SALT LAKE CITY, UTAH
`AAPG Annual Meeting
`May 17-20, 1998
`
`***************-*~*****CAR-RT
`803165-3 1'1Y
`Ut1iversit'::l or Wisc.onsi 1--:
`Geolo9'::1/GeoPh'::lsic::. L i bt~,=u~\:1
`1215 W DAYTON ST
`MADISON WI 53706-1600
`
`GEOLOGY-GEOPHYSICS
`LIBRARY
`
`MAY 1 8 1998
`
`PGS Exhibit 2041, pg. 1
`WesternGeco v. PGS (IPR2015-00313)
`
`

`
`ExPLORER
`
`5
`
`On the cover: Make that two covers this month , both designed to
`celebrate the setting of this month's AAPG annual meeting in Salt Lake
`City. The gatefold , an example of the state's magnificent geology and
`scenic splendor, shows Waterpocket Fold in Capitol Reef National Park;
`the barn is part of a pioneer Mormon settlement. Photo by Tom Till. The
`second cover features several shots that pay tribute to Utah's petroleum
`and natural gas history. Photos courtesy of the Utah Geological Survey.
`
`AAPG Newsletter Introduced
`
`The AAPG Newsletter, a supplement to the AAPG EXPLORER, debuts in this
`issue.
`The purpose of the Newsletter is to convey information and commentary that
`has a limited association focus .
`The Newsletter, which can be found at page 98 of this issue, will appear on a
`"as needed" basis. The inaugural issue of the Newsletter focuses on discussion
`concerning actions that involve the AAPG Constitution and Bylaws.
`
`These days it seems difficult for geologists to agree on
`just about anything - anything , that is, except the ethics
`question posed in the March EXPLORER.
`
`A stable oil and gas pricing climate boosted salaries for
`petroleum geologists in all experience categories in 1997,
`according to this year's EXPLORER salary survey.
`
`The time has arrived: The AAPG annual meeting will be
`held this month in Salt Lake City.
`
`Albert Bally , an outstanding geologist in his own right and
`the mentor of countless young geoscientists, is this year's
`recipient of the Sidney Powers Medal , AAPG 's highest honor.
`
`Walter Alvarez began a journey of discovery in the late
`1970s, with a unique notion about fossils in Italian limestone
`-and today, that journey has led him to international fame.
`
`New technologies used by NASA's Mars Pathfinder and
`Mars Global Surveyor spacecraft missions may lend
`themselves to the oil patch.
`
`Thinking about becoming a consultant? You 're not alone -
`and some experts have some advice that may help.
`
`Geophysical Corner
`
`Business Side of Geology
`
`Kenneth F. Wantland
`
`International Bulletin Board
`
`Professional News Briefs
`
`Membership and Certification
`
`Foundation Update
`
`64
`
`80
`
`82
`
`86
`
`88
`
`90
`
`92
`
`Meetings of Note
`
`May Advertisers
`
`Education Calendar
`
`Readers' Forum
`
`In Memory
`
`Classified Ads
`
`Director's Corner
`
`6
`
`14
`
`18
`
`30
`
`32
`
`42
`
`50
`
`96
`
`97
`
`98
`
`101
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`103
`
`104
`
`107
`
`Communications Director
`Larry Nation
`e-mail: lnation@aapg.org
`
`Managing Editor
`Vern Stefanic
`e-mail: vstefan@aapg.org
`
`Communications Assistant
`Joey Mechelle Dawes
`e-mail: jdawes@aapg.org
`
`Correspondents
`David Brown
`Diane Freeman
`Mary Fritz
`Michael J. Major
`Kathy Shirley
`Katherine Thomas
`Ray Tuttle
`Richard Williamson
`
`Graphics/Production
`Rusty Johnson
`e-mail: rjohnson@aapg.org
`
`Advertising Coordinator
`Brenda Merideth
`PO. Box979
`Tulsa, Okla. 74101
`telephone: (918) 560-2647
`(North America only: 1-
`800-288-7636)
`(Note: The above number is for
`advertising purposes only.)
`fax: (918) 560-2636
`e-mail: bmer@aapg.org
`
`Vol. 19, No. 5
`The AAPG EXPLORER (ISSN 0195-2986) is published monthly for members. Published at MPG headquarters, 1444 S
`Boulder Ave., P.O. Box 979, Tulsa, Okla. 74 101 , (918) 584-2555. e-mail address: postmaster@aapg .org
`Periodicals postage paid at Tulsa, Okla., and at additional mailing oHices. Printed in the U.S.A.
`Note to members: $6 of annual dues pays for one year's subscription to the EXPLORER. Airmail service for members:
`$45. Subscription rates for non-members: $50 for 12 issues; add $45 for airmail service. Advertising rates: Contact
`Brenda Merideth, AAPG headquarters. Subscriptions: Contact Veta McCoy, AAPG headquarters. Unsolicited
`manuscripts. photographs and videos must be accompanied by a stamped , self-addressed envelope to ensure return.
`
`The American Association of Petroleum Geologists (AAPG) does not endorse or recommend any products or services
`that may be cited, used or discussed in MPG publications or in presentations at events associated with MPG.
`
`Copyright 1998 by the American Association of Petroleum Geologists. All rights reserved.
`
`POSTMASTER: Please send address changes to AAPG EXPLORER, P.O. Box 979, Tulsa, Okla. 74101 .
`
`Take Action on What
`Can Be Controlled
`
`By EDWARD K. "EDDIE" DAVID
`Our professional lives as
`geoscientists can be divided into two
`parts - one part we can control and the
`other part we cannot control.
`The recent drop in oil prices
`includes both parts.
`The current, relatively high global oil
`production , an unstable Asian
`economy and a mild winter were some
`of the reasons given for the recent
`decline in oil prices. Clearly, these
`external forces affecting supply and
`demand involve sudden changes and
`shifts in global economics, oil markets
`and weather that are simply beyond
`our control as geologists.
`But internally we can control how
`we think, behave and even react to
`these external events. Andy Grove, the
`microchip pioneer who co-founded
`Intel Corporation, the maker of
`computer semiconductors, said it like
`this:
`"Take control of the timing and
`direction of the changes in your career
`or business. Be proactive. Start the ball
`rolling rather than waiting for events to
`put you in a defensive mode."
`
`A message similar to Andy Grove's
`belief is interwoven in an excellent
`article in the October 1997 issue of the
`AAPG EXPLORER . Twelve AAPG
`members who had experienced the
`good and not so good times of the
`petroleum industry over the years were
`contacted to "give their view on how to
`deal with the opportunities presented
`to the industry, and the pitfalls to be
`avoided. "
`I studied and grouped their
`comments in light of the things we, as
`geoscientists, can control under the
`following three categories that I
`arbitrarily selected:
`0 Our attitude, behavior and beliefs.
`0 Our education, learning ,
`knowledge and personal development.
`0 Our thinking, ideas and creativity.
`The article appropriately closed with
`these words of Robert J. Weimer,
`former AAPG president, to the rookie:
`"Be prepared as best you can for
`change- it will happen. Insofar as
`possible, maintain control over your
`professional career and unpredicted
`opportunities will present themselves."
`
`The adage that "Life is not always
`fair" is suggestive, I believe, of
`unfavorable events that occur in our
`lives that we cannot control. A personal
`incident involving the idea behind this
`saying occurred in the early 1970s,
`when I was the master of ceremonies
`
`for a seventh and eighth grade speech
`contest sponsored by my
`Toastmaster's Club in the local public
`schools.
`The day after the speech contest
`the mother of a daughter who received
`second place told me her daughter
`thought the speech contest was not fair
`since she heard our judges gave the
`championship to another girl solely
`because she was the mayor's
`daughter.
`
`'Take control of the
`timing and direction of
`the changes in your
`career or business. Be
`proactive. Start the ball
`rolling rather than waiting
`for events to put you in a
`defensive mode. "
`
`I assured her this was not the case
`and I suggested that her daughter, a
`seventh grader, devote the time and
`effort to become so good at public
`speaking that the judges would have to
`award her first place the following year.
`I was not involved in helping with
`the speech contest the following year,
`so I do not know if her daughter won or
`not. But I always wanted to believe that
`her young daughter accepted the
`challenge, rededicated herself to the
`task at hand and won the next year's
`championship trophy.
`The school girl's story illustrates that
`how we respond and react to events
`that we consider unfavorable and
`unfair is more important than the
`events themselves, no matter how
`painful or distressing they are at the
`time.
`
`The recent decline in oil prices is a
`clear signal for us as geologists to
`pause and remind ourselves that we
`may not be able to control and improve
`the wellhead price of hydrocarbons,
`but we can take control and work on
`improving our value as geoscientists.
`In doing so, we will have prepared
`ourselves to be able to capitalize on
`any opportunities that may appear from
`time to time in our professional careers.
`
`MAY 1998
`
`PGS Exhibit 2041, pg. 2 WesternGeco v. PGS (IPR2015-00313)
`
`

`
`64
`
`(cid:3) (cid:55)(cid:75)(cid:76)(cid:86)(cid:3)(cid:80)(cid:68)(cid:87)(cid:72)(cid:85)(cid:76)(cid:68)(cid:79)(cid:3)(cid:80)(cid:68)(cid:92)(cid:3)(cid:69)(cid:72)(cid:3)(cid:83)(cid:85)(cid:82)(cid:87)(cid:72)(cid:70)(cid:87)(cid:72)(cid:71)(cid:3)(cid:69)(cid:92)(cid:3)(cid:38)(cid:82)(cid:83)(cid:92)(cid:85)(cid:76)(cid:74)(cid:75)(cid:87)(cid:3)(cid:79)(cid:68)(cid:90)(cid:3)(cid:11)(cid:55)(cid:76)(cid:87)(cid:79)(cid:72)(cid:3)(cid:20)(cid:26)(cid:3)(cid:56)(cid:17)(cid:54)(cid:17)(cid:3)(cid:38)(cid:82)(cid:71)(cid:72)(cid:12)(cid:3)
`
`Dip MoveOut Just Isn't 'Normal'
`
`(Editor 's note.· The Geophysical
`Corner is a regular column in the
`EXPLORER and is produced by the
`AAPG Geophysical Integration
`Committee. This month 's column is
`the second of a two-part series on
`"DMO - The Other MoveOut. ")
`
`By CHRISTOPHER L LINER
`You can talk about Normal
`MoveOut (NMO) al l day long without
`mentioning migration - but Dip
`MoveOut (DMO) is another matter.
`In fact , DMO started out with the
`cumbersome-but-descriptive name
`"pre-stack partial migration." That
`was in 1979, but at least two years
`earlier there was a DMO processing
`product on the market. It was
`named DEV ILISH, an acronym for
`"dipp ing event veloc ity inequality
`licked. "
`You th in k I am making th is up,
`but it's true .
`Before moving on, I shou ld say
`something about name-dropping .
`Un like NMO , the development of
`DMO is very recent. The peop le
`involved are still alive and kicking.
`We owe a debt of grati tude fo r
`thei r hard work and ingenuity, but if
`I mention one name I wi ll have to
`mention them all. So we wi ll deal
`here with the concepts and not th e
`names.
`We wil l attempt to understand
`
`orig offset
`trace
`
`s
`
`S/R
`
`R
`
`zero offset
`NMOtrace
`
`r --------------N MO ------------~
`
`Earth model
`
`time
`
`time
`
`Figure 1. Normal MoveOut (NMO) is a process applied to pre-stack data. Here the
`effect is shown on a single trace with one reflection event (left) . NMO assumes the
`reflection comes from a horizontal interface in the earth (center). Using a velocity
`function supplied by the processor, NMO adjusts the original time (red) to that which
`would have been observed at the midpoint, marked S/R. The blue path is two-way
`time down and back, which must be less than the red path time. So NMO's job is to
`move the reflection event up the trace (right). Note NMO operates on one trace at a
`time, which makes it inexpensive.
`
`This new trace is a zero-offset
`trace , and adding (stacking) all
`such traces that live at this midpoint
`yie lds a stack trace.
`All the stack traces plotted side(cid:173)
`by-side fo rm the stack section,
`which is raw material for post-stack
`migration processing .
`Figure 1 illustrates the NMO idea.
`On the left is a field trace with
`some arbitrary offset and one
`ref lection event. NMO assumes the
`reflection comes from a horizontal
`interface as shown in the middle
`figure .
`This is an important and
`restrictive assumption .
`The NMO correction adjusts
`observed travel time (red path) to
`midpoint zero-offset travel time
`(blue path) . So after NMO , the event
`is moved up in time . Technically, we
`are changing time coordinate from
`raw time, t, to NMO time , ln.
`
`what DMO is and does, not c reate a
`hi storical who's who.
`
`Now, back to busi ness.
`In the field, a source and receiver
`are located, say, 3, 000 meters apart
`(th e offset) and a trace is record ed.
`
`Graphics courtesy of Christopher L Liner
`
`Th is is pre-stack data.
`From last month's arti c le, we
`know that NMO lives to remove
`offset from pre-stack data. In the
`computer, we adjust this trace to
`simulate one that woul d have been
`reco rded with no effect at a point
`half-way between the source and
`receiver (th e midpoin t).
`
`But what if the interface is not
`horizontal?
`It's temptin g to think that the
`reflector cou ld be anywhere and still
`be consistent with the observed
`travel time . But thi s is not the case .
`Let's say the original travel time
`
`continued on next page
`
`MAY 1998
`
`PGS Exhibit 2041, pg. 3 WesternGeco v. PGS (IPR2015-00313)
`
`

`
`conti nued from previous page
`
`is 1.0 second , and we know the
`velocity is 3,000 m/s. The total
`distance traveled has got to be
`3,000 meters. So all valid reflector
`positions have one thing in
`common : The total distance from
`source to reflection point to receiver
`is constant, namely 3,000 meters.
`Thinking back to Geometry 101 ,
`this is just the definition of an ellipse
`with the source and receiver at each
`focus.
`Figure 2 shows such an ellipse .
`Remember the goal is to remove
`offset and thus create a zero-offset
`section . NMO gives one of many
`possibilities, DMO gives all the rest .
`In Figure 2, some of the possible
`original travel paths are shown
`(red) , along with the single travel
`path after NMO (blue) and the many
`travel paths after DMO (green) .
`From Figure 1 we saw that NMO
`is a process that takes one trace in
`and gives one trace out . DMO is
`different. One trace into DMO
`generates many traces out - all of
`which live between the original
`source and receiver locations. This
`is illustrated in figure 2 (lower) and
`figure 3 (page 66) .
`
`Let's consider figure 3.
`We have a panel of data
`containing only two spikes of
`amplitude on one trace (left panel) .
`The other traces are there, but
`empty.
`NMO moves the spike up on the
`same trace (middle panel). DMO
`then throws the spike out along a
`curve, which lives between the
`source and receiver (right panel) .
`This is sometimes called the DMO
`smile . Since it comes from a sp ike
`or impulse on the input data, it is
`also called the DMO impulse
`response .
`Now here is some magic. By
`creating the DMO smile , all possible
`dips are handled simultaneously. We
`do not need to know what the dip is
`in the earth- by processing all
`traces with DMO the actual
`reflections will emerge because they
`are tangent, at some point , to DMO
`smiles .
`Also , DMO does not depend on
`the velocity, so long as the velocity
`is constant.
`While not strictly true , this is one
`of the things that got everyone
`initially excited about DMO. And its
`weak dependence on velocity is one
`reason it is still so widely used.
`Anyway, it is unlike NMO and
`migration , which always need
`velocity information , and are quite
`sensitive to it. Another big selling
`point is that NMO+DMO , rather than
`NMO alone, passes a// dips into the
`stack section .
`This gives more raw material for
`migration to work with in creating a
`final migrated image.
`Since DMO spreads things out
`across traces, it is much more
`expensive than NMO, which on ly
`shifts things up on one trace . Even
`so , NMO +D MO is still cheaper than
`pre-stack migration.
`Figure 4 (page 66) gives some
`representative run times for these,
`and other, processes .
`
`See DMO, next page
`
`ExPloRER
`
`65
`
`Figure 2. Dip MoveOut (DMO) is a
`process that is applied after NMO.
`Since NMO assumes the reflection
`comes from a horizontal bed, it is
`picking up only one of many
`possibilities. For one trace with one
`reflection event, all possible travel
`paths have the same length - that is,
`the distance from source to reflection
`point to receiver is a constant. The
`geometrical shape with this property
`is an ellipse (upper). Some of the
`original path possibilities are shown
`in red. NMO reduces travel time
`based on a horizontal reflector (blue
`path) , while DMO does all the other
`cases (green) . So the action of DMO
`(lower) is to take the NMO'd event
`(blue) and broadcast it across
`several nearby traces (green). Since
`DMO operates on several traces, it is
`expensive.
`
`zero offset
`NMO trace
`
`zero offset
`DMOtraces
`
`-----DMO -- - - -
`
`time
`
`time
`
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`
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`
`MAY 1998
`
`PGS Exhibit 2041, pg. 4 WesternGeco v. PGS (IPR2015-00313)
`
`

`
`66
`DMO
`from previous page
`
`So here is th e bottom line. If
`structure and velocity variation are
`not too nasty in an area, we can get
`away with a traditional processing
`sequence :
`NMO + DMO + Stack +
`PostStackMigration .
`In this equation ," +" means
`"followed by."
`However, if things get really tough
`down there (e .g., subsalt) , this
`sequence breaks down and fai ls to
`give a good image. In this case we
`are compelled to do one grand
`process called pre-stack migration .
`In fact, DMO was originally
`invented to comp lete the fo llowing
`equality under mild subsurface
`conditions :
`PreStackMigration = NMO + ? +
`Stack + PostStackMigration .
`
`The "?" turned out to be DMO -
`and is used world-wide every day.
`
`(Editor 's note: Liner is associate
`professor of geosciences at the
`University of Tulsa . He may be
`contacted via e-mail at
`cll@utulsa . edu, or
`http://douze. utulsa . edu/- c/1/ChrisLin
`er.html)
`
`ExPLORER
`
`Before NMO
`
`After NMO
`
`After NMO+ Dt10
`
`Figure 3. This numerical example illustrates the effect of NMO and DMO on a trace with two spikes, or reflection events. The
`spikes are shown on the left surrounded by a bunch of zero traces . The source and receiver location are denoted by Sand R,
`respectively. NMO shifts the spikes up in time, but only on the same trace (middle) . DMO throws the NMO'd spike amplitude out
`along a curve to handle all possible dips. This curve is called the DMO smile, or DMO ellipse, or DMO impulse response. Notice
`the DMO smile only lives between the original source and receiver positions.
`
`prestack mig
`
`poststack mig
`
`- - - - - - - - - - - - - - 5104
`18
`
`2845
`
`stack
`
`2
`
`dmo
`nmo 22
`decon 20
`9
`
`sort cos
`
`sort cmp
`
`filter
`
`gain
`
`8
`30
`28
`
`Figure 4. This chart illustrates
`processing time in seconds for a small
`sample data set. The relative times are
`important, not the size of the data set
`or kind of machine used. Starting from
`the bottom, the processes represent
`(in order) a more-or-less standard
`processing flow. By far the most
`expensive item here is DMO. But if we
`run pre-stack migration instead , it is
`even more expensive. Basically, the
`pre-stack migration replaces NMO,
`DMO, stack and post-stack migration.
`Due to the cost, pre-stack migration is
`a method to be used only when
`required by strong lateral velocity
`variations and/or extreme structure.
`
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`MAY 1998
`
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`
`to production
`
`FAPS 3 is tightly integrated with other
`interpretation and mapping systems
`
`for further information and case studies visit our web pages at: http://www.badleys.co.uk
`
`PGS Exhibit 2041, pg. 5 WesternGeco v. PGS (IPR2015-00313)