lllllllllllllllllIlllllllllligLiililslggilgilllllllllllllllllllllllllll
`
`United States Patent [19]
`Flentge
`
`[11] Patent Number:
`[45] Date of Patent:
`
`5,598,378
`Jan. 28, 1997
`
`[54] METHOD OF PERFORMING HIGH
`RESOLUTION CROSSED-ARRAY SEISMIC
`SURVEYS
`
`Inventor; David M_ Flentge’ Houston, Tex
`
`Assignee: Western Atlas International, Inc.,
`Houston’ Tex"
`
`Appl. No.: 339,489
`,
`F1led:
`Nov. 14, 1994
`
`Related U.S. Application Data
`'
`_
`_
`connnuatlon-lIl-pm of Ser. No. 71,515, Jun. 3, 1993, Pat.
`No. 5,511,039.
`Int. Cl.6 .............................. .. G01V 1120; GOlV 1/36
`U.S. c1. ........................... .. 367/56; 367/58
`Field Of Search ........................................ .. 367/56, 58
`
`References Cited
`
`[63]
`
`[51]
`[52]
`[58]
`
`[56]
`
`U-S- PATENT DOCUMENTS
`9/1943 Hoover et a1. .......................... .. 367/58
`
`2,329,721
`
`3,793,620
`2/1974 Miller . . . . . . . . . . . . . . .
`4,476,552 10/1984 waters er a1_
`4,597,066
`6/1986 Frasier . . . . . . . . .
`
`4,677,598
`4,742,497
`
`6/1987 Johnson - - - - _ - - - - - -
`5/ 1933 Beasley et a1- -
`
`. . . .. 367/56
`367/58
`. . . .. 367/50
`
`- - - -- 367/56
`367/52
`
`OTHER PUBLICATIONS
`
`Ritchie, W; 61st Annv. Seg Mtg, Nov. 10, 1991, V-1, pp.
`750-753; abst. only herewith.
`Buchholtz, H.; Circum~Paci?c Counc. Energy Mineral
`Resources; China, Sep. 20, 1984, vol. 10, pp. 737-752 abst.
`only herewith
`Primary Examiner—Nelson Moskowitz
`Attorney, Agent, or Firm—Charles R. Schweppe
`
`ABSTRACT
`
`57
`t
`1
`This invention provides a method for performing three
`dimensional seismic surveys. In one con?guration, receiver
`lines containing equally spaced receiver stations run in one
`direction while the source station lines run orthogonal to the
`receiver station lines. The receiver stations and/or the source
`stations are offset to obtain a desired spatial sampling
`(number of bins) or multiplicity of the Common mid Points
`In an alternate Con?guration’ the receiver line Spacing is
`oifset by a fraction of the source station spacing and/or the
`source line spacing is offset by a fraction of the receiver
`station spacing to obtain the desired spatial sampling. These
`con?gurations provide higher spatial sampling (smaller
`blnsnompamdwfhe ConvenFimlal ge°m@t_?@_S-_The $91311‘?
`
`blns may be comblned to Obtain folds (mulilpllcliyl whlch is
`su?icient to provide desired seismic imaging while preserv
`ing the benefits provided by the higher spatial sampling by
`
`the method of the present invention. Improved offset distri
`bution is obtained by placing the source lines non-orthogo
`
`4,933,912
`
`6/1990 Gallagher . . . . . . . . .
`
`. . . .. 367/56
`
`Hal to the receiver lines_
`
`. . . .. 367/56
`5,029,145
`7/1991 Marsden et a1. . . . . .
`367/15
`5,257,241 10/1993 Henderson et al. .
`5,402,391
`3/1995 Cordsen .................................. .. 367/56
`
`3 Claims, 6 Drawing Sheets
`
`0
`
`o
`
`O
`
`Q
`
`o
`
`o
`o
`+ + + + + +O + + + + + i
`o
`d 2 o
`o i ‘(
`
`0 30m
`
`-
`_
`o
`_
`+ +0 + + + + + + j
`o
`o
`‘
`0
`I
`
`- _ - _ _ - 9 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ e _ _ _ _ _ _ _ _ _ _ _
`
`_
`
`o- — ——————————— — — o- ————————————— — ~ 6 — —
`
`-
`
`o
`
`o
`
`O
`
`0
`
`0*“42
`O
`
`I
`_
`
`0
`
`o
`O
`
`o
`
`o
`
`0
`
`:++o++++0++++++++O++++o++j
`I
`SS 0
`0
`I
`_
`_
`o—— —
`;
`o 7/ w 42
`cw 42
`;
`I
`0'"
`0" 4
`I
`o
`_
`2
`_
`0 30C
`O,__ 4 2
`j
`+ + + + + +9 + + + + + / + + +0 + + + + + + j
`0
`o
`0
`g
`_
`400 \o _
`
`I
`_
`'
`I
`i
`
`_
`
`-
`
`I
`_
`
`I
`_
`
`O
`A 40/1
`o
`
`o
`
`0
`
`o
`
`o
`
`o
`
`0 a o
`
`F
`
`0 40C
`
`O
`
`0
`O
`
`o
`
`,
`
`I
`i
`
`o
`
`o
`
`0
`
`H
`
`:
`_
`_
`..
`
`:++o++++++-l‘>x+o+ +(++++ +o+\+:
`42 _
`o
`o d \lt :
`'
`;
`o 1
`I
`1
`30b 0 32
`OM12 ;
`-
`I
`l
`o
`7
`I
`I
`I
`i
`_
`i
`:
`_
`O
`E
`+ +O+ +5
`a
`o
`_
`-
`
`_
`
`_
`I
`_
`_
`
`_
`
`O
`+ +OR+
`0 S
`
`i
`
`o
`
`+o+
`
`o
`
`300 o
`{
`O
`+O+ + # +o+
`o
`
`o
`
`l
`i
`o
`,
`,
`o
`IIIIIIIIIIIIIlril|IIiIIIIIIIIIItlltItIlIiI lillllll
`
`_
`
`WesternGeco Ex. 1009, pg. 1
`
`

`

`Jan. 28, 1997
`
`OOOOOOOOOOOOOOOOOOOO+ + + + + + H ++++++++++++++++++++
`
`%+ + + + + H ++++++++++++++++++++
`H+ + + + + H ++++++++++++++++++++
`2+ + + + + H ++++++++++++++++++++
`
`+ + + + + H ++++++++++++++++++++
`
`OOOOOOOOOOOOOOOOOOOOI + + + + + H ++++++++++++++++++++
`
`Sheet 1 0f 6
`
`5,598,378
`
`OOOOOOOOOOOOOOOOOOOOI _+ + + + + -
`
`++++++++++++++++++++
`
`&+ + + 2\+ 2\+ H ++++++++++++++++++++
`2+ + + 2+ 2+ m ++++++++++++++++++++
`+ + + + + H ++++++++++++++++++++
`
`+ + + + + H ++++++++++++++++++++
`
`
`
`OOOOOOOOOOOOOOO OOOOH
`
`_\_r____|_r_,h_______»_____M_h_____n______h____________ % +nru + %+ %+ nw+ H ++ +++++++++_+++++++
`‘4+ + + + + - ++++++++++++++++++++
`%+ + + 2\+ 2\+ H ++++++++++++++++++++
`
`oooooooooooooooo .oooH 2
`nw+ + + + %+ m 2++++++++++++++++++++
`2+ + + 2+ 2+ H ++++++++++++++++++++
`~+ + + + MV+ - 9 +++++++++++++++++++
`
`
`
`+l|2 + 2(+ 2(.+ 2J H 8+++ ++++++++++++++++
`2+ + + +% + H ++++++++++++++++++++
`+ + + +% + H ++++++++++++++++++++
`
`9 2
`
`US. Patent
`
`
`
`l__ _____.____________________________.__.______
`
`FIG. 1
`(PRIOR ART)
`
`FIG.
`D: (
`R m Du
`
`1U R A
`
`WesternGeco Ex. 1009, pg. 2
`
`

`

`US. Patent
`
`Jan. 28, 1997
`
`Sheet 2 0f 6
`
`5,598,378
`
`O
`
`O
`
`0
`
`O
`
`O
`
`0
`
`+ +0 + + d+2 +0 + + + +o\+ + + + + .
`
`0
`
`O
`
`_
`
`O
`
`(
`
`Q
`
`0
`
`IIIAL
`O
`
`O
`
`+ +0 + +
`
`0
`
`“
`I
`P
`
`~
`
`_
`
`Z
`
`-_ _ ___e _ _ _ _ _ _ _ _ _ _ _ _ _ _ __e _ _ _ _ _ _ _ _ _ _- __
`
`:
`_
`_
`
`_
`
`:
`
`_
`
`_
`
`_
`
`_
`_
`
`____
`
`0
`
`O
`
`-
`
`0~42
`0*42
`
`l
`
`0 0 0
`
`0/‘42
`O~42 0
`0”‘42
`0642 +0
`_
`+ + + + +
`‘
`o
`o
`[G 2 :
`O
`o
`'
`:
`I
`0
`x
`A4011 0
`_
`o
`o
`_
`I + + *
`+ + + +
`_
`OT
`_
`~
`I
`_
`_
`V
`
`o
`
`O
`
`o
`
`300 o
`
`o—— ——————————— ———o— ————————————— ———o——— -
`Q
`0
`I
`O
`O
`O
`_
`- + + o+ + + + 0+ + + + c>+ + + + c’+ + + + 0-1- + :
`Z
`S O
`O
`-
`_
`o——;6 s
`Z
`3
`O
`»
`j
`_
`0
`0 230C
`“
`+ + + + +
`o
`o
`+ + + + + + +0 + +:
`O
`400\O
`:
`#400
`'
`0
`"40b 0
`'
`o
`_
`0
`_
`+ O+\ + :
`42 _
`o\
`_
`—
`-
`I
`0
`-
`+ +o+ +1
`:
`-
`-
`
`o
`IIIIIIJTITII|1|||III||I
`
`:
`-
`“
`
`++++++
`
`FIG. 2A : ++++++++++++++++++++++++++++++++++
`
`0
`
`0
`
`0
`+ +o+
`RS
`0
`
`++++++++++++++++++++++++++++++++++++++++
`
`++++++++++++++++++++++++++++++++++++++++
`
`++++++++++++++++++++++++++++++++++++++++
`
`“++++++++++++++++++++++++++++++++++++++++
`
`++++++++++++++++++++++++++++++++++++++++
`
`++++++++++++++++++++++++++++++++++++++++
`
`++++++++++++++++++++++++++++++++++++++++
`
`++++++++++++++++++++++++++++++++++++++++_
`
`++++++++++++++++++++++++++++++++++++++++
`
`++++++++++++++++++++++++++++++++++++++++
`
`o
`,,
`o
`+
`+!
`+ '‘1:- O +( + + + +
`ll
`0
`0
`d‘lNl 0 30b
`O
`I
`l
`II
`I
`I
`H 0
`+O+ +\+ +o+(+ + +o+
`0
`H
`O
`H o
`.1
`
`0
`
`++++++++++++++++++++++++++++++++++++++++
`
`++++++++++++++++++++++++++++++++++++++++
`
`++++++++++++++++++++++++++++++++++++++++
`
`++++++++++++++++++++++++++++++++++++++++
`
`++++++++++++++++++++++++++++++++++++++++
`
`+++++++++++++++++++++++++w+++++++++++++++
`
`++++++++++++++++++++++++++++++++++++++++
`
`++++++++++++++++++++++++++++++++++++++++
`
`++++++++++++++++++++++++++++++++++++++++
`
`++++++++++++++++++++++++++++++++++++++++
`
`H++++++++++++++++++++++++++++++++++++++++
`
`++++++++++++++++++++++++++++++++++++++++
`
`_++++++++++++++++++++++++++++++++++++++++
`++++++++++++++++++++++++++++++++++++++++
`
`++++++++++++++++++++++++++++++++++++++++
`
`V++++++++++++++++++++++++++++++++++++++++
`++++++++++++++++++++++++++++++++++++++++
`
`_++++++++++++++++++++++++++++++++++++++++
`++++++++++++++++++++++++++++++++++++++++
`
`_++++++++++++++++++++++++++++++++++++++++
`++++++++++++++++++++++++++++++++++++++++
`
`_++++++++++++++++++++++++++++++++++++++++
`++++++++++++++++++++++++++++++++++++++++
`
`++++++++++++++++++++++++++++++++++++++
`
`'++++++++++++++++++++++++++++++++++++++
`
`o
`
`o
`
`++++++++++++++++++++++++++++++++++++++++'
`_++++++++++++++++++++++++++++++++++++++++
`
`U1 O Q.
`
`+++++++++++++++++++++++++++++++++++++
`
`+++++++++++++++++++++++++++++++++++++
`
`WesternGeco Ex. 1009, pg. 3
`
`

`

`U.S. Patent
`
`Jan. 28, 1997
`
`Sheet 3 of 6
`
`5,598,378
`
`o
`7 -
`
`On
`
`V
`_
`_
`_
`j + + +
`
`o
`0
`
`o
`-
`o
`
`"
`-
`:
`
`o
`-
`700 O 60’.
`d
`c
`+ + + + 0+ + + + +o/+ + + -)\O+ + + E
`
`oo+oooo+oo
`
`_
`
`:
`
`l
`
`FIG. 3 i
`
`—
`
`0
`
`:
`
`O
`
`O
`
`m’oSTATlONSO
`
`"
`
`:
`III
`
`0
`+ + + + + + + + + + + + + + + + -
`o
`o \
`o
`
`0
`
`o
`
`*
`
`000
`
`} P62
`0
`
`+ + + + o+/+ + + +0 + + + + 0+ /+ +
`
`-
`-
`O
`O
`_ + + + +0 + + + + o+\+ + + +0 + + + + + + + E
`
`o
`
`o
`o+b=O1/q STAT!
`
`000
`
`_
`
`i
`:
`
`_
`
`-
`
`O
`
`b
`
`O
`
`o<——>0
`
`—e—
`
`o
`o
`0
`llIlllllllllllllllllllllllllllllllllll\l
`
`O
`
`O
`
`o
`
`_
`
`l
`
`:
`
`
`
`
`+++-+++++++++++ +++++++++++++++++ +++ ++++++
`++++++++++ ++ ++++++++++++++++ ++ + +++ + +++++
`
`
`
`
`
`
`
`
`
`+ +++++++++++++ ++++ +++++ ++++++++ ++++ ++++ + + +++++++++++ ++ +++++++++ +++++ ++++++ + +++++
`
`
`
`++ +++++++ +++ ++++++ ++ +++ +++ + ++ + +++++++
`
`
`
`
`+++ + +++ +++++ +++++++++++ ++++ +++ ++++++++++
`
`
`+++ + ++++++++++ + ++++++ +++++++++++++++++ +++++
`
`
`+++ + ++++++ ++ ++ +++++ ++++ + ++++++ + ++++ +++++
`
`
`++ ++ +++++ + + + ++ ++++++++++++++++ + +++ ++++++
`+ + ++ + +++++ ++ ++ + +++++++++++++++ + +++++++++
`
`FIG. 3A '
`
`
`
`
`
`++++++++ +++ + ++ ++++++ ++++ ++ ++ +++ ++ + ++ + +++
`
`
`
`_+++++++++++++++++++ ++++ ++++++++ ++ + + + + ++ +
`
`
`'+ ++++++ +++++++ +++++ ++ ++ ++ + + + + ++ ++ + + + + ++ +
`
`
`++++ ++++ ++++++ + +++++++++++ ++ +++ +++ + + ++ ++
`
`
`
`++++ ++++++++ +++++++ + + ++ ++++++++ ++++ ++ +++
`
`
`
`++++++++++++++ +++ + + +++ + +++++ _+ +++++++ + ++++++++
`
`
`++++ ++ +++ + +++++++++++++ +++++ + +++ +++++ +++ ++++ _+ +++ ++ ++++++ ++ +++++ + +++ +++++ +++
`
`
`
`
`
`
`++++++ +++++ ++ + + ++ + +++++++ + +++ +++ +++ ++++++ ++ +++ + ++ +++++++++ +++++ ++ ++ +++++ + +++++++
`
`
`
`+++++ ++ + ++++++ ++++++++++++ ++ +++ ++++ +++++
`
`
`
`
`
`++++ + ++ +++++ +++ +++++ ++ + +++ +++++ ++ ++ ++ + +++++ ++ +++ ++++++ +++++ + ++++++ ++++++++++ + +++
`
`
`
`
`
`
`++++++ ++ +++++++ ++ +++ + ++++ +++ ++++++ +++ +++++++++ ++ +++ ++++ +++++
`
`++++ + +++ +++ +++ + +++++
`
`
`
`
`+++ ++ ++ + + ++ ++ + + ++++++++++ + +++++ ++++ + +++ +
`
`+++ + + ++ + ++++ ++++++ ++ +++ ++++++++++ + ++++++
`
`
`
`+ ++ ++ +++ + ++ +++ + +++ ++ +++++ + +++++ ++++ +++++
`
`
`
`
`
`
`
`
`
`“+++ ++++++++ +++ ++++++ +++ +++ +++ ++++ ++ + +++ +
`
`
`
`
`++++ ++++++++++ ++++++++++++++ +++ +++++++++
`
`
`+ +++ ++++ ++++++ ++++++ +++++ + +++ ++++ + ++ ++++
`
`
`
`
`+ +++++ ++ ++++++ +++++++++++++++++++ + ++++++
`
`
`
`
`
`
`
`
`
`++++++++++++ ++ +++++++++ ++++++++++++ +++++
`
`
`
`
`
`
`
`
`
`++++ ++++ +++++++ +++ +++++ +++++ ++ + ++ + + ++ +++
`
`
`
`
`
`+++ + + ++ + ++++++ + +++ + +++++++++ ++ + + ++ + ++ + ++
`
`+ +++ + +++ ++++++ +++++++++ ++++++++ ++ + +++ +++
`
`
`
`+++ + +++ + +++ +++ + ++++++++++++++++ ++++ +++++
`
`
`
`
`
`
`
`
`+++++++ + ++++++ + ++ + + ++ ++ ++++ ++ + + ++ +++ + + ++ +++++++ ++ +++ +++++++++++++++++++ ++ ++++ +++
`
`
`
`
`+ +++ +++ ++ ++++++++++++++ ++++++++ +++++++++
`
`WesternGeco Ex. 1009, pg. 4
`
`

`

`US. Patent
`
`Jan. 28, 1997
`
`Sheet 4 of 6
`
`5,598,378
`
`
`
`384
`
`i88
`
`i92
`
`396
`
`i100
`
`1104
`
`i108
`
`i112
`
`’
`
`\
`
`FIG 4
`
`‘""""“’X W
`
`o
`
`o
`
`o
`
`
`0
`
`m0Z<|
`
`_.
`
`9D
`
`90°
`
`900
`
`QOOTBOF
`92:31—23
`:
`1+er+++o+++++++++++++
`
`92b—~
`‘
`
`o
`
`0 Z
`
`’_3
`0
`
`92b
`
`+++++++++o+++++++++
`
`o o
`
`'-96b
`
`92b 0
`+++++++++++++++++++---;~r
`o
`o
`o
`
`900”“0
`92b“—0
`0
`o
`o 94 94
`o
`94
`800
`+°+LIO++++°++ +++++°++I++
`0‘95
`92b"~
`
`°~96
`
`900
`
`i84
`
`i88
`
`i92
`
`i100
`196
`—>X
`
`i104
`
`i108
`
`i112
`
`WesternGeco Ex. 1009, pg. 5
`
`r26
`
`r25
`
`r24
`
`r23
`
`r22
`
`y
`
`is
`filc;
`.
`(PR/ORART)
`
`WesternGeco Ex. 1009, pg. 5
`
`

`

`US. Patent
`
`Jan. 28, 1997
`
`Sheet 5 of 6
`
`5,598,378
`
`+0L
`O
`
`O
`
`O
`
`O
`
`O
`
`100m
`++++++Q+++++++¢+++++++Q+++++++-b+
`O
`/
`O
`O
`O
`o 102m°
`O
`
`O
`
`O
`
`O
`
`O
`
`O
`
`O
`
`O
`
`O
`
`O
`
`O
`
`O
`
`O
`O
`O
`O
`O
`+++O++++OL+++O++++Q+++O++++
`O
`
`O
`
`O
`
`O
`
`O
`
`O
`
`O
`
`o
`o
`
`O
`
`O
`
`O
`
`O
`
`O
`
`O
`
`O
`
`O
`
`O
`7000 o
`
`O
`
`O
`
`O
`
`o
`O
`O
`0104 0 104 O
`O
`O
`O
`+o+ +
`+++G+++++++G++
`106 0
`O
`o
`Cl 0
`0
`"SS 0
`
`o
`o oRs/20
`O
`O
`702r o
`o/
`
`O
`
`O
`
`D
`
`O 1 00Gb o
`
`+
`
`+o+ +
`
`O
`
`07
`
`O
`
`O
`
`0
`
`o
`
`oss/zl
`
`o
`O
`++++o++++o
`
`O
`
`o
`
`0 Q7020 0702b 0
`o)
`1000 0)
`o
`0704 o
`+g+++9++++++++J9+++++++19gr++
`+++
`
`O
`
`o
`
`o
`
`O
`
`o
`
`o
`
`o
`
`o~106o
`
`o
`
`o
`
`o
`++++++
`
`WesternGeco Ex. 1009, pg. 6
`
`

`

`US. Patent
`
`Jan. 28, 1997
`
`Sheet 6 of 6
`
`5,598,378
`
`...m-.uu-«....."mun“... mum..." mu...
`
`moz<km5
`
`WesternGeco Ex. 1009, pg. 7
`
`WesternGeco Ex. 1009, pg. 7
`
`

`

`5,598,378
`
`1
`METHOD OF PERFORMING HIGH
`RESOLUTION CROSSED-ARRAY SEISMIC
`SURVEYS
`
`CROSS-REFERENCE TO RELATED
`APPLICATION
`
`This application is a continuation-in-part to US. patent
`application Ser. No. 08/071,515, ?led on Jun. 3, 1993, now
`US. Pat. No. 5,511,039.
`
`l0
`
`BACKGROUND OF THE INVENTION
`
`2
`etry wherein shot lines 26a—26n are orthogonal to the
`receiver lines 20a-20r. The resultant seismic traces (seismic
`data) are recorded corresponding to the common-midpoints
`(“CMP”) between the source points and the receivers. A
`common-midpoint being the same midpoint for seismic
`traces obtained from different combinations of source points
`and the receivers in a seismic survey geometry. Common
`midpoints are also referred to in the art as common-depth
`points or common-re?ection-points. Once the source has
`been activated at each of the predetermined source points
`and the resultant data has been recorded, the swath is moved
`to an adjacent terrain and the above-noted process is
`repeated.
`In the prior art seismic survey geometries, the receivers on
`all the receiver lines are equidistant and all lines are sym
`metrically placed, i.e., the receivers are in a rectangular
`array. There is no stagger between the receivers in two
`adjacent receiver lines. The source lines are likewise sym
`metrical and are placed midway between adjacent receivers,
`as shown in FIG. 1. Such a survey geometry provides
`seismic data for common-midpoints, which correspond to
`cells or bins having the dimensions of one-half (1/2) the
`spacing between adjacent receivers on the receiver lines and
`one-half (1/2) the spacing between adjacent source points
`along the source lines. For example, if the receivers and the
`source points are each ?fty (50) meters apart, each bin will
`be twenty-?ve by twenty—?ve (25x25) meters. Each such bin
`will contain seismic data corresponding to one common
`midpoint. The resultant bins obtained from the survey geom
`etry of FIG. 1 are shown in FIG. 1A. Each solid lined square
`28 indicates the bin size and the center 29 of each such bin
`represents the common-midpoint associated with that bin.
`During surveying operation, each source point produces
`seismic traces for each midpoint in the survey geometry. As
`the source is moved, the midpoints overlap. The data for
`each midpoint is collected for all shots and the data common
`to a midpoint is added or stacked to obtain better de?nition
`of the data for each common-midpoint. The spacing between
`the receivers and the shot points, or the bin size de?nes the
`spatial resolution of a survey geometry. The spatial resolu
`tion of such prior art survey geometries may be improved by
`reducing the bin size, i.e., by decreasing the receiver and/0r
`shot point spacings, which increases the equipment cost,
`operational time to perform the survey and the data process
`ing time. Also, in the prior art methods, the bins are
`su?iciently large and may not be appropriately combined
`(“macrobinned”), for example, when data from certain
`CMP’s is either not recorded due to physical con?guration
`di?iculties or equipment failure.
`It is therefore highly desirable to have a method of
`geophysical prospecting which provides small data bins
`(higher spatial resolution) compared to the prior art bins
`(“standard” cells or bins) without substantially increasing
`the cost of the equipment or requiring additional operational
`time while allowing one to preserve the bene?ts of the
`standard cells.
`The quality of the results, i.e., seismic maps, obtained
`from the processing of seismic data using processing tech
`niques, such as stacking, normal-moveout correction, dip
`moveout correction and migration, depends partially on the
`bin size. When a smaller bin size is desired, the prior art
`survey would need to be performed using a narrower grid
`(smaller receiver and/or source spacing), which is some
`times not possible due to the nature of the terrain or is cost
`prohibitive. On the other hand, it is highly desirable to
`perform seismic surveys having wider spaced grids but
`which provide spatial resolution equivalent to a narrower
`
`1. Field of the Invention
`This invention relates generally to seismic prospecting,
`and more particularly to a method of performing three
`dimensional seismic surveys on land utilizing staggered
`crossed-array survey geometries.
`2. Description of Related Art
`In seismic exploration, to obtain information relating to
`the substrata located below the earth’s surface, seismic
`waves in the form of pressure pulses or shock waves are
`induced into the earth. These shock waves propagate
`through the substrata beneath the earth’s surface where they
`are re?ected by the subterranean interfaces back to the
`earth’s surface. The re?ected seismic waves are detected by
`a plurality of spaced apart receivers placed on the earth’s
`surface, which convert the re?ected seismic waves into
`signals. A geophone or a group of geophones is typically
`used as a receiver. The (stratigraphical information) of the
`substrata. Seismic sources, such as seismic vibrators and/or
`explosive devices, are used to produce the shock waves.
`In recent years, three dimensional (“3D”) seismic surveys
`have become very common for they provide more compre
`hensive geophysical information about the earth’s subsur
`face compared to the conventional two dimensional (“2D”)
`surveys. However, 3D surveys require the use of complex
`survey geometries and they produce signi?cantly more
`seismic data compared to the two dimensional surveys.
`Three dimensional surveys are typically performed using
`what is called a “swath method.” In a swath method, a
`plurality of very long (3000-6000 meters) receiver lines,
`each containing a plurality of uniformly spaced apart receiv
`ers (receiver stations), are placed in parallel on the earth’s
`surface (terrain) which is to be surveyed. Each receiver
`de?nes a single receiver point on the receiver line. The data
`gathering equipment limitations and other economic con
`siderations frequently dictate the number of receiver lines,
`number of receivers on each receiver line and the receiver
`spacing that can be used to perform a survey.
`After placing the receiver lines on the earth’s surface, a
`seismic source such as a seismic vibrator or an explosive
`device is activated at predetermined spaced-apart locations
`(“source stations” or “source points”) to impart desired
`shock waves into the earth. The source stations are placed
`along source lines which run orthogonal to the receiver lines
`and midway between adjacent receivers.
`A typical prior art three-dimensional survey geometry is
`shown in FIG. 1. A plurality of receiver lines 20a, 20b .
`.
`.
`20r, each containing a plurality of equally spaced apart
`receivers 22 are placed in parallel on the earth’s surface. A
`seismic source is activated at predetermined source stations
`24, placed along source lines or shot lines 26a, 26b . .
`. 26n,
`which run orthogonal to the receiver lines 20a-20r. The
`source lines lie at the middle of predetermined adjacent
`receivers. This provides a symmetrical crossed-array geom
`
`15
`
`25
`
`35
`
`45
`
`55
`
`60
`
`65
`
`WesternGeco Ex. 1009, pg. 8
`
`

`

`3
`grid. Furthermore, it is highly desirable to have a method for
`performing seismic surveys which, for given equipment,
`provides ?exibility with the bin size without compromising
`spatial resolution and without increasing the operational
`cost.
`As noted earlier, to improve the quality of data, seismic
`traces for common-midpoints are collected. Such traces
`result from re?ections from the common-midpoints from
`several combinations of source points and the receivers in
`the survey geometry. There is associated an “offset” with
`each such trace. For the purpose of this invention, the term
`“offset” is de?ned as the surface distance between a source
`point and a receiver. It is known in the art that “offset
`distribution” relating to common-midpoints is an important
`parameter in any 3D survey. The ideal offset distribution is
`completely uniform or linear. Two dimensional surveys, due
`to their simple survey geometries, provide linear o?fset
`distribution. However, due to the complexity of 3-D geom
`etries, the offset distribution is nonuniform or nonlinear.
`To obtain a more uniform offset distribution, survey
`geometries referred to as the “stairstep” or “bricklayer”
`survey geometries have been used. FIG. 5 shows a com
`monly used stairstep geometry. Such a survey geometry
`improves the offset distribution, but does not provide frac
`tional binning. Additionally, such a geometry is di?icult to
`use in the ?eld and costs more to perform the survey. The use
`of such a survey geometry is described later.
`The present invention provides methods for performing
`seismic surveys which address the above-noted problems.
`The methods of the present invention provide smaller or
`fractional bins compared to the bins obtained using conven
`tional methods, ?exibility of manipulating bin sizes,
`improved offset distribution compared to the conventional
`methods and allows the use of differently spaced receiver
`and source lines for performing seismic surveys.
`
`SUMMARY OF THE INVENTION
`
`This invention provides a method of performing high
`resolution crossed-array seismic survey. A plurality of
`receiver lines, each having equally spaced receiver stations,
`are placed equidistant from and parallel to each other.
`Seismic shock waves or energy pulses are generated at
`predetermined spaced-apart source points along equally
`spaced source lines. In one con?guration, the receiver lines
`and the source lines are orthogonal to each other and the
`receiver stations in adjacent receiver lines are staggered by
`a fraction of the receiver spacing or the source stations in
`adjacent source lines are staggered by a fraction of the
`source station spacing or both the receivers and the source
`stations are staggered to obtain a desired number of frac
`tional bins (spatial sampling).
`A seismic source is energized at the source points to
`induce seismic pulses into the earth and the re?ected seismic
`pulses from the substrata are detected by the receivers. The
`receivers provide signals representative of seismic pulses
`re?ected from the earth’s subsurface, which are then
`recorded and processed to obtain geophysical information.
`Thus, this con?guration contains a crossed-array seismic
`survey geometry, wherein the receiver stations in adjacent
`receiver lines and/or the source stations in adjacent source
`lines are staggered. Such a survey method provides higher
`spatial sampling (smaller bins) compared to the crossed
`array survey geometries wherein the receivers or source
`point are not staggered.
`In an alternate method, no stagger between the receivers
`or the source points is provided, but smaller bins are
`
`5,598,378
`
`4
`obtained by adjusting either the receiver line spacing or the
`source line spacing or both. The receiver line spacing is
`made equal to an integer and a fraction times the source
`station spacing and/or the source line spacing is made an
`integer and a fraction times the receiver station spacing. This
`con?guration also provides fractional bins and thus higher
`spatial sampling (smaller bins) compared to the conven
`tional geometries.
`Yet in an another method, the receiver and/or the source
`locations are staggered and the source lines are placed at a
`predetermined angle other than ninety degrees (orthogonal)
`to the receiver lines. Such survey geometries provide frac
`tional bins and also provide more uniform o?'set distribution
`compared to the survey geometries described hereinabove
`and the conventional survey geometries, such as the survey
`geometry shown in FIG. 1.
`The smaller bins may be combined to obtain folds (mul
`tiplicity) which are su?icient to provide desired seismic
`imaging while preserving the bene?ts provided by the higher
`spatial sampling of the method of the present invention.
`Examples of the more important features of the invention
`thus have been summarized rather broadly in order that
`detailed description thereof that follows may be better
`understood, and in order that the contributions to the art may
`be appreciated. There are, of course, additional features of
`the invention that will be described hereinafter and which
`will form the subject of the claims appended hereto.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`For detailed understanding of the present invention, ref
`erences should be made to the following description of the
`preferred embodiment, taken in conjunction with the accom
`panying drawings, in which like elements have been given
`like numerals and wherein:
`FIG. 1 shows a prior art seismic survey geometry of
`receivers and source points.
`FIG. 1A shows the common-midpoint bin sizes which
`result when the survey geometry of FIG. 1 is used.
`FIG. 2 shows a seismic survey geometry of receivers and
`source points according to the present invention.
`FIG. 2A shows the common-midpoint bin sizes which
`result when the survey geometry of FIG. 2 is used.
`FIG. 3 shows an alternate seismic survey geometry of
`receivers and source points according to the present inven
`tion.
`FIG. 3A shows the common-midpoint bin sizes which
`result when the survey geometry of FIG. 3 is used.
`FIG. 4 shows a typical offset distribution corresponding to
`the survey geometry shown in FIG. 1.
`FIG. 5 shows a “stairstep” or “bricklayer” survey geom
`etry.
`FIG. 6 shows a survey geometry in which the receivers
`and the source points are staggered and that the source lines
`are placed non-orthogonal to the receiver lines.
`FIG. 7 shows a typical o?’set-distribution corresponding
`to the survey geometry shown in FIG. 6.
`
`10
`
`25
`
`35
`
`40
`
`45
`
`50
`
`55
`
`DETAHJED DESCRIPTION OF THE
`PREFERRED EMBODIIVIENTS
`
`65
`
`As noted earlier, FIG. 1 shows a typical prior art (con
`ventional) seismic survey geometry of receivers and shot
`points. FIG. 1A shows the bin sizes for conunon-midpoints
`that result from the seismic survey geometry of FIG. 1.
`
`WesternGeco Ex. 1009, pg. 9
`
`

`

`5,598,378
`
`5
`In the present invention, smaller bin sizes compared to the
`bin sizes of the conventional seismic survey geometries
`(utilizing the same receiver station spacing and the same
`source station spacing) are obtained by staggering the
`receiver stations in adjacent receiver lines and/or by stag
`gering source stations (source points) in adjacent source
`lines, or by adjusting the receiver line spacing relative to the
`source station spacings and/or by adjusting the source line
`spacing relative to the receiver station spacings.
`Improved offset distribution is obtained by placing the
`source lines non-perpendicular to the receiver lines while
`keeping the orthogonal distance between the receiver lines
`and the source points to be the same as in the above
`described staggered survey geometries.
`It is considered helpful to explain the survey geometries
`of the present invention by way of speci?c examples. It will,
`however, be understood that the survey geometries
`described herein are used to aid the reader in understanding
`the present invention and not as limitations to the present
`invention.
`FIG. 2 shows an example of a survey geometry according
`to the present invention, wherein both the receiver stations
`and the source points are staggered to provide smaller bins
`compared to a standard bin. In FIG. 2, a plurality of receiver
`lines 30a, 30b .
`.
`. 30m are placed in parallel on the terrain
`to be surveyed. Each such receiver line has a plurality of
`spaced apart receivers 32. The spacing Rs between adjacent
`receivers on the receiver lines is the same. However, the
`receivers in adjacent receiver lines are staggered by a
`predetermined distance dlzl/j (Rs), where j is an integer
`greater than or equal to two (2). For simplicity and conve
`nience, FIG. 2 is shown with j:2, i.e., the receiver stagger is
`one-half (1/2) the receiver spacing. Staggering the receivers
`in this manner produces multiple common-rnidpoints along
`the x-axis, such as shown by 45 in FIG. 2A. In general,
`staggering the receivers by l/j the receiver spacing provides
`j common-midpoints along the x-axis for each standard bin.
`Thus, in FIG. 2, staggering the receiver in adjacent receiver
`lines by one-half (1/2) the receiver spacing provides two (2)
`common-midpoints for each standard bin. Similarly, stag
`gering receivers by one-third, the receiver spacing will
`provide three common-midpoints along the x-axis.
`A plurality of equally spaced apart parallel source lines
`40a, 40b .
`.
`. 40n are de?ned along the terrain. Each such
`source line contains a plurality of source stations 42. The
`spacing Ss between adjacent source stations along the source
`lines is the same. However, the source stations are staggered
`by a distance d2=l/k (Ss), where k is an integer greater than
`or equal to two (2). For simplicity and convenience, the
`source station stagger in FIG. 2 is shown to be one-half (1/2)
`the distance between adjacent source stations along the
`source lines. Staggering the source stations produces mul
`tiple common-midpoints along the y-axis, such as shown by
`46, in FIG. 2A. In general, staggering the source stations by
`l/k the source station spacing Ss provides k common
`midpoints along the y-axis. Thus, in FIG. 2, staggering the
`source station by one-half (1/2) the source station spacing
`provides two (2) common-midpoints. Sinrilarly, staggering
`source stations by one-third the source station spacing will
`provide three common-midpoints. From the above explana
`tion, it should be obvious that staggering the receivers by l/j
`the receiver spacing and staggering the source stations by
`UK the source station spacing provides j><k common-mid
`points for each standard cell.
`FIG. 2A shows the common-midpoints corresponding to
`the seismic survey geometry of FIG. 2. Such a survey
`
`20
`
`35
`
`45
`
`50
`
`55
`
`65
`
`6
`geometry provides four (j><k=4) common-midpoints for each
`standard cell. In FIG. 2A, the bins corresponding to the cells
`of FIG. 1 are outlined in solid boxes. Each such standard bin
`contains four midpoints 50a, 50b, 50c and 50d. The survey
`geometry of FIG. 2A results in the same trace sampling
`density as that of the survey geometry of FIG. 1, yet
`provides improved spatial sampling in each direction by a
`factor of two (2). Thus, using the seismic survey geometry
`of FIG. 2 allows binning the fold of a prior art cell into four
`(4) evenly spaced “quarter cells” or “quarter bins” some
`times referred to herein as “microbins”, each rnicrobin
`having dimensions of 1/2 standard bin><1/2 standard bin. It
`should be obvious that the time which it will take to perform
`a seismic survey using the survey geometry of FIG. 1 or
`FIG. 2 will substantially be the same. It should be noted that
`multiple common—midpoints for each standard bin may be
`obtained by staggering the receivers alone or by staggering
`the source stations alone.
`The receiver line spacing, number of receiver lines,
`number of receivers in each line and the shot point spacing
`generally depend upon the equipment used to collect seismic
`data, terrain con?guration, depth of target or multiple targets
`and other technical and economic considerations. To per
`form a survey using the survey geometry of FIG. 2, the
`receiver lines are ?rst placed as desired according to the
`method noted above. A source such as a seismic vibrator or
`an explosive device is then placed at the predetermined
`source stations 42 and activated. The source generates
`seismic pulses which are induced into the earth and are
`re?ected by the substrata layers back to the earth’s surface.
`The re?ected waves are detected by the receivers 32. The
`receivers 32 convert the received seismic waves into elec
`trical signals, which are transmitted to recording and pro
`cessing equipment (not shown).
`After all the data has been recorded corresponding to a
`source point, the source is moved to the next source point
`along the source line. When the source is activated, each
`receiver provides data corresponding to the midpoint
`between the source and the receiver, thereby providing data
`for a row of common-midpoints for each receiver line. When
`the source is moved to the next source point, the receivers
`provide data for some new comrnon-midpoints and for some
`of the previously recorded common-midpoints, thereby pro
`viding overlapping data. The data belonging to the same
`common-midpoint is combined by known methods in the art
`of seismic