scholarly journals KEDALAMAN BATUAN KERAS PERAIRAN SELAT LAUT SEBAGAI DATA AWAL UNTUK RENCANA PEMBANGUNAN JEMBATAN PULAU LAUT - KALIMANTAN

2016 ◽  
Vol 5 (1) ◽  
Author(s):  
Noor C.D. Aryanto ◽  
Yogi Noviadi

Kotabaru merupakan ibukota Kabupaten Pulaulaut, Kalimantan Selatan. Guna mempercepat proses pembangunan, diupayakan untuk membangun jembatan yang menghubungkan daratan Pulau Laut dengan daratan Kalimantan. Berdasarkan data seismik hasil survei pendahuluan diperoleh dua lokasi usulan untuk tapak fondasi kaitannya dengan kedalaman batuan kerasnya yang dikenali dari perbedaan reflektor yang demikian ekstrim, baik dari bentuk ataupun warna terhadap reflektor di atasnya. Lokasi-1 memiliki kedalaman batuan keras berkisar antara 4 hingga 20 meter dan 12 hingga 22 meter di bawah dasar laut. Di lokasi ini juga dikenali adanya struktur yang diperkirakan berupa sesar pada kedalaman 14 meter bawah dasar laut. Lokasi-2 di sayap barat dan timur P. Suwangi, memiliki kisaran kedalaman batuan keras antara 2 hingga 18 meter bawah dasar laut dengan kecenderungan makin dalam ke arah tengah perairan Selat Laut. Kata kunci : batuan keras, seismik, Selat Laut dan Pulau Laut, Kalimantan Selatan. Kotabaru is the capital of the Pulaulaut regency, South Kalimantan. The construction of the bridge that will connect Pulaulaut and Kalimantan is aimed to accelerate the development of the areas. Based on the preliminary seismic data, two propose locations for bridge foundation relates to the depth of hard rock that can be recognized by the extremely differences of acoustic impedance. Location-1 has a hard rock’s depth between 4 to 20 meters and 12 to 22 meters beneath sea floor. In this location, it is also recognized a fault structure at 14 meters depth. Location-2 in the west and east wings of Suwangi Island has the acoustic basement depth between 2 to 18 meters from the sea floor and it is deeper toward the centre of Selat Laut waters. Keywords : hard rock, seismic, Laut Strait and Laut Isle, South Kalimantan.

2016 ◽  
Author(s):  
John Milsom ◽  
Phil Roach ◽  
Chris Toland ◽  
Don Riaroh ◽  
Chris Budden ◽  
...  

ABSTRACT As part of an ongoing exploration effort, approximately 4000 line-km of seismic data have recently been acquired and interpreted within the Comoros Exclusive Economic Zone (EEZ). Magnetic and gravity values were recorded along the seismic lines and have been integrated with pre-existing regional data. The combined data sets provide new constraints on the nature of the crust beneath the West Somali Basin (WSB), which was created when Africa broke away from Gondwanaland and began to move north. Despite the absence of clear sea-floor spreading magnetic anomalies or gravity anomalies defining a fracture zone pattern, the crust beneath the WSB has been generally assumed to be oceanic, based largely on regional reconstructions. However, inappropriate use of regional magnetic data has led to conclusions being drawn that are not supported by evidence. The identification of the exact location of the continent-ocean boundary (COB) is less simple than would at first sight appear and, in particular, recent studies have cast doubt on a direct correlation between the COB and the Davie Fracture Zone (DFZ). The new high-quality reflection seismic data have imaged fault patterns east of the DFZ more consistent with extended continental crust, and the accompanying gravity and magnetic surveys have shown that the crust in this area is considerably thicker than normal oceanic and that linear magnetic anomalies typical of sea-floor spreading are absent. Rifting in the basin was probably initiated in Karoo times but the generation of new oceanic crust may have been delayed until about 154 Ma, when there was a switch in extension direction from NW-SE to N-S. From then until about 120 Ma relative movement between Africa and Madagascar was accommodated by extension in the West Somali and Mozambique basins and transform motion along the DFZ that linked them. A new understanding of the WSB can be achieved by taking note of newly-emerging concepts and new data from adjacent areas. The better-studied Mozambique Basin, where comprehensive recent surveys have revealed an unexpectedly complex spreading history, may provide important analogues for some stages in WSB evolution. At the same time the importance of wide continent-ocean transition zones marked by the presence of hyper-extended continental crust has become widely recognised. We make use of these new insights in explaining the anomalous results from the southern WSB and in assessing the prospectivity of the Comoros EEZ.


2019 ◽  
Vol 16 (2) ◽  
Author(s):  
Ir. Udaya Kamiludin

Secara regional daerah Bangka merupakan bagian dari Jalur Granit Utama Pembawa Timah.  Daratan nya ditandai oleh intrusi Granit Klabat yang merupakan batuan penting sumber endapan plaser. Untuk mengetahui lembah purba  maka dilakukan perekaman seismik saluran tunggal. Daerah penelitian secara administratif merupakan bagian dari wilayah Kabupaten Bangka Tengah, Propinsi Bangka Belitung. Perairan  Tanjung Berikat dan sekitarnya dicirikan oleh kelerengan dasar laut rata-curam dengan  kedalaman terukur antara 0-45 meter. Interpretasi seismik saluran tunggal menunjukkan stratigrafi seismik dari muda ke tua yaitu Runtunan A, Runtunan B, intrusi, dan Runtunan C sebagai dasar akustik. Ketebalan sedimen Runtunan A antara  5-30 meter dari  permukaan dasar laut. Lembah purba memanjang cukup lebar dan dalam pada Runtunan B yang diduga sebagai fasies pengisian lembah berupa onlap fill.  Fasies ini memiliki internal reflektor bebas pantulan-kaotik yang ditafsirkan sebagai wadah mineral plaser dan mineral ikutan pembawa  unsur tanah jarang. Endapan plaser diperkirakan merupakan  hasil pengerjaan ulang batuan granitoid.Kata Kunci : Dasar laut, runtunan stratigrafi, lembah/alur Purba, endapan plaser, dan Perairan Tanjung Berikat dan Sekitarnya, Bangka-Belitung. Geologically regional, the Bangka area is part of the Main Tin Belt Granite. The mainland of the study area is characterized by Klabat Granite intrusion which is an important rock source of placer deposits. To find out the placer availability of deposits on Paleo channel it was carried out for the recording of single channel seismic data. The study area is administratively part of the area of Central Bangka, Bangka-Belitung Province. Tanjung Berikat waters and its vicinity are characterized by the slope of the flat sea floor to steep with a measured depth of 0-45 meters. Seismic interpretation shows seismic stratigraphic from young to old consisting of sequence A, sequence B, Intrusion, and sequence C as acoustic basement. Sediment thickness of sequence A between 5-30 meters from seafloor surface sediment. Paleo channel with an elongated shape that is wide enough and deep in sequence B is interpreted as a channel filling facies in the form of onlap fill. This facies is characterized by the free to chaotic reflector configuration which is interpreted as a place for mineral placer and accessory minerals which contain rare earth elements. The availability of placer deposits is interpreted as the result of reworking of granitoid source rock.Keywords: Sea floor, stratigraphic seismic, Paleo channel, placer deposits, and Tanjung Berikat waters and surrounding, Bangka-Belitung.


Author(s):  
A. Ogbamikhumi ◽  
T. Tralagba ◽  
E. E. Osagiede

Field ‘K’ is a mature field in the coastal swamp onshore Niger delta, which has been producing since 1960. As a huge producing field with some potential for further sustainable production, field monitoring is therefore important in the identification of areas of unproduced hydrocarbon. This can be achieved by comparing production data with the corresponding changes in acoustic impedance observed in the maps generated from base survey (initial 3D seismic) and monitor seismic survey (4D seismic) across the field. This will enable the 4D seismic data set to be used for mapping reservoir details such as advancing water front and un-swept zones. The availability of good quality onshore time-lapse seismic data for Field ‘K’ acquired in 1987 and 2002 provided the opportunity to evaluate the effect of changes in reservoir fluid saturations on time-lapse amplitudes. Rock physics modelling and fluid substitution studies on well logs were carried out, and acoustic impedance change in the reservoir was estimated to be in the range of 0.25% to about 8%. Changes in reservoir fluid saturations were confirmed with time-lapse amplitudes within the crest area of the reservoir structure where reservoir porosity is 0.25%. In this paper, we demonstrated the use of repeat Seismic to delineate swept zones and areas hit with water override in a producing onshore reservoir.


1988 ◽  
Vol 140 ◽  
pp. 64-66
Author(s):  
J.A Chalmers

A pilot study is being conducted to determine if the use of seismo-stratigraphic interpretation techniques can increase the understanding af the geology of offshore West Greenland in order to reassess the prospectivity of the area. During the period 1975 to 1979, a number of concessions offshore West Greenland were licensed to various consortia of oil companies to search for petroleum. Some 40 000 km of seismic data were acquired, all of which is now released. Five wells were drilled, all of them dry, and all concessions were relinquished by the industry by 1979. The regional geology of offshore West Greenland has been summarised by Manderscheid (1980) and Henderson et al. (1981). They show the West Greenland Basin to consist of fairly uniformly westward dipping sediments bordered near the shelf break by a basement ridge. These authors used what may be termed 'conventional' techniques of seismic interpretation. However, since that time the techniques of seismo-stratigraphy (Vail et al., 1977; Hubbard et al., 1985) have become established. They are now being applied to study seismic data acquired during the mid-1970s.


Author(s):  
S. N. Smolin ◽  
◽  
G. M. Mitrofanov ◽  
◽  
◽  
...  

The search for nonstructural hydrocarbon accumulations is a Herculean task that requires the use of delicate tools. Such tools include the Prony filtration technology. It allows for direct qualitative forecasting of hydrocarbon bearing features based on frequency-dependent analysis of the observed wave field of CDP reflection-time sections and includes four steps. The article shows capabilities of technology and specific examples of its application by correlation of frequency-dependent Prony images of wave fields with deep drilling data. The performed studies were carried out using CDP 2D seismic data and deep drilling data of 32 wells obtained in the territory of the West Siberian Plate, mainly for the Middle Jurassic (Late Bajocian-Bathonian, Malyshev horizon) interval of terrigenous-sedimentary deposits. At times, the underlaying and overlying Middle and Upper Jurassic deposits were captured. The manifestation forms of various oil and stratum water accumulations and their possible prospecting indicators, as well as signs of the absence of reservoirs are given. As an example, the manifestation and possible prospecting indicators of gas accumulation from a neighboring region within the West Siberian Plate are shown.


2018 ◽  
Vol 22 (4) ◽  
pp. 335-339
Author(s):  
Jingfeng Wu ◽  
Qi'an Meng ◽  
Xiaofei Fu ◽  
Yuling Ma ◽  
Meifeng Sun ◽  
...  

Fangzheng fault depression is controlled by the northern of the Tan-Lu fault zone. It undergoes multi-stage strike-slip, extrusion modification, and erosion of the thermal uplift, forming a tectonic pattern of uplifts connected with sags. Through the regional dynamic analysis, the study of the activity law of the western Pacific plate has clarified the formation and transformation of the regional tectonic stress field. Under the background of the multi-stage of the strike-slip mechanism in the northern part of the Tan-lu fault, the Fangzheng fault depression has a characteristic of the “left-lateral strike-slip pull-apart basin, right-lateral strike-slip extrusion transformation.” According to the difference of the strike-slip, the Fangzheng fault depression has divided into two parts: the East fault depression and the West fault depression. The seismic data, seismic attribute analysis, and geological modeling techniques have applied to analyze the two fault depressions, the East fault depression has actively controlled by the strike-slip activity, and the structure is complex. The seismic data quality is poor; the structure of the West Fault Depression is the opposite and structural characteristics of asymmetrical difference strike-slip in the East and West fault depressions. Interpretation of seismic sections through a slippery background, the strike-slip attributes of the whole fault depression from south to north are segmented, and the strike-slip mechanism from east to west is different. Under the control of the multi-stage strike-slip mechanism, the Fangzheng fault depression is divided into six stages of strike-slip evolution, corresponding to the six different stages of the strike-slip control basin, the formation process of the asymmetric difference strike-slip fault basin is clarified, which provides a reference for the study of the strike-slip pull-apart basin with multi-stage structure.


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