDDOOODUDDDDDII13!
`-AHII0000000000000000UOODDUUOUDODODODMMHGGGAA
`-IJKLOODODOGOOOODDOOOGOODOOOOUDUUDDUUODOJIICB
`-BJlM0000000000000000DOODOOODOOODDUDOUDDKJJCA
`-AIKL0000DODODDDODDDDDODDDODDOOOOOODEOODKJJCA
`-AIKL00000000000000fl000000000DDDDDUDODUOKJJCA
`-AIKLODUDDUDDDDDUDOUUOODUDODDDODDDOODOODKJJCA
`-9GIJ00000000000000OUUDODOOOOUOODODOOOOOIHHI9
`-9GIJ00000000000000UOUDODBODDDUOODDOOOUDIHHl9
`-9GIJ00000000000000BDDODDDODDDDUDODDDODOIHHI9
`-9GIJ00000000000000DOODDDOOOOOOUDOUUOOODIHHI9
`-9GIJ00000000000000DOOODDODOOOOUOOOOUOUUIHHI9
`-9GIJ00000000000000DDODDOOODODOOOOOOOOODXHfll9
`-9GXJODOOODBOOOOOOOU000DDODDOOOOOODOUDDOIHHI9
`-7DFGLLMDD000000DDDDOUODDDUDODDDDDODDKKKFEE97
`'7DFGLLHODODOODDDDDOUDODODUOOODDDDDUDKKKFEE97
`-7DFGLLHUOOUODDDUUDDflDDOOODOUOODOODODKKKFEE§7
`-7DFGLL"0000000000000DDODDDDUUUDDDDOUKKKFEE97
`-GlDEIIJNNDDOOOODO000000000000DDDUNMKHHNDCCBG
`-6IDEIIJNNODOOOOUOOOODOOOUDOOOUODOHHKHHMDCCBG
`-5ACDHMIMNNODOODDODDDDDDODDOOODDODHLJGGGCII75
`-48AIEEFIIJMNUDODOODOOOOOODODOOHHLIMFDDDA9964
`-48AIEEFIIJMNDDDOOOODOODDOOBDOOMHLIHFDDDA9966
`-4BIIEEFIIJMHDOODBOOBOODDOOODBOMHLIHFDDDA9966
`-679ACCDFFGIJLMHHDUODDDDDDNHKKJHHGEDIAAA87753
`-479ACCDFFGIJLMHHDUDDOUDDUNMKKJMHGEDIAAAS7753
`-36l9IICEEFHIKLLLN00OODDOONHKKJHHGEDIAAA87755
`-265677899llCD EEFGGHJLLJHGFEEDCCIA9I77765542
`-2667889AABCDEEFFGHHIKHMKIGFEEDCCIA9877765562
`-1233fi¢65556667778889AIIA98877766655564433321
`
`7
`
`WesternGeco Ex. 1005, pg. 8
`
`

`

`US. Patent Jun. 12,1990
`
`Sheet 8 of 8
`
`4,933,912
`
`2
`
`10
`
`LINE
`2O
`30
`
`4O
`
`2
`
`10
`
`LINE
`2O
`30
`
`40
`
`FIG. 8
`
`WesternGeco Ex. 1005, pg. 9
`
`

`

`1
`
`THREE DIMENSIONAL SEISMIC PROSPECI‘ING
`METHOD
`
`5
`
`4,933,912
`2
`stacking velocity is used to correct for normal moveout
`among the traces. Maximizing the distribution of offset
`values serves to enhance the accuracy of the derived
`stacking velocity and thus also the accuracy of the
`resulting normal movement correction.
`With respect to azimuth, it desirable to have a maxi
`mum variation in azimuth angles among the source
`receiver pairs corresponding to a particular common
`midpoint. By having many different azimuth angles, the
`accuracy of 3-D statics solutions is enhanced. Statics are
`' corrections applied to seismic data to correct for low
`velocities (weathering velocities) of seismic waves en
`countered in unconsolidated sediments near the earth’s
`surface.
`Planning the positioning of sources and receivers in a
`3-D seismic areal array to optimize the various parame
`ter conditions discussed above is typically done by trial
`and error placement of sources and receivers until the
`desired optimization of conditions is obtained. Such a
`procedure is extremely time consuming. Depending on
`the size of the areal array, such a procedure can take
`from about a week to several weeks to carry out. This
`translates to a high expense and an adverse effect on the
`ef?ciency of a particular seismic prospecting project.
`
`25
`
`BACKGROUND OF THE INVENTION
`This invention relates to a three dimensional (3-D)
`seismic prospecting method wherein data is collected
`for a 3-D seismic areal array of sources and receivers
`and wherein such data is processed in a manner which
`optimizes certain seismic parameters which are dis
`cussed further below.
`In 3-D seismic prospecting, an areal array of seismic
`sources and receivers are positioned over an area of the
`earth’s surface and seismic data is collected in the form
`of seismic traces which are generated by the receivers in
`response to re?ected acoustic waves. This is in contrast
`to two dimensional seismic prospecting wherein a line
`rather than an areal array of sources and receivers is
`utilized. In 3-D as well as in two dimensional seismic
`prospecting it is desirable to “stack” a number of traces
`(commonly called a common midpoint bin or gather)
`which correspond to a number of source-receiver pairs
`which share a common midpoint. As used herein, the
`term “source-receiver pair” refers to a source position
`and receiver position located on opposite sides of a
`common midpoint and spaced substantially equidis
`tantly from the common midpoint. Stacking of seismic
`traces corresponding to such source-receiver pairs in
`volves summing of the traces so as to enhance important
`re?ection events in the traces and remove spurious
`noise which can obscure the re?ection events. In other
`words, stacking enhances the signal to noise ratio.
`Certain parameters which characterize a group of
`3-D source-receiver pairs corresponding to a particular
`common midpoint include fold, offset and azimuth.
`Fold refers to the number of source-receiver pairs shar
`ing a common midpoint for which traces are stacked.
`For example, if thereare l6 source-receiver pairs for a
`particular stack, there are 16 folds. Offset is simply the
`distance between the source and receiver of a particular
`source-receiver pair. Azimuth is the angular orientation
`of the source-receiver pair. More precisely, the azimuth
`angle for a particular source-receiver pair is the angle
`de?ned between the line along which the source
`receiver pair lies and a preselected direction such as
`true east or north.
`In planning a 3-D seismic areal array according to
`conventional techniques, it is desirable to position the
`sources and receivers to optimize certain conditions
`with respect to fold, offset and azimuth.
`With respect to fold, it is desirable to have an ade
`quate number of folds for each common midpoint in
`order to give an acceptable signal to noise ratio in the
`resulting stacked trace. It is also desirable to have uni
`formity of fold among a maximum number of common
`55
`midpoints for a particular areal array. This results in a
`uniform signal to noise ratio for the various stacked
`traces. With such a uniform signal to noise ratio among
`stacked traces, any variation of amplitude from trace to
`trace will be related to the strength of reflection events
`and not the difference in the number of traces being
`summed. This makes seismic interpretation easier and
`more accurate.
`With respect to offset, it is desirable to have a maxi
`mum variation of offsets for the source-receiver pairs
`65
`corresponding to a particular common midpoint. The
`different offset values are utilized to derive an average
`stacking velocity for the traces being stacked. Such a
`
`SUMMARY OF THE INVENTION
`It is, therefore, an object of the invention to provide
`a 3-D seismic prospecting method which yields seismic
`data optimized with respect to fold, offset and azimuth
`parameters.
`It is a further object of the invention to provide such
`a seismic prospecting method which is less time con
`suming and thus more ef?cient then prior methods.
`The above objects are realized by a 3-D seismic pros
`pecting method which comprises the steps of: (a) pro
`ducing a plurality of seismic traces respectively corre
`sponding to a plurality of seismic source-receiver pairs
`which de?ne an areal array of source positions and
`receiver positions, wherein each source-receiver pair
`includes a source position and a receiver position and
`wherein any one seismic trace is produced by a seismic
`receiver located at the receiver position of the corre
`sponding source-receiver pair in response to the re?ec
`tion of at least one seismic wave transmitted into the
`subsurface of the earth by a seismic source located at
`the source position of the corresponding source
`receiver pair; (b) selecting a fold number m, where n1 is
`an integer of at least 2; (c) selecting a common midpoint
`(CMP) of a set of source-receiver pairs which de?ne at
`least a portion of the areal array, wherein the source
`position and receiver position of each source-receiver
`pair of the set has said CMP as the midpoint therebe
`tween and wherein the number of source-receiver pairs
`in the set is greater than m; (d) segregating the areal
`array into 112 angularly separated sections de?ned by at
`least one imaginary boundary passing through the
`CMP, where n2 is an integer and Zéngém; (e) segre
`gating at least a portion of the areal array into n3 shells
`de?ned by n, imaginary closed and nonintersecting
`boundaries which surround the CMP, such that the
`innermost shell is de?ned by the boundary closest to the
`CMP and such that each other shell is de?ned between
`adjacent shell boundaries, where n3 is an integer and
`Zémém; (f) selecting n1 source positions or n1 re
`ceiver positions in the areal array which correspond to
`n1 source-receiver pairs of the set of source-receiver
`pairs having the CMP as their midpoint, such selecting
`
`35
`
`45
`
`60
`
`WesternGeco Ex. 1005, pg. 10
`
`

`

`4,933,912
`4
`FIG. 6 is a common midpoint fold map which illus
`trates the number of folds for each common midpoint of
`the FIG. 4 areal array before processing of data in ac~
`cordance with the invention.
`FIG. 7 is a common midpoint fold map which illus
`trates the number of folds for each common midpoint of
`the areal array after data processing in accordance with
`the invention.
`FIG. 8 illustrates a set of stacked traces correspond
`ing to a particular line number for each of the FIG. 6
`and FIG. 7 maps.
`
`10
`
`3
`of source positions or receiver positions being per
`formed such that each shell and each section includes at
`least one selected source position or receiver position
`therein to the extent that each section or shell has at
`least one source position or receiver position which
`corresponds to a source-receiver pair of the set of
`source-receiver pairs having the CMP as their mid
`point; (g) summing the seismic traces which correspond
`to the n1 source-receiver pairs of step (f) so as to yield a
`stacked trace.
`The method can be applied to a plurality of common
`midpoints corresponding to the areal array. Since a
`constant number of source-receiver pairs are selected
`for the various common midpoints, uniform fold is
`achieved. By segregating the areal array into shells and
`angularly separated sections, and then selecting source
`positions or receiver positions such that each shell and
`section has a selected source position or receiver posi
`tion therein, this ensures that the source-receiver pairs
`for a particular common midpoint have associated
`therewith a plurality of different offsets and azimuth
`angles. The shells force the selection of a range of off
`sets whereas the sections force the selection of a range
`of azimuth angles. As discussed previously, uniform
`fold, and a good offset and azimuthal distribution are
`particularly advantageous in processing of the seismic
`traces.
`In accordance with a preferred embodiment of the
`invention, an areal array pattern can be selected arbi
`trarily before step (a) of the invention as described
`above, most typically in the form of a symmetrical ar
`rangement of source positions and receiver positions.
`The resulting data as collected by means of step (a) is
`then processed or “decimated” to achieve the desired
`conditions with respect to fold, offset and azimuth. In
`effect, then, only part of the seismic data actually ob
`tained is selected for a particular common midpoint, and
`the remainder of the data is not used. It is desirable,
`therefore, in accordance with the invention to “over
`shoot” the areal array, or employ a sufficient number of
`source-=receiver pairs so as to have sufficient data from
`which to select. That means, of course, that more
`source-receiver pairs are typically utilized for a particu
`lar common midpoint in accordance with the invention
`than in the conventional trial and error procedure de
`scribed previously. However, planning of the areal
`array and processing of the data in accordance with the
`invention takes only, for example, a matter of hours as
`compared to the considerable amount of time (i.e.
`weeks) required using the conventional procedure. The
`savings in time utilizing the invention has been found to
`contribute to the overall efficiency of a 3-D seismic
`prospecting project and also lower expenses, despite the
`use of a larger number of source-receiver pairs.
`
`DETAILED DESCRIPTION OF THE
`INVENTION
`A preferred embodiment of the invention will now be
`described with reference to FIG. 1. The following de
`scription will be broken down into the various steps of
`the preferred embodiment. Some of the steps can be
`performed in a different order if desired. The steps of
`this preferred embodiment are set forth in the flow
`chart of FIG. 2.
`With respect to terminology used herein and in the
`appended claims, the term “areal array” as applied to
`source positions and receiver positions means that such
`source positions and receiver positions do not lie along
`a single line but instead generally de?ne a plane. As
`used in the following discussion, the term “array” will
`be understood to denote an areal array.
`1. Select Array of Source Positions and Receiver
`Positions
`An arrangement of source positions and receiver
`positions is selected, such as, for example, the array
`shown in FIG. 1. Receiver positions are indicated by
`circles and source positions are indicated by X’s. A
`circle with an X therein indicates a source position and
`receiver position being at the same location. The partic
`ular array shown has 25 lines (columns) and 25 stations
`(rows). Source or receiver positions can be easily de
`noted using such a line, station coordinate system. For
`example, the receiver position at line number 1 and
`station number 5 can be denoted as being at coordinates
`(1,5). The particular arrangement of source positions
`and receiver positions selected for this array can be
`expressed as a 3X3 array. That is, every third line and
`every third station has an associated source position,
`whereas each line and station of the array has an associ
`ated receiver position.
`Of coures, other arrays are within the scope of the
`invention, such as 2X3, 3X4, 4X4, etc. Modifications
`of such columnXrow arrays are also within the scope
`-of the invention. For example, the outer edges can be
`“padded” with extra source positions to maximize fold
`for common midpoints near outer edges of the array.
`Or, an array could be selected which has no particular
`pattern (i.e. orderly distribution) whatsoever. However,
`a predetermined pattern of source and receiver posi
`tions is generally preferred.
`It is further preferable that the “shot density”, or
`number of source positions per unit area, is sufficient to
`give the maximum number of folds which might be
`desired in subsequent data processing of traces associ
`ated with common midpoints of the array. Such an
`acceptable shot density can be easily checked by a cur
`sory check of a few randomly selected midpoints. One
`can determine by a visual examination of an array illus
`tration, such as FIG. 1, whether or not a sufficient num
`ber of source-receiver pairs share a particular common
`midpoint. Alternatively, a portion of a computer pro
`
`35
`
`45
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`FIG. 1 shows a source-receiver areal array and the
`boundaries of shells and sections in accordance with a
`preferred embodiment of the invention.
`FIG. 2 is a flow chart which sets forth the steps of a
`preferred embodiment of the invention;
`FIG. 3 shows a planned source-receiver areal array
`for an example described herein in which the invention
`was applied in the field.
`FIG. 4 shows the areal array which was actually
`employed in the above-mentioned example.
`FIG. 5 shows the common midpoints for the FIG. 4
`areal array.
`
`65
`
`WesternGeco Ex. 1005, pg. 11
`
`

`

`5
`
`25
`
`5
`gram like that set forth later in this application can be
`employed to derive a common midpoint fold map be
`fore any seismic shooting is actually carried out. Such a
`map is discussed in a' subsequent example, and indicates
`the number of folds for each of the common midpoints
`associated with the array. If it appears from such a map,
`or from a cursory visual examination, that the fold num
`bers are not high enough, the shot density for the array
`can simply be increased to accordingly increase fold.
`With regard to shape of the selected array, it is pref
`erable that the outer perimeter of the array be in the
`shape of a parallelogram. The array perimeter in FIG. 1
`is in the shape of a particular parallelogram, a square.
`2. Collect Seismic Data
`In this embodiment, it will be assumed that receivers
`are positioned at each of the receiver positions of FIG.
`1, and that each receiver detects re?ected seismic waves
`resulting from a single shot. However, it is within the
`scope of the invention to shoot the array in multiple
`layouts, where each layout includes receivers posi
`tioned at only a portion of the receiver positions of the
`selected array. Such a multiple layout shooting tech
`nique will be discussed further in a subsequent example.
`Referring to FIG. 1, at least one seismic wave is
`generated by a source from each source position of the
`illustrated array in sequence by any suitable technique,
`such as Vibroseis or detonation of explosive charges.
`For example, a sequence of shots could be undertaken
`starting with the source position at (1,1), followed by
`the source position at (4,1), etc., and ending with the
`source position at (25,25).
`_
`For any particular source which transmits a seismic
`wave into the subsurface of the earth, such seismic
`wave is reflected by strata boundaries in the subsurface
`so as to be received by each of the receivers. Each such
`receiver generates in response thereto a seismic trace.
`Accordingly, any one seismic trace corresponds to a
`particular source-receiver pair. If a computer is being
`used to implement the method, as is preferred, each
`resulting trace is stored in the computer along with its
`associated source-receiver pair. The identity of a
`source-receiver pair can be stored in computer memory
`by means of station and line coordinates, for example.
`This data is therefore stored and ready for access in
`subsequently described data processing steps.
`3. Select Fold Number
`The number of folds desired is selected, which will
`hereinafter be denoted by m. The number m corre
`sponds to the number of source-receiver pairs to be
`selected in accordance with subsequent step 7 which
`share a common midpoint. The number of folds selected
`depends on such factors as the number of available
`source and receiver equipment, the desired signal to
`noise ratio, and the size of the area over which uniform
`fold is desired. Such factors will become more apparent
`55
`in the description of a subsequent example. The number
`n1 is an integer, and is at least 2 since a minimum of two
`traces can be stacked for a particular common midpoint.
`For the illustrated embodiment, n1 has been selected to
`be 16.
`4. Select a Common Midpoint (CMP)
`A common midpoint is selected with respect to a set
`of source-receiver pairs which have corresponding
`seismic traces. Each source-receiver pair of the set has
`a source position and a receiver position having the
`selected common midpoint as the midpoint therebe
`tween. The selected common midpoint, which will
`hereinafter be referred to as the CMP, will be assumed
`
`4,933,912
`6
`.
`to be the CMP indicated in FIG. 1 for the sake of illus
`tration. It can be seen from an examination of FIG. 1
`that the set of sourc