the indonesian sedimentologists forum (fosi)

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Berita Sedimentologi MARINE GEOLOGY OF INDONESIA

Number 32 – April 2015

Published by

The Indonesian Sedimentologists Forum (FOSI) The Sedimentology Commission - The Indonesian Association of Geologists (IAGI)

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Editorial Board

Minarwan Chief Editor

Bangkok, Thailand

E-mail: [email protected]

Herman Darman Deputy Chief Editor

Shell International EP

Kuala Lumpur, Malaysia E-mail: [email protected]

Fatrial Bahesti PT. Pertamina E&P

NAD-North Sumatra Assets Standard Chartered Building 23rd Floor

Jl Prof Dr Satrio No 164, Jakarta 12950 - Indonesia

E-mail: [email protected] Wayan Heru Young University Link coordinator

Legian Kaja, Kuta, Bali 80361, Indonesia

E-mail: [email protected] Visitasi Femant Treasurer

Pertamina Hulu Energi

Kwarnas Building 6th Floor

Jl. Medan Merdeka Timur No.6, Jakarta 10110


Rahmat Utomo Bangkok, Thailand


Farid Ferdian Saka Energi Indonesia Jakarta, Indonesia


Guest Editors

Dr. Susilohadi Pusat Penelitian dan Pengembangan Geologi Kelautan,

(Marine Geological Institute)

Bandung, Indonesia

Dr. Udrekh Al Hanif BPPT (Agency for the Assessment and Application of

Technology)

Jakarta, Indonesia

Advisory Board

Prof. Yahdi Zaim Quaternary Geology

Institute of Technology, Bandung

Prof. R. P. Koesoemadinata Emeritus Professor

Institute of Technology, Bandung

Ir. Wartono Rahardjo University of Gajah Mada, Yogyakarta, Indonesia

Dr. Ukat Sukanta ENI Indonesia

Mohammad Syaiful Exploration Think Tank Indonesia

F. Hasan Sidi Woodside, Perth, Australia

Prof. Dr. Harry Doust Faculty of Earth and Life Sciences, Vrije Universiteit De Boelelaan 1085

1081 HV Amsterdam, The Netherlands

E-mails: [email protected];

[email protected] Dr. J.T. (Han) van Gorsel 6516 Minola St., HOUSTON, TX 77007, USA

www.vangorselslist.com


Dr. T.J.A. Reijers Geo-Training & Travel

Gevelakkers 11, 9465TV Anderen, The Netherlands

E-mail: [email protected] Dr. Andy Wight formerly IIAPCO-Maxus-Repsol, latterly consultant

for Mitra Energy Ltd, KL


• Published 3 times a year by the Indonesian Sedimentologists Forum (Forum Sedimentologiwan Indonesia, FOSI), a commission of the

Indonesian Association of Geologists (Ikatan Ahli Geologi Indonesia, IAGI).

• Cover topics related to sedimentary geology, includes their depositional processes, deformation, minerals, basin fill, etc.

Cover Photograph:

A 3D model of Indonesian seafloor, taken from the

proceedings of a scientific meeting to commemorate

the 10th anniversary of the French-Indonesian

cooperation in oceanography (1993).

mailto:[email protected]

mailto:[email protected]

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Dear readers,

Welcome to the first volume of

Berita Sedimentologi in 2015!

Berita Sedimentologi publications

in 2015 are dedicated to topics

related to Marine Geology of

Indonesia and are supported by

Dr. Susilohadi of Marine Geological Institute (Pusat

Penelitian dan Pengembangan

Geologi Kelautan) and Dr. Udrekh

Al Hanif of Agency for Assessment

and Application of Technology (Badan Pengkajian dan

Penerapan Teknologi) as guest

editors. This volume, Berita

Sedimentologi No. 32, will be the

first of 3 volumes on the

particular theme. In this issue, we

present you 2 full articles on

seismic stratigraphy and heat

flow estimation from bottom simulating reflectors of gas

hydrates; an extended abstract on

integrated multibeam, drop core

and seismic interpretation of

North Banggai-Sula seafloor and

a short article on marine expeditions in Indonesia during

the Colonial years.

We also welcome Dr. Andy Wight

who recently agreed to become one of our International

Reviewers. Dr. Wight is a highly

experienced Petroleum Geologist

who has spent most of his

professional career in SE Asia,

therefore he knows the geology of

the region pretty well. He replaces

Dr. Peter Barber, who has been

very helpful to FOSI in the past. On behalf of FOSI, I would like to

express our gratitude and thanks

to both Drs. Andy Wight and

Peter Barber.

We continue to seek high quality articles to be included in Berita

Sedimentologi, so please contact

one of the editors if you are

interested to contribute to our

society. In the meantime, we hope you enjoy reading this volume.

Chief Editor

Minarwan

Regards,

Minarwan

Chief Editor

INSIDE THIS ISSUE

Plio-Pleistocene Seismic Stratigraphy of the Java Sea between Bawean Island and East Java – S. Susilohadi and T.A. Soeprapto

5

Book Review : The SE Asian : History and Tectonic of the Australian-Asia Collision, editor: Robert Hall et J.A. Reijers

56

Merits and Shortcomings of Heat Flow Estimates from Bottom Simulating Reflectors – Minarwan and R. Utomo

17

Book Review - Biodiversity, Biogeography and Nature Conservation in Wallacea and New Guinea (Volume 1), Edited by D. Telnov, Ph.D. – H. Darman

58

Frontier Exploration Using an Integrated Approach of Seafloor Multibeam, Drop Core and Seismic Interpretation – A Study Case from North Banggai Sula – F. Ferdian

27

Marine Expeditions in Indonesia during the Colonial Years – H. Darman

30

Berita Sedimentologi

A sedimentological Journal of the Indonesia Sedimentologists Forum

(FOSI), a commission of the Indonesian Association of Geologist (IAGI)

From the Editor

Call for paper BS #33 –

to be published in August 2015

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About FOSI

he forum was founded in 1995 as the Indonesian

Sedimentologists Forum

(FOSI). This organization is a

communication and discussion

forum for geologists, especially for those dealing with sedimentology

and sedimentary geology in

Indonesia.

The forum was accepted as the

sedimentological commission of the Indonesian Association of

Geologists (IAGI) in 1996. About

300 members were registered in

1999, including industrial and

academic fellows, as well as students.

FOSI has close international relations with the Society of

Sedimentary Geology (SEPM) and

the International Association of

Sedimentologists (IAS).

Fellowship is open to those holding a recognized degree in

geology or a cognate subject and

non-graduates who have at least

two years relevant experience.

FOSI has organized 2 international conferences in 1999

and 2001, attended by more than

150 inter-national participants.

Most of FOSI administrative work will be handled by the editorial

team. IAGI office in Jakarta will help if necessary.

The official website of FOSI is:

http://www.iagi.or.id/fosi/

Any person who has a background in geoscience and/or is engaged in the practising or teaching of geoscience

or its related business may apply for general membership. As the organization has just been restarted, we use LinkedIn (www.linkedin.com) as the main data base platform. We realize that it is not the ideal solution,

and we may look for other alternative in the near future. Having said that, for the current situation, LinkedIn

is fit for purpose. International members and students are welcome to join the organization.

T

FOSI Membership

FOSI Group Member as of APRIL 2015

http://www.iagi.or.id/fosi/

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Plio-Pleistocene Seismic Stratigraphy of the Java Sea

between Bawean Island and East Java Susilohadi Susilohadi and Tjoek Azis Soeprapto

Pusat Penelitian dan Pengembangan Geologi Kelautan, (Marine Geological Institute), Bandung, Indonesia

Corresponding author: Jalan Dr. Junjunan 236, Bandung-40174, Indonesia; Tel.:+62-22-603-2020;

Fax:+62-22-601-7887; E-mail address: [email protected] (S.Susilohadi)

ABSTRACT

The southeast Java Sea forms a submerged part of the Sunda Shelf and lies on a relatively stable continental shelf, which reached its final form during the Quaternary. Marine geological investigations in this area have mostly been carried out as part of regional studies on the Sunda Shelf. Detailed studies, particularly for younger sequences, are lacking and, as a result, the neo-tectonics and response of the shelf area to extreme sea level fluctuations during Plio-Quaternary times are poorly known. A set of high resolution reflection seismic profiles totalling some 3750 line km has been studied. All data were acquired by the Marine Geological Institute of Indonesia, which ran the survey in the southeast Java Sea in 1989-1990. The data show that the Late Tertiary sedimentation in the study area partly occurred in half graben basins, mostly bounded by northeastward trending faults which may be related to the regional suture belts running from central Java to south Kalimantan. Towards Pliocene time, the sedimentation occurred in east-trending synclinal basins, which indicate the dominance of a northward tectonic compressional stress. This continued until the Early Pleistocene, as indicated by some local thickening of the Early Pleistocene deposits. Since then, further basin development appears to have ceased, and a tectonically stable condition may have been reached. Quaternary sedimentation

gradually changed the basin morphology into a relatively flat plain characterised by multiple erosional features resulting from extreme sea level fluctuations.

Keywords: Seismic Stratigraphy, Pliocene, Pleistocene, Java Sea.

INTRODUCTION The southeast Java Sea forms the submerged part

of the Sunda Shelf and lies on a relatively stable

continental shelf (Figure 1). Marine geological investigations in the southeast Java Sea have

mostly been carried out as part of regional studies

on the Sunda Shelf (e.g. Emery et al., 1972; Voris,

2000; Ben-Avraham & Emery, 1973). Detailed and

published studies, particularly for the Plio-Pleistocene periods, are rare, although such studies

are necessary in order to understand the tectonic

and response of the shelf area to extreme sea level

fluctuations during these times.

The present study discusses the sedimentary facies distribution, chronology and the related tectonism

in the southeast Java Sea during the Late Tertiary

and Quaternary. The discussion relies heavily on

sparker single channel seismic data (Figure 2),

which have been interpreted by applying the

sequence stratigraphic concepts developed by Vail et al. (1977) and Posamentier and Vail (1988).

However, this study lacks reliable age

determinations, as well as other published

geological studies. In addition, problems inherent

from the equipment include: (1) the limited

penetration, (2) and the presence of strong multiple

reflections, particularly in the area where surficial

reflections are strong.

REGIONAL GEOLOGY Based on regional geophysical data, Ben-Avraham

and Emery (1973) noted that Tertiary sedimentation

in the southeast Java Sea occurred in basins which

were bounded mostly by northeastward trending faults (Figure 1). Many of these structures are half

grabens that formed on the pre-Tertiary shelf

(Kenyon, 1977; Bishop, 1980). These major features

were interpreted by Ben-Avraham and Emery (1973)

as resulting from past interaction between the

Eurasian and Indian-Australian lithospheric plates, the principal ridges probably representing part of an

island arc system that was active during the Late

Cretaceous-earliest Tertiary (Bishop, 1980). Such

an island arc complex has been deduced from the

occurrence of pre-Tertiary ophiolites cropping out in Central Java and in Southeast Kalimantan (van

Bemmelen, 1949) possibly representing a previous

subduction complex (Katili, 1989).

The Karimunjawa Arch is the dominant ridge in the

eastern Java Sea. It extends into the offshore area of southern Kalimantan as a broad positive feature

(Bishop, 1980).

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It is capped by the Karimunjawa Islands on which pre-Tertiary quartzite and phyllitic shale, cut by

basic dykes, and probable Quaternary fissure-

eruptive sheets crop out. This arch is separated by

the narrow, northeast trending Muria Basin (West

Florence Deep) from the Bawean Arch. The Bawean Arch is characterised by alkaline volcanism of the

latest Neogene or Quaternary and steeply dipping

Miocene marine strata (van Bemmelen, 1949).

DATA The data base for this study is drawn from seismic

profiles of about 3750 line km in the Java Sea

(Figure 2). All geophysical data were obtained from the Marine Geological Institute of Indonesia which

ran the survey in 1989/1990. The seismic system

used is a single channel 600 Joule sparker system,

fired every 1 second. These setting have allowed of

about 400 milliseconds penetration below the seabed. The seismic signals were not tape recorded,

but were directly band pass filtered (200-2000 Hz)

and graphically recorded in analog format during

the survey. Due to this technique, no further data

processing was carried out. The ship positions

during the survey relied mostly on GPS navigation system, and by the time the acquisition was

conducted, the horizontal accuracy was not less

than 100m. The profiles were mostly oriented north-

south and spaced 5 to 10 km apart.

Stratigraphic control for calibration of the seismic

data was provided by six petroleum exploratory

wells, JS1-1, JS2-1, JS3-1, JS8-1, JS10-1 and

JS16-1. However, these data cannot provide a

reliable stratigraphic timing resolution as the

biostratigraphic and lithofacies analyses done were based on well cuttings which were commonly

sampled every 30 ft penetration. Even so, they have

narrowed the age estimation of the stratigraphic

time markers.

SEISMIC STRATIGRAPHY

Seismic analysis indicates that the Late Tertiary

and Quaternary sediments in the study area can be subdivided into three major seismic units. These

units correspond to the Miocene, Pliocene and

Quaternary and are referred to as Units 1, 2 and 3

respectively.

Figure 1. Location of the study area and the generalized Tertiary basement configuration according to Kenyon (1977). Superimposed on the Java Sea is Molengraaff river system of the last glacial period,which has been

deduced from the first Snellius expedition (Molengraaff, 1921; Kuenen, 1950).

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Unit 1 This Miocene unit can only be observed on the

structurally high areas, such as near the Bawean

and Karimunjawa Arches, and on Madura Island.

The age of Unit 1 is confirmed by well data of JS8-1

and JS3-1. The internal seismic reflection patterns and areal distribution are poorly defined,

particularly because of the limited penetration of

the seismic system used and strong multiple

reflections. The lower boundary is unidentifiable,

but the upper boundary is a regional unconformity

as shown by a pronounced erosional surface on the structurally high areas (Figures 3, 4, 5 and 6). On

most of seismic sections, Unit 1 is characterised by

a medium amplitude, continuous parallel-

subparallel reflection pattern of possibly

interbedded sandstone and mudstone (Figures 3, 4 and 5). The sections acquired near the

Karimunjawa and Bawean Arches suggest that the

lower part of Unit 1 is probably equivalent to the

Miocene strata exposed on these islands, which are

characterised by the occurrence of limonitic

sandstone, interbedded with lignite, marl and crystalline limestone (Bemmelen, 1949). A mounded

structure characterised by low amplitude of internal

reflectors is observed on the top of Unit 1, and

probably represent a highstand reef (Figure 6).

Unit 2 Unit 2 is relatively thick and was deposited

following sea level fall at the end of the Miocene. It

consists of two subunits: 2a and 2b, with subunit

2a forming the major part of the sequence. Correlation between the seismic and the

micropalaeontological data from some petroleum

exploratory wells confirmed that this unit developed

during the Pliocene. The top boundary of Unit 2 is

an erosional surface marking extensive subaerial exposure in the study area. Based on reflection

configuration patterns, the sediment sources of

these subunits were mainly the Karimunjawa and

Bawean Arches in the western half of the study

area. In the eastern half, the deposits were sourced

from both the Bawean Arch and Madura Island, but the distribution was complicated by the

development of folds.

On the stable area, such as on the Karimunjawa

Arch, the Pliocene unit was thinly deposited on top of the Miocene unit which suggests that the

subsidence rate on the arch was very low. The

seismic characters are mainly form a strong

amplitude parallel reflection pattern (Figure 3)

which is often associated with mounded forms of

possibly reefal limestone. In the areas where the depositional slope was high, such as near the

margins of the Muria Trough, the East Bawean

Trough and the growing Madura Island, the

deposition of the lower part of Unit 2 may be divided

into two main systems tracts: the lowstand and highstand systems tracts (Figures 5 and 6).

Figure 2. Tracklines of single channel sparker seismic records used in this study superimposed on the bathymetric map of the study area. Thicker lines are parts of seismic lines presented in this paper for

discussion. Dots in the Java Sea represent the oil exploration wells.

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of 34



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The transgressive systems tract on most of the

seismic lines studied is absent or unidentified,

probably due to a rapid sea level rise which did not

permit formation of a seismically resolvable transgressive unit.

In the western part of the study area, the upper

part of Unit 2 is recognised as a thin prograding

complex downlapping onto the erosional surface at

the top of Unit 2a (Figure 7). This erosional surface should be correlated with a lowstand of sea level

and the prograding complex with the highstand

deposits. On the flank of Madura Island a thicker

unit was deposited, which may be resolved into

lowstand and highstand deposits (Figure 6).

Figure 9 shows palaeogeographic maps during the

lowstand period of subunit 2a. These maps indicate

that the Pliocene basin in the western half of the

study area was still influenced by the normal fault

movement of the half graben system in the Muria Trough. The occurrence of the deepest basin and

accumulation of the thickest Pliocene sediments in

this trough (particularly along the normal faults)

has further suggested probable faster subsidence

and sedimentation rates. In the eastern half of the area, the influence of the previous structural

configuration (Figure 3) is not obvious. The Pliocene

structural development (east-west trending folds)

had more influence on the sedimentation

particularly in the area between Java and Bawean

Islands and near the Madura Island, as indicated by the trends of basin morphology and the Pliocene

sediment accumulation (Figure 8).

Unit 3 Unit 3 was deposited following a sea level fall which

exposed the whole study area at the end of the

Pliocene. The seismic characters and sedimentation

patterns of Unit 3 differ significantly from those of

the preceding Unit 2. They appear to be strongly

influenced by extreme and rapid sea level fluctuations. Such fluctuations during the

Quaternary have been demonstrated by many

workers through the oxygen isotope records of deep

sea cores, which they have related with the

orbitally-induced fluctuations of global ice volume. These glacio-eustatic sea level fluctuations are particularly apparent since 0.97 Ma (Harland et al.,

1989) with a relatively constant period. The global

sea level falls may have reached 130 m below present level during the glacial maximum (Bloom et al., 1974; Chappell & Shackleton, 1986; Fairbanks,

1989).

The present seismic study identified five main

Quaternary seismic subunits in the area. These

subunits are characterised mostly by parallel to

subparallel reflection patterns or are reflection free. Each of them ended with channel cut and fill along

their upper part and are interpreted to represent

marine deposition and fluvial channelling

respectively. In some areas the thickness of these

subunits appears to be similar, which may indicate

constant subsidence rates combined with periods of

sea level fluctuation. Because these subunits have a

similar seismic character and do not represent thick

deposits, lateral correlation is difficult and tends to

be speculative. But they can be grouped into five subunits, 3a to 3e, based on the occurrence of

widespread unconformities on top of each unit.

These unconformities are commonly associated with

rather deep and wide fluvial channelling.

a. Subunits 3a and 3b The subunits 3a and 3b were deposited during the

Early Pleistocene, based on their stratigraphic

position overlying Pliocene Unit 2. A stratigraphic

subdivision between these subunits in the western

part of the study area is rather speculative, but clear differentiation can be made in the areas near

the Java and Madura Islands due to the higher

subsidence rate and the occurrence of a relatively

large sea level fall at the end of subunit 3a

deposition (Figures 6 and 7). Seismic features, such

as rapid basinward thinning (Figure 6) and pronounced anticlines (Figure 7) indicate that their

distribution was influenced by local structural

development. There, subunit 3a can be further

subdivided into subunits 3a-1 and 3a-2 based on

the occurrence of an internal erosional surface (Figure 7). The thickness of subunit 3a-1 reaches

100 msec TWT (about 75 m) in the deepest portion

of the basin, and it gradually thins toward the basin

margin. The maximum thickness of subunit 3a-2 is

about 60 msec TWT (about 45 m). The thickness

variation is mainly due to local subsidence, post depositional erosion and a gradual thinning

because of the rising of the basin margin. Subunit

3a-2 onlaps on subunit 3a-1 on the southern

margin, and on Unit 2 when subunit 3a-1 wedges

out. The seismic character of these subunits is similar, a subparallel reflection pattern with

medium amplitude and medium continuity which

suggests deposition in a shallow marine

environment (Sangree & Widmier, 1977). To the

north of Madura Island a local deepening occurred

(Fig. 6), and subunits 3a-1 and 3a-2 are characterised by northward prograding clinoform

deposits, indicating that the sediments were derived

from the growing Madura Island. Subunits 3a-1 and

3a-2 may be regarded as the units responsible for

the flatness of this area.

The subunit 3b was deposited on a flat surface and

has an extensive coverage although its thickness is

less than 35 msec TWT (26 m). Seismically, this

subunit is characterised by a similar appearance to

subunits 3a-1 and 3a-2, and probably was deposited in a similar environment. The upper part

tends to show subparallel to hummocky patterns

with variable amplitude which indicates a shoaling

(regression) of the unit before finally being exposed

subaerially.

b. Subunits 3c, 3d and 3e

Subunits 3c and 3d can further be subdivided into

three (3c-1, 3c-2 and 3c-3) and two (3d-1 and 3d-2)

respectively.

of 34



Fig

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of 34



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t to

p M

ioce

ne.

of 34



These subdivisions can only be recognised in a

limited area where the subsidence and

sedimentation rates were relatively high, such as in

the area just north of Java (Figure 7).

Subunits 3c-1 and 3c-2 are similar in seismic

character, showing a medium amplitude,

subparallel reflection pattern which probably

represents a shallow marine environment. Subunit

3c-3 is reflection free, indicating most probably homogeneous mudstone. Subunit 3d is extensively

distributed and in some areas is characterised by

an almost reflection free character suggesting a

nearly homogeneous deposit probably of mudstone.

In the western part, subunits 3d-1 and 3d-2are very thin to absent, which indicates a low depositional

rate.

Subunit 3e consists of a single reflection-free

sequence of possibly homogeneous mudstone. The

maximum thickness in the basinal area is about 30 msec TWT (about 22 m) with a little variation on the

western part of the study area. On some parts to

the north of Madura Island this subunit is too thin

to be identified, but locally thick deposits of up to

25 msec TWT (about 19 m) occur in a limited area, particularly near the river mouths on the northern

coast of Java. The fluvial channelling at the base of

subunit 3e in some areas is very pronounced

(Figure 6). Its occurrence can be related to the last

glacial period, during the oxygen isotope stage 6,

when the sea level was -130 m below present level (Chappell & Shackleton, 1986).

DISCUSSION AND CONCLUSION The Miocene basin configuration of the study area

is poorly known, but it is suspected that the basin

development was still strongly influenced by the

northeast-trending structures related to the basement configuration. These structures are half

grabens and have been the major control for the

Early Tertiary sedimentation. Although some

elements of these structures were still active until

the Pleistocene, their effectiveness in controlling the

sedimentation during the post-Miocene was diminished. The Pliocene sedimentation, in general,

occurred in E-W trending synclinal basins which

indicate the dominance of the northward tectonic

compressional stress. This continued until the Early

Pleistocene, as is indicated by some local thickening of the Early Pleistocene deposits. Since then,

further basin development appears to have ceased,

and a tectonically stable condition may have been

reached.

The Quaternary units, which are represented by nine thin subunits, tend to be distributed widely

because of deposition on a relatively flat lying area.

The seismic characters are very similar, comprising

subparallel reflection or almost reflection free

patterns at the bottom which represent marine deposits, topped by extensive fluvial channelling.

This repetitive succession is thought to represent

highstand and lowstand periods of sea level

respectively. Because the average water depth in the

study area is about 60 m, the fluvial channelling

may be correlated with the major sea level lows

during the Quaternary. The bases of subunits 3e, 3d and 3c are tentatively correlated with the glacial

periods during oxygen isotope stages 2, 6 and 16 of Harland et al. (1989) respectively, while subunits 3a

and 3b represent earlier periods. During the glacial

periods the Sunda Shelf became widely exposed,

and river systems such as the Molengraaff river (Molengraaff, 1921; Kuenen, 1950; Voris, 2000)

may have developed in the last glacial period.

ACKNOWLEDGEMENTS The authors wish to thank the Head of the Marine

Geological Institute of Indonesia for permission to

use the data. This paper is part of the first author’s

PhD thesis supervised by Dr. Leonie Jones, Prof. Colin Murray-Wallace and Prof. Brian G. Jones.

Therefore, their supervision, support and

contribution are greatly acknowledged.

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of 34



Merits and Shortcomings of Heat Flow Estimates from

Bottom Simulating Reflectors Minarwan and Rahmat Utomo

Mubadala Petroleum (Thailand) Ltd, Bangkok, Thailand

Corresponding author: [email protected]

ABSTRACT

The presence of gas hydrates in deep marine sediments and their Bottom Simulating Reflectors

(BSRs) on seismic lines can be used to estimate present-day surface heat flow. Despite its limited

accuracy, the estimated heat flow is still useful as an input in thermal maturity modeling of a

frontier basin.

BSRs commonly occur at several hundred meters below the seafloor, in low latitudes generally in areas with water depth greater than about 700-1000m. They run parallel to the sea floor and may

cross-cut lithological boundaries. They represent a phase boundary between a gas-hydrates-stable

zone and underlying free gas- and water-saturated sediments. Since the depth of the hydrate- free

gas phase change is a function of temperature, depth (pressure) and gas composition for a given

gas composition (assuming hydrostatic pressure and mainly methane gas), the temperature gradient between seafloor and the BSR can be calculated from its depth. The temperature gradient

can then be converted into heat flow, provided that thermal conductivity of the sediment is known.

Keywords: heat flow, gas hydrates, bottom-simulating reflectors.

INTRODUCTION

Modeling source rock maturity in a basin requires reliable thermal calibration, ideally by using

vitrinite reflectance data or other maturity

indicators. It is also important to calibrate the

present-day heat flow or geothermal gradient used

in the modeling against the present-day thermal condition, which can be done by using

temperature gradient data from wells or direct heat

flow measurements. If vitrinite reflectance or other

thermal indicators are not available, then the

minimum pre-requisite would be to find the

present-day geothermal gradient and/or heat flow data in order to predict the current level of thermal

maturity. As a temperature model forms an

important part of source rock maturity modeling,

maximum efforts have to be made in order to get

the most representative temperature input.

In a frontier deepwater basin with a good coverage

of seismic data and where gas hydrates are

present, heat flow can be estimated by deriving

temperature of the phase change in relation to the

gas hydrate system. The method for estimating heat flow from marine gas hydrates was introduced

by Yamano et al. (1982) and to date, it has been

applied in many regions including Sebakor Sea,

Irian Jaya, Indonesia (Hardjono et al., 1998),

Kerala-Konkan, India (Shankar et al., 2004), Caribbean offshore Colombia (López and Ojeda,

2006), offshore Southwest Taiwan (Shyu et al.,

2006), Gulf of Cadiz, Spain (León et al., 2009),

Simeulue fore-arc basin, Indonesia (Lutz et al.,

2011) and the Andaman Sea (Shankar and Riedel,

2013; Shankar et al., 2014).

Despite its usefulness, calculated heat flow from

BSRs can be inaccurate and show some disparities

with measured heat flow as reported by Kaul et al.

(2000) and He et al. (2009). This paper reviews advantages and shortcomings of BSR heat flow

based on personal experience and some published

materials. We present the methods to derive heat

flow from BSRs, within the context of Indonesian

sea waters, and provide suggestions on how to use

them as inputs in thermal maturity modeling. We will also review potential errors associated with

parameter assumption and theoretical errors as

shown by previous publications.

GAS HYDRATES AND BOTTOM SIMULATING REFLECTION (BSR)

Gas hydrates are ice-like crystalline solids formed

from water and gases (mostly CH4) under low temperature and moderate to high pressure

conditions. They can be present in an area where

abundant supply of methane exists in the system.

Their stability is controlled by methane solubility

(the required minimum methane concentration) and a three-phase equilibrium curve of CH4-

hydrates-water (e.g. Kvenvolden, 1988; Davie et

al., 2004—Figure 1).

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In cold or deep marine environments, gas hydrates

are stable between the sediment-water interface

and the intersection of the geothermal gradient with a CH4-hydrates-water equilibrium curve

(Dickens and Quinby-Hunt, 1997—Figure 2).

Initial research on methane gas hydrates

occurrence in marine sediments inferred that the base of Gas Hydrates Stability Zone (GHSZ) or

Methane Hydrates Stability Zone (MHSZ), which

represents the phase boundary from marine

sediments containing solid gas hydrates to those

containing only water and free gas, is frequently

imaged on seismic sections as a high amplitude reflection that mimics the seafloor and cross-cuts

reflections of sedimentary layers. The reflection is

called a Bottom-Simulating Reflection (BSR) and it

always shows reverse polarity from that of the

seafloor, due to the decrease in velocity and density across the boundary (Yamano et al., 1982).

The BSR is distinguishable from seafloor multiples

as the multiples occur at twice the two-way time

(TWT) between sea surface and seafloor. A BSR can

be present at depths of 100 to 1100 m below the

seafloor (Collett, 2002) and the thickness of gas hydrates is usually 220–400 m (León et al., 2009).

Following Ocean Drilling Program (ODP) Leg 164 in

late 1995, Xu and Ruppel (1999) developed a

better analytical formula to explain evolution and

accumulation of methane hydrates in marine

sediments. The most relevant points from their

work regarding gas hydrate & BSR are: (1) the base of the zone where actual gas hydrates occur is not

always at the base of GHSZ, but rather lies at

shallower depth than the base of the stability zone;

(2) If the BSR marks the top of the free gas zone,

then it will occur substantially deeper than the base of the stability zones in some settings and (3)

the presence of methane within the pressure-

temperature stability field for methane gas

hydrates is not sufficient for gas hydrates to occur. Gas hydrates “can only form if the mass fraction of methane dissolved in liquid exceeds methane solubility in seawater and if the methane flux exceeds a critical value corresponding to the rate of diffusive methane transport”. Figure 3 illustrates

the relationship between tops and bottoms of

actual gas hydrate, hydrate stability zone and top

of free gas according to the model developed by Xu & Ruppel (1999).

ESTIMATING HEAT FLOW FROM THE BSR The commonly accepted method to estimate heat

flow from gas hydrates requires the geothermal

gradient from the seafloor to the base of the GHSZ

(note: main assumption here is the BSR marks the

base of GHSZ and also the top free gas) and

thermal conductivity of the sediments where the

Figure 1. P-T diagram of gas hydrate stability

based on a three-phase equilibrium curve (after

Davie et al., 2004). Solid squares are P-T at the

base of natural GHSZ drilled by Ocean Drilling

Program, which show good correlation with

experimental three-phase P-T curve (sea water).

Figure 2. Gas hydrate stability zone in marine

environment is located between sediment-water

interface and the intersection of geothermal

gradient and the CH4-hydrates-water equilibrium

curve (Dickens and Quinby-Hunt, 1997). Graphic is

from Davie et al. (2004).

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gas hydrates are present. The geothermal gradient

can be calculated if temperatures and depths of

the BSR and the seafloor are known. The simplest

approach would be to relate temperature (T) and depth (Z) at the base of the GHSZ as a function [T=f(Z)] because Z is the first variable that can be

estimated by using seismic and bathymetric data.

However, as the stability of the gas hydrate phase

is determined by temperature (T) and pressure (P), then another function [P=f(Z)] correlating P and Z

has to be known first.

The BSR heat flow is estimated by using the

following equation (e.g. Shankar and Riedel, 2013):

Qbsr = 1000 x k x [(Tbsr - Tsea)/(Zbsr - Zsea)] (1)

where Qbsr is BSR heat flow (in mW/m2), k is the

thermal conductivity of marine sediments (in

W/mK), Tbsr (K) is the temperature at the depth of

BSR (Zbsr) and Tsea is the temperature at the seafloor (Zsea).

The temperature at the BSR (Tbsr) is estimated by

using the published empirical equation from

Dickens and Quinby-Hunt (1994), which relates pressure to temperature of methane hydrate

disassociation in a laboratory experiment by using

seawater (salinity of 33.5 ppt). For any given

pressure between 2.5–10 MPa, their experiment

shows that P and T follow this equation:

1/Tbsr = 3.79 x 10-3 – [2.83 x 10-4 x log(P)] (2)

where Tbsr is temperature (K) and P is pressure

(MPa).

Assuming pore-waters are connected and there is

no overpressure in the system, then pore pressure

equals hydrostatic pressure (León et al., 2009) and

therefore, P in Equation (1) can be calculated from

this equation:

P = ρ x g x Zbsr (3)

where P is pressure at depth (MPa), ρ is density of

water (kg/m3), g is gravity acceleration (9.81 m/s2)

and Zbsr is depth of the BSR (m subsea).

The density of seawater can be estimated by

assuming constant salinity and sea surface

temperature for practicality. The salinity and sea

surface temperature data can be taken from the World Ocean Atlas (2013), which can be accessed

online at US National Oceanic & Atmospheric

Administration (NOAA) website. As an example, the

average salinity and surface temperature of

Indonesian seawater are 33.5 ppt and 28.4 C, respectively (World Ocean Atlas, 2013). Using

these numbers, the density of Indonesian seawater would be 1021.182 kg/m3 (Millero et al, 1980). If

this value is used in Equation (3) then the

equation becomes:

P = 0.010017795 x Zbsr (4)

Figure 3. Possible location of BSR and its relationship to the base of Gas Hydrate Stability Zone

(GHSZ)/Methane Hydrate Stability Zone (MHSZ). BSRG1 is the estimated thermal gradient if the BSR

represents the base of Methane Hydrate Zone (this will give higher BSR heat flow than the measured

heat flow). BSRG2 is the estimated thermal gradient if the BSR represents the top of free gas zone (this

will give lower BSR heat flow). Graphic is from He et al. (2009), based on the model developed by Xu &

Ruppel (1999).

of 34



The Zbsr is calculated by converting Two-Way-Time

(t) from seismic into depth. The depth conversion

can be done by using the following steps

(assuming constant seismic velocity in seawater of 1500 m/s):

Zbsr = Zsea + Dbsr (5)

Zsea = 1500 (1⁄2 tsea) (6)

Equations (7) and (8) are taken from Equations (1) & (2) of He et al. (2009), which were used to

estimate depth for the upper 1s seafloor sediments

in the Xisha Trough and Northern South China

Sea.

Dbsr = 982.576 (tbsr – tsea); if (tbsr – tsea) ≤ 0.5s (7)

or

Dbsr = 121.52 (tbsr – tsea)2 + 1269.1 (tbsr – tsea) –

173.692; if 1s ≥ (tbsr – tsea) > 0.5s (8)

where Dbsr is thickness of the BSR (m from seafloor), tsea and tbsr are TWT of the sea floor and

the BSR, respectively, from seismic datum (sea

level) in seconds.

The Dbsr can also be estimated from depth conversion by using a constant interval velocity for

the upper 1km of marine sediments. For examples,

Yamano et al. (1982) used 1.85±0.05 km/s in the

Nankai Trough, Japan; Davis et al. (1990) used

2000 m/s in the Northern Cascadia margin; while

in the Simeulue fore-arc basin the interval velocity may range from 1900 m/s to 2200 m/s (Franke et

al., 2008).

After solving Equation (4), the calculated pressure

can be used to solve Equation (2) and this gives the temperature of the BSR (Tbsr). The seafloor

temperature (Tsea in K) ideally should be taken from in situ measurement, however in the absence

of CTD (Conductivity-Temperature-Depth) and

Expandable Bathythermograph (XBT), Tsea can be

estimated from the World Ocean Atlas (2013) dataset, providing representative data points are

available. Otherwise, another way to get seafloor

temperature is by adopting an equation used by

Shankar and Riedel (2013) in the Andaman Sea:

Tsea = 278.645 – (0.0002 x Zsea) (9) The equation above was based on in situ

measurements and published data near Little

Andaman Island, which is relatively close to

Indonesia region. It must be noted that seafloor

temperature can be affected by deep current flow, therefore it is possible to get different temperatures

from different measurements throughout the year.

The seafloor temperatures generated by the two

methods mentioned above can differ by approx. 1

C, hence creating some uncertainties on estimated heat flow (see next section).

The last parameter to be estimated before

calculating heat flow from the BSR is the thermal

conductivity (k) of marine sediments. Davis et al.

(1990) suggested an empirical solution that gives

average thermal conductivity of sediments starting

from the sea floor as follows:

k = 1.07 + (5.86 x 10-4) x Dbsr – (3.24 x 10-7) x Dbsr

2

(10)

where k is thermal conductivity of sediments (W/m

K) and Dbsr is the thickness below the sea floor (m).

This equation in general is consistent with measured thermal conductivity in the Xisha

Trough (He et al., 2009). The measured thermal

conductivity of marine sediments actually can

range pretty wide, for examples 1.1–1.8 W/m K (0–

3 m bsf) in the Makran accretionary prism, offshore Pakistan (Kaul et al., 2000) and 1.0–1.4

W/m K (0–300 m bsf) in the Cascadia margin

(Ganguly et al, 2000). However the average thermal

conductivity of marine sediments can also be

assumed to be approx. 1.2 W/m K (Davis et al.,

1990) to 1.27 W/m K (Kaul et al., 2000).

ADVANTAGES AND SHORTCOMINGS Advantages

In a frontier basin where no prior hydrocarbon

exploration activities have taken place and no

present-day heat flow measurements are available,

BSR heat flow estimates are useful as a present-

day heat flow input in basin modeling. Having a favorable thermal maturity model of a basin would

support a decision of whether or not to explore for

conventional hydrocarbon in a frontier area. The

method is considerably less expensive and more

practical than acquiring heat flow data directly through heat flow probes, because BSR can be

identified even from regional 2D seismic lines and

calculations of heat flow values can be done

quickly by using publicly available parameter

assumptions. If BSR's occur in many regional

seismic lines across a basin, then more heat flow values can be derived and variation of these values

can be taken into consideration to get appropriate

thermal maturity model(s).

Shortcomings As previously explained in the methodology to

derive heat flow from the BSR, various levels of

assumptions and simplification must be applied,

due to either lack of data or naturally insufficient

empirical solution to constrain physical and

chemical properties of the required input parameters. The assumptions and simplifications

may eventually lead to inaccurate BSR heat flow,

which may show large variation and even

disparities to measured heat flow values.

Another limitation of using BSR to estimate heat

flow is related to the Tbsr-Pressure relationship

(Equation 2) and the sea floor temperature

(Equation 9) that are best-applied in the deepwater

setting (WD > 750m). Using these equations for

shallow water setting can give Tsea > Tbsr, hence giving negative heat flow values.

of 34



BSR Heat Flow Variation

It is common to get a large variation of heat flow

when they are derived from the BSR in a basin.

The following examples demonstrate how wide the range can be:

36–90 mW/m2 (average 60.8 mW/m2) in one Indonesian basin (unpublished)

34.8–59.9 mW/m2 (average 47.7 mW/m2) in the Sebakor Sea, Irian Jaya (Hardjono et al., 1998)

32–80 mW/m2 in the Xisha Trough (He et al., 2009)

37–74 mW/m2 in the Simeulue fore-arc basin (Lutz et al., 2011), and

12–41.5 mW/m2 in the Andaman Sea (Shankar and Riedel, 2013).

In some cases, heat flow variation follows both

regional and local trends. For example on the

northern Cascadia margin, Canada, the regional

BSR heat flow increase towards the deformation

front, which is consistent with the trend shown by

heat flow probe, and locally, they are low over topographic highs and high over the flanks of the

highs (Figure 4; Ganguly et al., 2000]. Similar

regional BSR heat flow behavior has also been

seen by Kaul et al. (2000) in the Makran

accretionary prism offshore Pakistan. This large

variation of heat flow values could be controlled by active geological process such as proximity to

active deformation front and effects of rapid

sedimentation, but could also be due to poor

control of subsurface velocity variation. Local heat

flow variation may be caused by dynamic effects such as upward migration of warm fluids along

permeable faults and the displacement of isotherm

by thrust faulting (Ganguly et al., 2000).

Figure 4. Local variation of BSR heat flow in the Cascadia Margin, Canada, showing low heat

flow values on the topographic highs and high heat flow on the flank (Ganguly et al., 2000).

of 34



Disparities between BSR and Measured Heat

Flow

Disparities between BSR-derived and measured

heat flow were reported by Kaul et al. (2000) in the Makran accretionary prism and He et al. (2009) in

the Xisha Trough, South China Sea. In the Makran

accretionary prism, the BSR heat flow values are

consistently higher than the measured heat flow

by about 15 to 25 mW/m2. The discrepancies were

attributed to high sedimentation rate and tectonic uplift that led to the upward migration of gas

hydrate stability zone (as gas hydrates are

dissolved at the base of the GHSZ).

In the Xisha Trough, the BSR heat flow values are 32–80 mW/m2 and are significantly lower than the

measured values of 83–112 mW/m2. He et al.

(2009) argued that the disparities are caused by

theoretical errors rather than parameter errors

because the discrepancies are larger than a change

in the input parameters would have contributed to. They estimated that the parameter errors would

have affected the BSR heat flow by only less than

25%, while their calculations indicate

discrepancies of up to 50% in some geological

settings.

Source of Error and Implications to BSR Heat

Flow Uncertainties in Input Parameter Assumptions

The first source of errors in BSR heat flow

estimation is due to uncertainties in input parameter assumptions, particularly from

subsurface velocity (for time-depth conversion),

seafloor temperature, thermal conductivity and gas

composition. Tables 1 and 2 show the sensitivity of

various input parameters changes to the estimated heat flow. Assuming all other parameters are

similar, an increase in the interval seismic velocity

by 10% would increase the estimated heat flow by

around 8-9%, while a decrease of 10% would make

the calculated heat flow lower by around 6–7%

(Table 1). A variation in seafloor temperature of 1 ºC lower or higher would contribute to the increase

or decrease of estimated heat flow by ±6-10%,

respectively (Table 2, columns 2 & 3).

A change in thermal conductivity by 0.1 W/mK (Table 2, columns 4 and 5) correlates to a change

in the estimated heat flow by ±8-9%. As the

thermal conductivity may range from 1.0 to 1.4

W/m K for the first 300 m of sediments below the

seafloor (Ganguly et al., 2000), then the estimated

heat flow can vary by 18% colder for lower thermal conductivity and 15% hotter for higher thermal

conductivity (Table 2, columns 6 and 7). At some

circumstances, when the TWT thickness between

the BSR and the seafloor is within the range of

0.5–1.0 s, a thermal conductivity of 1.0 W/m K can lead to approximately 24% colder heat flow

(Table 2, column 6 Case 2). The thermal

conductivity may also vary spatially depending on

sediment types, therefore using a single thermal

conductivity for every calculation is not perfect.

The biggest uncertainty is the gas composition, because the general assumption is that gas in

hydrates is pure methane (CH4). León et al. (2009)

showed that if the gas is thermogenic (i.e. contains

C2 to C5), for any given depth between 2000 and

3000 m, the T at the base of the GHSZ will be 5 ºC

higher than that of biogenic methane hydrates, which means the estimated heat flow will be hotter

by approximately 29 to 35%.

Geological Phenomenon

Examples of the geological phenomenon that can influence heat flow near the seafloor is the

thickening of sediment wedge towards the

coastline from the deformation front of a

subduction zone (e.g. Northern Cascadia, Canada

and Makran accretionary prism, Pakistan) and

upward migration of warm fluid through permeable faults or due to rapid dewatering

process when sediments are compacting. Wang et

al. (1993) modeled that heat reduction due to the

thickening of sediment wedge is more significant

than the heat increase caused by the upward-migrating fluid expulsion, which consequently

significantly can depress the seafloor heat flow to

become lower than the deep lithospheric heat flow.

Theoretical Errors

The model involving a critical value of methane flux to exceed methane solubility in seawater,

necessary for methane hydrates to form, was

developed by Xu and Ruppel (1999) to explain

natural occurrence gas hydrates and its

relationship to the BSRs on the Blake Ridge (offshore southeast US). Their work demonstrates

that the base of GHSZ (MHSZ) does not necessarily

coincide with a BSR and in some geological

settings the BSRs can represent the base of the

actual methane hydrates or the top of the free gas

zone. The meaning of ‘some geological settings’ here is those with different combination of water

depth, regional heat flow and available mass

fraction of methane. In some settings, if the BSR

represents the base of methane hydrate zone

(shallower than the base of the stability zone), then the BSR heat flow will be higher than the regional

heat flow. However, if the BSR represents the top

of free gas zone, then the BSR heat flow will be

lower (see Figure 3). The latter case was proposed

by He et al. (1999) as the reason for the much

lower BSR heat flow in the Xisha Trough, South China Sea. The disparities were caused by an

oversimplification of the BSR as the base of the

GHSZ (MHSZ) in every setting. This is a potential

error in the theoretical assumption of BSR heat

flow calculation and can only be solved when heat flow probes or direct drilling data are available.

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USING BSR HEAT FLOW IN THERMAL MATURITY MODELLING We suggest the following steps to capture

uncertainty generated by large variation of

calculated BSR heat flow when they are used as

inputs in a thermal maturity modeling:

1. Apply a simple statistical analysis to get arithmetic mean and standard deviation. Check

against frequency and suitable range

to identify where the heat values are

concentrated;

2. Compare the results with published present-day heat flow at

the surface of the Earth's crust

(Global Heat Flow Database of the

International Heat Flow Commission,

Figure 5; Pollack et al., 1993), or for

SE Asia and Indonesia region compare with the published heat

flow data compilation from Smyth

(2010).

3. Build low, expected and high

case heat flow models that are sensible to present-day heat flow

values as guided by global database

and also tectonic setting of the

basin. Currie and Hyndman (2006)

observed that the typical heat flow

for fore arc basins is approx. 40 mW/m2, while for Indonesian back

arc basins it is 76±18 mW/m2.

CONCLUSIONS

The method of deriving heat flow

from BSRs, despite not being new

and highly accurate, is still useful to

evaluate hydrocarbon potential of a

frontier region. It can give significant input for making a quick decision in

evaluating a new area with limited

information. The method can be

applied to any frontier basin where

gas hydrates are present, providing the assumptions to derive the heat

flow are appropriate to local

conditions.

Input parameter assumptions are a

source of uncertainties in estimating heat flow by using the BSR method.

Parameters that are sensitive to the

resultant heat flow estimation include gas

composition (29-35%), thermal conductivity

(±17%), depth conversion (±8%) and seafloor temperature (6-10% for 1 ºC change). In order to

reduce uncertainties and to get a more accurate

estimation, it is important to use real

measurements as much as possible, however when

real data are not available, then care should be

taken when making assumptions for those four components. Another source of error is the

possibly erroneous assumption of the BSR as the

base of GHSZ (MHSZ) in all settings, leading to

disparities between BSR-derived and directly

measured heat flow. This theoretical error can only be solved when real measurements or drilling data

are available.

Table 1. Sensitivity of average seismic velocity

changes to estimated BSR heat flow. The 'Base

case' Dbsr was calculated by using Equations (7)

& (8) for Case 1 and Case 2, respectively. The

Dbsr in other cases was calculated from assumed

single seismic velocity in marine sediments.

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Table 2.

Sensitivity of

seafloor

temperature

and thermal

conductivity

changes to

estimated

BSR heat

flow. Columns

(6) and (7) are

for assumed

average

thermal

conductivity

(see text for

more

explanation).

Figure 5.

Present-day

heat flow at

the surface of

the Earth's

crust (Global

Heat Flow

Database of

International

Heat Flow

Commission)

as compiled

by Pollack et

al. (1993).

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As the BSR heat flow results cover a wide range, it

is advisable to use statistical analysis prior to

using the estimated heat flow as inputs in a

thermal maturity modeling. It is also important to compare the estimation results with the global

heat flow database because the database has been

compiled from direct heat flow measurements.

ACKNOWLEDGEMENTS We would like to thank Dr. J.T. van Gorsel and Dr.

Udrekh Al Hanif for their comments and

corrections that helped to improve this article.

REFERENCES Collett, T. S., 2002, Energy resources potential of

natural gas hydrates: AAPG Bulletin, 86

(11), p. 1971–1992.

Currie, C. A. and R. D. Hyndman, 2006, The

thermal structure of subduction zone back arcs: J. Geophysical Research, 111, B08404,

doi:10.1029/2005JB004024, 22p..

Davie, M. K., O. Y. Zatsepina, and B. A. Buffett,

2004, Methane solubility in marine hydrates

environments: Marine Geology, 203, p. 177–

184. Davis, E. E., R. D. Hyndman, and H. Villinger,

1990, Rates of fluid expulsion across the

Northern Cascadia accretionary prism:

Constraints from new heat flow and

multichannel seismic reflection data: J. Geophysical Research, 95 (B6), p. 8869–

8889.

Dickens, G. R. and M. S. Quinby-Hunt, 1994,

Methane hydrate stability in seawater:

Geophysical Research Letters, 21 (19), p.

2115–2118. Dickens, G. R. and M. S. Quinby-Hunt, 1997,

Methane hydrate stability in pore water: A

simple theoretical approach for geophysical

applications: J. Geophysical Research, 102

(B1), p. 773–783. Franke, D., M. Schnabel, S. Ladage, D. R. Tappin,

S. Neben, Y. S. Djajadihardja, C. Mueller, H.

Kopp, and C. Gaedicke, 2008, The great

Sumatra-Andaman earthquakes: Imaging

the boundary between the ruptures of the

great 2004 and 2005 earthquakes: Earth and Planetary Science Letters, 269, p. 118–

130.

Ganguly, N., G. D. Spence, N. R. Chapman, and R.

D. Hyndman, 2000, Heat flow variations

from bottom simulating reflectors on the

Cascadia margin: Marine Geology, 164, p. 53–68.

Hardjono, T. S. Asikin, and J. Purnomo, 1998,

Heat flow estimation from seismic reflection

anomalies in a frontier area of the Sebakor Sea, Irian Jaya, Indonesia. In: J.L. Rau

(Ed.): Proc. 33rd Session Co-ord. Committee

Coastal Offshore Geosci. Programmes East

and SE Asia (CCOP), Shanghai 1996, 2, p.

56–83.

He, L., J. Wang, X. Xu, J. Liang, H. Wang, and G.

Zhang, 2009, Disparity between measured

and BSR heat flow in the Xisha Trough of

the South China Sea and its implications for the methane hydrate: J. Asian Earth

Sciences, 34, p. 771–780.

Kaul, N., A. Rosenberger, and H. Villinger, 2000,

Comparison of measured and BSR-derived

heat flow values, Makran accretionary

prism, Pakistan: Marine Geology, 164, p. 37–51.

Kvenvolden, K. A., 1988, Methane hydrate—a

major reservoir of carbon in the shallow

geosphere?: Chemical Geology, 71, p. 41–51.

León, R., L. Somoza, C. J. Giménez-Moreno, C. J. Dabrio, G. Ercilla, D. Praeg, V. Díaz-del-Río,

and M. Gómez-Delgado, 2009, A predictive

numerical model for potential mapping of

the gas hydrate stability zone in the Gulf of

Cadiz: Marine and Petroleum Geology, 26, p.

1564–1579. López, C. and G. Y. Ojeda, 2006, Heat flow in the

Colombian Caribbean from the Bottom

Simulating Reflector (BSR): Ciencia,

Tecnología & Futuro, 3 (2), p. 29–39.

Lutz, R., C. Gaedicke, K. Berglar, S. Schloemer, D. Franke, and Y. S. Djajadihardja, 2011,

Petroleum systems of the Simeulue fore-arc

basin, offshore Sumatra, Indonesia: AAPG

Bulletin, 95 (9), p. 1589–1616.

Millero, F., C. Chen, A. Bradshaw, and K.

Schleicher, 1980, A new high pressure equation of state for seawater: Deep Sea

Research, Part A, 27, p. 255-264 (water

density equation was accessed at

http://www.csgnetwork.com/water_density_

calculator.html , on 10th of March, 2015). Pollack, H. N., S. J. Hurter, and J. R. Johnson,

1993, Heat flow from the earth's interior:

Analysis of the global data set: Review of

Geophysics, 31 (3), p. 267–280. (Note: global

heat flow database is also available at

http://www.heatflow.und.edu/ and the colour-coded world heat flow distribution is

available at http://www.geophysik.rwth-

aachen.de/IHFC/heatflow.html)

Shankar, U., N. K. Thakur, and S. I. Reddi, 2004,

Estimation of geothermal gradients and heat flow from Bottom Simulating Refelectors

along the Kerala-Konkan basin of Western

Continental Margin of India: Current

Science, 87 (2), p. 250–253.

Shankar, U. and M. Riedel, 2013, Heat flow and

gas hydrate saturation estimates from Andaman Sea, India: Marine and Petroleum

Geology, 43, p. 434–449

Shankar, U., K. Sain, and M. Riedel, 2014,

Assessment of gas hydrate stability zone and

geothermal modeling of BSR in the Andaman Sea: J. Asian Earth Sci.79, p.

358-365.

Shyu, C.T., Y. J. Chen, S. T. Chiang, and C. S. Liu,

2006, Heat flow measurements over Bottom

Simulating Reflectors, offshore southwestern

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http://www.csgnetwork.com/water_density_calculator.html

http://www.heatflow.und.edu/

http://www.geophysik.rwth-aachen.de/IHFC/heatflow.html

http://www.geophysik.rwth-aachen.de/IHFC/heatflow.html

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Taiwan: Journal of Terrestrial Atmospheric

and Oceanic Sciences, 17 (4), p. 845–869.

Smyth, H., 2010, SE Asia heatflow database:

Accessed online on March 20, 2015 http://searg.rhul.ac.uk/current_research/h

eatflow/index.html

Wang, K., R. D. Hyndman, and E. E. Davis, 1993,

Thermal effects of sediment thickening and

fluid expulsion in accretionary prisms:

Model and parameter analysis: J. Geophysical Research, 98 (B6), p. 9975-

9984.

World Ocean Atlas, 2013,

http://www.nodc.noaa.gov/cgi-

bin/OC5/SELECT/woaselect.pl accessed

online on March 8, 2015. Xu, W. and C. Ruppel, 1999, Predicting the

occurrence, distribution and evolution of

methane gas hydrate in porous marine

sediments: J. Geophysical Research, 104

(B3), p. 5081–5095.

Yamano, M., S. Uyeda, Y. Aoki, and T. H. Shipley, 1982, Estimates of heat flow derived from

gas hydrates: Geology, 10, p. 339–343.

http://searg.rhul.ac.uk/current_research/heatflow/index.html

http://searg.rhul.ac.uk/current_research/heatflow/index.html

http://www.nodc.noaa.gov/cgi-bin/OC5/SELECT/woaselect.pl

http://www.nodc.noaa.gov/cgi-bin/OC5/SELECT/woaselect.pl

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Frontier Exploration Using an Integrated Approach of

Seafloor Multibeam, Drop Core and Seismic Interpretation

– A Study Case from North Banggai Sula Farid Ferdian

Saka Energi Indonesia


EXTENDED ABSTRACT

Exploration in frontier areas is always challenging

and has resulted in the development of various

new technologies including georeferenced, high resolution seafloor multibeam bathymetry and

backscatter. The multibeam bathymetry data

provides sea floor depth information, while the

backscatter data records the amount of acoustic

energy received by the sonar after interactions with

the sea floor and are used to infer seabed features

and materials. Interpretation of these new dataset combined with piston cores and seismic data have

been conducted in the offshore of North Banggai

Sula. This integrated approach has been termed as

SeaSeepTM technology.

Figure 1. Regional Structures Map (After Ferdian, 2010 and Ferdian et al., 2010).

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In 2007, TGS-NOPEC with co-operation of Migas has conducted Indodeep multi-client project which

is comprised of acquiring seafloor multibeam

bathymetry and backscatter, seafloor piston cores

and regional 2D seismic survey across the frontier

areas of Eastern Indonesia, including the study area presented here (Figure 1). Subsequent

publications on the application of these new data (e.g. Decker et al., 2009; Noble et al., 2009; Orange

et al., 2009; Riadini et al., 2009; Ferdian et al.,

2010; Rudyawan et al., 2011 etc.) have given a

new understanding of the geology and hydrocarbon

prospectivity of these frontier areas. One of the publications, entitled “Evolution and hydrocarbon

Figure 2. Seafloor multibeam bathymetry (a) and backscatter (b) of the western portion of study area (After Ferdian, 2010).

Figure 3. Seafloor multibeam bathymetry and backscatter which corresponds with: 3a. Mounded feature

interpreted as mud volcano; 3b. Subsea outcrop due to fault displacement.

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prospects of the North Banggai-Sula area: an

application of Sea SeepTM technology for

hydrocarbon exploration in underexplored areas”

and was written by current author and published in the Proceedings of 2010 IPA Convention, is

summarized here as this extended abstract.

Interpretation of both seabed multibeam

bathymetry and 2D seismic lines has identified

several new structures in the area (Figure 1). In the west, a dextral fault system is clearly identified

which is thought to continue onshore to the Poh

Head of Sulawesi’s East Arm. In this Poh Head

area, an abrupt elevation change with steep-sided

topography most likely indicates a strike-slip fault. Along the slope base of Banggai-Sula

Microcontinent (BSM) a series of relatively south-

verging thrusts is identified. However, these

thrusts are not a single fault system such as the

so-called North Banggai-Sula fault that has been

published by many workers (Hamilton, 1978; Silver, 1981; Silver et al., 1983; Garrard et al.,

1988; Davies, 1990). These thrusts are actually

formed by at least two different events: in the west

it relates to the dextral fault system described

above, while in the east it formed as a southward continuation of the widespread south-verging

thrust due to gravitational slide from the Central

Molucca Sea Collision Zone. In the middle area

where these two structure systems met, a large

scale slip plane was formed at the seafloor.

Multibeam backscatter data show numbers of

anomalously high backscatter areas across the

study area which correspond to locations of fault

lineaments (Figure 2), mud volcanoes (Figure 3a),

authigenic carbonates and possibly outcrops (Figure 3b) [Ferdian, 2010]. The well-positioned of

the piston cores deployed into these anomalies can

give further insights on the sedimentology of the

basin through subsequent geochemical analyses

performed by TDI Brooks. Seven core locations

contain possible migrated liquid hydrocarbon (oil), 5 locations of possible migrated thermogenic gas

and another 5 locations of possible migrated both

oil and gas. Hydrocarbon charges from certain

parts of this area show definite marine

characteristic (Noble et al., 2009) with the Mesozoic marine shale (i.e. Buya Fm.) being the

possible source rocks. REFERENCES Davies, I. C., 1990, Geology and exploration review

of the Tomori PSC, eastern Indonesia:

Indonesian Petroleum Association, Proceedings of the 19th Annual Convention,

p. 41–68.

Decker, J., S. C. Bergman, P. A. Teas, P. Baillie,

and D. L. Orange, 2009, Constraints on the

tectonic evolution of the Bird’s Head, West

Papua, Indonesia: Indonesian Petroleum

Association, Proceedings of the 33rd

Convention and Exhibition. Ferdian, F., 2010, Evolution and hydrocarbon

prospect of the North Banggai-Sula area: an

application of Sea SeepTM technology for

hydrocarbon exploration in underexplored

areas: Indonesian Petroleum Association,

Proceedings of the 34th Convention & Exhibition.

Ferdian, F., R. Hall, and I. Watkinson, 2010,

Structural re-evaluation of the north

Banggai-Sula, eastern Sulawesi: Indonesian

Petroleum Association, Proceedings of the 34th Convention and Exhibition.

Garrard, R. A., J. B. Supandjono, and Surono,

1988, The geology of the Banggai-Sula

microcontinent, eastern Indonesia:

Indonesian Petroleum Association,

Proceedings of 17th Annual Convention, p. 23–52.

Hamilton, W., 1978, Tectonic map of the

Indonesian Region: U.S. Geological Survey

Map G78156.

Noble, R., D. Orange, J. Decker, P. A. Teas, and P. Baillie, 2009, Oil and Gas Seeps in Deep

Marine Sea Floor Cores as Indicators of

Active Petroleum Systems in Indonesia:

Indonesian Petroleum Association,

Proceedings of the 33rd Convention and

Exhibition. Orange, D., J. Decker, P. A. Teas, P. Baillie, and T.

Johnstone, 2009, Using SeaSeep Surveys to

Identify and Sample Natural Hydrocarbon

Seeps in Offshore Frontier Basins:

Indonesian Petroleum Association, Proceedings of the 33rd Convention and

Exhibition.

Riadini, P., A. C. Adyagharini, A. M. S. Nugraha, B.

Sapiie, and P. A. Teas, 2009, Palinspastic

reconstruction of the Bird Head pop-up

structure as a new mechanism of the Sorong fault: Indonesian Petroleum Association,

Proceedings of the 33rd Convention and

Exhibition.

Silver, E. A., 1981, A New Tectonic Map of the

Molucca Sea and East Sulawesi, Indonesia With Implications for Hydrocarbon Potential and Metallogenesis. In: Barber, A. J. and

Wiroyusujono, S. (Editors). The Geology and

Tectonics of Eastern Indonesia: Geological

Research and Development Centre – Special

Publication No. 2 Pergamon Press. Silver, E. A., R. McCaffrey, Y. Joyodiwiryo, and S.

Stevens, 1983, Ophiolite emplacement and

collision between the Sula platform and the

Sulawesi island arc, Indonesia: Journal of

Geophysical Research, 88, p. 9419–9435.

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Marine Expeditions in Indonesia during the Colonial Years Prepared by Herman Darman based on 2005 publication by van Aken


During the colonial years there was little support

from the Netherlands government for non-applied

scientific work. The colonies had to pay for themselves and had to be profitable for the

Netherlands; science was not considered to be a

good investment. Nevertheless, a number of

important oceanographic expeditions took place,

for example, the Siboga and Snellius expeditions.

Both were named after the ships that carried the scientists and both were paid for by the

Netherlands government. The objective was to

prove that the Dutch Indies were not only the best

governed, but also the scientifically most developed

tropical colony. Moreover there were the Dutch who needed to consolidate colonial rule by showing

the flag over the whole archipelago. Germans,

British, Americans and Japanese were encroaching

on the Far East (New Guinea, Philippines,

Malaysia and Taiwan) and in some ways the

expedition can be considered as ‘gunboat science’. Even so, vast amount of prime oceanographical,

hydrographical, biological and geological data were

collected with state-of-the-art equipment.

The Siboga expedition (1899-1900, Figures 1 and

2) was executed with an adapted gunboat made

available and paid for by the colonial government. It was very much biologically oriented (Figure 3),

but useful oceanographical data were also

collected. Some 238 depth soundings were added

to the 50 already measured, but few purely

geological data were collected. Of interest is the

fact that a female scientist, Mrs. Weber-Van Bosse (Figure 4), specialist in algae, participated in the

entire trip; she was probably the first woman in

the history of oceanography to serve in such a role.

She also was the wife of the leader of the

expedition, the biologist Max Weber, but she fully earned her keep and published three monographs

on the algae collected during the expedition.

Amongst other things she proved beyond doubt,

that coccoliths are of organic origin and belong to

the algae (Weber-Van Bosse, 2000). She received

an honorary doctorate from Utrecht University in 1910, another first in history for a Dutch woman.

Figure 1. The Siboga at sea (source: http://hydro-international.com &

http://nl.wikipedia.org/wiki/Siboga-expeditie).

Figure 2. The Siboga expedition trips 1, 2 and 3. (source: van Aken, 2005).

http://hydro-international.com/

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The Snellius expedition (1929-1930,

Figures 4, 5 and 6) focused on the physical

and chemical oceanography of the deep

basins of the East Indies and the geology of its coral reefs. Again the government

provided the ship, this time built as a

scientific vessel, named it after one of the

greatest Dutch scientists Snel(lius) van

Royen and paid for the expedition

expenses. The expedition leader was P. M. van Riel, a retired naval officer, head of

oceanography and maritime meteorology at

the Royal Meteorological Institute of the Netherlands (Koninklijk Nederlands Meteorologisch Institut, KNMI). On board

was also Philip Kuenen (Figure 4), who was to become an internationally

renowned sedimentological and marine

geologist at Groningen University. A total

of 374 station soundings were recorded

and over 500 bottom samples were

collected during three trips. Regular shore parties were organized to visit the coral

islands and to study their geology. The

echo sounder was in nearly constant use,

resulting in 33,000 measurements and

this alone immensely improved our knowledge of these deep-sea tract.

Study of the vast amount of data collected

by the expedition was greatly delayed,

especially as far as the purely

oceanographic data were concerned, but also the geological and biological data

proved too much to be quickly dealt with. This is

aptly demonstrated by the fact that, as late as

1978, an article was published on the foraminifers

from the Snellius expedition, as a final addition to the already published 23 volumes of Snellius

reports (Figure 7).

Figure 3. Cover of a report from Siboga Expedition, a collection of the Naturalist Museum,

Leiden, the Netherlands (photo by H. Darman).

Figure 4. Left: Anne Antoinette Weber-van Bosse (1852-1942); Source:

Wikipedia (left); and Right: Philip H. Kuenen (1902-1976); Source: http://resources.huygens.knaw.nl/bwn1880-2000/lemmata/bwn5/kue

nen).

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REFERENCES

Boekschoten, B. et al., 2012, Dutch Earth

Sciences: Development and Impact, Royal

Geological and Mining Society of the

Netherlands, 1912-2012 Centenary Volume. http://resources.huygens.knaw.nl/bwn1880-

2000/lemmata/bwn5/kuenen)

http://hydro-international.com http://nl.wikipedia.org/wiki/Siboga-expeditie

van Aken, H. M., 2005, Dutch oceanographic

research in Indonesia in colonial times: Oceanography 18(4), p. 30–41.

Figure 5. Snellius expedition 1929-1930 (1st trip) (Boekschoten. et al., 2012).

Figure 6. The Hr. Ms. Snellius ship at sea (Boekschoten. et

al., 2012).

Figure 7. Example of a Snellius expedition report in the Naturalist Museum, Leiden, the Netherlands (Photo

by H. Darman).

http://hydro-international.com/

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.

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Berita Sedimentologi BIOSTRATIGRAPHY OF SE ASIA – PART 2

Number 30 – August 2014

the indonesian sedimentologists forum (fosi)

Documents