Highly Confidential
`
`Steerable Streamer Benefits
`
`There are two aspects
`DigiFIN devices
`
`to the benefits
`
`of using steerable streamers
`
`utilising
`
`Seismic Contractors
`
`looking for cost/time/efficiency/HSE
`
`benefits
`
`Oil companies
`
`looking for geophysical
`
`benefits
`
`easier
`
`factor
`
`steerable
`
`The
`
`latter
`
`is probably
`
`appreciate
`
`that
`
`to promote
`as
`oil companies
`in general
`influencing the success of 4D studies is
`the key
`the operational
`in the monitor survey of all
`i.e the preservation
`repeatability
`and geometrical
`The
`use of
`the baseline
`of
`survey
`aspects
`and automated shot control means that source-receiver
`streamers
`positions
`and therefore CMP positions
`closely replicated Most 3D
`can be more
`in the North Sea has some 4D objective and this is increasingly
`seismic shot
`conditions make
`the world where environmental
`the case in other regions
`of
`4D surveys feasible
`
`However
`
`this study will
`
`look at
`
`the contractor argument only
`
`Contractors
`
`As the actual buyers
`of
`they have to understand
`already have
`
`significant
`
`the DigiFiN system will be the seismic
`what benefits can be achieved
`given that
`investment
`in in-water equipment
`
`contractors
`
`they
`
`is simple i.e Time Money Saving
`For them the situation
`and increases
`revenue earning vessel ulilisation
`
`time saves money
`
`Things that cost money take time
`
`Mobilisation transit to prospect and crew changes
`
`Deploying equipment
`
`Shooting the survey
`
`Line changes
`
`Keeping the vessel
`
`fuelled and supplied
`
`Chase boats
`
`Infill shooting
`
`There is also the HSE consideration
`
`The less time the survey takes and in
`of an
`then the less
`the likelihood
`the fewer small boat operations
`
`particular
`LTI
`
`WESTERNGECO
`
`09-CV-O1 827
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`PTX398
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`EXHIBIT
`
`10
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`FGRPROD000154144
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`PGS v WESTERNGECO (IPR2014-00689)
`WESTERNGECO Exhibit 2083, pg. 1
`
`

`
`Highly Confidential
`
`How can DigiFiN reduce any of these
`
`steerable streamers with
`
`this could
`
`to
`
`Streamer deployment
`can be speeded up Using
`the DigiFIN units active
`the streamers
`can be steered
`during deployment
`from each other as they are laid With
`wide enough vessel
`away
`be deployed simultaneously
`allow for
`four streamers
`without
`fear of
`entanglement whereas
`on some of
`the broader-beamed seismic
`currently
`vessels only two streamers
`are deployed simultaneously
`This implies that
`contractor can halve the time taken
`for deployment This could save 1-2 days
`the start of each survey Against
`this crews may not have sufficient
`the same time
`to safely deploy multiple cables at
`personnel
`
`at
`
`the prime lines DigiFin would
`the Survey In terms
`of shooting
`Shooting
`allow the cables to be steered more accurately
`for coverage
`This could also
`instance
`permit closer approaches
`areas for
`in restricted
`See the section on infill
`
`in undershoot
`
`operations
`
`in coming onto line is to have most of
`The key factor
`the cable
`Line changes
`reaches the first shotpoint This constrains
`straight as the vessel
`essentially
`the length and tightness of
`the line change
`especially with tear-drop
`style
`to be turned onto
`line changes DigiFIN should in principle allow the streamers
`the line change
`line more rapidly thereby
`time Additionally with
`ORCA more efficient
`configuration can be
`patterns for
`given
`shooting
`saving of 20 minutes per
`survey with 100 sail-lines
`developed For
`change would deliver an overall saving on the survey of about 33 hours
`
`reducing
`
`line
`
`can be made Shooting
`infill This is where the real savings
`survey DigiFIN can reduce
`days or even weeks to
`by simply making
`in The main
`there are fewer holes left
`in the prime coverage
`to fill
`sure that
`feather angles which may not be matched
`such as the trouser
`cable behaviour
`left effect
`the back of
`
`cause of holes are large
`line and aberrant
`effect where
`to be
`spread thought
`
`adjacent
`
`swallow-tail
`
`This
`
`is particularly
`
`the streamers
`
`diverge
`
`of
`
`interaction
`
`it can create
`
`infill
`
`can add
`
`infill
`
`at
`
`the
`
`or
`
`towards
`the
`with the vessel prop-wash
`low far offset
`
`consequence
`unwelcome
`as
`along the entire line length
`extending
`the line One approach
`constrain the
`centre
`
`coverage
`complete re-shoot of
`often requiring
`this has been to physically
`has noise
`rope This
`cross-bracing
`the cable shape It also
`implications and can lead to unnatural bowing of
`online increasing HSE exposure Steerable
`small-boat operations
`involves
`cables obviously allow for better
`feather matching Steering the streamer will
`also mean that on
`is easier to fill
`in multiple gaps in the
`single
`infill pass
`coverage that may be on opposite sides
`
`tried in the past
`
`to counter
`
`cables with
`
`it
`
`FGRPROD0001
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`54145
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`PGS v WESTERNGECO (IPR2014-00689)
`WESTERNGECO Exhibit 2083, pg. 2
`
`

`
`Highly Confidential
`
`Two case studies are presented below using data from real surveys In each
`the time saving that steerable streamers might
`case an estimate is given of
`have produced
`
`Case Study
`
`This was
`
`contractor
`
`3D multi-streamer
`
`survey
`
`shot off West
`
`Africa
`
`by
`
`major
`
`of 6000m with
`twin sources Navigation
`was
`The
`configuration
`and positioned by DigiCourse
`was by Spectra and the cables were controlled
`and acoustics
`compass-birds
`
`streamers
`
`The survey was affected by large cross-currents causing excessive feathering
`from cable
`and difficulties
`It also suffered severely
`feather matching
`with
`due to prop-wash
`the
`centre
`
`swallow-tailing
`
`whereby
`
`cables
`
`diverged
`
`interaction
`
`on the logs relating to problems with
`lines shot 29 had comments
`Of the 121
`cable movement and subsequent poor coverage
`
`The
`
`following
`
`statistics are extracted
`
`from the OC consultant
`
`navigation
`
`line
`
`logs
`
`Survey Statistics
`
`SurveyArea
`Number of Pre-plot
`line km
`
`Pre-Plot
`
`lines
`
`lines shot
`
`Number of actual
`Number of infill
`lines
`Percentage infill as coverage
`Total
`time for survey
`Time spent on infill
`Percentage infill as time
`Number of infill shots
`km due to infill
`
`Additional
`
`sailing
`
`1730 km2
`84
`4600 km including run-out but
`disregarding line changes
`121
`
`27
`15%
`
`48.2 days
`10.5 days
`22%
`44094
`2060
`
`km including
`
`run-outs
`
`line changes
`
`First it can be seen that
`
`needed to be in-
`
`of coverage which
`the percentage
`in acquiring it This
`time spent
`less than the percentage
`filled was signifcantly
`scheme
`an optimal shooting
`is due in part
`to
`to the difficuLty
`in planning
`to fill-in scattered and irregular
`efficiently move the vessel around the prospect
`is just how far the vessel
`point worth noting
`second
`holes
`large 3D vessel will use
`the infill programme
`
`coverage
`travelled in order to complete
`in 2D00 km
`
`lot of
`
`fuel
`
`FGRPROD0001
`
`54146
`
`PGS v WESTERNGECO (IPR2014-00689)
`WESTERNGECO Exhibit 2083, pg. 3
`
`

`
`Highly Confidential
`
`Estimating Steerable Streamer Effects
`
`How Could DigiFin
`survey
`
`steerable streamers have affected the performance of
`
`this
`
`infill
`
`infill
`
`for this project was strong cross-currents
`As noted the main cause of
`Cross-currents tend to produce high feather angles and
`and swallow-tailing
`although DigiFIN may only be able to achieve
`few degrees of correction it
`decreased the feathering Lets say it might make
`would have nonetheless
`by 2% However
`could
`the swallow-tailing
`difference in the degree of
`to be as pronounced
`This tends not
`be reduced significantly
`probably
`angles As the graphs at
`the end of this section
`problem in terms of deflection
`show for near offsets out to 2000m DigiFin
`can induce crossline movement of
`lOOm This is sufficient
`to counter-act any swallow-tailing For this particular
`estimate would be that
`effects were
`conservative
`if swallow-tail
`requirement would be reduced
`
`project
`removed the infill
`
`by 5%
`
`of
`
`these two effects
`
`from 15%
`The combination
`the infill percentage
`to 8% Noting that
`in this case is
`time spent acquiring the infill
`the percentage
`time percentage
`the infill percentage this implies that
`the infill
`1.5
`drops
`from 22% to
`12% For this case this represents
`saving of 4.8 days due to
`reduced infill
`
`reduces
`
`Another possible saving due to the use of DigiFin
`is shorter line changes
`had been possible to shave 10 minutes off each line change for this prospect
`then 1200 minutes or2O hours would have been saved
`
`If
`
`it
`
`add-in
`
`Finally
`potential
`the cables as they are laid
`
`day saved in deployment by using DigiFin
`
`to steer
`
`Added together this means that from 48 day survey approximately 6.5
`days could be saved
`
`EGRPR00000I
`
`54147
`
`PGS v WESTERNGECO (IPR2014-00689)
`WESTERNGECO Exhibit 2083, pg. 4
`
`

`
`Case Study
`
`This was
`in the Mediterranean
`survey shot
`two source eight streamer
`major contractor Navigation was again by Spectra with DigLcourse
`birds and acoustics
`
`compass-
`
`Highry Confidential
`
`by
`
`spreader
`
`in
`
`This had fewer problems than the West Africa
`above
`survey described
`problem In an
`however swallow-tailing was
`terms of strong local currents
`rope was attached between the centre pair
`to counter
`attempt
`this
`tended
`to give the cables an
`of cables This had only
`limited benefit as it
`noise onto the cables Also on more than
`shape and also induced
`unnatural
`additonal
`small boat
`occasion
`snapped
`spreader
`to carry out repairs
`
`one
`
`operations
`
`ropes
`
`required
`
`total of 168 lines shot 28 had comments regarding loss of coverage
`Out of
`due to cable movement
`
`Survey Statistics
`
`Survey Area
`Number of Pre-plot
`line km
`
`Pre-Plot
`
`lines
`
`Number of actual
`Number of infihl
`
`lines shot
`
`lines
`
`Percentage intill as coverage
`
`Total
`time for survey
`Time spent on inflll
`Percentage infill as time
`Number of infill shots
`km due to infill
`
`Additional
`
`sailing
`
`2500 km2
`
`117
`6600 km including run-out but
`disregarding line changes
`168
`
`25
`Not available estimate 9%
`57 days
`days
`14%
`38803
`970 km estimating 1500 km including
`line change
`
`than the case Study
`This survey had considerable
`less infill
`to poor cable separations
`the intill could be attributed
`much of
`remove the swallow-tail
`should be able to almost completely
`above DigiFin
`estimate would be that
`this particular
`from 9% by coverage to 5%
`would reduce
`would drop to 8% i.e
`the infill as
`time percentage
`This would imply that
`saving of 3.5 days for the survey in terms of reduced infill
`
`although again
`As described
`
`infill
`
`effect
`
`In
`
`case
`
`conservative
`
`time again proposing
`If we consider
`the possible reduction
`in line-change
`saving of 10 minutes per line that means 1680 minutes 28 hours
`
`Finally add-in
`the cables as they are laid
`
`potential
`
`day saved in deployment by using DigiFin
`
`to steer
`
`FGRPR00000 154148
`
`PGS v WESTERNGECO (IPR2014-00689)
`WESTERNGECO Exhibit 2083, pg. 5
`
`

`
`Highly
`
`Confidential
`
`So even for
`
`case with relatively
`
`low infill DigiFin could save 5.5 days
`
`FGRFROD000154149
`
`PGS v WESTERNGECO (IPR2014-00689)
`WESTERNGECO Exhibit 2083, pg. 6
`
`

`
`Highly Conflderitial
`
`Combining the Figures
`
`Consider
`back with
`
`hypothetical situation where these surveys were shot back to
`day transit demob/mob period
`
`Actual
`
`time spent on surveys
`
`48
`
`57
`
`112
`
`Modelled
`
`DigiFin
`
`saving
`
`6.5 5.5
`
`12 days
`
`For
`
`crew working all year round the number of days saved is
`
`365112
`
`12
`
`39 days per year
`
`39
`
`$50000 means $1.95 million
`
`fudge factor of 70% so as not
`Introducing
`to 27 days
`
`reduces
`
`to seem too optimistic
`
`this
`
`$1.35 million
`
`Conclusion
`
`different
`
`in character
`
`and
`
`had different
`
`two surveys were
`These
`very
`they were not
`problems however
`in any way extraordinary Although they are
`layouts are now more common
`few years old 2002 and 10-12
`streamer
`reasonably average deployment More case
`the
`streamer configuration is
`the case
`studies need to be looked at and no amount of modelling can prove
`arguments and
`real data Hopefully
`this analysis indicates
`than
`that can be used by contractors
`the advantages of
`using DigiFIN
`
`better
`
`numbers
`
`to understand
`
`Graphical Displays
`
`page show the effect
`The two graphs on the following
`the cable
`has on the cross-line movement of
`
`actually
`
`that an angle correction
`The modelling
`the sine of
`the deflection
`angle
`the crossline distance
`is just
`second plot shows this distance
`by the offset along the cable The
`the number of 25m cross-line bins that would be covered
`
`is very
`
`simplistic
`
`multiplied
`
`in terms of
`
`and 600Dm cable the tail of
`The extreme example is that
`deflection
`for
`small angle can
`the cable 30Dm offline covering 13 bins This shows that
`the minor angular corrections induced
`can
`make
`big difference
`have
`effect on coverage
`especially if controlled
`
`by DigiFin
`
`applied in
`
`significant
`dynamic fashion
`
`FGRPROIJ0001
`
`54150
`
`PGS v WESTERNGECO (IPR2014-00689)
`WESTERNGECO Exhibit 2083, pg. 7
`
`

`
`Highly Confidential
`
`3500 ........
`
`Cable
`
`Angle
`
`vs Crossline Offset
`
`.y1rr
`
`00
`
`50.0
`
`141JT
`
`12
`
`..
`
`0.5
`
`1.5
`
`2.5
`
`Cable
`
`Angle
`
`En Degrees
`
`Cable
`
`Angle
`
`vs Number
`
`of Crossline Bins
`
`f.
`
`0.5
`
`2.5
`
`Cable Angle In Degrees
`
`FGRPR000001 54151
`
`PGS v WESTERNGECO (IPR2014-00689)
`WESTERNGECO Exhibit 2083, pg. 8