Carnarvon Basin (Barrow Sub-Basin) Geochemical Calibration ... · OBJECTIVES Hydrocarbon accumulations in the BarrowlDampier Sub-basins had been, until recently considered to fall

BMR GEOLOGY AND GEOPHYSICS AUSTRALIA

BMR RECORD 1992/45

CARNARVON BASIN (BARROW SUB-BASIN)

GEOCHEMICAL CALmRA TION SURVEY

PROJECT 121.18

G.P. Bickford, D. Heggie, B. Hartman and J. Bishop

t q~~ / 4-)MARINE GEOSCIENCE AND 'PETROLEUM GEOLOGY PROGRAM c.<./-

11111111111 *R9204501*

BMR RECORD 1992/45

CARNARVON BASIN( BARROW

SUB-BASIN) GEOCHEMICAL CALIBRATION

SURVEY

PROJECT 121.18 G.P. Bickfordl , D.Heggie1, B. Hartman2 and J.Bishopl

1 Bureau of Mineral Resources 2 Transglobal Environmental Geoscience

-----BUREAU OF MINERAL RESOURCES, GEOLOGY AND GEOPHYSICS, AUSTRALIA -----

DEPARTMENT OF PRIMARY INDUSTRIES AND ENERGY

Minister: The Han. Alan Griffiths

Secretary: G.L. Miller

BUREAU OF MINERAL RESOURCES, GEOLOGY AND GEOPHYSICS

Executive Director: R.W.R. Rutland AO

© Commonwealth of Australia, 1992.

This work is copyright. Apart from any fair dealing for the purpose of study, research, criticism, or review, as permitted under the Copyright Act, no part may be reproduced by any process without written permission. Copyright is the responsibility of the Director, Bureau of Mineral Resources.

In reference to digital data these conditions apply to all digital data purchased or acquired, or generated by any subsequent data processing:

1. The purchaser is buying the right to use the digital data, but not the ownership of the data. Ownership of the data remains with the Commonwealth of Australia, which has copyright of the data.

2. All digital data must be kept exclusively for the use of the purchasing company, agency or organisation and must not be transmitted, traded or sold to any third party without the permission in writing of the Executive Director, Bureau of Mineral Resources.

3. An organisation or individual may, with the permission of the Director, reprocess BMR digital data and market products thus derived on a multi-client basis. Generally, the organisation or individual would be required to enter into an agreement with the BMR which would include the following:

a) The Commonwealth will retain copyright of the original data.

b) A copy of the product(s) will be supplied to the BMR.

c) The BMR will claim a licence fee for each copy of the product sold.

d) After a specified period of time the right to copy or sell the product(s) may be exercised by the Commonwealth.

Inquiries should be directed to the Principal Information Officer, Bureau of Mineral Resources, GPO Box 378, Canberra City, ACT, 2601.

ISSN 0811-062 X ISBN 0 642 18250 7

EXECUTIVE SUMMARY ......................................................................................... iii

mTRODUCTION ...................................................................................................... 1 Surface geochemistry and offshore exploration for hydrocarbons ...................... 1 BMR Surface geochemistry overall program objectives .................................... 2

BARROW SUB-BASm: BACKGROUND AND OBJECTIVES ................................ 4

BARROW SUB-BASIN: DHD RESULTS .................................................................. 5 Eastern sector of the Barrow Sub-basin (survey lines Carn 1-3) ........................ 5 Western sector of the Barrow Sub-basin (survey lines Cam 4, 5) .................... 7 Hydrocarbon 'source' ........................................................................................ 8

SUMMARy ................................................................................................................ 9

REFERENCES ........................................................................................................... 11

LIST OF TABLES ...................................................................................................... 12

LIST OF ENCLOSURES ............................................................................................ 15

LIST OF FIGURES .................................................................................................... 16

APPENDIX I ............................................................................................................. .

Carnarvon survey lines 1 through 5 ............................................................................. .

APPENDIX II ............................................................................................................ . DHD METHODOLOGY ................................................................................ .

APPENDIX ill ........................................................................................................... . mTERPRETATIVE METHODOLOGY ........................................................ .

Light Hydrocarbons In Seawater .......................................................... . Data interpretation: the mixing model ................................................. .. Classification of anomalies ................................................................... .

APPENDIX III REFERENCES ................................................................................. .

APPENDIX IV .......................................................................................................... . SYSTEM OPERATIONS REPORT ............................................................... . DHD ............................................................................................................... . NON GEOCHEMICAL SySTEMS ............................................................... .

Enclosure 1 ................................................................................................................ .

Enclosure 2 ................................................................................................................ .

-----BUREAU OF MINERAL RESOURCES, GEOLOGY AND GEOPHYSICS, AUSTRALIA n

EXECUTIVE SUMMARY

Transglobal Environmental Geosciences (TEG) and the Bureau of Mineral Resources,

as part of the Joint Research Agreement into hydrocarbon seepage around the

Australian Continental margin, conducted a calibration survey over some known

hydrocarbon accumulations in parts of the Barrow Sub-basin and the Rankin Platform

during 1989. This survey was conducted at the end of a larger and proprietary

geochemical 'sniffer' survey conducted by TEO (for Amoco Production Co., USA) in

the Perth Basin.

Approximately 220 line km of Direct Hydrocarbon Detection (DHD) data were

collected during the survey in the vicinities of known hydrocarbon accumulations,

Saladin, South Chervil, Chervil, North Herald and South Pepper in the inshore part of

the Barrow Sub-basin. Additional survey lines were run in the deeper water part of the

basin, on the landward side of the rift, in the vicinities of Chinook and Griffm, and

further to the north, on the southern extension of the Rankin Platform (Alpha Arch)

over the Gorgon gas/condensate field.

Light hydrocarbon anomalies were detected in bottom-waters in the vicinities of

Saladin, Chervil, South Chervil, North Herald and South Pepper, although the

anomalies were generally weak « five-fold background). No anomalies were detected

near Chinook and Griffin, nor Gorgon, although problems with the tow-cable and tow

fish resulted in the tow-fish being too high above the seafloor to detect any significant

seepage.

iii ------BUREAU OF MINERAL RESOURCES, GEOLOGY AND GEOPHYSICS, AUSTRALIA --~~--

INTRODUCTION

Surface geochemistry and offshore exploration for hydrocarbons

The aim of surface geochemical techniques in offshore petroleum exploration is: (a) to

detect direct evidence for thermogenic generation of hydrocarbons in a sedimentary

basin, (b) to assist in locating sub-surface hydrocarbon accumulations, and (c) to

provide information on the likely composition of hydrocarbon accumulations within a

given geologic province. The most common technique used to detect hydrocarbon

seepage offshore involves towing a submerged 'fish' close to the seafloor which

continuously pumps seawater into a geochemical laboratory in the tow-vessel. There,

hydrocarbons are extracted and measured by gas chromatography. This equipment,

commonly known as a geochemical 'sniffer' (Schink et al. 1971; Sigalove and

Pearlman 1975) - or what we refer to as Direct Hydrocarbon Detection (DHD) - has

been widely used overseas for offshore petroleum exploration. InterOcean Systems

Inc., a US-based corporation has collected over 1.5 million line kilometres of data

from about 140 surveys around the world. However, most of the data gathered by

contractors for clients remains proprietary and the opinions expressed publicly, about

surface 'sniffer' geochemical techniques, by the petroleum exploration community

remain divided. Schiener et al. (1985) have commented about the use of the

geochemical 'sniffer' in the North Sea.

Within Australia, the 'sniffer' has been a relatively under-utilised tool in offshore

hydrocarbon exploration, with only four surveys being carried out prior to 1988.

Those surveys were all located in southeastern Australia, specifically in: (1) the

Duntroon Basin, for Getty Oil Development Company Ltd. in 1983, (2) the Otway

Basin (Sprigg 1986) for Ultramar Australia in 1981, and (3) two small surveys in the

Gippsland Basin for Esso Exploration and Production, Australia Inc., in 1983.

------BUREAU OF MINERAL RESOURCES, GEOLOGY AND GEOPHYSICS, AUSTRALIA ------

The Bureau of Mineral Resources (BMR), as part of the Continental Margins

Program, and a joint Agreement with Transglobal Environmental Geoscience

(TEG) of Leucadia California (Heggie et al., 1990), has been conducting surface

geochemical (bottom-water DHD and sediment [hydrocarbon-headspace]

geochemistry) surveys on parts of the Australian continental margin since 1989.

Part of this work includes research into:

• the origins (biogenic or thermogenic?) of bottom-water light hydrocarbons

• light hydrocarbon 'sources' (liquids, condensate or gas?)

• bottom-water and seafloor expressions of seepage

• the relationships of seepage to the surface and sub-seafloor geology, including

hydrocarbon accumulations and source rock types and distributions.

BMR Surface geochemistry overall program objectives

The overall objective of the BMR offshore surface geochemistry program is to

evaluate the application of surface geochemical techniques (both direct hydrocarbon

detection (DHD) and sediment [hydrocarbon-headspace] techniques) to hydrocarbon

exploration around the Australian continental margin. Specific objectives include:

• To collect, via reconnaissance surveys, new information on the thermal

generation of hydrocarbons in under-explored Australian basins.

• To test the application of both bottom-water DHD and sediment geochemical

techniques to hydrocarbon prospect ('target') evaluations in both known

hydrocarbon provinces and frontier basins.

• To test, develop and refme criteria to recognise thermally generated migrated

hydrocarbons from background biogenic hydrocarbons in both seawater and

sediments.

------BUREAU OF MINERAL RESOURCES, GEOLOGY AND GEOPHYSICS, AUSTRALIA __ ~2,",,--__

• To examine the relationship between hydrocarbon generation and migration by

relating the surface and sub-seafloor expressions of hydrocarbon seeps to the sub

seafloor geology and probable locations and type(s) of source rocks .

• To relate the chemical and isotopic compositions of seeps to 'source'

characteristics, i.e. gas, condensate, liquids, and to predictions from geohistory

and maturation modelling of different source rock types.

• To test bottom-water DHD and sediment geochemistry techniques in the

search for hydrocarbons sealed by stratigraphic traps.

• To examine the biogenic processes influencing the concentrations, distributions

and chemical compositions of hydrocarbon seeps in bottom-waters and the near

surface sediments.

• To examine oceanographic dispersal processes of seeps.

To achieve this, multi-disciplinary programs involving the simultaneous collection of

bottom-water DHD, seismic reflection, gravity, magnetic and side-scan sonar data

have, and will be, carried out by the BMR's research vessel "Rig Seismic" (and

occasionally on other vessels) around the Australian continental margin. These data

are both integrated with each other, and also with sediment geochemical data which

may sometimes be collected during the surveys.

The geochemical analysis system (Direct Hydrocarbon Detection or DHD) that has

been installed aboard the Rig Seismic as part of the Agreement is shown schematically

in Figure II -1 of Appendix II. The laboratory system analyses a variety of gases

extracted from seawater, including CI-C8 hydrocarbons with facilities to collect gases

for shore-based isotopic analyses. Complete details of both the DHD system and the

interpretative methodologies used are given in Appendices II and III.

This BMR Record presents the geochemical data obtained during a very short and very

constrained 'calibration' exercise in the Barrow Sub-basin of the Carnarvon Basin

------BUREAU OF MINERAL RESOURCES, GEOLOGY AND GEOPHYSICS, AUSTRALIA ___ -"3~ __

(Fig.1) during July of 1989. These data were obtained by TEG aboard the 'M.V.

Mermaid Searcher', at the completion of a larger, proprietary 'geochemical sniffer'

survey conducted for AMOCO Production Co., in the Perth Basin.

BARROW SUB-BASIN: BACKGROUND AND

OBJECTIVES

Hydrocarbon accumulations in the BarrowlDampier Sub-basins had been, until recently

considered to fall into two trends. There existed an inner trend of oil-prone

hydrocarbon discoveries e.g., Barrow Island and associated accumulations, such as

Saladin, Chervil, North Herald, South Pepper, Harriett, Bambra and Rosette on the

eastern flank of the Barrow Sub-basin, while an outer trend of predominantly

gas/condensate accumulations were associated with the western side of the Barrow

Sub-basin along the Rankin Trend e.g., Gorgon, West Tryall Rocks. However, more

recently, there have been oiVgas discoveries in the what had previously been

considered gas/condensate-prone areas, eg Griffin and Chinook, Wanaea and Cossack.

Given the occurrences of gas/condensate and oiVgas accumulations within the Barrow

Sub-basin and the distinction between the inner oil-prone and outer gas/condensate

trends becoming blurred, it was considered that surface geochemical techniques,

specifically DHD (geochemical 'sniffer'), could be a useful complementary exploration

tool that may be used to distinguish gas from oil prone accumulations, and hence

reduce exploration risk in this part ofthe North West Shelf.

The objectives of this survey therefore were to; (i) measure the concentrations of light

hydrocarbons in the bottom-waters of the Barrow-Sub-basin, in areas of known

hydrocarbon (both gas/condensate and oiVgas discoveries) accumulations, hence (ii) to

______ BUREAU OF MINERAL RESOURCES, GEOLOGY AND GEOPHYSICS, AUSTRALIA ___ 4.:.-. __

evaluate the potential application of bottom-water geochemical data in new exploration

on the N orth-West Shelf.

BARROW SUB-BASIN: DHD RESULTS

Bottom-water geochemical data were collected along five survey lines (Figs. 1 and 2).

These lines (Carn 1, Carn 2, Carn 3, Cam 4, Cam 5) are presented in this record as

both the individual lines and also as a composite line in Figure 13. The corresponding

shot-point numbers and line numbers of the composite data set are shown in Table 1.

The geochemical analysis system used to acquire the bottom-water light hydrocarbon

data is identical to that installed on the Rig Seismic and is described in Figure 11-1,

Appendixll.

Eastern sector of the Barrow Sub-basin (survey lines Carn 1-3)

Line summary plots of light hydrocarbons are shown in Figures 3 through 9. Line

summary plots of total hydrocarbons (THC; Fig. 3), sum CI-C4 (Fig. 4) and the

individual saturated hydrocarbons methane (Fig. 5), ethane (Fig. 6) and propane (Fig.

8) show similar trends: bottom-water anomalies were found on survey lines Carn 1 and

Carn 2, in the eastern part of the survey area.

All anomalies are weak (generally less than five-fold typical background

concentrations), but nevertheless are clearly distinguishable from the local background

hydrocarbon concentrations. Methane concentrations are highest in the anomalies on

line Carn 2, and increase from background of about 3.5 ppm to about 9 ppm (Fig. 5).

------BUREAU OF MINERAL RESOURCES, GEOLOGY AND GEOPHYSICS, AUSTRALIA __ ---'5:::...-__

Similarly, ethane concentrations increase about five-to-ten-fold above background

levels in the anomalies measured on lines Carn 1 and 2 (Fig. 6). Maximum ethane was

measured at about 0.1 ppm, typically, 0.04 - 0.08 ppm (typical background about 0.01

ppm). The increases in ethane are not accompanied by corresponding increases in the

unsaturated biogenic hydrocarbon (ethylene) (Fig. 7). Propane concentrations varied

similarly to ethane, but propane only showed minor increases above local background.

For example, in the strongest anomaly on line Carn 2, propane increased to levels

typically 0.025 to 0.05 ppm, and the local background was about 0.015 ppm (Fig. 8).

Propylene concentrations (biogenic hydrocarbons) were relatively high on lines Carn 1

and Carn 2 (Fig. 9).

The anomalies are also reflected in the line summary plots of the Bernard parameter

(methane/(ethane+propane) Fig. 10); the ratio of methane/ethane (Fig. 11), variations

in the ethane/propane ratio (Fig. 12), and variations in the % hydrocarabon wetness

(Fig. 14). It should be noted that the sudden increase in wetness on survey line Cam 5

results from the rapid appearance of iso-butane and trace levels of propane, but no

increases in methane and ethane, and is not believed to be seepage from the seafloor

(see below).

The positions of the anomalies are summarised in Table 2. The anomaly on survey line

Carn 1 (Appendix I), corresponds closely to the location of the Saladin 1 oil and gas

field. The anomalies on line Carn 2 (Appendix I), correspond closely to the

accumulations of South Chervil and Chervil oil and gas fields, while the northernmost,

and very weak anomaly corresponds to the North Herald and South Pepper oil and gas

condensate accumulations.

At a ship speed of about 5 knots, the anomalies measured on Carn 1, near Saladin

(Appendix I) could be detected over distances of about 17 km, those anomalies near

South Chervil and Chervil, over distances of about 5 km each, while that near North

------BUREAU OF MINERAL RESOURCES, GEOLOGY AND GEOPHYSICS, AUSTRALIA ___ 6~ __

Herald and South pepper, about 6 -7 Ian (Appendix I). During this part of the survey,

the tow-fish was consistently at an altitude of about 10 m above the seafloor (Fig.13).

At the end of the survey line Carn 2, a transit line (Carn 3) was run westward toward

the Chinook and Griffm oil and gas/condensate accumulations (Fig. 2). No anomalies

were found on this line although it did not pass near any known accumulations, and the

tow-fish altitude was more than 20 m above the seafloor (SP 324 to 462; Fig. 13).

Western sector of the Barrow Sub-basin (survey lines Cam 4, 5).

Survey line Carn 4 was designed to test for seepage near Chinook and Griffm. No

anomalies were found possibly because the tow-fish (due to mechanical problems with

the winch and cable) was at an altitude of 30 - to - 40 m above the seafloor for much

of this line (sp 463 to 529; Fig. 13), at a total water depth of about 140 to 168m.

Geochemical data collection was commenced again further to the north near Spar 1,

and passed over the Gorgon gas/condensate field, and continued to survey near to

West Tryall Rocks. No anomalous concentrations of CI-C3 hydrocarbons were

detected, although elevated iso-butane concentrations were found (SP 38-90;

Appendix I), which persisted for a distance of about 12 Ian, near Central Gorgon and

North Gorgon. These result in a sudden increase in wetness values on Carn 5 (Fig. 14).

However, for much of this part of the survey, continued mechanical problems with the

winch (App. IV) resulted in the tow-fish being more than 40 m above the seafloor

(Fig. 13), and these instantaneous appearances of anomalous levels of i-butane (which

are not accompanied by increases in methane or ethane although trace increases in

propane were found, Figs. 5, 6 and 8), are probably not related to seepage. Time

constraints meant these survey lines could not be re-run. Because of the unusual

elevation of the tow-fish above the seafloor in these sectors (Carn 4 and 5) of the

survey, the lack of bottom-water anomalies is inconclusive as a calibration exercise.

------BUREAU OF MINERAL RESOURCES, GEOLOGY AND GEOPHYSICS, AUSTRALIA ___ ..:...7 __

Hydrocarbon 'source'

The molecular compositions of the anomalies may provide some clues to the potential

'source' (liquids, condensate or 'dry' (biogenic or thermogenic) gas). According to the

cross-plot model of Figure III-I, Appendix III, potential liquid-prone accumulations

are indicated by increasing hydrocarbon wetness values with increasing methane

concentrations. Gas/condensate sources are reflected in near constant hydrocarbon

wetness values with increasing methane while 'dry' gas is indicated by decreasing

wetness values with increasing methane.

In the anomalies found during this survey, methane co-varies with both ethane (Fig.

15) and propane (Fig. 16), although the propane increases above background represent

only trace amounts. In the plot of percent hydrocarbon wetness versus line number

(Fig. 14), typical background wetness values are < 1 %. Increases in wetness values (up

to about 2%) are associated with the anomalies near Saladin, S. Chervil, Chervil and

N.HeraldlS.Pepper. Wetness values increases rapidly to above 2 % in the southern part

of line Cam 5, but these are associated with the unexplained appearance of i-butane

when the tow-fish was high in the water column (above).

The cross-plot of methane versus percent wetness (Fig. 17) shows two trends of

increasing wetness with increasing methane. The trend of increasing wetness at

background methane (3 ppm, closed squares) is associated with the iso-butane

increases on Cam 5 (propably not related to seepage). However, the trends on

increasing wetness with increasing methane are associated with the bottom-water

anomalies near Saladin, South Chervil, Chevil and North HeraldiSouth Pepper. These

are expanded in Figure 18, which shows the data separated by survey line. Background

data are indicated by the transit line (Cam 3, closed squares); data from Cam 1, near

Saladin (closed diamonds) and data from Cam 2 (S.Chervil, Chervil and

N.HeraldlS.pepper, open squares). The data from line Cam 2 are shown in Figure 19,

------BUREAU OF MINERAL RESOURCES, GEOLOGY AND GEOPHYSICS, AUSTRALIA ___ -loS"--__

and indicate separate trends for South Chervil (sp 1-35, closed squares); Chervil 1-3

(SP 36-98, open squares and closed diamonds), and for N.Herald/S.Pepper (SP 99-

182, open diamonds). However, because of the generally low concentrations of all

hydrocarbons measured during the survey (methane increases only about two-fold

above background) and wetness values increase about twice background, these trend

lines are not strongly developed. However, they do indicate trends of varying wetness

with increasing methane, which are at least qualitiatively consistent with the oil/gas

nature of these accumulations.

SUMMARY

Approximately 220 line km of bottom-water light hydrocarbon data were collected

from the Barrow Sub-basin of the Carnarvon Basin during July 1989. The survey was

limited in scope, and intended as a brief calibration exercise only, to test the potential

application of DHD ('geochemical sniffer') techniques to new exploration in this area.

The survey was conducted by TEO (with BMR participation) aboard the vessel M.V.

Mermaid Searcher.

Light hydrocarbon CI-C3 anomalies were detected in bottom-waters in the vicinity of

the Saladin, South Chervil, Chervil and N.Herald/S.Pepper oil and gas/condensate

accumulations. Because these anomalies were detected close to the seafloor, they

probably represent hydrocarbon seepage from the subsurface into the overlying

bottom-waters. These anomalies were weak, but could be detected over distances of

about 5 - 20 km.

A cross-plot of methane versus percent hydrocarbon wetness indicates small increases

(about double) in wetness for increases (about threefold) in bottom-water methane

concentrations. At these low hydrocarbon concentrations this cross-plot model, used

------BUREAU OF MINERAL RESOURCES, GEOLOGY AND GEOPHYSICS, AUSTRALIA ___ -=9:.....-__

as a rapid guide to potential hydrocarbon 'source', is not very sensitive. However, the

model does distinguish the Saladin, South Chervil and Chervil, and the

N.HeraldlS.Pepper accumulations. The cross-plot model suggests the anomalies are

sourced from liquids, or gas/condensate hydrocarbon accumulations.

------BUREAU OF MINERAL RESOURCES, GEOLOGY AND GEOPHYSICS, AUSTRALIA ___ ;;;.;10"--__

REFERENCES

Heggie, D.T., Falvey, D.A. and Hartman, B. (1990), Joint geochemical Research: An

Agreement between the Commonwealth of Australia and Transglobal Exploration and

Geoscience (USA). Bureau of Mineral Resources Record 1990174.

Scheiner, E.I, Stober, G. and Faber, E. (1985), Surface geochemical exploration for

hydrocarbons in offshore areas - principles, methods and results. In: Thomas, B.N.

etal. (eds), Petroleum geochemistry in exploration of the Norwegian Shelf. Norwegian

Petroleum Society, Graham and Trotman Ltd, London, 223-38.

Schink, D.R., Guinasso Jr, N.L. Sigalove, IJ. Cima, B.E. (1971), Hydrocarbons under

the sea - a new survey technique. In: 3rd Annual Offshore Technology Conference

Houston, Texas OTC 1339, 1-15.

Sigalove, J.J. and Pearlman, M.D. (1975), geochemical seep detection for offshore oil

and gas exploration. In: 7th Annual Offshore Technology Conference Houston, Texas,

OTC 2344, 95-100.

Sprigg, R.C. (1986), A history of the search for commercial hydrocarbons in the

Otway Basin complex. In: Glenie, R.C.(ed.), Second South-Eastern Australia Oil

Exploration Symposium. Petroleum Exploration Society of Australia, 173-200.

11 ------BUREAU OF MINERAL RESOURCES, GEOLOGY AND GEOPHYSICS, AUSTRALIA ----..;:~--

LIST OF TABLES

Table 1. Shot-point numbers and survey line names for the composite data ftle and

reference to Figure 13.

Table 2. Bottom-water anomalies and locations of hydrocarbon accumulations.

12 ------BUREAU OF MINERAL RESOURCES, GEOLOGY AND GEOPHYSICS, AUSTRALIA ----==---

Table 1. Shot-point numbers and survey line names refering to the composite data set

shown in Figure 13.

Shot-point Line name

1-140 Carn 1

140-322 Carn2

323-462 Carn3

463-529 Carn4

530-767 Carn 5

------BUREAU OF MINERAL RESOURCES, GEOLOGY AND GEOPHYSICS, AUSTRALIA __ ---::;1.:::,3 __

Table 2. Bottom-water anomalies and locations of hydrocarbon accumulations.

Survey line Anomaly (sp:lat;long) Accumulation (lat;long)

Carn 1 sp 74: 21.4605; 115.1540 21.4416; 115.0531

spI25:21.4775;115.0830

Carn2

Carn2

Carn2

sp 37: 21.3745;115.2100

sp 50: 21.3487;115.2063

sp 69: 21.3319; 115.2297

sp 84: 21.2733;115.2250

21.3444;115.2033

21.3036; 115.2258

sp 122: 21.1330;115.2605 21.1762;115.2674

sp 140: 21.0687;115.2365 21.1249;115.2747

Name

Saladin-l

S.Chervill

Chervil-l

N.Herald-l

S.Pepper-l

-----BUREAU OF MINERAL RESOURCES, GEOLOGY AND GEOPHYSICS, AUSTRALIA ___ 1;;\,.;;4~_

LIST OF ENCLOSURES

Enclosure 1: Floppy disk with ASCII files of geochemical data

Enclosure 2: Map showing DHD survey lines

------BUREAU OF MINERAL RESOURCES, GEOLOGY AND GEOPHYSICS, AUSTRALIA __ --=10.:;;,5 __

u68590

Text Box

Enclosure 1 data has been made available as a separate download file.

LIST OF FIGURES

Figure 1. Map of the survey area showing geochemical survey lines and arrows to

represent anomalies.

Figure 2. Map of the survey area showing geochemical survey lines and locations of

select wells on the North West Shelf.

Figure 3. THC versus survey line number.

Figure 4. Sum C1-C4 saturated hydrocarbons versus survey line number

Figure 5. Methane versus survey line number.

Figure 6. Ethane versus survey line number

Figure 7. Ethylene versus survey line number.

Figure 8. Propane versus survey line number.

Figure 9. Propylene versus survey line number.

Figure 10. Bernard parameter versus survey line number.

Figure 11. Methane/ethane versus survey line number.

Figure 12. Ethane/propane versus survey line number.

^BUREAU OF MINERAL RESOURCES, GEOLOGY AND GEOPHYSICS, AUSTRALIA^16

Figure 13. Fish altitude versus shot-point.

Figure 14. Percent hydrocarbon wetness versus survey line number.

Figure 15. Methane versus ethane, all survey lines.

Figure 16. Methane versus propane all survey lines.

Figure 17. Methane versus percent hydrocarbon wetness for all survey lines.

Figure 18. Methane versus percent hydrocarbon wetness for survey lines Cam-1, 2,3.

Figure 19. Methane versus percent hydrocarbon wetness for survey line Cam-2.

17BUREAU OF MINERAL RESOURCES, GEOLOGY AND GEOPHYSICS, AUSTRALIA

114° 115° 116° //

/ // /

// tOO /

// /1 / / .

,,;;/ _ ... NthRonk"",,- ~·.E'''t p.-

117°

• rlhlmln

h 4.~- - v/ • Angel , // <cO"" /. C .. ",k

/ /::: ~" P Goodwyft/ • Wanaea 1/% .... 'l ~s R nil / 111,1,1 ... 1 1/1 .... ,,,,, .>'<0' on / -" .lo,on'"

~T" v '''"/ ~""

/ ~/ / /;/ / ~~ / ,o .... GJ

\"-~ .//~.l,,,,, _. ~,:,::/// .. , .... "" '" / r // <:l'

~~ //

t"l / /

/ ' , / // /,/ I/'''

// // /.1 I" o,So ~ U .//,:' «:' c; /\QQ~/'./ /. ;- q," / /~/.: q,~

.' . ,q'

/ / / / / ./ /. // [ , / / // Chinook

~I :'

" -..""U

i / q~ 1/( # )/1 /~ '" ,!' / ~ 0 .,,1/ s ii' //(' ~o . I <J

~

o~ n C .. mpbtll

.H .. rril'

WESTERN

AUSTRALIA

-- Ships track

e

p

~

Oil field

Gas field

Location of geochemical anomaly

pit <:> '" oq

r:;::J"""Oampilf

20°

I?

I !

21J 50 km

1

",o,.,:1j 12/0"',116

Figure 1 - Cruise track of the calibration survey in the Barrow Sub-basin also

showing (arrows) the approximate location of anomalies.

~------BUREAU OF MINERAL RESOURCES, GEOLOGY AND GEOPHYSICS, AUSTRALIA -------

CRR~~RRVON BRS I N 225000M E 300000M E 375000M E ------,

-\.1ST YAL RCKS 3 ~f(E I I

'" "TRYRL RCKS I. 2

"TRYAL ROCKS I

?8 33 035

+ + ( ) <- 7725000M N "

I)

() ,.

/g) 0 P \ -!lAseo 4'

21 aa 2215 <.i

0 0 11 0 :; 0

I')

7G50000M N 7 -CHINOOK

+ fRIFFIN 1-3

<J

21 38 iJ8S

a C.

+ + + 7575000M N \"

2:3 20S 114 ~21 03E 114 30 flOE 115 fl0 fl0E 115 30 00E 116 0e1 eleIE

Figure 2 - Cruise track of the calibration survey in the Barrow Sub-basin.

------- BUREAU OF MINERAL RESOURCES, GEOLOGY AND GEOPHYSICS, AUSTRALIA -------

THC v. Line number

.inimo... ,Fp •

rage; • IP!• •

L I aterimitELTIP1.1111• • Fa • VI

^1 0.00^ IL■111■ 1 1Li ^•

1 • I.ÎI -îirPi6-1 117 it.rerwrini n„,.^m

N to INa W

I

cn 8.00 —^

.00., 0 •Uv^• ill mil:IP a

i Itn ,•

•• on ,. FR -^••P.^le4 il•^• •

1 pii! 7r747061

tjrr■F4gl• p

C^...1•71 - ..rowittipr dog, r

• ra_ L,

eO 1, nogrire-firArrougha,,,,,- roar err rt,r,peaTri ,îng,I ,PilIII11111rJO0 r 7-1^

ri. bwrisl.

Or I. p •asO Lel^

LFILVIrtillargrairll IN 1106

^

i.L. VErlim^Lelt.- 111115,

2 6.00 —^ .13›..I

ECLCL

4.00 —

2.00 —

^0.00 ^

ctsEC 0-) (v) 1.r) Lc)

as(1:3^0C 3^61 3^0(^0C^C'^0

▪^

16^L-6^S

12.00 —

Figure 3. 'THC versus survey line number.

6.0000

10.000

9.000

8.000

7.000

C12

5.000

4.000 J

^

3.000 ^

2.000

1.000

^

0.000 ^

4.

I^1^1^1ÎÎÎÎ^1111 1

friteritagoiX

EL II^F-4

Tiff milititilLPITIVS*Attirr I. AL liwom

ted•

C1-C4 v. Line number

(.4^ N-3^,R1-•^ LL--)^Lr>^1176_^6_C7^ C,

C.>^C.,^L.>^L.>^ 7->^C.>^ C.>^C.7^Cl^C.>^C>

Figure 4. Sum C1-C4 saturated hydrocarbons versus survey line number

?1J-rkirr Pir4 . e

Iss^rrorra4.11i

traurreAsrivaog■-

Tomirigarl rr.reirefedrargidfell

Methane v. Line number

9.00

8.00

7.00

6.00

-151 5.00CY0

2:7

K. 4.00

3.00

2.00

1.00

0.00 I 1^1Î^1IÎÎÎÎIÎÎCV^ tr,^LC)

•^

u-)^kr)- C7^C7^

•^

C7^7=7^C7C-7^ C-7^ C.7^C-7^C-7^ C-7^C-7^ C-7^C-7^4-7^C-7

Figure 5. Methane versus survey line number.

14% ukto

Ethane v. Line number

0.100

0.090

•

•0.080

•0.070

0.060

0.050

cm_0,- 0.040

0.020

0.010

0.030

I.IIIII • ill

i a • IIk • •'iim •

IN 1k

P INII 1 pi .• 1 MI

I I

• r ••bI

ill^k v •

• •^L 'IN•I^1ÎI

^

/Î N.îji goAir.Îffir^•

* bho^1 I Sink• 16^V P IN Oink^w IMP.

lh ji Ill•1Îr Ir.

^

IIIIIk•Ô PrllittloIP1m^

im IFOLI

•

YR PM^ !Visor sr a^PA

Wk.^ • igtornaim us Fri! PP pT l• WHOP •111111V1110^ Ilk1111160 i •Ib Toper mos h• P• • • 1011,11P1•11r. IP116 ■Ir••PIO^ •

Mill I. Pk. IIIIPPACI■ 44101112 WirallA irelealgiPitilAbit^• •^ rpp s,...Mk. PIIP-III•PAN VELIN INN Iila 11105•11. , • PO i

• k III Mkt^k IN^lalh^• IRO., 1 MP 1/11• RP • IP a. IIP . Cry!' rarnrIllonahlfflii...P• PPIPIOPIIIIINPICIP PIIIIr•P•tim MIMI. WIMP. , k Iiii■11.•••IIVIPIN PIP , •III4■■ 101r. PPIlirr•IiII116•111111111110111- Willis I•Îllk l•WIIIIIIIMIkallii • IPsfilikblIk. IN lila Inkk

^

OE^ •

0.000 I IÎÎÎÎÎÎÎÎÎÎÎÎCJ

C.> C-7

Figure 6. Ethane versus survey line number

Ethylene v. Line number

0.120

CNI CNA

C.)

_u") Lc)

1prr-ram• , ilrerno •fa, • a. • • a.^•^• ri iiihirirriffilPia 61411"rlit'&01-101.11 !• ki•

•IA 61 1;•••kit ,y •er 45.irdit Jr I I dim •IL^WitiiIN

.6 ill ilk^%nal^• • II^. ,Qr LA: •

NE •• •• r-• rr^*r,

0.1 00 -I Lei leP. PIrli • • Tim •

Tor 1 • ...Ir. •• 1.5.îi . . Ws * .'qra,, 1

,. ir • ii pigin•L NI. • era'qpip . .7.,.. • INleÎf p i11 •he 1 111.011060.080^'-riti r kii my- • • Lima -titre 1 Ims r di II Ir. II Ilk I • II

^

1^1 • 1111• iii Mill p^PI'rill I Iiiiril iril. II1. • _ Lii„.2 1„,...

^

'II.^ . ... •., • .1. it

• • rP

I.- rim& IlL iris. •ro 911.1111 — rilualm. •^W^"I" •Ir-^r r •Ns -r

*m-t.a.141. •^m,^• a be II •

• • •

Ng•1^—î411009,.trrotÔWirT^r 171% Ell O1^WO. I^r--.•o • 'Fool •^1•11111167grVP^-11-1. A^k—.

, I^• •1:11 • iv Term. „7„ MrilleafrafarrfillittO;^r

gg^•^ •0111-.4% • tirww,

0.040

0.020

0.000

Figure 7. Ethylene versus survey line number.

• Nall

11 1=

C-) C-3

Cs)

S_)

C`.1

C.)

N.)

I^11a

iii nil•

tv*,Il It *IN II^ •

^1 1 IÎ^1*âs Iv^7 •âtrara NIÎI •^111

• a

• AN NI IN um I • •• ai^• "Pt 7^:IF^•

Î (alit^• Pot• •1^tamp 111p• 7 .1 •Likibq iÎ Fault? i

•0 .1•11111 §^154:114NA Mil N 111 win

• at• •

ki.4111 •^• III•"%a intaTii: a • fsisilta)

f^ViiiirtoP#10• arum )^liarityCips

^

fp • j al^lif *rani

^

I Nap laôr ita•

Propane v. Line number

0.050

0.045

0.040

0.035

o: 0.030c.

..„,e 0.025

cm-cL 0.020

0.015

0.010

0.005

0.000

Figure 8. Propane versus survey line number.

Propylene v. Line number

0.060

•0.050

•0.040 •IR •mot

IA. 1 • II^WIPIE• II • Pa 10110 • inwit. limn • • li 0,11,10 Ails!

Omit^: Nam, com,..,,D•1 •NIB [ii ii ID, • 1 lions, • 1NE immorn,^• II U •^•• •IiIIiuNÎ 41

IN is^• • •

III^•IPÎ^1, • 0Î

• • II mi^*0• 1•11**N0 NA um

• i•ommunimmil OM

^

I^11.1 ill •^• 11 I!'!.l•om

n0 1 1 um!.

^

II•ÎI NIIIVi• I V411100*^1• 11 •îi III•11•^• I Mill III^• 1111••

•

•

• •

• •• PP

U .

^m I pm !Wm II ism^• • 1 I EL mom Illmml• • IAÎ^• ••

• l••1 11411ÎI

^P ^s6 ill

• 1 I fin • •• 1.• 1 iliT • j•

MI I^PPÎ I 1111•110.14••• IP HP* I PlIIPM A I • • • ll WillÎI I^. um Iil

^

IÎmtolt lumHIPP I^PI 11•11 2 I NM I i 1011 .. No PIIIPIINI I IM II AM • III NI IÎl• NI^11•11111111••fit• l•

1OPPI1

• ullslomm• I Imo. • ••••• INN mipm• tiV • OH mi...• piimmmusimim im Iwoî. a1PPIIIP •PPRIPI II PUMP 111 W It ll•I i 1 PI PIO 11011PRIP• WIMP PP •OI 1••••••• 1 Dm I anom 1 AI I il • • II • mil mom um • I mum 111111ÎV I fit r• •,1••• Ion^•DI 1 r• • km^1 l• I.^• I• •^m• Mt mom II Mg I • 01^• •

• • IÎ •^ EA.•• • •• •^•^ nii

COI0

0.030

eL

0.020

nol ip^•^•

•• Al^717 •

0.010

0.000

1 1^1

1^1^1

IÎÎÎÎÎÎÎÎ

CNJ C`L.1 C".1 N) 1.0 LC)L._

Figure 9.9. Propylene versus survey line number.

Bernard Parameter v. Line number

C-7

CVJ

C-7 C-7

CV! Cc"

C7

17,-)

C-,

LC) LC)

L-C7C-7

LC) LC) Lf)

250.000

200.000

150.000

ce.j

100.000

50.000

0.000

•1III 11 1411 '1111. 7:1 ,: win ION rig,0 11 4 4" •"1 frit„.^1 II

Ft!.^ra•1117 1 a^'rail •I. .iv 1:17011.111r. pripm ' 11 il ill WO Teal '

aki,11 s L Re . qj all -1 W-1 11-19

• I I aiii 0^

Ni71 t•2.... b ,I !Ill.,.

11 1I in ell^ is^-i.a

0 •w.1 Ili^*al ir i n,c.•î ll

Îl l °el^Ca V •

jairgton 616

^

Iî^1

111ît=^..-- b.um

^1 1^v irimII•i•

il tolilt^ II ?I itIra il^• ja i• trift. • iii 4,6plil.41.Paii,. 10î .

if•

Bil lal^• II allî 1 14:#^, iiti nfripoll 1, iii.z .iiiikilhr

isâ

• v7.4 r iratil îllilir nig) rail fill"fh:111.11. I" "" IÎ

▪

ÎN Ell11.11•IR ti* • In^%II 7 111011r IN • 114 "4^1. 1^•ISO 111

Cili "11II

illL. Iîl

Figure 10. Bernard parameter versus survey line number.

C1/C2 v. Line number

600.000

500.000

400.000

••

r^•âum ...^•el •eii-. I, . 01.1 ...to a!I ill Tr.

0.000 IÎÎÎÎÎÎÎÎÎÎÎÎÎÎ0.1^CN^CNI^C.1^ND^ND^ND^.4-^LED^LLD^LID^Lr)^Lc-)

c^c^c^c^c^=^c^c^=^=^c^c^c^c^c^cL_^ L_^L_^s__c,^ 6^ ‘.._^L._^,..c3^L._

c,^c.^c+^co^c.^C:.^ CZ,^C7^ 17^1:::7^C:,^,0^ 0

C-.)^C..)^C.J^C..)^C...)^L.?^C.2^C....)^C..>^V^C_,^C-.)^C..)^C..)_

Figure 11. Methane/ethane versus survey line number.

I IÎÎÎÎÎÎÎÎ

C21C3 v. Line number

4.500

4.000

3.500

3.000

2.500

L' 2.000

1.500

1.000

0.500

0.000

VU1Iii

•

• LiLo, N il •

^

Immo ill^• 1 i^1. •. SiÎnT .II elINî ii^11110 •

1

•I 1 likrisgir.

al frikt

IÎN 11^•^-■

e . •I •^'• IIîllN. !I 1

irîn

17•• IN

P

II^ri ■•

aIII

^

,..711::^•,:.;P r.".........11,:,;-;..,B;_!:..11:...19 orl

^

I •I Tritlifl 1^llimi^

..l^millîii

4111_11 III: iiiI • ilmeli [•^111 ril r

^

, ..^.^.....74,.,,,,,tr ,...,.,..- rip . .....•^,..^. • ••I-ION ^!Ns I i

• a L

li I MIMI masa• %Int • m111. i 1911 ill;

• 1 P: —• LI Is%1.• 1• •^...^•r•limml • I" LO a' 11 r Vitil•" Ail if gilj înii % 1 . 11 uric 1101 1 0.,,,_10 _ 1._

•• %kite i i • yoll, I ILL L irl a il ..li iiii ,,1114_ dill I^1111

Ha 41

rtii.I.,1 .1 ili,t7 1,...7.,ty,..,r.i. • tr. ,. Immo., .4 rause r i=_,•I 11. 1■ L i PA. nor • il• Isom or ,

• a^,I am IP^• li •^• ••

•

•I• •

• 10-1•Ler ?PrArri-WeaVirerili

C■I^

CNI^

1.0^

1,1")^

1-C)^ kr)

t-,^

1->^

C-)^

C_7

Figure 12. Ethane/propane versus survey line number.

.-1

2cc

•

r•1

CC

LI

• ••

••o^•

•(J •••••

414WM•

44'

•••000^•

•••• • •

••••

•

1.1)

•cr

•

••

•• 1106 • NI

• • •0• a.• 0100^•

••^•^111•1111111•11111111 6 •• 0• 0^•^• • • .1^• • •

01041 • 4100 *Ma/ • 10 NM 101 • •• 00111• •0• 1111 • • • 4064 • •

•110^• • • •4^• •

•• •6• • •••• •10 4

60

50

40

30

20

10

• Fish Altitude

^ Carnarvon Basin - Fish Altitude Vs Shot Point

0^100^200^300^400^500^600^700^800

Shot Points

Figure 13. Fisrtude versus shot-point.

* ;;:0

\Q

N

0 .f:'

VI

0 VI

*

rn en tP

3.00

2.50

2.00

~ 1.50 ~

1.00

0.50

0.00 ~ '" E E E t:: .....

<::> 0 <:> 0 <..> '-' u U

% Wetness v. Line number

'" '" '" l"0 I"") I"") --r L(") L(") L(") L(") L(")

E E c: E E c:: c: E E E E c: '-- 0 ..... .....

<::> <::> <::> 0 <:> 0 0 0 0 <::> <:> u u U t.:> '-' U U U U c..> u u

Figure 14. Percent hydrocarbon wetness versus survey line number.

0.100

0.090

0.080

0.070

0.060 Q)

<= c ~ w 0.050 E c.. c..

0.040

0.030

0.020

0.010

0.000

0.00 1.00 2.00 3.00

Methane v. Ethane

•• •• • • • Ii

•• •••• • iii

• •

• •••

•

•• - •• .1.

• .-!IIiI." ••• ., •• • .. ,. . . .

• • I ••• • • 1.1 :. II. • •• ...... Ii •••

4.00 5.00

ppm Methane

• ••

•

•

• • •

•

• •• • .. ...

•

6.00

Figure 15. Methane versus ethane, all survey lines.

• •

• • •

•

• •

7.00

•

• •

•

8.00

•

•

• •

9.00

0.050

0.045

0.040

0.035

0.030 Q.) <= 10 c... 0

c:t 0.025 E c... c...

0.020

0.015

0.010

0.005

0.000

0.00 1.00 2.00

Methane v. Propane

• • • • .1 . . .

• •• •••••• ••• ••••

• •• • • • .1... •

• •

•

• •••• • ••

•

••• ••• •• • • ••• •••• ••• •••• ••• • •• •• 1 •••• 1 ••••• 1.. ••• •• • • . 1.... • .. ... . •.• .. . .. 1.... . .. 1 ... ... . 1 ...... 11.. I........ . .. .... . ... 11 ••• 11... .••. I... •. •••• 11 •• 1. •••• • •••••••• .1 ..... 1.. ... I. I.. . . .. .1........ • ..... ... . .. IIII1 .. Ja •• 1.11....... .. .1

11 •• 1 •• 1.1 ••• U •• II.. . .. ••• 11.... • •••• 1 •• 1. • • ••• • •• • 1111 •••• II... • • • . • II.. . .

• • ••

• •••• • • •

• • •

•

•

•

3.00 4.00 5.00 6.00

ppm Methane

• •

• • • •

• • • •• .1

Figure 16. Methane versus propane all survey lines.

• • • • •

• • • • •

• • • • • •

7.00 8.00 9.00

Methane v. % Wetness

3.00

• Carn-5 •

2.50 D Carn-4 • • o .. • Carn-3 •

•• ·ti· 2.00

0 Carn-2 ••• o

•• '" Carn-l • ••

on on Cl) .::

1.50 ...... Cl)

:;:: ~

••• -. 0

0 0 0

0 00

0 0 0

0 0 1.00 0 0 0

0 0 0 0 0

0.50

0.00 .. 0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00

ppm Methane

Figure 17. Methane versus percent hydrocarbon wetness for all survey lines.

'" '" Q.) .:: ....... Q.)

:s: ~

3.00

2.50

2.00

1.50

1.00

0.50

0.00

0.00

• Carn-3

0 Carn-2

• Carn-l

1.00

Methane v. % Wetness

o

o

0

0

0 0 DO

0 0

0 0 0

0 0 0 0 0

2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00

ppm Methane

Figure 18. Methane versus percent hydrocarbon wetness for survey lines Carn-I, 2,3.

3.000

0.000

0.000 1.000

Methane v. % Wetness: Line Carn-2

2.000 3.000 4.000 5.000 6.000 7.000 8.000 9.000

ppm Methane

Figure 19. Methane versus percent hydrocarbon wetness for survey line Cam-2.

APPENDIX I

Individual line plots and line summary sheets,

Carnarvon survey lines 1 through 5.


Line Summary

Line Number carn1 No. of Shotpoints 139

Shotpoint Date 1 29-Jul-89

Time 16:23:34 Start

End 139 29-Jul-89 20:59:29

THC Methane Ethane Mean 9.316 4.299 0.024 Std. Dev. 0.753 0.702 0.014 Minimum 7.504 3.514 0.011 Maximum 10.452 5.678 0.065

Condo Temp. F. Depth Mean 23.265 Std. Dev. 0.430 Minimum 22.540 Maximum 23.810

Notes Methane and ethane anomaly towards end of line No conductivity data were collected

10.000 0.000

10.000 10.000

Latitude 21 21

Ethylene 0.083 0.007 0.067 0.101

W.Depth 20.763

1.107 18.000 27.000

Longitude 33.061 114 26.760 115

Propane Propylene 0.016 0.034 0.003 0.003 0.010 0.022 0.026 0.043

Altitude 10.763 1.107 8.000

17.000

59.853 05.159

i-Butane 0.000 0.000 0.000 0.000

n-Butane 0.000 0.000 0.000 0.001

i-Pentane n-Pentane i-Hexane n-Hexane %Wetness 0.895 0.227 0.582 1.594

p p m

12.00

10.00

H 8.00

Y d r

6.00 o c a r b 4.00

o n s

2.00

0.00

Line CARN1 THC, Methane

• ................... -\ •• • iii ••

................................................................ Ii Ii •

\ .... ~ II: •••• ·rr •• II! .Ii ........... 111 • ••• ...... .-

-..,/ Ii .Ii ~ JIll .II! • • •• ~ ..... 1. ••• ....... ~/

•

---THe

--0-- Methane

o 20 40 60 80 100 120 140

Shotpoint

Line CARN1 Methane, Ethane, Ethylene

10.00

•••••••••••••••••••••••••••••••••••••••••••• • •• Ii ••• I! ••••••••• I! ••• ........... ~ ............................................................ ..

p P 1.00 m

H y d -II-- Methane

r 0

0.10 ---0- Ethane

c a

--+-- Ethylene

r b 0 n 0.01

s

0.00

o 20 40 60 80 100 120 140

Shotpoint

Line CARN1 Methane, Propane, Propylene

10.00

.~ •••••••••••• r .............. ~ •••••••••• w. •• ~ ...... Il - .r ......... 1l •••

•••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••

p P 1.00 m

H y d -.- Methane

r 0

0.10 -0-- Propane

c a r b

....................... .c.\~ ••• t~ ••••••••• / ........... ~.~'" •• ~ ... ~.~..... .~ .... -.: ........................ , f>~+ ...... \/ ........... , ••••• ,., .. ;t> •••• ., ... T. ," "-':T ••• T.~~ \! .. .~. . .'., ~

--.-- Propylene

0

n 0.01

s

0.00

o 20 40 60 80 100 120 140

Shotpoint

Line CARN1 Depths, Altitude

Shotpoint

0 20 40 60 80 100 120 140

0.0

10.0 -, ' -"',,'" ---,

20.0

30.0

40.0

M 50.0 e --- F. Depth

t 60.0 r

- - - W. Depth

e 70.0 s

- - - - - Altitude

80.0

90.0

100.0

110.0

120.0

Line Summary


Start End

Mean Std. Dev. Minimum Maximum


Notes

Shotpoint Date Time 1 29-Jul-89 21 :11 :06

182 30-Jul-89 03:19:22

THC Methane Ethane 8.508 4.748 0.032 1.202 1.265 0.016 7.072 3.417 0.013

11.914 8.792 0.100

Condo Temp. F. Depth 22.442 6.637 0.470 8.483

21.890 0.000 23.560 30.000

Latitude 21 20

Ethylene 0.074 0.007 0.059 0.091

W.Depth 19.493 10.138 4.000

65.800

Longitude 26.289 115 57.253 115


Altitude 12.855 2.612 1.000

35.800

04.642 10.Q15

i-Butane 0.000 0.000 0.000 0.000

n-Butane i-Pentane n-Pentane 0.000 0.000 0.000 0.000

THe, methane, ethane and slight propane anomalies at SP 20 to 80, corresponding with South Chervil and Chervil fields Weak anomaly at SP129 near North Herald and South Pepper accumulations

i-Hexane n-Hexane %Wetness 1.200 0.364 0.490 2.425

p p m

H Y d r o c a r

12.00

10.00

8.00

6.00

b 4.00

o n s

2.00

0.00

o 20 40 60

line CARN2 THC, Methane

80 100

Shotpoint

120

---THe

--D-- Methane

140 160 180 200

10.00

P P 1.00 m

H Y d r 0

0.10

c a r b 0

n 0.01

s

0.00

o 20 40


60 80 100

Shotpoint

120 140

-.- Methane

-0-- Ethane

--+-- Ethylene

160 180 200

10.00

p

P 1.00 m

H Y d r

0.10 0

c a r b 0

n 0.01

s

0.00

o 20 40


60 80 100

Shotpoint

120 140 160

--.-- Methane

-0-- Propane

--+-- Propylene

180 200

o 0.0

10.0

20.0

30.0

40.0

M 50.0 e t

60.0 r e

70.0 s

80.0

90.0

100.0

110.0

120.0


Shotpoint

20 40 60 80 100 120 140 160 180 200

F. Depth

- - - W. Depth

- - - - - Altitude

Line Summary


Shotpoint Date Start End



Notes No hydrocarbon anomalies No conductivity data

1 30-Jul-89 140 30-Jul-89

THC Methane 6.769 3.107 0.202 0.119 5.981 2.889 7.484 3.542

Condo Temp. 23.304

0.171 22.970 23.610

No water depth of fish altitude data after SP58

Time 03:23:42 08:03:37

Ethane 0.013 0.002 0.010 0.019

F. Depth 14.000 0.000

14.000 14.000

Latitude 20 21

Ethylene 0.064 0.004 0.050 0.072

W.Depth 39.930

8.229 34.000 64.000

Longitude 57.308 115 02.625 114

Propane Propylene 0.017 0.024 0.004 0.003 0.012 0.Q18 0.027 0.037

Altitude 25.930 8.229

20.000 50.000

09.784 41.535

i-Butane 0.000 0.000 0.000 0.004

n-Butane 0.000 0.001 0.000 0.006


Line CARN3 THC, Methane

12.00

10.00 P P m

8.00 H Y d r

6.00 0

• • 11 .... ., iii ...... • ............... . • • I: •• ..1' ............................. .,.. ................................................... _ ......... 1' ......................... rI'\/ Ii... -. lia.

• -·-THe

---0- Methane c a r b 4.00

0

n s

2.00

0.00

o 20 40 60 80 100 120 140

Shotpoint


10.00

p P 1.00 m

H y d -.- Methane

r 0.10 0

c ........ "'4;.'.t; • ., ............... ~.-..; ........ '* ............................ 4fi············'t'+·~·ifi··· ... ··.·"'tft ... ·..,.·'.;···-.,;·-.;·4i· ... ·~· .. • •• *\t':t;.·':,;···'.,;········· ... ·..,:· .. • .. • .. ••• + •

-0--- Ethane

--+-- Ethylene a r b 0

n 0.01

s

0.00

o 20 40 60 80 100 120 140

Shotpoint


10.00

p P 1.00 m

H y

-.- Methane d r 0

0.10 -0- Propane

c --+-- Propylene a r b 0 n 0.01

s

0.00

o 20 40 60 80 100 120 140

Shotpoint

10.0

20.0

30.0

40.0

M 50.0 e t

60.0 r e s 70.0

80.0

90.0

100.0

110.0

120.0

o 20 40

, , ---' ..


Shotpoint

60 80 100 120 140

--- F.Depth

- - - W. Depth

- - - - - Altitude

Line Summary


Shotpoint Date Time Start End



Notes No hydrocarbon anomalies No conductivity data

1 30-Jul-89 08:05:36 67 30-Jul-89 10:17:39

THe Methane Ethane 6.614 3.179 0.013 0.120 0.122 0.002 6.361 2.990 0.010 6.856 3.624 0.016


23.560 130.000 24.310 130.000

Latitude 21 21

Ethylene 0.067 0.003 0.061 0.073

W.Depth 157.955

8.925 140.000 168.000

Longitude 02.607 114 12.510 114


Altitude 27.955 8.925

10.000 38.000

41.135 38.052

i-Butane 0.000 0.000 0.000 0.003

n-Butane 0.000 0.000 0.000 0.001


Line CARN4 THe, Methane

12.00

10.00 P P m

H 8.00

Y d r

6.00 0

Ik - _ _ _ _ _ _._ •.• -.-.-. ... · ·-.'.'.-.-.'·'.r.-.-_-____ . __ -~",-.-_'-'._Ik _____ --'.'--- ----.'----.--'-_.'.-.'-'.r.---.--'.'---'.-.'--. - - - -·-THe

-----0- Methane c a r b 4.00

0

n s

2.00

0.00

o 10 20 30 40 50 60 70

Shotpoint


10.00

~._.-._._.r.-.-._._~.-.-~._~.-.-.-.-.---.-~._._._._._._._._._._._._._._._._._.-.-.-.-.-~.-.-.-.-~.-~._~._.-.-~.-~.-.-.-.-.

P P 1.00 m

H y d -.- Methane

r 0

0.10 -D--- Ethane

c a

--.-- Ethylene

r b 0

n 0.01

s

0.00

o 10 20 30 40 50 60 70

Shotpoint


10.00

~~~~.-.-~.-.-.-.-.-.-~~.-.-.-.-.-.-.-.-.-~.-.-.-.-.-.-.-.-.-.-.-~.-.-~.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-~.-.-.-.-.-.-.-~.-.-.

p P 1.00 m

H y --.-- Methane d r 0

0.10 -0--- Propane

c --+-- Propylene a r b 0

n 0.01

5

0.00

o 10 20 30 40 50 60 70

Shotpoint


Shotpoint

o 10 20 30 40 50 60 70

o +1--------~--------~--------~--------~--------4_--------4_--------~

20 I ._ . . .... 401 ........... ······························

- - - - - - - I ,- I'

. , . ,

60

M e 80 ---- F. Depth

t r - - - W. Depth

e 100 - - - - - Altitude s

120

140 r-/-----'"

\ / 160 J

180

Line Summary


Start End



Notes

Shotpoint Date Time 1 30-Jul-89 18:50:57

238 31-Jul-89 02 :44:47

THC Methane Ethane 6.855 3.204 0.009 0.372 0.253 0.001 6.294 2.954 0.006 7.782 3.916 0.014


23.780 50.000 24.830 70.000

Latitude 20 20

Ethylene 0.061 0.004 0.051 0.069

W.Depth 75.752 17.317 61.000

119.000

Longitude 36.732 114 09.914 115


Altitude 18.082 9.827

10.000 49.000

I-butane anomaly SPs 39-90, in the vicinity of Central Gorgon and North Gorgon No conductivity data No water depth and altitude data between SP6 and SP 170

50.379 23.726

i-Butane 0.005 0.012 0.000 0.051

n-Butane 0.000 0.000 0.000 0.002


Line CARNS THC, Methane

12.00

10.00 P P m

H 8.00

Y d r 6.00

---THe

0 -0--- Methane

c a r b 4.00

0

n 5

2.00

0.00

o 50 100 150 200 250

Shotpoint

Line CARNS Methane, Ethane, Ethylene

P P 1.00 m

H y d -.- Methane

r 0

0.10 -0-- Ethane

c a

--.-- Ethylene

r b 0

n 0.01

s

0.00

o 50 100 150 200 250 Shotpoint

Line CARNS Methane, Propane, Propylene

p P 1.00 m

H y d --.-- Methane

r 0

0.10 -0-- Propane

c a

--+-- Propylene

r b 0

n 0.01

s

0.00

o 50 100 150 200 250

Shotpoint

0 50

0.0

10.0

20.0

30.0

40.0

M 50.0 e t

60.0 r e

70.0 s

80.0

90.0

100.0

110.0

120.0

Line CARNS Depths, Altitude

Shotpoint

100 150

, ,

"

, I , .. 1\

.J..J"', ,

200

~v~ ('V

/ I J

I

250

--- F. Depth

- - - W. Depth

- - - - - Altitude

APPENDIX II

DHD METHODOLOGY

Direct hydrocarbon detection in bottom-water (DHD) is accomplished with the

equipment schematically shown in Figure II-I. The equipment comprises four major

components.

(1) The over-the-side gear includes a towed 'fish' fitted with a submersible pump which

delivers seawater to the geochemical laboratory on the ship via a hollow cable. A

conductivity/temperature/depth sensor (CTD) in the 'fish' measures the depth of the

'fish' as well as the temperature and salinity of the seawater (to relate the depth of

sampling to the depth of the thermocline, to detect hydrographic 'fronts', and to detect

sub-seafloor freshwater aquifers that may drain through sedimentary layers from the

continent). A sonar measures and continuously displays the altitude of the 'fish' above

the seafloor allowing the operator to maintain the 'fish' at an altitude of about 10 m.

(2) A hollow cable (consisting of medical grade nylon tubing wrapped with insulated

conductors which both transmit power to the fish and relay CTD and sonar data from

the 'fish') delivers bottom-water to the geochemical laboratory. The tubing and

conductors are wrapped in a stainless steel braid. Plastic fairings, which are attached to

the cable to reduce frictional drag, allow the 'fish' to be towed almost directly beneath

the ship.

(3) The analytical equipment includes a gas extraction unit and gas chromatographs

connected in parallel to measure the concentrations of a variety of (C l-CS)

hydrocarbons extracted from the seawater. The total hydrocarbon concentrations are

measured every 30 seconds or at a ship speed of 5 knots, a distance of about 75 m on


the seafloor. The light hydrocarbons (C l-C4) are measured at 2 minute intervals

(approximately 300 m on the seafloor), whereas the CS-Cg hydrocarbons are measured

every g minutes (approximately 1200 m). Sub-samples of extracted gas may be taken

and stored for subsequent shore-based isotopic analyses.

(4) The data acquisition system is PC based: all data is displayed, edited and stored in a

database for plotting at sea.

The towed 'fish' is deployed over the stern from the M.V. Mermaid Searcher. Echo

sounder data and GPS navigation are displayed in the laboratory and these provide

clues to the locations of surface expressions of gas seeps on the seafloor. All data are

recorded continuously so that any hydrocarbon anomalies in the water column can be

quickly recognised and additional measurements (or samples can be collected) if

appropriate.

Detector sensitivity is < 10 parts per billion in the stripped heads pace sample.

Calibrations were conducted on a daily basis and were within 10% for the entire

program and system blanks were less than 2 ppm for methane and 5 ppb for C2+

compounds.


The following parameters are measured:

Parameter Units

Total Hydrocarbon (THC) ppm

Methane

Ethane

Ethylene

Propane

Propylene

i-Butane

n-Butane

i-Pentane

n-Pentane

i-Hexane

n-Hexane

Water Depth

Fish Altitude

Conductivity

Water Temperature

Fish Depth

ppm

ppm

ppm

ppm

ppm

ppm

ppm

ppm

ppm

ppm

ppm

Metres

metres

mmhos/cm

°Celsius

d-bar

Equipment Used

Shimadzu GC with Fill

Detector using 6" Glass

bead column

Shimadzu GC with FID

Detector using 42"

Activated alumina column

" " " "

"

" Shimadzu GC with FID

Detector using 30

Megabore DB! column

" Shimadzu GC with FID

Detector using 30

Megabore DB! column

"

On-board Echo sounders

Water Depth minus Fish

Depth

Conductivity Meter

Temperature thermistor

Pressure transducer


Seawater

i Dissolved Co gases .~ ... (J)

Drain

Concentration

L Position

Shurebased

High resolution seismic, side scan sonar, 3 and 12 KHz

23/J55/48

Figure II -1. Schematic of the geochemical equipment aboard Rig Seismic for the

continuous profiling of hydrocarbons in seawater: the bottom-water DHD technique.

-------BUREAU OF MINERAL RESOURCES, GEOLOGY AND GEOPHYSICS, AUSTRALIA -------

APPENDIX III

INTERPRETATIVE METHODOLOGY

The DHD equipment installed on Rig Seismic can be used for measuring hydrographic,

environmental or petroliferous parameters. The light hydrocarbon data (C 1 to C6)

contained in this report can be produced by a variety of sources. These sources

include biological activity associated with the degradation of organic matter in

seawater and near-surface sediments and reservoired petroleum products (oil, gas and

condensate). The aim of the data interpretation is to determine the origin (biogenic or

thermogenic) of the light hydrocarbon gases measured, and via a variety of cross-plots

of molecular and isotopic compositions of gases, to infer the 'source' (dry gas, gas

condensate or liquids) of detected seepage.

Light Hydrocarbons In Seawater

Light (C1-C4) and intermediate (C5-C8) hydrocarbons are present in seawater and

sediments principally as a result of the following three processes.

(l)Thermogenic processes. The effect of heat on organic matter (catagenesis and

metagenesis) buried to depths of several kilometres in sedimentary basins produces

thermogenic hydrocarbons (Hunt 1979; Tissot and Welte 1984). The products of

these reactions include methane and the saturated (C2-C8) hydrocarbons, which are

the hydrocarbons mostly analysed in surface geochemical techniques. Some of the

thermogenic hydrocarbons migrate to the surface, either directly from source rocks

(primary migration) or indirectly, from gas, gas-condensate or liquid reservoirs

(secondary migration). Hydrocarbons may migrate kilometres to permeate the near-


surface sediments and seep into the overlying bottom-water resulting in thermogenic

anomalies.

(2)Biological processes. Hydrocarbons are produced microbially and photochemically

in seawater. In addition, during early diagenesis, a variety of hydrocarbons are

produced by the activities of microbial organisms during aerobic and anaerobic

destruction of organic matter which occurs primarily in the top few tens of metres of

sediments. The products of these reactions include methane and minor quantities of

both saturated and unsaturated hydrocarbons (Hunt 1979; Claypool & Kvenvolden

1983 and references cited therein). The presence of the unsaturated hydrocarbons,

which are only produced biochemically (Primrose & Dilworth 1976; Claypool &

Kvenvolden 1983), provides one criteria to distinguish between biogenic and

thermogenic hydrocarbons.

These compounds produced in-situ generally occur in low concentrations as

background hydrocarbons in seawater (Claypool & Kvenvolden 1983). However, high

concentrations of biogenically-produced hydrocarbons may accumulate in relatively

shallow-buried sediments and seep into the overlying water, resulting in biogenic

anomalies (Brooks et al. 1974; Bernard et at. 1976).

(3)Anthropogenic processes. Man's activities can introduce anthropogenically-sourced

hydrocarbons into the marine environment. Anthropogenic hydrocarbons may be of a

thermogenic origin (e.g., ship spills, refined petroleum products used in industrial

processes) or a biogenic origin (such as those produced from urban sewage when

excessive loads of organic matter are dumped into the sea and degraded microbially).

The concentrations of in situ biogenic (i.e., background) light hydrocarbons in

seawater are generally an order of magnitude lower than those in the underlying

seafloor sediments (Claypool & Kvenvolden 1983). Consequently, it is relatively


easier to detect migrated thermogenic hydrocarbons in seawater (low background

concentration) than in seafloor sediments (high and variable background

concentrations). Herein, lies one perceived advantage in the use of bottom-water DHD

compared with sediment geochemistry in offshore petroleum exploration.

The bottom-water DHD technique is dependent upon hydrocarbons migrating from

hydrocarbon reservoirs or petroleum source rocks to the seafloor. Although the exact

mechanism(s) of migration may be variable or even unknown, some form of vertical

migration, as evidenced by the many observations of seepage (e.g., Brooks et aI. 1974;

Bernard et aI. 1976; Reed & Kaplan 1977; Cline & Holmes 1977; Nelson et aI. 1978;

Reitsma et aI. 1978; Brooks et aI. 1979; Kvenvolden et aI. 1979; Kvenvolden & Field

1981; Hovland & Judd 1988) does occur (via porous sediments, fault planes and

microfissures etc). It is generally accepted that migration by diffusion is not important

(Leythaeuser etal., 1982; Reitsma et aI. 1981; Whelan et aI. 1984) although bubble

ebullition from saturated solution, oil and gas transport in solution in carbon dioxide

and advective processes involving basinal fluids are all likely mechanisms (e.g.,

Kvenvolden & Claypool 1980; Hunt 1984; Sweeney 1988; Hovland & Judd 1988).

Data interpretation: the mixing model

The detection of seepage requires that anomalous concentrations of hydrocarbons be

distinguished from the background inventory of hydrocarbons. Thermogenic

hydrocarbons that seep into the bottom-waters mix with the background concentration

of hydrocarbons. One approach to defining anomalies and distinguishing seep

hydrocarbons from background hydrocarbons requires that a mean background

concentration be defmed (either statistically or graphically), and this mean

concentration is then subtracted from the measured concentrations. Because of

variability in the background concentrations, this approach may be problematic,

particularly where seepage is weak and the anomalies are very subtle.


Our initial approach is to review the data on a line-by-line basis and compare measured

concentrations with the regional background. Then, a variety of hydrocarbon cross

plots are constructed, particularly where methane is plotted versus percent

hydrocarbon wetness (wetness % = [SUM(C2-C4)/SUM(Cl-C4)] xlOO) to delineate

seepage. The rationale behind this plot (Figure III -1) is that different hydrocarbon

'sources' e.g., biogenic versus thermogenic gas, condensate and liquids, can be

distinguished on the basis of differences in their light hydrocarbon molecular

compositions (Hunt 1979; Tissot & Welte 1984; Claypool & Kvenvolden 1983). In

this model background hydrocarbons plot in a narrow range towards the left origin

(low concentrations), while end-member 'source' hydrocarbons i.e., hydrocarbons from

either oil-prone, condensate-prone or gas-prone source rocks or reservoirs, plot to the

right (high concentrations).

As the hydrocarbons in bottom-waters represent mixtures of the end-member

background (low) and 'source' (high) concentrations, the trends between the end

members in these plots are indicative of the 'source' of the hydrocarbons comprising the

anomalies. For example, when the % hydrocarbon wetness increases with increasing

methane concentration, the trend indicates that the anomaly was probably derived from

a gas-condensate or oil-prone 'source'. In contrast, increasing methane concentrations,

coupled with decreasing % hydrocarbon wetness, suggest that the anomaly was

derived from a gas-prone thermogenic 'source' or is of a biogenic origin. This model

cannot distinguish between biogenic and gas-prone thermogenic anomalies. Carbon

isotope (e.g., Fuex 1977; Bernard et al. 1977) and molecular compositional data are

required to discriminate between biogenic gas and 'dry' thermogenic anomalies.


Classification of anomalies.

'Strong' (arbitrarily defmed here as when some of the measured CI-C4 concentrations

increase more than an order of magnitude above the background concentration) and

'moderate' thermogenic anomalies (some CI-C4 increase 5-10 fold above background)

are obvious and are accompanied by large increases in individual C I-C4 hydrocarbons

with no increase in the biogenic components (ethylene and propylene). Weak'

anomalies (individual CI-C4 is less than five-fold the background concentration) are

more difficult to discern. In some cases, what appear to be weak anomalies may result

from variations in the depth of the fish above the seafloor, a shoaling of the water

depth, penetration of the fish above the local thermocline or combinations of these

factors. In these cases, plotting the saturated hydrocarbon (methane, ethane, propane)

concentrations against the 'fish' depth, seawater temperature and salinity, or against the

biogenic hydrocarbons (ethylene, propylene), generally resolves apparent anomalies

from those anomalies related to seepage.

A cross plot of two compounds (e.g., ethane vs. methane) indicates whether the

compounds are being added to the natural hydrocarbons in an area. Positive trends on

plots of one compound versus another indicate that both compounds are being added

concurrently and thus, the source of the anomaly contains both compounds. Because a

mixing trend is created by one hydrocarbon source supplying hydrocarbons to the

background, all data on the same trend reflect the same source regardless of the

absolute concentrations or absolute ratios. For example, an anomaly with ethane at 0.1

ppm would reflect the same hydrocarbon source as a second anomaly with ethane

values at 1.0 ppm if the data from the two anomalies lie on the same mixing trend.

Similarly, an anomaly with a wetness of 2% (oil-like) may actually represent a dry gas

source if it falls on a mixing trend that has low wetness values at higher concentrations.


+

'" () I LOW --+-

OIL-SOURCED HYDROCARBONS

WET GAS AND CONDENSATE

DRY' IHERMOGENI OR BIOGENIC GAS

HIGH

Methane concentration 12/0A/17

Figure III-I. Cross-plot of methane versus hydrocarbon wetness, showing the general

decrease in wetness with increasing methane for gas-prone or biogenic sources.

Conversely, oil-prone sources are indicated by increasing wetness with increasing

wetness with increasing methane. Gas-condensate sources fall between the dry gas and

oil-prone trends.

------~BUREAU OF MINERAL RESOURCES, GEOLOGY AND GEOPHYSICS, AUSTRALIA -------

APPENDIX III REFERENCES

Bernard, B.B., Brooks, J.M. & Sackett, W.M. (1976), Natural gas seepage in the Gulf

of Mexico, Earth and Planetary Science Letters 31, 48-54.

Bernard, B.B., Brooks, J.M. & Sackett, W.M. (1977), A geochemical model for

characterization of hydrocarbon gas sources in marine sediments. In: 9 th Offshore

Technology Conference, Houston, Texas, OTC 2934, 435-438.

Brooks, J.M. Gormly, J.R. & Sackett, W.M. (1974), Molecular and isotopic

composition of two seep gases from the Gulf of Mexico. Geophysical Research Letters

1,213-216.

Brooks, J.M., Bernard, B.B. Sackett, W.M. & Schwarz, J.R. (1979), Natural gas

seepage on the south Texas shelf. In: 11th Offshore Technology Conference Houston

Texas, OTC 3411, 471-474.

Claypool G.E. & Kvenvolden, K. A. (1983), Methane and other hydrocarbon gases in

marine sediment. Annual Review of Earth and Planetary Science 11,299-327.

Cline, J.D. & Holmes, M.L. (1977), Submarine seepage of natural gas in Norton

Sound, Alaska. Science 198, 1149-1153.

Fuex, A.N. (1977), The use of stable carbon isotopes in hydrocarbon exploration.

Journal of Geochemical Exploration 7,155-188.

Hovland, M. & Judd, A.G. (1988), Seabed Pockmarks and Seepages Impact on

Geology, Biology and the Marine Environment. Graham and Trotman, Ltd. London.,

293pp.


Hunt, J.M. (1979), Petroleum Geochemistry and Geology, Freeman & Co, San

Francisco., 617pp.

Hunt, J.M. (1984), Generation and migration of light hydrocarbons Science 226,

1256-1270.

Kvenvolden K.A., Vogel, T.M. & Gardner, J.V. (1979), Geochemical prospecting for

hydrocarbons in the outer continental shelf, southern Bering Sea. Journal of

Geochemical Exploration 14,209-219.

Kvenvolden K.A. & Claypool, G. E. (1980), Origin of gasoline-range hydrocarbons

and their migration by solution in carbon dioxide in Norton Sound, Alaska. American

Association of Petroleum Geologists Bulletin, 64, 1078-1086.

Kvenvolden, K.A. & Field, M.A. (1981), Thermogenic hydrocarbons in

unconsolidated sediment of Eel River Basin, offshore northern California. American

Association of Petroleum Geologists Bulletin, 65, 1642-1646.

Leythaeuser, D., Schaefer, R.G. & Yukler, A. (1982), Role of diffusion in primary

migration of hydrocarbons. American Association of Petroleum Geologists Bulletin

66,408-429.

Nelson, H. Kvenvolden, K.A. & Clukey, C. (1978), Thermogenic gases in near-surface

sediments of Norton Sound, Alaska. 10th Offshore Technology Conference, Houston,

Texas, OTC 3354, 2623-2333.

Primrose, S.B., & Dilworth, M. J. (1976), Ethylene production by bacteria. Journal of

General Microbiology 93,177-181.


Reed, W.E. & Kaplan, I.R (1977), The chemistry of marine petroleum seeps. Journal

of Geochemical Exploration 7, 255-293.

Reitsma, RH., Lindberg, F.A. & Kaltenback, AJ. (1978), Light hydrocarbons in Gulf

of Mexico water: sources and relation to structural highs. Journal of Geochemical

Expwration 10, 139-151.

Reitsma, RH., Kaltenback, A.J. & Lindberg, F.A. (1981), Source and migration of

light hydrocarbons indicated by carbon isotopic ratios. American Association of

Petroleum Geologists Bulletin 65, 1536-1542.

Sweeney, R E. (1988), Petroleum-related hydrocarbon seepage in a recent North Sea

sediment. Chemical Geology 71,53-64.

Tissot, B.P. & Welte, D.H. (1984), Petroleum Formation and Occurrence. Springer

Verlag, New York., 697pp.

Whelan, 1K., Hunt, 1M., Jasper, J. & Huc, A. (1984), Migration of CI-C8

hydrocarbons in marine sediments. Organic Geochemistry 6,683-694.


APPENDIX IV

SYSTEM OPERATIONS REPORT

Relatively few problems were encountered with the geochemical laboratory acquisition

system during the survey. Water depth data was determined with a portable over-the

side echo sounder. The intermittently faulty digital altimeter meant that ftsh altitude

was calculated from water depth and ftsh depth for much of the survey. Problems with

the tow cable and winch on survey line Carn 4 and Carn 5 resulted in the tow ftsh not

being able to be towed close to the seafloor.

DHD

Conductivity data is not included in the line summary sheets for this report, however,

salinity data is included in the ASCII files in Enclosure 1.

NON GEOCHEMICAL SYSTEMS

Navigation was provided by a combination of Global Positioning Satellite (GPS) and

transit satellite navigation by Racal Survey Ltd (Perth W A). Accuracy of recorded

positions are +/- 20 metres when GPS was operational and +/- 100 metres when transit

satellite was on-line.


Enclosure 1

Floppy disk with ASCII fIle of geochemical data.


u68590

Text Box

Enclosure 1 data has been made available as a separate download file.

Enclosure 2

Map showing DHD survey lines


CRRNRRVON BRSIN 225~H?J0M E

20 00 00S

20 3121 I2II21S

+

21 00 01215

+

21 30 I2II21S

~o ...

o I (0

6'

~/

/ -CHINOOK

tRIFFIN 1-3 (,j

(?

~~

<i'

... It.

+ ~ ..

22 00 ~101 00 1210E 114 3121 00E

I;HII:'II:'II:'II:'II:'I ~ ~ ~ W M ~ L.. ---J I I I I

KILOMETRES

" 11:'1 21!! 31!! 41!! 51!! I I

MILES UNIVERSAL TRANSVERSE MERCATOR PROJECTION

AUSTRALIAN NATIONAL SPHEROIO CENTRAL MERIDIAN 117 ee BBE

o

312112101210M E

rF

'TRYAL ROCKS 1

+

+

+

115 00 00E

f) I"

"

P \ ~SCO 4 .......

-PEPPER 1 o\.JBsT PEPPER 1

:\ :SoTt-fPEfPERP

\)

115 30 00E

375121121I21M E

+. ~~T 11_61.2

r 'g)

/t. W

0

0 a 0

0 r;

+

772500121M N

0

765121121121I21M N

7575000M N

116 0121 I2II21E

l OHD SURVEY LINES I TEG/BMR CALIBRATION SURVEY

/ ..-(

RRRFURf~ SER 200000H E 400000H E 600000H E

8 30 005

I + + + 9000000M N

I

" 10 00 005 !W!II9

8800000H N

I

134 00 00E 136 00 00E 137 30 00E

_____ ~DH~D=_ ~SLURVEY LINES

RRRFURR BRS I N SURVEY

S16RRRFU.PIC -=~~~==~~tilE~~====~B~~=-- l~~

UNIVERSAL MILES .d TR'FI45VEIt3: !'£RCR

RUSTRR...JAN ~TJ()..IRL rm PRDJECTICH

C£NTRIL tt:KIOIFH SPIfl!OlD 1~5 111 IIIE

J NEEDHRM

1-

20 30 00S

21 00 005

21 30 005

22 00 00S 114 em 00E

2~ !

225000M E

+

+

~O Q

+ ~.

CARNRRVON BRSIN 300000M E

r/'

·TRY;AL ROCKS 1

~-'

7 ~HINOOK· I

IRIFFIN 1~3 I +

I

(j'

~~ •

o i u 4'

6' ... ..

+

1.1

P ~SCO

-PEPPER T PEPPER

f) c". \..

\ 4"'-

1 1

. :S-T#~~rpE~P

~

HERVIL t-v H CHERVIL D

~~ 1-7 cJ

IJ / Pn ~v

0

0 I'J

114 30 00E 115 00 00E 115 30 00E

1: HI~~~~~ 40 60

I I 80

I 100

I

OHD SURVEY LINES

375000M E

7725000M N

r /g) 0

0

0°

7650000M N

+ 7575000M N

116 00 00E

KILOMETRES TEG/BMR CALIBRATION SURVEY

~ H~ 211J 311J 411J 511J !~~=-~!======b!=====d!======±!=====:d=d

MILES UNIVERSAL TRANSVERSE MERCATOR PROJECTION

RUSTRALIRN NATIONRL SPHEROID CENTRA.. nERIDIFt.! 117 I!l0 lIE

L-______________________________________________________ ~. __ .-.~~ __ ~ ________ __

Documents

Carnarvon Basin (Barrow Sub-Basin) Geochemical Calibration ... · OBJECTIVES Hydrocarbon accumulations in the BarrowlDampier Sub-basins had been, until recently considered to fall