shell 2012 beaufort and chukchi seas exploratory drilling

1

Shell’s Alaska Venture

Program Update – Open Water

Meeting

March 7, 2012

2

Agenda

Presentation Materials

� Proposed operations for 2012

� Proposed monitoring program overview

� Details of select aspects of monitoring program

� MMO programs

� Acoustics

� Sound Source Characterization – vessel strategy

� Real time Sound Source Characterization

� Optimal placement of arrays

� Aerial

� Beaufort

� Chukchi

� Power analyses Beaufort / Chukchi

� Peer review questions

Q&A

Discussion of Comprehensive Report

3

Chukchi and Beaufort Seas

Burger to Barrow 140 miles

Burger to Wainwright 78 miles

Burger to Point Lay 92 miles

Burger to Point Hope 206 miles Kaktovik to Topedo 55 miles

Nuiqsut to Sivulliq 118 miles

Barrow to Sivulliq 256 miles

Burger

TorpedoSivulliq

4

2012-13 Proposed Operations

Chukchi Sea: Drill up

to three wells per year during open

water drilling season (July-October)

Noble Discoverer

CDU Kulluk

Beaufort Sea: Drill

up to two wells per

year during open

water drilling season

(July-October)

5

2012-13 Science Program

Joint Industry

Program

Offshore ecological

studies

Mammal Monitoring

Program

Ice & Metocean

Buoys

On-shore and Near

shore ecological

studies (continued

from 2010 and 2011)

Drilling Monitoring

6

Fleet Overview

AffinityFuel Supply

&

CSR Tanker

Arctic Challenger &

TugContainmt System

2 x Cargo Barge & TugSupply & Waste Storage

Harvey HaulerSupply Vessel / Waste

Klamath & Tug

Spill Recovery

NanuqSpill Recovery &

Accommodation v/l

Harvey SpritSupply Vessel

Harvey Explorer

Supply Vessel

Endeavor / Pt Oliktok

Spill RecoveryBarge & Tug

FennicaPrimary Ice Management Vessel

AiviqAHTS & Secondary Ice Managmt

Arctic SealLanding Craft

Kulluk

BARROW

DEADHORSE

POINT HOPE

NOME

WAINWRIGHT

Tor VikingAHTS & Secondary Ice Managmt

NordicaPrimary Ice Management Vessel

Discoverer

Landing Craft

25 mi. Exclusion Zone

7

Mitigation Commitments

Plan of Cooperation

Beaufort Sea shutdown and remove drilling rig assets by midnight August 25

Beaufort Sea Captured Discharge:

� Drilling fluids

� Cuttings after 20” casing

� Treated sanitary and gray water

� Ballast and bilge water

Communication Plan for avoiding conflicts with subsistence users

Collaboration and Communication with Whaling Associations, AEWC, Walrus,

Nanuq, Beluga, and Seal Commissions

No transiting without communicating

Commitment to hire Subsistence Advisors

Marine Mammal Observers on all vessels

Robust Marine Mammal Monitoring Protocol

8

Mitigation Commitments

Capping stack and Arctic Containment System

Real time Ice and Weather Forecasting

Crew change by helicopter and collaboration on routes to and from operations

Barrow, Deadhorse, and Wainwright shore bases

Full OSR capabilities for each sea

Second rig relief well capability

9

Shell’s 2012 Drilling Program

Community Mitigation Measures

Barrow Com Center, SA (Subsistence Advisor), CLO (Community Liaison Officer), transit offshore

Kaktovik Com Center, SA, CLO, cease program 8/25 until after bowhead whale hunt, crew change by helicopter sensitive to subsistence hunting

Nuiqsut Com Center, SA, CLO, cease program 8/25 until after bowhead whale hunt, zero discharge at Camden Bay well-sites

Wainwright Com Center, SA, CLO

Community Mitigation Measures

Point Hope Com Center, SA, CLO

Point Lay Com Center, SA, CLO, sensitivity to beluga hunt

Kivalina & Kotzebue

Com Center, CLO, SA, sensitivity to beluga hunt

St. Lawrence Island Com Center, SA

Wales Com Center, SA

Diomede SA

Torpedo

Burger

Sivulliq

10

Plan of Cooperation Meetings

2011 Village meetings:• Kaktovik

• Nuiqsut

• Barrow

• Wainwright

• Point Lay

• Point Hope

2012 Village meeting plans:• Kaktovik

• Nuiqsut

• Barrow

• Wainwright

• Point Lay

• Point Hope

• Atqasuk

• Kivalina

• Kotzebue

• Kiana

• Shishmaref

• Gambell

• Savoonga

• Anaktuvuk Pass

• Kivalina

• Kotzebue

• Wales

• Gambell

• Savoonga

11

Questions

&

Discussion

12

Science and Monitoring

Program Overview

13

Alaska Venture Science Studies Program

Monitoring

• Permit driven (compliance)• Marine Mammal MP• Threatened & Endangered• Air

Baseline studies

• Provides basis for project design

• Identifies issues• Fills data gaps• Provides basis for

NEPA documents (EIS)

• Ecological• Ice/weather• Ice gouge / streudel

scour / soil testing• Traditional knowledge

Engineering & Technology

• Enabling both E & P• Unmanned aerial• Autonomous underwater• On-ice seismic• Sound mitigation• Ice forces

14

Alaska OCS Science Collaboration

Majority of Shell science is through collaboration

�ConocoPhillips key along with Statoil, GXT, Pioneer, & ENI

�Universities (UAF, UT, UMD) and Government including USGS, BOEM, NOAA

�Research entities including NFWF, Northern Forum, SINTEF

60 % of Shell Alaska science is leveraged

Shell - North Slope Borough Science Agreement to fund local community

directed priorities w/ $5 million/5 years

Shell/ConocoPhillips/Statoil – NOAA agreement on sharing scientific studies

data and ice and weather monitoring/forecasting

15

Chukchi Sea Lease Areas and Baseline Studies

Jointly funded by ConocoPhillips

& Statoil

Operated by native corporation

Three areas of top priority

Subject to intensive

interdisciplinary study each year

since 2008

� Physical oceanography

� Benthos

� Plankton

� Acoustics

� Fishes

� Marine Mammals

� Marine Birds

16

Marine Mammal Observations

Triad of Information

Vessel based observations

�MMOs on every vessel

� Integrated biologist/local

knowledge staff

Aerial observations

Acoustics

�Open water since 2006

�Year around since 2007

17

Acoustics – Regional arrays

Acoustic recorders

deployed in the Chukchi

& Beaufort

Localization capability in

Beaufort

Goals

�Understand effects of

industry sound on the

distribution and

behavior of marine

mammals.

�Understand patterns of

distribution and

movement

18

Acoustics – Sound Source Characterization

SSC conducted on all

vessels unless previously

assessed at location

Vessel SSCs at initiation of

activities

Rolling SSC for drilling

�Real time evaluation

�Weekly reporting

19

Acoustics – Site specific arrays

Monitor and evaluate drilling

related sound levels

Collect distribution and

movement information

through call data

Based upon learnings since

2006

�Masking

�Localization

�Calling behavior

Need input on final plan

20

Aerial Program

Offshore overflights in the Beaufort

�Manned flights w/ photography

�Stratified sampling strategy

Chukchi nearshore

�Sawtooth pattern

�Manned flights w/ photography

Chukchi Burger prospect

�Photographic survey

�Manned aircraft

�No MMOs

21

Drilling Monitoring

Before

�Sediment/water chemistry

�Biota community assessment

�Repetition of Joint studies evaluations localized at drill site(s)

During

�Plume monitoring – turbidity, chemistry

�Deposition

�Water chemistry

After

�Sediment/water chemistry

�Biota Community assessment

�Bioaccumulation

22

Questions

&

Discussion

Shell 2012 MMO Program: Capturing Past Recommendationsfrom NMFS and Local Stakeholders

MMO Platforms:

Aerial (n = 2)

Vessel (n =18)

~58 MMOs in the field5 - 6 MMOs per aircraft

1 - 5 MMOs per vessel

“Qualified MMOs are key elements of successful monitoring

and mitigation efforts…” NMFS Expert Panel, 2010

• MMOs on ALL Project Vessels plus 2 Aircraft

• Qualified Alaska Natives and Professional

Biologists trained together through extensive

use of visual aids over course of 3 days:

• Emphasis on ID, Regulatory Context,

Sighting/Mitigation Scenarios

• Performance-based assessments/exams

• Recruiting from N. Slope and NANA

region

• Maximize eyes on water in areas relevant to

mitigation

• Appropriate use of Big Eyes + low-powered

optics and naked-eye search patterns

Additional NMFS Expert Panel Recommendations within Shell’s 2012 MMO Program

• MMOs stationed in areas that maximize viewing (e.g., bridge)

• Importance of ‘unidentified’ ID stressed, focus on what was/was

not observed and record in detail in comments

• Improved real-time data recording into computer, including

ability to geo-reference sightings for operational context

• Daily correspondence with shore-based support, data reports

• Debriefs following shift/season


• Relevant environmental data collected every 30 minutes or

when conditions change. Data-analysis criteria to account for

detection bias at increasing distance from platform and during

periods of poor visibility:

• Data from periods of favorable conditions used for density /

abundance estimates

• Compare data from periods of drilling vs. non-drilling

• Continued use of night-vision devices (NVDs): drilling and ice-

scouting/management activities


• Use of aerial surveys to visually monitor animals at distances

greater than can be detected from vessels

• Aerial MMOs communicate sightings to MMOs on vessels

29

Questions

&

Discussion

Sound Source Characterization Plan

Objectives for Sound Characterization and SSV

Measurements

Quantify industrial underwater sound levels and sound

spectra as functions of distance from the drilling program

sources

Determine 1/3-octave band source levels of each industrial

noise source

The purpose of these measurements is to gauge potential

impacts on marine fauna (including takes under MMPA),

and to provide relevant information for predicting sound

levels during similar future operations

Vessel sound characterization

approach

SSC measurements will be made on all vessels that have not

previously had sound characterizations

Most SSC measurements will be performed outside the 25 mi

exclusion zone for air permits

Will make all measurements with a single deployment of recorders

as shown above

Drill Rig Acoustic Monitoring and SSV

SSV for drilling and ZVSP

- Monitor at distances

corresponding to >120 dB for drilling and for 190 to 160 dB re 1 µµµµ

Pa for ZVSP- Real-time transmitting buoy at 500

m

- Coordinate with Joint acoustics

program for lower level ZVSP

measurements at greater distances

Objectives for Chukchi Regional

Acoustics Monitoring by the Joint

Science Program

Measure ambient noise levels over a large area of the

northeastern Chukchi Sea

Measure long-range industrial sound levels from Shell drilling

operations, including vessel activities

Detect marine mammal calls to define spatial and temporal

distributions

Investigate possible changes to vocal behavior due to the

presence of industrial noise

35

Questions

&

Discussion

Beaufort Regional Acoustics Program

Deployment locations since 2007:

Beaufort Sea Acoustic Monitoring

Two DASARs added in 2010 and 2011 to gather background levels near the future drilling locations:

Site 1

15'

50 km

50mi

j

Site 2

I Prudhoe Bay

Site 3 ... ... ... ... ... ... ...

~~

Site 4

4H • ... • 41 .. ... ... ... ...

Site 5

Camden Bay

Suggested 2012 deployments near sites 3 and 4:40'

Site 3 Site 4

• G • F 30' • E • D • • • c • G

B • • • • H F A • E

70°N • • 20.00' -l_ I D • c •

... • B

- - A

-10' ~

~ • Sivulliq drill site e Torpedo drill site

• Original DASAR locations 1::::. Flipped OASAR locations

10 km

• Site 1 DASAR {A, B, C, G) moved to Site 4 10 mi /:;,. Small "triplet" array

147°W 40' 20' 146°W 40 ' 20'

Suggested 2012 deployments near sites 3 and 4:40'r-~r-------~--------~---------r--------~--------~------,

30'

10'

Site 3

.. G

.. E

.. c

.. A

.. F

.. D

.. B

-- -e Sivulliq drill site e Torpedo drill site _. Original DASAR locations

1::::. Flipped DASAR locations

.. e H

.. I

10 km

_. Site 1 DASAR {A, B, C, G) moved to Site 4 10 mi t::. Small "triplet" array

40'

Site 4

• .. F

.. D

.. B

1::::. G'

1::::. E'

1::::. C'

1::::. A'


Site 3 Site 4

• • G • • M F • L • 30' E • K D • • • J

c !::::.

• G' B • • • • H F

A !::::. E'

70°N • • 20.00' -l_ I D

!::::. C' •

... B !::::. - - A'

-10' ~


• Original DASAR locations !::::. Flipped OASAR locations

10 km

• Site 1 DASAR {A, B, C, G) moved to Site 4 10 mi /:;,. Small "triplet" array

147°W 40' 20' 146°W 40 ' 20'


Site 3 Site 4

• • G • • M F • L • 30' E • K D • • • J

c !::::.

• 1:::../:::,. G' B ~ • • • • H F

A !::::. E'

70°N • • 20.00' -l_ I D

!::::. C' •

... B !::::. - - A'

-10' ~



10 km

• Site 1 DASAR {A, B, C, G) moved to Site 4 10 mi 1:::.. Small "triplet" array

147°W 40' 20' 146°W 40 ' 20'


Site 3 Site 4

• • G • • M F • L • 30' E • t:.t:.

K D • • t:. • J

c !::::.

• G' B • • • • H F

A !::::. E'

70°N • • 20.00' -l_ I D

!::::. C' •

... B !::::. - - A'

-10' ~



10 km

• Site 1 DASAR {A, B, C, G) moved to Site 4 10 mi t:. Small "triplet" array

147°W 40' 20' 146°W 40 ' 20'

Drillship sounds from previous measurements:

Ku/luk drilling (1984) Explorer II drilling (1981) Explorer /logging (1982)

Explorer II tripping (1986) o Frontier Discoverer (2009) Explorer II cleaning (1986) Explorer II drilling (1986)

150 ~----------------------~------------------------~--------------~

145 ..-

~ 140

;: 135 i Q) ' .... co 130 "0 --Q) 125 > Q)

_J 120 "0 Q)

.~ 115 Q) (.)

~ 110

105

co

100+-----------~------~---+--------------~----~--+---------------~

0.1 1 10 50 Distance from Drillship (km)

Broadband (10-450 Hz) levels at DASARs 4H and 4I in 2010:

20 (i) -- 15 E ..._.. 10 '0 c: 5 ~

140

130

120

ro- 110 a.. :::.

..- 100

100

90

so ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

12 14 16 18 20 22 24 26 28 30 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 3 Date in August, September, and October 2010

Broadband (10-450 Hz) levels at DASARs 4H and 4I in 2010:

20 (i) -- 15 E ..._..

10 '0 c: 5 ~

140

130

120

ro- 110 a.. :::.

..- 100

100

90

so ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

12 14 16 18 20 22 24 26 28 30 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 3 Date in August, September, and October 2010

95th - 114 dB

50th - 102 dB

5th -89 dB

Adding in ambient sound levels as recorded at 4H and 4I in 2010:

Drilling

Anchor retrieval

Turret turn

Adding in distances from drillships to S3 & S4 DASARs:

Ku/luk drilling (1984) Explorer II drilling (1981)

Explorer /logging (1982)

Explorer II tripping (1986)

Explorer II cleaning (1986)

Explorer II drilling (1986)

o Frontier Discoverer (2009)

--- 4H & 41 ambient

• o o DASAR dist. to Sivulliq &Torpedo

• ~ 00 ···---·· 0 0 00 000 0 CD<D a::D 0 CD <m 150 ~----------------------~------------------------~--------------~

145 ..-

~ 140

~ 135 i ..... co 130 "'0 --0,) 125 > 0,)

_J 120 "'0 0,)

.~ 115 0,) (.)

~ 110

105

100 0.1

co

----------------- 9~h

1 10 50 Distance from Drillship (km)

Audibility of average bowhead call at different DASARs:

Question: what is the range of distances at which the RL of an average bowhead call would be above the sound produced by the drillship?Assumptions:•Used bowhead call SL of 150 dB re 1 uPa (“average”, SLs in the range 130-170 dB)•Used drillship regression for Explorer II cleaning•Ambient sound levels are low (below drillship sounds)•Used spreading loss of 15log(distance) and 10log(distance)

Audibility of average bowhead call at different DASARs:40'~~--------~------~--------~--------~------~------,

30'

10'

...

DASAR4H 4.1 km from Sivulliq RL=121.2dB 80-710 m

•

---

e Sivulliq drill site e Torpedo drill site .A. Original DASAR locations

6. Flipped DASAR locations 10 km

.A. Site 1 DASAR (A, B, C, G) moved to Site 4 10 mi &;. Small "triplet" array

40'


30'

10'

...

Triplet DASAR 6 km from Sivulliq RL = 118.6 dB 120-1220 m

•

---



.A. Site 1 DASAR (A, B, C, G) moved to Site 4 10 mi !:;;. Small "triplet" array

40'


30'

10'

...

DASAR 4F 16 km from Sivulliq RL = 109.4 dB 490-6300 m

•

---



.A. Site 1 DASAR (A, B, C, G) moved to Site 4 10 mi 1::. Small "triplet" array

40'

Audibility of average bowhead call at different DASARs:40'~~--------~------~--------~--------~------~----~

30'

10'

...

DASAR4B 20 km from Sivulliq RL = 106.5 dB 760-9200 m

---

e Sivulliq drill site e Torpedo drill site .6. Original DASAR locations


.6. Site 1 DASAR (A, B, C, G) moved to Site 4 10 mi 1:::. Small "triplet" array

40'

0

55

Questions

&

Discussion

Chukchi Regional Acoustics Program

2010 and 2011 Regional Program Acoustic Buoy Layouts

2011 Program also deployed 6 buoys in late August around

Hanna Shoal that will record through August 2012

168c0'0"W

168°0'0"W

156c0'0"W

z 0 0 N I'-

. OL N120B

5001 ef'LN~

. PL I'WJ . 0011'

ePLN40

Kl01 • .Pl. N2IJ

PLSO •

156°0'0"W

z 0 0 0 N 1'-

z 0 0 0 0 1'-

168°0'0"W

168°0'0"W

CL 20 •

162°0'0"W

WN80 ... Pl N100 1 W N4D ... . 50 01

. PLN8b

Pl50 •

162°0'0"W

156°0'0"W

Legend • Burger..vray·..-l!h 16lm &paCing ..&. 2011 Proposed Late summer • 20 11 Proposeo R~onal ,..rray • oru ste

conocoPnlll" s Lease Areas sne:J Lease Areas Sta:oll t ease Are-as

c_:::.J CIWkCil l t easeArw

156°0'0"W

z 0 0 0 N 1'-

z 0 0 0 0 1'-

Bowhead distribution (acoustic)

72°

71 °

69°

165°W

Call counts - 1 - 10

- 11 - 1000

·,,,,, ............................ , .............. , . 1001-2000

- 2001-4000

- 4001-8000

- 8001- 12000

- 12001 - 15000

15001 - 23251

0 25 50

160°W

- 2001 -3000

- 3001-5000

- 5001-6000

- 8001 - 10000

- 10001 - 12000

12001 - 16600

165°W 160°W

Walrus Distribution (acoustic)

16s·w 16o·w

61

Questions

&

Discussion

Beaufort Aerial Program

Beaufort Prospect Aerial Survey

Initiated in 2006 as part of an

integrated monitoring program

Manned flights in 06,07,08,10

Will fly in 2012 with MMOs aboard

to evaluate impacts of drilling

activities on migrating bowheads

and other species

Flight pattern will be modified per

findings of peer review

recommended power analysis

Aircraft will have both MMOs and

photographic equipment

Beaufort Prospect Aerial Survey

Long term goal to utilize

Unmanned Aerial Systems (2013?)

2 still frame cameras + HD video

Dual observation will allow direct

comparison of results & derivation

of correction factors

Photography will provide lasting

record

Photo analyses will be done when

not flying

Evaluating multi-spectral scanner

Sensors

2 Still Cameras- Cannon 5D Mk II digital SLR camera – one with 20

mm lens and other with 20 (Beaufort) or 100 mm

(Chukchi?) lens

- 5D is a 21.1 megapixel camera that stores imagery

in a 5616 × 3744 pixel array

One HD Video- Canon XF305

- 1920 × 1080 resolution

- NTSC video is 640 × 480

Survey Area

Still Camera

Single DSLR camera with 20 mm lens covers 720 m swath, 100 mm lens covers 144 m

swath

One pixel is 12 cm with 20 mm lens and 2.4 cm with 100 mm lens

Effective Strip Width for manned survey of bowheads has varied from 500 to 700 m and

for belugas was ~300 m

Can detect (20 mm) and identify and count (100 mm) animals that cannot be reliably

detected during visual surveys (seals)

Video Camera

Camera fixed to cover a 600 m swath

One pixel on water is 25 cm (same as Koski et al. 2009)

Provides constant coverage rather than soda-straw coverage making detection easier

67

Questions

&

Discussion

Chukchi Aerial Program

Chukchi Burger Prospect Aerial Survey

Since 2006 conducted nearshore

surveys

Surveys in 06,07,08, 10

Benefits have been initial

observation of walrus haulouts

Desire to collect data in the

offshore despite risks

2012 will add photographic

offshore surveys

Pilot & co-pilot but no MMOs

Chukchi Burger Prospect Aerial Survey

Offshore unmanned will be flown preferentially

Nearshore will be flown with MMOs and photography when Burger is not available or needed

Comparisons to Beaufort and nearshore will enable calibration

Based out of Barrow, MMOs will analyze data when not flying

Photographic results will be available

Eventually computer assisted detection is a goal.

71

Questions

&

Discussion

Aerial Survey Power Analysis

Background

One aspect of aerial monitoring is to investigate potential differences

in marine mammal densities around industrial activity.

At present, comparisons are made between sighting rates for

different received sound pressure level categories.

This analysis addresses a request by NMFS for a power analysis to

investigate the probability of the proposed survey design to detect

such effects

Original Proposed Beaufort Survey Design

... ' .

Aerial Survey Lines

g • Sivulliq-N

I Sivulliq_N - 10, 20, 30 km rings

Kulluk 120 dB zone {19.9 km) 0 5 10 20 30 40

Miles - Discoverer 120 dB zone (5 km) 0 5 10 20 30 40 Kilometers

147 143

Survey Sub-areas and Effect Sizes

Potential

Impact

Zone

Outer

Zone

0.02 bowheads / km2

Potential Impact Zone bowhead density assumed to be 25% (Big effect), 50% (Medium effect) or 75% (Small effect) of underlying density in Outer Zone.

Area = 20

or 30 km

radius

Estimating Power of Aerial Survey Design through

Simulation

Underlying bowhead density, detection function, g(0) etc. based on

existing data.

Expected effort in 2012 equal to average effort achieved during recent

survey seasons.

Effort in each zone proportional to zone’s area divided by total survey

area.

Also ran exploratory power analysis for Chukchi, accounting for

additional transit length to offshore survey area

0 10 20 30 40

010

20

30

40

Example Simulated Survey (Impact Zone)

Track-line

Vis. Range (2 km)

Not sighted

Sighting

Power: Original Proposed Survey Design (i.e. Uniform Transect-Line Spacing)

2) Chukchi

1) Beaufort

Radius of impact zone (km) Big effect (25%) Medium effect (50%) Small effect (75%)

20 1 0.49 0

30 1 1 0.38

Impact zone density as % of outer zone density

Radius of impact zone (km) Big effect (25%) Medium effect (50%) Small effect (75%)

20 0.993 0.113 0

30 1 0.999 0.142


Concentrated Effort in Impact Zone

0 10 20 30 40

010

20

30

40

0 10 20 30 40

010

20

30

40

Power:

Concentrated Effort in Impact Zone

2) Chukchi

1) Beaufort

Impact zone effort multiplier Big effect (25%) Medium effect (50%) Small effect (75%)

Base case 1 0.49 0.00

1.2 x 1 0.88 0.01

1.4 x 1 0.99 0.01

1.6 x 1 0.99 0.06


Impact zone effort multiplier Big effect (25%) Medium effect (50%) Small effect (75%)

Base case 1 0.11 0.00

1.2 x 1 0.33 0.00

1.4 x 1 0.69 0.00

1.6 x 1 0.87 0.00


Revised Proposed Aerial Survey Design

Outer Survey Lines (1 0 km Spacing)

Intensive Survey Lines (6 km spacing)

D 60x60 km Intensive Survey Area

• Exploration Drilling Location

149•o·o·w 14a•o·o·w 14700'0'W 14e•o·ow

0 5 10 40 •=--=---c::=::::::l---Miles

20 30

0 5 10 20 30 40 • • Kilometers

14500'0'W 144°0'0'W

Impact Zone Density as % of Outer Zone Density

Pow

er

0 20 40 60 80 100

0.0

0.2

0.4

0.6

0.8

1.0

Power Function (20km Impact Radius)

Big change in Density -----------� Small change

Summary

•If impact radius is 30km, power to detect differences in densities is

generally high.

•If impact radius is 20km, power is high for larger changes in density but

drops off rapidly for smaller changes.

•In general, maximizing effort around industrial activity maximizes the

power to detect differences in underlying densities.

•

•There is a limit to the amount of effort achievable around industrial

activity however, as dictated by a minimum desirable spacing of transect

lines (else risk double counting).

•The revised aerial survey design has improved power to detect

differences in densities over the original design.

shell 2012 beaufort and chukchi seas exploratory drilling

Documents