Proceedings of International Conference on Geological Engineering
Geological Engineering Department, Engineering Faculty, Gadjah Mada University
December, 11-12 2013
iii
Message from Head of Geological Engineering Department,
Gadjah Mada University
This proceeding consists of selected papers presented on the International
Conference on Geological Engineering (ICGE) held in Yogyakarta, Indonesia, December
11–12, 2013, which is hosted by Geological Engineering Department, Faculty of
Engineering, Universitas Gadjah Mada (GED-UGM). The ICGE 2013 conference is the
first year program on Geological and Georesources Engineering on phase III of
AUN/SEED-Net. As the host institution for ICGE 2013, GED-UGM becomes the center
for the continuation of international relationships in geological and georesources
engineering fields.
The ICGE 2013 that addresses strengthening geo-resources and geo-engineering
management for green economic growth accommodate for more than 12 various topics
related to geological and georesources engineering discussed in this conference. Those are
earth resources, exploration geosciences, environmental geosciences, hydrogeology, slope
stability, landslides susceptibility, rock mechanics, strategic development, mineral
resources, safety management, mineral processing techniques, industrial minerals, and
more topics that related to geological engineering. ICGE 2013 aims at creating dialogue
between academics, experts, governments, and industries as well as those who have
interest in addressing those issues in the international level. We expect solutions for the
problems arise from the participants during this event to be adopted to help resolve global
geological engineering problems.
Sponsorship of this meeting is an important feature of its success. On behalf of the
host institution Geological Engineering Department, Faculty of Engineering, Universitas
Gadjah Mada, we thank the sponsors who have helped to promote the meeting and
supported the events.
I wish this proceeding can give a big contribution for developing research and
invention in the geological and georesources engineering field in the ASEAN countries as
well as all around the world.
Respectfully Yours,
Dr. Sugeng Sapto Surjono
Head of Geological Engineering Department
Faculty of Engineering
Universitas Gadjah Mada
Proceedings of International Conference on Geological Engineering
Geological Engineering Department, Engineering Faculty, Gadjah Mada University
December, 11-12 2013
ii
FOREWORD
First of all, I would like to express my sincere thanks to all of you for participating in
this International Conference on Geological Engineering (ICGE) held in Yogyakarta
Indonesia, December 11–12, 2013 with the theme of “Strengthening geo-resources and
geo-engineering management for green economic growth”.
More than 12 various topics related to geological engineering are discussed during the
conference. Those consist of earth resources, exploration geosciences, environmental
geosciences, hydrogeology, slope stability, landslides susceptibility, rock mechanics,
strategic development, mineral resources, safety management, mineral processing
techniques, industrial minerals, and others that related to geo-resources and geo-
engineering aspects.
The call for papers attracted 52 submissions from 10 different countries and over 15
different institutions. The program committee accepted 42 papers that cover all of the
topics related to the georesources and geological engineering to be published in this ICGE
2013 proceeding. In addition, the program includes a panel of georesources and geological
engineering expertise from academic, governments, and industries. Hence, this conference
truly serves as an international forum for geoscientists and other stakeholders in providing
an interesting and multidimensional views, knowledge, and relevant information on
georesources and geological engineering.
Finally, we would like to thank to the AUN/SEED-Net, which initiated and support
this event and Geological Engineering Department, Gadjah Mada University as host
institution of the ICGE 2013. Thank also to the sponsorships for their support to this
conference. Special thank to the board of organizing committee, whose effort and hard
work reflecting their commitment to this conference.
Yogyakarta, December 11-12, 2013
Dr.rer.nat. Arifudin Idrus
Chief of organizing committee
ICGE 2013
Proceedings of International Conference on Geological Engineering
Geological Engineering Department, Engineering Faculty, Gadjah Mada University
December, 11-12 2013
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TABLE OF CONTENTS
Cover Page .................................................................................................................... i
Foreword ....................................................................................................................... ii
Message from Head of Geological Engineering Department-UGM ............................ iii
Table of Contents ......................................................................................................... iv
EARTH RESOURCES TOPICS
KS01 Understanding The Natural Changes of Volcano-Hosted Geothermal
System and Its Implication to The Field Development
Utami, P.,........................................................................................................ 1
ER01 Granitic Magmatism in Sulawesi Island, Indonesia; Implication for
Metallogenic Province
Maulana, A., Watanabe, K., Yonezu, K., and Imai, A., .................................. 2
ER02 Relationship Between Granitoid Types and Tin Mineralization: A Review
Of Tertiary Granitoids in Central Granitoid Belt, Myanmar
Myint, A.Z., Watanabe, K., and Yonezu, K., ................................................... 13
ER03 Geochemistry and Alteration Facies Associated with High-Sulfidation
Epithermal Mineralization At Cijulang Prospect, Garut, West Java
Tun, M.M., Warmada, I.W., Idrus,A., Harijoko, A.,
Verdiansyah, O., and Watanabe, K., .............................................................. 22
ER04 Potential of Primary Gold Mineralization Within The Upper Sungai Galas
Prospect, Gua Musang, Kelantan, Malaysia
Ariffin, K.S., Nakamura, K., Takahashi, R., Cheang, KK.,
and Zabidi,H.M., ............................................................................................ 34
ER05 Jadeite Jade from South Sulawesi in Indonesia and Its Geological
Significance
Setiawan, N.I., Osanai, Y., Nakano, N., and Adachi, T., ................................ 40
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December, 11-12 2013
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ER06 Magnetic Susceptibility and Mineral Exploration: Case Study of Granitic
Rocks in Cambodia
Kong, S., Watanabe, K., and Imai, A., ............................................................ 57
ER07 Geostatistics Model for Original Gas in Place (OGIP) Estimation
Muchalintamolee, N., Udomlaxsananon, P., Summapo, S.,
and Pumjan, S.,............................................................................................... 63
ER08 Sphalerites’ Mineral Chemistry and Sulphidation State of Polymetallic
Epithermal Quartz Veins at Soripesa Prospect Area, Sumbawa Island,
Indonesia
Khant, W., Warmada, I.W., Idrus, A., Setijadji, L.D., and Watanabe, K., ..... 70
ER09 Ore and Alteration Mineralogy of Muara Bungo Gold Prospect, Jambi
Province: Implication for Deposit Genesis
Hakim, F., Idrus, A., and Sanjaya, I., ............................................................. 80
ER10 Characterization of Maar Deposits from Ranu Segaran, Ranu Agung and
Ranu Katak, as Well Magmatic Evolution that Form Maar Eruption in
Tiris District, Probolinggo Regency, East Java
Prakosa, B.B., Harijoko, A., and Warmada, I.W., ......................................... 87
ER11 Ore and Alteration Mineralogy of Paningkaban-Cihonje Gold Prospect,
Gumelar Sub-District, Banyumas Regency, Central Java: A New
Discovery of Carbonate Base Metal Gold Epithermal Deposit
Idrus, A., Hakim, F., Kolb, J., Appel. P., and Aziz, M., .................................. 100
ER12 Progress on Rare Earth Elements (REE) Research in Indonesia 2008-2013
Setijadji, L.D., Warmada, I.W., Yonezu, K., and Watanabe, K., .................... 113
ER13 The Dioritic Alteration Model of The Randu Kuning Porphyry Cu-Au Ore
Deposit, Selogiri Area, Central Java, Indonesia
Sutarto., Idrus, A., Meyer, F.M., Harijoko, A., Setijadji, L.D., Dany, R., ...... 122
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December, 11-12 2013
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EXPLORATION GEOSCIENES TOPICS
XG01 Potential Use of Synthetic Aperture Radar (SAR) Data for Geothermal
Exploration
Saepuloh, A., ................................................................................................... 132
XG02 Sedimentary Facies of Middle Miocene Balikpapan Formation, Samarinda
Area, Lower Kutai Basin, Indonesia
Win, C.T., Surjono, S.S., Amijaya, D.H., Husein, S., Watanabe, K.,
and Astuti, B.S., .............................................................................................. 139
XG03 “Unconventional Reservoir” Shale Gas Potential Based on Source Rock
Analysis in Sumatran Back Arc Basin
Wibowo, R.C., ................................................................................................. 151
XG04 Facies Analysis and Depositional Environments of The Ngrayong
Formation in The West Madura Area, North-East Java Basin, Indonesia
Htwe, P., Surjono, S.S., Amijaya, D.H., Sasaki. K., and Khemera. D., .......... 164
XG05 DHI Skimming, A Proposed Seismic Interpretation Technique for Quick
Reading on Speculative Hydrocarbon Fields
Zulfadli., Surjono, S.S., ................................................................................... 177
XG06 Inversion Analysis of AIGI in Seismic Data for Hydrocarbon
Identification in Sandstone Reservoir, Case Study in Mustika Field, Kutai
Basin, East Kalimantan
Asrim., Nugraha, T., Wintolo, D., and Setyowiyoto, J., ................................. 187
XG07 Relationship Between Rock Eval Pyrolysis Data and Abundance of
Liptinite Macerals in Shale of Talang Akar Formation, South Sumatera
Basin
Novianti, W., and Amijaya, D.H., ................................................................... 203
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Geological Engineering Department, Engineering Faculty, Gadjah Mada University
December, 11-12 2013
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ENVIRONMENTAL GEOSCIENCES TOPICS
EG01 Estimation of Strong Ground Motion in Palu, Indonesia
Thein, P.S., Pramumijoyo, S., Brotopuspito, K.S., Wilopo, W.,
Kiyono, J., and Setianto, A ., .......................................................................... 211
EG02 Seismic Microzonation of The Populated Urban Area Using Densely
Single Microtremor Observations [Case Study: Yogyakarta City-
Indonesia]
Kyaw, Z.L., Pramumijoyo, S., Husein, S., Fathani, T.F., and Kiyono, J., ...... 226
EG03 Investigation and Assessment of The Earthquake Hazards in Myanmar:
Background, Characterization, Causes, and Mitigation Measures
Kham, N.M., and Htun, K., ............................................................................. 241
EG04 Development of Seismic Microzonation Maps of Mandalay City,
Mandalay Region, Myanmar
Thant, M., Mon, C.T., Tin, T.H., Oo, K.K.K., Aung, L.T., Win, Z.M.,
Tun, N.T., Soe, M.Y., and Kawase, H., ........................................................... 258
EG05 A Sustainable Solution to Disposal Problem of Mine Tailings
Adajar, M.A.Q., and Zarco, M.A.H., .............................................................. 274
EG06 Shoreline Changes and Its Influence for Level of Coastal Vulnerability
Sirajuddin, H., Suriamihardja, D.A., Imran, A.M., and Thaha, M.A., ........... 289
GROUNDWATER AND HYDROGEOLOGY TOPICS
GH01 The Type of Water in Spring Water Hydrogeochemistry in The Eastern
Flank of Mount Merapi, Boyolali and Klaten District, Central Java,
Indonesia
Santi, N., Hendrayana, H., and Putra, D.P.E., .............................................. 299
Proceedings of International Conference on Geological Engineering
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December, 11-12 2013
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GH02 Determination of Suitable Groundwater Quality for Agriculture by Using
Gis Application, Bantul Regency, Yogyakarta Special Province, Indonesia
Kong, C., Hendrayana, H., and Setianto, A., ................................................. 304
GH03 Study on River Morphology, Gravel-Sand Depositions and Tests for Civil
Engineering Purposes, Case Study River Nam Ma, Xiengkhor, Ad and Sop
Bao Districts, Houaphanh Province
Visane, N., Sitha, and Phommasone ............................................................... 317
LANDSLIDE SUSCEPTIBILITY TOPICS
LS01 Development of A Rapid Condition Assessment Tool for Landslide
Susceptibility in The Philippines
Victor, J.A.S., and Cristobal Jr, R.A., ............................................................ 331
LS02 Community Empowerment Program of Landslide Hazard in Sepanjang
Village
Yanto, E., Andaru, A., Rudianto., Indrawan, I.G.B., and Wilopo, W., ........... 345
ROCK MECHANICS TOPICS
RM01 Piles Foundation in Phnom Penh Capital of Cambodia
Sieng, P., ......................................................................................................... 352
RM02 Strengthening Soft Soil by Electro-Kinetic Method Case Study Clayey
Soil From Ngawi Regency, East Java, Indonesia
Thuy, T.T.T., Putra, D.P.E., Budianta, W., and Hazarika, H., ....................... 371
RM03 Numerical Study of Storage Capacity and Potential Ground Uplift Due to
CO2 Injection Into Kutai Basin by Using Coupling Hydromechanical
Simulator
Arsyad, A., and Samang, L., ........................................................................... 382
Proceedings of International Conference on Geological Engineering
Geological Engineering Department, Engineering Faculty, Gadjah Mada University
December, 11-12 2013
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SAFETY MANAGEMENT
SM01 Threat, Hazard, Risk and Vulnerability Assessment of Merapi Volcano in
Yogyakarta, Indonesia
Brunner, I.M.I.M., and Setianto, A., ............................................................... 392
STRATEGIC DEVELOPMENT ON MINERAL RESOURCES TOPICS
SD01 Strategies for Sustainable Mining: A Case of Lead (Pb) Mining in Thailand
Boonpramote, T., ............................................................................................ 402
MINERAL PROCESSING TOPICS
KS02 Soil Reinforcement Using Calcium Phosphate Compounds
Kawasaki, S., and Akiyama, M., ..................................................................... 412
MP01 Hydrometallugical Process for Poor Zinc Oxide Ores
Dang, V.H., Dang, T.V., ................................................................................. 422
MP02 The Influence of Coal Ash Content Relating to Slagging nd Fouling on Its
Utilization as Direct Combustion
Gany, M.U.A., ................................................................................................. 430
MP03 Precursors of Coal in The Kutai Basin, East Kalimantan, Indonesia: Result
From Gas Chromatography Mass Spectrometry
Widodo, S.,...................................................................................................... 436
INDUSTRIAL MINERALS TOPICS
IM01 Carbon Dioxide Mineral Sequestration by Using Industrial Waste Gypsum
Junin, R., Rahmani, O., and Azdarpour, A., ................................................... 451
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DHI SKIMMING, A PROPOSED SEISMIC
INTERPRETATION TECHNIQUE FOR QUICK
READING ON SPECULATIVE HYDROCARBON
FIELDS
Zulfadli1, Sugeng S. Surjono
2
Geological Engineering Dept., Faculty of Engineering, Universitas Gadjah Mada
Jl. Grafika No.2. Yogyakarta, 55281, Indonesia, 1E-mail: [email protected],
2 E-mail: [email protected]
Received: November 15, 2013
Abstract
Seismic exploration for finding new hydrocarbon field is a real challenge today. Exploration
success even more crucial this day because of the greater pressure from expensive survey activities
and complex subsurface interpretations. Those issues sometimes drop the spirit to discover new
hydrocarbon fields. In order to help providing solution, we try to propose DHI Skimming. This
technique performs a quick reading of Direct Hydrocarbon Indicator (DHI) in the exploration area
covered by 3D seismic data and helps to shape the focus of exploration since early phase. DHI
Skimming particularly looks for bright spot and flat spot based on energy seismic attribute as the
earliest indicator of the hydrocarbon accumulation presence. It treats them as DHI-Energy
anomalies that predominantly associated with gas reservoirs. We introduce the concept of DHI
Skimming together with usage conditions, confirmation steps, and the interpretation result on
Dutch Offshore F3 Block, North Sea.
DHI Skimming successfully detected existence of eight speculative fields and a regional
distribution of deeper potential reservoir. Seismic structural interpretation found some faults as
structural controls on several fields indicated the presence of hydrocarbon migration path.
Advanced seismic interpretation tested one of the speculative fields with some confirmation
techniques, which showed consistency in the prospective values. These results demonstrate the
effectiveness of speculative hydrocarbon fields detection using DHI Skimming. This technique is
able to provide early anticipation for subsurface uncertainty and to strengthen decision making in
order to avoid exploration failures.
Keywords: Direct Hydrocarbon Indicator, Seismic Attributes, Speculative Hydrocarbon Field
Introduction
Southeast Asia holds significant prospect of undiscovered hydrocarbon resources together
with its risk. An assessment within 23 geologic provinces in Southeast Asia finds that more
than 90 percent of undiscovered resources are offshore, and there are more than twice of
undiscovered gas resources (49,794 MMBOE) than undiscovered oil resources (21,632
MMBO) [1]. Those opportunities are transformed into some exploration changes
correlated with major industry investment: 1) exploration trend shifts from well-explored
areas to least-explored areas, 2) exploration activities move from onshore to offshore
(including deep-water), and 3) exploration target changes from oil to gas [2]. Nonetheless,
these huge opportunities are also accompanied by trembling challenges. In Indonesia, some
major players tapped to very expensive deep-water projects decided to return their blocks
after discovering their exploration wells turned out to be dry holes [3]. This fact reflects
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that geological complexity of subsurface [4] can be very challenging for any exploration in
the least-explored area to become a successful discovery. This situation needs new
solutions to deal with the problems of subsurface uncertainty for exploring new petroleum
fields.
A very common way to observe the prospect of any seismic exploration area is by
looking for anomalies in seismic amplitude. Direct Hydrocarbon Indicator (DHI) is
important seismic amplitude phenomena, especially bright spot and flat spot, related with
presence of hydrocarbon accumulation and reservoir detection [5,6,7,8]. DHI commonly
relates to gas rather than oil reservoirs because the effect on acoustic properties of gas in
the pores is greater than oil [5]. The problem of using DHI comes from the facts that not
only hydrocarbon accumulations can be represented by amplitude anomalies as bright
spots and they may lead to dry holes drilling [5,6,8]. This problem is solved by some
confirmation/validation steps to ensure the DHI truly represents oil or gas reservoirs, in
form of question lists or additional techniques [6,8].
Figure 1. Netherlands geographical and geological map showing location of 3D seismic
survey on F3 Block as the data for this study [9,10, with minor modification].
We propose DHI Skimming to help solving the prospect identification problem at least-
explored areas and ambiguous representation problem of DHI. We introduce DHI
Skimming as a technique to do quick reading of DHI to shape the prospective focus of
exploration area covered by 3D seismic data. We equip this technique with some
confirmation steps to ensure the skimming result is related with hydrocarbon accumulation.
We tested this technique on Dutch Offshore F3 Block 3D seismic dataset (Figure 1) to
provide open opportunity for anyone to review our idea freely. We hope this technique can
be applied in Southeast Asia for increasing successful ratio of new petroleum field
(Wong, et al., 2007; Schroot & Schüttenhelm, 2003; with minor modification)
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exploration in the future. This publication will focus on discussing concept of DHI
Skimming together with its usage conditions, confirmation steps, and the result on F3
Block.
DHI Skimming
Concept
DHI Skimming allows enhancement of seismic data visualization by running energy
attribute as pre-identification tool for detecting speculative hydrocarbon fields. This
seismic attribute can be used to perform a quick reading of energy related with seismic
amplitude anomalies to characterize acoustic rock properties and bed thickness [11].
Energy attribute calculates the squared sum of the sample values in the specified time-gate
divided by the number of samples in the gate [11]. Without need to consider the positive-
negative signs, we can find that the higher the amplitude values, the higher the energy
values. Since seismic amplitude relates with DHI [5,6,7,8,10], then energy attribute
reading can be correlated to DHI too. We call the result of DHI Skimming as DHI-Energy
objects, either in 2D profiles or 3D geobodies. This is the basic concept of DHI Skimming.
The difference between DHI from common seismic amplitude observation and DHI-
Energy from DHI Skimming happens on capability of reservoir separation (Figure 2a and
2b). DHI Skimming only finds the reservoir without knowing its layers as detail as
common DHI observation. The positive side of using DHI Skimming is its capability to
rapidly scan entire seismic data as quantitative approach that can be confirmed multiple
times later. DHI Skimming also provides opportunity to directly model the DHI-Energy in
form of geobody objects relate with potential reservoirs (Figure 2c). Together with its
usage conditions and confirmation steps, the superiority of DHI Skimming can be useful
for increasing awareness to anticipate speculative prospects, focusing exploration targets in
more detail, avoiding further exploration failures, and hopefully shortening exploration
phase.
Figure 2. Visual comparison of (a) common DHI profile, (b) 2D DHI-Energy profile, and
(c) 3D DHI-Energy geobody. The DHI-Energy object is the DHI Skimming detection
result.
Common DHI profile DHI-Energy in 2D profile DHI-Energy in 3D geobody
a b c
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Usage conditions
We propose DHI Skimming on several usage conditions based on standard requirement
from some references and our test on F3 Block 3D seismic dataset. The usage conditions of
DHI Skimming cover some aspects as follow:
Seismic data setting:
DHI Skimming needs zero-phased 3D seismic data (inferred from [5,6])
Confirmation steps:
DHI Skimming result extremely needs to be confirmed (inferred from [5,6,8])
Availability of additional data:
DHI Skimming needs well logs data (even from dry holes) for going through
advanced confirmation steps
Early detection:
DHI Skimming is intended to do early detection only. It can not replace advanced
reservoir characterization methods (e.g. AVO analysis, core analysis)
Confirmation steps
We equip DHI Skimming with some confirmation steps to ensure the results directly
represent hydrocarbon accumulations. The confirmation steps consist of two main parts i.e.
standard and advanced confirmations. Standard confirmation steps verify the DHI-Energy
objects are hydrocarbon accumulations by investigating connectivity of fault and presence
of some DHI types (i.e. bright spot, flat spot, and polarity reversal). Advanced
confirmation steps verify the DHI Skimming result by using spectral decomposition,
seismic inversion, and neural network porosity inversion. The idea of those confirmation
steps are developed from some confirmation questions for common DHI observation [6]
and available techniques to study seismic reservoirs [5,11,12].
This publication will discuss the application of standard confirmation steps dominantly.
The advanced ones will be explained in concise way only. Table 1 shows the list of
confirmation steps for verifying DHI Skimming result.
Table 1 Confirmation Steps to Verify DHI Skimming Result
Confirmation Types Steps
Standard Confirmation Finding fault connecting two reservoirs
Finding bright spot, flat spot, and polarity reversal in a reservoir
Advanced Confirmation
Applying spectral decomposition on the reservoir
Applying seismic inversion on the reservoir
Applying neural network porosity prediction on the reservoir
The standard confirmation steps begin with finding fault as hydrocarbon migration path
[5,6]. This fault should be clearly connected with two different level reservoirs (deeper vs.
shallower) to ensure it is really eligible as hydrocarbon migration path. In this fault
confirmation step, we need to define the fault, two reservoirs on different level as DHI-
Energy objects (preferably in 3D geobodies), and their clear connectivity based on seismic
data structural interpretation.
The next standard confirmation step is to completely find three DHI types in one
reservoir. They are bright spot, flat spot, and polarity reversal. Bright spot is responsible to
show hydrocarbon presence, especially gas [5,10]. Since bright spot is non-unique
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indicator, we need to find flat spot to make a better confirmation [5,6,8]. Flat spot is more
powerful than bright spot because it can show the unique character of fluids i.e. flat
hydrocarbon-water contact [5,8]. Flat spot also relates with good reservoir thickness [5], so
it can also indicate economic potential of the reservoir. We can still ensure more by finding
polarity reversal. Polarity reversal can be correlated with situation where water sand has
higher acoustic impedance than the embedding shales [5]. This is very important indicator
because we can surely know that our reservoir contains hydrocarbon and water, which
confirms DHI Skimming really detected petroleum accumulation. This DHI types finding
step will be ideally useful in Tertiary clastics (inferred from [5]).
The advanced confirmation steps allow specific examinations on reservoirs that passed
standard confirmations. Spectral decomposition will be able to reveal stratigraphic and
reservoir intricacies [5]. Seismic inversion will be able to construct acoustic impedance
variation in the subsurface [6,12] allowing easier interpretation on reservoir layers and
building relationship to porosity [5]. Neural network porosity prediction will be able to
construct porosity volume and study the reservoir characteristic [11].
Figure 3. DHI Skimming detected DHI-Energy anomalies on F3 Block 3D seismic dataset.
The result of DHI Skimming showed 8 speculative reservoirs on Upper North Sea Group
(green geobodies) and 1 regional potential reservoir on Chalk Group (yellow geobody).
Results and Discussions
DHI Skimming result
The result of DHI Skimming on Dutch Offshore F3 Block 3D seismic dataset showed eight
speculative reservoirs and a regional distribution of deeper potential reservoir in form of
DHI-Energy geobodies (Figure 3). In this stage, we used DHI Skimming to read entire
= DHI-Energy geobodies on Upper North Sea Group
= DHI-Energy geobody on Chalk Group
Tulip Alpha
Tulip Sigma
Tulip Sigma
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seismic data for finding significant energy anomalies and then we converted them into
speculative reservoir geobodies. The eight speculative reservoirs were detected on Upper
North Sea Group, and the deeper regional potential reservoir was on Chalk Group. Chalk
Group has hydrocarbon play dominated by oil, and hydrocarbon play for Upper North Sea
Group is dominated by gas [13,10].
We selected the biggest reservoir on Upper North Sea Group and named it “Tulip
Alpha”. We also named the regional potential reservoir on Chalk Group as “Tulip Sigma”
(Figure 3). Our target reservoir in this publication is Tulip Alpha. We will test it by using
standard and advanced confirmation steps to examine whether this DHI Skimming result
really correlates with hydrocarbon accumulation or not.
Standard confirmation steps
The first standard confirmation step is finding fault that connecting two reservoirs. Our
target reservoir in this publication is Tulip Alpha, and another reservoir to pair with is
Tulip Sigma as a deeper one. We found a regional normal fault connecting Tulip Sigma to
Tulip Alpha on this standard confirmation step (Figure 4). This confirmation step passed
Tulip Alpha as a speculative reservoir that has hydrocarbon migration path and direct
connection with other reservoir.
This first confirmation step ensured that Tulip Alpha has a historical connection with
Tulip Sigma through the normal fault. Since both of them show good DHI-Energy
anomalies, then we can increase our confidence to decide that these reservoirs have greater
probabilities containing hydrocarbon accumulations.
Figure 4. Standard confirmation step on DHI-Energy profiles by finding connecting fault
between Tulip Alpha and Tulip Sigma. A regional normal fault (green curve) is found and
clearly observed on seismic data connecting the reservoirs.
Tulip Alpha
Tulip Sigma
Tulip Sigma
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The second standard confirmation step is completely finding three DHI types on Tulip
Alpha as our target reservoir. The three DHI types are bright spot, flat spot, and polarity
reversal. We found all of them on this standard confirmation step at Tulip Alpha. This
confirmation step passed Tulip Alpha as a speculative reservoir that has confirmed
qualitative DHIs relate with potential hydrocarbon accumulation.
This second confirmation step ensured that Tulip Alpha fulfills the requirement to
become a hydrocarbon reservoir based on tight qualitative observation at its amplitude
anomalies. Besides the presence of bright spot, we also found flat spot and polarity reversal
on Tulip Alpha. Flat spot presence indicates this reservoir is thick enough, so we can think
that Tulip Alpha is an economic reservoir regarding its thickness (inferred from [5]).
Polarity reversal presence indicates there is fluids lateral change on this reservoir, so we
can think that Tulip Alpha has greater probability contains water and hydrocarbon (inferred
from [5]). The result of second standard confirmation step on Tulip Alpha is shown on
Figure 5.
Figure 5. Standard confirmation step on DHI-Energy profile by completely finding bright
spot, flat spot, and polarity reversal on Tulip Alpha. Those three DHI types are
successfully found by using qualitative observation on seismic data.
Advanced confirmation steps
Advanced confirmation steps on Tulip Alpha consist of applying spectral decomposition,
seismic inversion, and neural network porosity prediction. All of these steps examine Tulip
Alpha based on frequency response to hydrocarbon presence, acoustic impedance of
petroleum-filled reservoir, and its predictive porosity value (Figure 6).
We used Continuous Wavelet Transform (CWT) as the spectral decomposition
technique on Tulip Alpha. The result on low frequency showed that Tulip Alpha has strong
indicator to be a hydrocarbon reservoir, based on hydrocarbon attenuation effects. The
Bright spot
Flat spot
Polarity reversal
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result also showed that eastern part of Tulip Alpha is more prospective than its western
part (Figure 6a).
Figure 6. The results of advanced confirmation steps on Tulip Alpha as DHI-Energy
profile by doing (a) CWT spectral decomposition, (b) seismic colored inversion, and (c)
neural network porosity prediction. These confirmation steps consider Tulip Alpha as a
prospective reservoir on Dutch Offshore F3 Block.
a
b
c
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We used Seismic Colored Inversion (SCI) to get acoustic impedance value on Tulip
Alpha. The result showed the clear layering of Tulip Alpha that relates with fluid contents.
The result also showed distinct separation between this reservoir and its non-reservoir
environment around it (Figure 6b).
We used supervised neural network to do porosity prediction on Tulip Alpha. The
result showed a very good porosity value of Tulip Alpha i.e. 35-40% (Figure 6c). This
porosity prediction step gave a great closure of confirmation steps on Tulip Alpha as one
of DHI Skimming result.
All of those advanced confirmation steps passed Tulip Alpha as a prospective reservoir
in Dutch Offshore F3 Block. This final result confirmed Tulip Alpha, as one of DHI-
Energy objects from DHI Skimming, is strongly correlated with hydrocarbon
accumulation. This result also proved effectiveness of DHI Skimming and its confirmation
steps to do a quick reading on speculative hydrocarbon fields.
DHI Skimming is intended to be a tool for early detection of speculative prospects
only. The strength of using DHI Skimming is its capability to scan entire seismic data and
to quickly reveal speculative reservoirs as DHI-Energy anomalies in there. Although the
result of DHI Skimming and its confirmation steps are really good, they still can not be
considered as final exploration decision directly.
Conclusion
DHI Skimming as a proposed seismic interpretation technique for speculative hydrocarbon
fields quick reading successfully found eight speculative reservoirs and one regional
distribution of deeper reservoir from the seismic data. This preliminary findings
demonstrated detection effectiveness of DHI Skimming.
DHI Skimming came with its usage conditions and some confirmation steps to ensure
the result is reliable and directly correlates with hydrocarbon accumulation. There are
standard and advanced confirmation steps to examine DHI-Energy objects from DHI
Skimming. We tested Tulip Alpha as one of speculative reservoirs from DHI Skimming by
using all confirmation steps. The confirmation steps passed Tulip Alpha as a prospective
reservoir on Dutch Offshore F3 Block. This result showed capability of DHI Skimming to
help solving prospect identification problem on least-explored areas and ambiguous
representation problem of DHI.
This technique can be really useful to manage uncertainty and risk on exploration
phase. The successful identification using DHI Skimming on this study can be re-applied
in other hydrocarbon exploration areas or blocks, including at Southeast Asia that holds
significant prospect of undiscovered hydrocarbon resources.
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ISBN