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First EAGE South-East Asia Regional Geology Workshop - Workshop on Palaeozoic Limestones of South-East Asia and South China
- Conference date: 05 Dec 2011 - 08 Dec 2011
- Location: Ipoh, Malaysia
- ISBN: 978-94-6282-051-7
- Published: 05 December 2011
30 results
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Late Palaeozoic Evolution of the Peri-Gondwanan Plates of SE Asia
By M. KrobickiThe continents forming the core of Gondwana include South America, Africa, Madagascar, India, Antarctica and Australia. The location of numerous smaller continental blocks that bordered Gondwana is less certain. These smaller blocks were assembled during the Early Paleozoic time to Gondwana, forming the so-called Peri-Gondwanan zone. The following were adjacent to Gondwana during the Paleozoic times: Yucatan, Florida, Avalonia, central European (Cadomian) terranes between the Armorica and Bohemian Massif, Moesia, Iberia, Apulia and the smaller, southern European terranes, central Asian terranes (Karakum and others), China (several separate blocks), and the Cimmerian terranes of Turkey, Iran, Afghanistan, Qiangtang, Lhasa and Southeast Asia (Golonka et al., 2006). The European Avalonian plates probably started to rift from Gondwana and move towards Baltica in the earliest Ordovician and were in a drift stage by the Middle Ordovician time and originated Rheic Ocean. It is quite possible that South China and Indochina plates also were rifted from Gondwana in the Ordovician.
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Geomorphology and Characterization of Palaeozoic Carbonate in Peninsular Malaysia - Comparison on Environment of Deposition
Authors N.F.A Sharif, N. Ahmad and S. ShaharPaleozoic limestones are widespread in Malaysia, typically distributed along northwestern, western and central belt of Peninsular Malaysia. Outcrop photos and satellite images were widely used in the study. Karstification geomorphology generally observable on high resolution satellite image and aerial photos, as well as outcrop observation. Steep-sided, isolated limestone hills surrounded by alluvial plains are commonly seen in most of the limestone buildup (Raj, 2009), except Setul Limestone who formed a long line of continuous hill at west of Perlis (Jones, 1981). Thick vegetation often occurred on top of limestone buildup, with steep side characterized by bare vegetation (Raj, 2009). Tower karsts, dolines and cavern were observed from the satellite image.
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Sedimentology of the Palaeozoic Limestone of the Kinta Valley, Malaysia
Authors B.J. Pierson, S. Kassa, H. Tsegab, A.A. Kadir, W. S. Chow, A. W. Hunter and Z. T. H. ZuharThe limestone hills of the Kinta Valley are remnants of extensive limestone beds, which are part of a Paleozoic carbonate complex that covered large parts of South-East Asia and south China. The original limestone beds of the Kinta Valley, presumed to be Carboniferous (Ingham & Bradford, 1960; Hutchison, 2007) or possibly Permian in age (Fontaine, 1995), have been severely eroded and karstified (Figure 1).
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Impressive Slump Structures in Permo-Carboniferous Limestone at Sg. Siput, Perak, Malaysia
Authors A.A. Kadir, B. J. Pierson, Z. T. H. Zuhar and W. S. ChowSlump structures may be created by submarine sediment slides with a rotational mode of failure. The limestone hills in Sg. Siput display impressive slump structures, especially in the upper section of a sequence exposed in an abandoned quarry, near Bt. Kemuning, NW of the town of Sg Siput. The sequence is mainly dominated by thinly laminated dark grey mudstone to wackestone with occasional turbidite beds and is part of the Kinta Valley limestones which are relicts of thick Paleozoic carbonate deposits, mainly Carboniferous to Permian in age. Intense slumping is mainly observed in the upper part of the section, where it is enhanced by thin beds of light grey chert and of dark grey to black shaley limestone, interbedded with medium-grey micritic limestone.
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Challenges in Seismic Imaging of Carbonates in SE Asia
By D. P. GhoshMost of the world oil and gas reserves come from carbonates. The world statistics shows that the carbonates represent only 20% of the total sedimentary rocks but 60% of world’s oil/gas reserves are from carbonates of various ages. In Malaysia, 40% of the gas reserves come from Miocene carbonates of offshore Sarawak. There are many issues in carbonates which have yet to be resolved. The link between geology and geophysics are essential elements in carbonate studies. There is a need to characterize these carbonates by establishing a link between sedimentology, Rockphysics and Seismic in order to/increase gas production to sustain LNG and other energy usage for the country. There is a strong relationship between sequence stratigraphic framework and present-day vertical distribution of different lithologies. The seismic response need to be investigated for different lithologies, lithofacies and structural or physical features.
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Fractures Delineation on Permian Carbonate Reservoir Utilizing Post-stack Seismic Enhancement and Fracture Attributes, Nang Nuan Field, Chumphon Basin, Thailand
More LessNang Nuan field is located in Chumphon basin, which is one of Tertiary half grabens in offshore Thailand. The main reservoir is the Permian Ratburi carbonate reservoir, known as basement of the overlying Tertiary clastic sediments (Figure-1). The geologic understanding of the Ratburi carbonate has been evolving from time to time as new information and analysis are obtained. However, secondary diagenetic process such as caving development system or karstification has been believed to be mainly responsible for the porosity enhancement of the otherwise tight Ratburi carbonates. This paper is aimed to show the influence of fractures to the development of the reservoir in the Pre- Tertiary section and provide different perspective of possible geologic model of Nang Nuan field.
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Analytical Review of Hamrong Geology and Geophysics Data
Authors K. Al-Atroshi, Tan Ching Kiang and Amri AmdanHam Rong Field is located in Block 106, Song Hong basin, offshore Vietnam, 75km SE of Hai Phong City. It is a proven Pre-Tertiary carbonate play with the discovery of Hamrong-1X ST4 and Hamrong- 2X. The field is located in the SW of block 106, at the SE edge of Thuy Nguyen Half Graben, Song Hong basin. The structure was formed as the results of a number of tectonic events such as regional uplift and extension creating a series of horst and grabens and the movement of the Red River fault. The study has targeted the qualitative and quantitative evaluation pf the pre-Tertiary carbonate reservoir.
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Seismic Imaging Near and within the Basement Offshore Malaysia; Including Comparisons of Imaging Algorithms
Authors N. El Kady, M. Shah Sulaiman, Zabidi M Dom, Wai Hoong Tang, Mei Lu Lee, Pavel Vasilyev and Martin BaylyBetter 3D acquisition and better imaging have made it possible to explore complex basement plays in Vietnam, Indonesia, and the Malay Basin with some success. It is postulated that oil from adjacent formations may get trapped (under favourable conditions) in vughs and fractures within the basement. Imaging the basement architecture is a key issue (Deva Ghosh et al., TLE, April 2010).
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Geomorphology and Characterization of Palaeozoic Carbonate in Peninsular Malaysia - Comparison on Environment of Deposition
Authors A.G.M. Adnan, C.T. Ang, M.H. Zahir and A. WardoyoThere are several seismic methods to image gas cloud areas such as multi-component Ocean Bottom Seismic (4C OBS) (Li et al., 2001 and Akalin et al., 2010) and full waveform redatuming operators (Ghazali, 2010). Converted wave (S-wave) travels through the subsurface rock matrix and not affected by the compressibility or the bulk modulus of the rock properties. It is used to improve imaging within and below gas accumulation, and increased the vertical resolution for the P-wave image. One of the most crucial steps to achieve an optimum subsurface response of the converted shear wave (PS) from compressional wave (PP) is to apply an accurate Vp/Vs ratio (gamma) operator in the stack and migration process. In this paper, we studied gamma estimation for 4C seismic imaging and a case example from an offshore field Malaysia is shown. Other special processes that we applied in the processing of the P and S-wave are anisotropic rotations, S-wave receiver statics, asymmetric and anisotropic binning and pre-stack migration with scanned gamma (VP/VS) to improve the final result.
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Overview of Palaeozoic Stratigraphy of SE Asia
By A. W. HunterThe session on the palaeontology and stratigraphy of South East Asia is introduced by discussing the general tectonostratigraphic structure of South East Asia. The structure of South East Asia is described with respect to its evolution during the Palaeozoic. We introduce the main structural regions in relation to their stratigraphy. Despite superficial resemblances in their geomorphology and composition, the palaeozoic limestones of South East Asia may have very different origins and tectonostraigraphy (Metcalfe 1996). Currently the pre-Tertiary of South- East Asia can be divided into four tectonostratigraphic terrains; these are: the Sibumasu (Burma (Myanmar), north-west Thailand, west Peninsular Malaysia and north-western Sumatra), east Peninsular Malaysia (including south-east Sumatra), Indo-China (east Thailand, Laos, Vietnam and Cambodia), and south-west Borneo. Evidence suggests that all of these terrains had their origin in the Indian–Australian fringes of Gondwana (Metcalfe 1988; Metcalfe 1996).
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A Review of Upper-Palaeozoic Biostratigraphy of the North-western Terrain of Peninsular Malaysia
Authors A. Bashardin and A. W. HunterThe overall stratigraphy of the Upper Palaeozoic of western Peninsular Malaysia remains unclear. Despite numerous studies, very low grade metamorphism has influenced lithologies throughout the northern region from the islands of Langkawi to the Kinta Valley. As a result subdividing lithologies into meaningful units purely on stratigraphic lines remains problematic. This is further complicated by the lack of index macrofossils. Jones (1981) noted that it is difficult to trace formations laterally over large areas relying solely on lithology, and the fossils that he identified had limited stratigraphical value. Despite this, several authors have attempted to address these issues, resulting in conflicting statigraphic frameworks for the region. In this study we focus on the Northwestern Terrain of Peninsular Malaysia, looking at Perlis and northern Kedah (including the islands of Langkawi) and reviewing these contradictory hypotheses with the aim of providing a new approach to resolving the stratigraphy of the terrain. To date, few studies have combined the middle and Upper Palaeozoic stratigraphy of the Northwestern Terrain. Cocks et. al (2005) proposed a revised stratigraphical framework, but still argued over the age of formations as a result of the conflicting biozonation between conodonts and macrofossils. Lee (2009) revised the stratigraphy proposed by Meor & Lee (2005), yet there are still gaps that need to be addressed.
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Stratigraphy of Permo-Triassic Limestone in Malay Peninsula and Thailand
By M.Yamin AliA widespread distribution of Permo-Triassic limestones in Peninsular Malaysia and Thailand marks an extensive shallow marine deposition during this period. The Permian limestone occurs as a massive, highly fossiliferous with significant Fenestellidae and Fusulinidae, and partly dolomitized limestone. The Chuping Limestone (Early to Late Permian) that exposes in the Northwest Belt of the Malay Peninsula and offshore Langkawi represents the example of the youngest Palaeozoic carbonate sequence. The Kinta Limestone deposition that was initiated earlier during the Silurian has also been reported to be partially extended into the Early Permian in the Western Belt. Simultaneously, the Gua Musang Limestone was developed within the Central Belt. The Sumalayang Limestone of the Dohol Formation in Eastern Belt also contains fusulinids indicating a Middle Permian age. All these limestones are of equivalent age and well correlatable with the Ratburi Limestone in the south of Thailand, and also the Khao Plukmu Limestone in the west, Doi Chiang and Tron Limestones in the north, and Bang Phra and Khao Cha Kan Limestones in the eastern Gulf of Thailand.
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Stratigraphy of Palaeozoic Carbonate Rocks in North Vietnam
Authors Nguyen Duc Phong and Tran Tan VanThe study integrates stratigraphic and biostratigraphical data from outcrops in North Viet Nam to better understand the sedimentary environments of the Paleozoic carbonate rocks in Viet Nam. The studied Paleozoic carbonate successions are represented by six sedimentary stages. These stages are as follow: the Early Cambrian stage, represented by the Cam Duong and Coc Bai formations, the Middle Cambrian - Early Ordovician stage, represented by the Ha Giang, Chang Pung, Lutxia and Ham Rong formations, the Middle Ordovician - Silurian stage, represented by the Sinh Vinh, Bo Hieng and Kien An formations, the Devonian - Early Carboniferous stage, represented by the Khao Loc, Si Phai, Na Quan, Ban Coong, Ban Pap, Trang Kenh, Mo Nhai, Toc Tat, Pho Han, Con Voi, Lung Nam and Da Nieng formations, the Carboniferous - Middle Permian stage, represented by the Bac Son, Song Da and Na Vang formations and Late Permian stage, represented by the Deo Son La and Dong Dang formations. These stages are suggested to be of different environment of deposition during the different transgressive and regressive cycles. The Early Cambrian stage is suggested to be of stable continental shelf depositional environment. The Middle Cambrian - Early Ordovician, Middle Ordovician - Silurian, Carboniferous - Middle Permian and Late Permian stages are indicated to be of shallow marine environment. The Devonian - Early Carboniferous stage is suggested to be of littoral shallow marine environment in the lower part, and of deep - water troughs environment in the upper part
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Shallowing-Upward Sequence in a Late Middle-Permian (Midian) Alatoconchid-Bearing Strata, Khao Khwang Carbonate Platform, Central Thailand
More LessExtensive field work to establish the occurrence and distribution of Permian alatoconchid-bearing strata in Thailand has been carried out in recent years. Alatoconchid faunas occur in limestone sequences within both the Indochina and Sibumasu (Shan-Thai) Terranes. In the Indochina Terrane, they were found in Khao Khwang and Pha Nok Khao platforms of the Saraburi Group. In the Sibumasu Terrane they were observed in carbonate platform sequences in the Ngao, Ratburi and Chantaburi Groups in northern, western and eastern Thailand, respectively. The current research has been carried out in the Saraburi Group. The key localities include Khao Somphot, Pak Chong and Tha Sa-ad sections in Lopburi, Nakhon Ratchasima and Loei areas, respectively. Microfacies study and palaeontological data indicate that shallow marine environments of deposition prevailed at all of these localities during Middle Permian time. In addition, evidence of occasional storm events and subaerial exposure were observed within shallowing-upward sequences at Khao Somphot.
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Review on Fossil records of the Kinta Valley Limestones
Authors H. Tsegab, W. A. Hunter, B. J. Pierson and W. S. ChowKinta valley was a focus of interest in search of geological resources for the last ten decades. Most of those studies were oriented to reveal the genesis of tin mineralization. Few workers including the current authors have identified some micro faunal (bivalves, gastropods, rugose corals, foraminifera, crinoids) records for relative dating of the limestone sequences. Even though present day accessibility of the reported fossiliferous sites is limited; areas which are dated based on the fossil records in Chemor (Silurian to Devonian), near Batu Gajah (Devonian), Malim Nawar (Carboniferous), Tualang limestone (Carboniferous to Permian), Kampar (Permian), and Kampung Sungai Keruh (Permian), are part of the Kinta valley limestone. The age difference in the limestones is interpreted as a result of migration of the coral reefs in the palaeodepositional setting. This current study will review the fossil collections of the JMG in Ipoh in order to test these original age determinations. We will demonstrate how these historic collections and macrofossil will contribute to our new research project. Furthermore, we will outline how these data will contribute to our ongoing research into defining a reference stratigraphic section that will enable correlation between scattered outcrops in the western Belt of Peninsular Malaysia.
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History of Karst Development in the Kinta Valley: Emphasis on the Main Controlling Factors
Authors S. Kassa, B. J. Pierson, W.S. Chow and B.A.T. JasmiPeninsular Malaysia is divided into three belts with the Kinta Valley situated in the center of the Western Belt. The Kinta Valley limestone, which is presumed to be Silurian to Permian in age (Peng, 2009), has been undergoing karstification ever since it was exposed to the surface. Since the valley is bounded by granite ranges, i.e. the Main Range in the east and Kledang Range in the west, the rivers descending from the non-soluble rock profoundly impacted on the development of karst in the area. The extant karst landscape, which constitutes about 2.5% of the Valley area (figure1), clearly illustrates the long term and immense dissolution process.
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Investigation of Karst Morphology in the Subsurface of Kinta Valley Using the Gravity Method
Authors A.R. Harun and A.R. SamsudinA regional gravity survey had been carried out in Kinta Valley, Perak in June 2009 and February 2010. The study area located between latitude line of 4°18’8.4” N and 4°44’04”N and longitude line of 100°55’03”E and 101°57’55.8”E. The valley situated at the centre between the peninsular main range at the western part and Kledang Hill in the east. A total of 372 gravity stations had been measured using the Scintrex CG-5 gravity meter, with stations interval range between 0.5 – 2 kilometre. The Tiernan-Wallace altimeter was use to determine the height of every stations. The reduction process had been done using the software “Magnetic and Gravity Reduction” (MREDUC), and then been gridded, filtered and analysed using the Oasis Montaj (Geosoft) software.
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Tropical Diagenesis of Carbonate Limestone and its Implications for Porosity Development, Case Study: Tendehhantu Formation
By D.P. AmiarsaThe study area is located in Sekerat Village, Bengalon district, Sengata Region, East Borneo Province, Indonesia. Approximately about 300km northern of Samarinda (capital city of East Borneo Province) (Figure 1 A.). This area is less than one degree of northern equator line. The objectives in this study are to know diagenesis stage in this area and relationship to tropical climate especially in porosity development. Indonesia has special case in carbonate diagenesis process. It has tropical climate and archipelago which surrounded by ocean. It means that high rainfall occurs in this country more less half a year. Evapotranspiration to precipitation (hydrology cycle) occurs so fast, so the influx of meteoric and freshwater are very intensive.
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Hydrothermal Alteration of Cambro-Ordovician Carbonates of North America: Lessons for the Palaeozoic Carbonates of SE Asia
Authors Richard D. Bray and Adriaan BalHydrothermal reservoirs and the related Mississippi Valley-Type mineral deposits (MVT) display a broad distribution in time and space, but are most abundant and prolific in North America. Hydrothermal alteration often is not recognized, distinguished, or even considered in the hydrocarbon provinces worldwide. With the exception of Nang Nuan, hydrothermal reservoirs are unreported in the Paleozoic (and younger) rocks of SE Asia. This is perhaps due to failure to appreciate and distinguish hydrothermal fabrics.
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Imaging the Subsurface Karst Morphology Using High- resolution 2D Resistivity Imaging Technique
More LessA survey was carried out on a flat sandy land in the neighborhood of Gunung Datuk limestone hills complex. All 9 (NINE) boreholes drilled in this area encountered solid limestone rock at various depth ranging from 14.30 meters to 41.50 meters, indicating possible presence of karstic features. This report presents the result of 2D earth resistivity survey carried out in 2009 to provide a 3D subsurface view of the limestone head or karstic features which hopefully will help in designing the suitable foundation for any structure to be build here. Resistivity images clearly show that this area is a limestone area with karstic surface features, such as pinnacles and cavities. The depth of this zone is ranging from 8 to 35m. In some cases, some boreholes penetrated pinnacles, thus giving a false impression that the solid limestone is very shallow. In order to create a 3D subsurface view of the karstic limestone head, a total of 7 parallel lines were collected for each proposed site, and interestingly the results show, some of the proposed site were located directly above a possible collapsed cave (valley), thus special care need to be considered when designing the foundation of any structure to be build here structure.
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Electric Modelling and Imaging of Sinkholes Developed after the 26 December 2004 Tsunami in the Karstic Limestone in Southern Thailand
Authors P. H. Giao, N. Prechavit and R. ManopSouthern Thailand has a distinguishing karst topography, which is underlain by soluble carbonate rocks with various systems of karsts. Sinkholes represent a common geohazard associated with karst terrain, and in reality they are found in many areas in Southern Thailand such as Krabi, Chumphon, Narathiwat, Phangnga, Yala, Ranong, Songkhla, Satun and Trang. The catastrophic 26th December 2004 tsunami and earthquake of 9.3 Richter have shaken many South and Southeast Asian countries, including Southern Thailand. This paper presents the results of an investigation, jointly conducted by the Asian Institute of Technology and Department of Mineral Resources of Thailand, aimed at detection of the sinkholes in carbonate rocks in the Southern Thailand, which were triggered by the 26 December 2004 tsunami. As reported, the largest of the eighteen sinkholes found in early January 2005 by the Department of Mineral Resources, Thailand (DMR) is in Nakhon Si Thammarat province, measuring 20 meters in diameter and 10 meters deep. In this paper, a brief review on sinkhole formation and data related to karst topography as well as main mechanism of sinkhole collapses in Trang and Satun provinces are presented. Electric modeling was done to study on the effectiveness of the electric imaging technique. Results of some field surveys are analyzed and shown.
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Limestone Hills, Rockfalls and the Developers
More LessLimestone hills provide scenic or picturesque settings. However, hidden amongst these limestone hills are potential geohazards in the form of rockfalls. Therein lies the dilemma faced by the submitting engineer for the developer who might want to carry out development projects in areas close to or in the vicinity of limestone hills
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Geomechanical Characterization of Limestone at Gunung Lang, Ipoh for Geohazard Mitigation
Authors A. Ghani Rafek and A. AzizanLimestone hills in the vicinity of Ipoh, Perak, while being picturesque and having geo-heritage value, also have a history of rock falls and rock slides, resulting in loss of human lives as well as damage to property and infrastructure. This paper discusses the geomechanical characterisation of limestone hills at Gunung Lang, an abandoned quarry area that has been gazetted as a recreational park by the Ipoh City Council.
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Formation of Sinkholes in the Kinta Valley, Perak
Authors W.S. Chow, B.J Pierson, A.K. Askury and Z.T.H ZuharThe first documented occurrence of sinkholes in the Kinta Valley was reported in the 1950s when a sinkhole occurred beside a railway track near Pengkalan. Since then, sinkhole occurrences were documented in the archives of the Minerals and Geoscience Department. The incidents of sinkhole occurrence reached a peak in the 1970s and 80s just before the collapse of the tin-mining industry in the Kinta valley where more than 50 sinkholes were found in the Lahat-Bukit Merah area.
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Prospects of Geotourism in Limestone Area: Experience from the Langkawi Global Geopark
By Che Aziz AliLimestone outcrops have long been associated with human civilizations and cultures. Many evidences of early settlements and burial ground have been found in limestone caves. In this modern era, limestone is regarded as a rock of a thousand uses and is being actively mined everywhere for short-term economic gain. At the same time, limestone outcrops have attracted a lot of people who come to admire their aesthetic, cultural and recreational values. Malaysia has very limited limestone areas but they are known for their high aesthetic and scientific values. However, in Malaysia today we are witnessing a conflict between destructive and non-destructive exploitations of limestone. Many beautiful limestone outcrops have been mined because of their high economic value without a slight consideration for other more important values that can bring in more cash in the long term.
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Geocellular Modelling of a Naturally Fractured Carbonate in the Song Hong Basin, Vietnam
More Less3D Geocellular Modeling of a Naturally Fractured Carbonate in the Song Hong Basin, Vietnam
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Potential Palaeozoic Hydrocarbon Plays in and around Peninsular Malaysia
Authors Bernard J. Pierson, Askury A.Kadir, Chow Weng Sum and Zuhar Z.T. HarithPaleozoic sedimentary deposits are exposed in several locations on Peninsular Malaysia and may contain all the elements of a hydrocarbon system. Initial observations, mainly in the Kinta Valley, suggest the presence of source rocks, reservoirs and seals within the Paleozoic interval. The limestone hills of the Kinta Valley were the initial focus of this research project. The hills are remnants of extensive limestone beds, which are part of a very large Paleozoic carbonate complex that covered large parts of South-East Asia. The limestone beds are interbedded with sandstone, siltstone and carbonaceous shale over a thickness of up to 3000m.
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Implications of Fracture Network Mapping in the Palaeozoic Limestone of the Kinta Valley, Malaysia
Authors Maryam S. Dzulkefli, L. Ducarme, S. Kassa and B.J. PiersonThe Palaeozoic limestone exposed at Tambun, near Ipoh, Malaysia, displays spectacular fracture networks. Fractures were mapped on a vertical cliff face representing the top of a vertically-dipping bed, striking approximately N-S. Four major fracture sets cover the bed surface: vertical fractures, horizontal fractures and 2 sets of oblique fractures. The vertical fractures are orientated along an east-west plane. The density of vertical fractures is the highest, with a frequency that is locally less than 2 cm. The horizontal fractures dip slightly to the east, locally show a displacement along the vertical fractures and have a frequency of about 10 cm. The oblique fractures are shear fractures, are at about 40º and 50º to the vertical fractures, respectively and have a frequency of about 50 cm. Mapping the fracture networks indicates a σ1orientated along an east-west axis and an σ3 orientated along a north-south axis. The fractures are the result of a compressional stress, along an east-west axis and have created a significant fracture porosity at the location of the Tambun outcrop. Similar fracture systems could be found in subsurface Palaeozoic limestones, including the ones that form fractured oil reservoirs in SE Asia. The measured outcrops could therefore be used as analogues.
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Palaeogeographic Evolution of the Southeast Asia Palaeozoic Carbonate Complexes
Amalgamation and accretion of Southeast Asia continental blocks has occurred during the Late Devonian to Late Cretaceous tectonic movements, its consequences led to the closure and opening of oceanic basins, and orogeny. The Southeast Asia carbonate complexes shared the same regional tectonic history of uplifting, faulting and compressional strains. The main Terranes of the present Southeast Asia were located within the palaeo-Thethys in an equatorial latitudinal setting in Permian period and the geological dating of the carbonates imply presence of regional relationship between carbonate buildups. Paleomagnetic data in northwestern Malaysia, biogeographic evidence throughout India, Australia, and China with palaeoclimatic conditions in the region were favored carbonate growth and might suggest that the Palaeozoic limestone formed continuous carbonate chain in the region, from Malaysia to Thailand. In addition to the microfossils, the absence of siliciclastics within the limestone sequences and syndepositional slope structures are considered as evidences for deeper depositional setting.
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Geophysical Reconnaissance of Housing Area in Klebang and Sinkhole Occurrences in Jeram, West Malaysia
Authors Riyadh Yassin and Ros Fatihah MuhammadGeophysical reconnaissance in two areas of different landuse has been carried out. Housing area in Klebang and Jeram shows some degree of difference of subsurface morphology. Subsurface karst in Klebang shows rather undulating limestone platforms while many cavities believed to be water conduits appear in Jeram. A rapid increase of sinkholes occurrences were reported after the disasterous 26th Dec. 2004 earthquake in Sumatera. Many cavities are present here are only covered by thin layers of loose sands and clay materials. These cavities are thought to be preexisting features that had been rapidly filled with sand/clay, due to the tremor triggered by the earthquake.
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