andang bachtiar

The multidisciplinary study of Gunung Padang has revealed compelling evidence of a complex and sophisticated megalithic site. Correlations between rock stratifications observed through surface exposures, trenching and core logs, combined with GPR facies, ERT layers, and seismic tomograms, demonstrate the presence of multi‐layer constructions spanning approximately 20–30 m. Notably, a high‐resistive anomaly in electric resistivity tomography aligns with a low‐velocity anomaly detected in seismic tomography, indicating the existence of hidden cavities or chambers within the site. Additionally, drilling operations revealed significant water loss, further supporting the presence of underground spaces. Radiocarbon dating of organic soils from the structures uncovered multiple construction stages dating back thousands of years BCE, with the initial phase dating to the Palaeolithic era. These findings offer valuable insights into the construction history of Gunung Padang, shedding light on...

The Northern Kutai Basin has been considered lacking hydrocarbon prospectivity when it’s compared to the Southern Kutai Ba sin or the Eastern Kutai Basin where many Neogene reservoir rocks has high h ydrocarbons productivity. The Kutai Basin’s sediments are older toward northern and western boundary of the Basin which is the Paleogene sediment was cropping out.

Basically, a well postmortem is carried out in order to find out as to why there is no producible hydrocarbon in a well despite the existence of favorable geological factors and convincing hydrocarbon shows either during drilling or based on well evaluation of E-logs. Subsequently, result of the postmortem can then be used to determine strategy for the next exploration/appraisal plan. A well postmortem often come up with findings that geologically the well is not really dry but was either considered as dry or inconclusive due to non-geological related factors.

Traditional perception considers the Sumatran splay fault act as boundary of Pre-Tertiary rock and Tertiary rock where Pre-Tertiary rock is thrusted (by thrust fault) upon the Tertiary rock, called ‘the Barisan Mountain Thrust Front’. The purpose of this paper is to understand whether the boundary character of Pre-Tertiary and Tertiary rocks in the western margin of the southern end of the North Sumatra Basin is thrust fault boundary or other kind. Method used in this study consists of examination of geological cross section on published geological maps, 2D seismic interpretations, and field observation in Batang Sarangan River, nearby the seismic lines area. The fieldwork result indicates outcrops of Belumai Formation (Tertiary rocks) near the seismic lines. The seismic sections also indicate there is no thrust fault geometry. Moreover, those sections indicate onlap of the Tertiary Rocks onto the Pre-Tertiary Rocks. It is concluded the boundary character of Pre-Tertiary and Tertiary rocks in the western margin of the southern end of the North Sumatra Basin is not necessary as a thrust fault. Hence, the perception of the boundary of Pre-Tertiary rock with Tertiary rock as thrust fault is questionable

Integrated analysis of geochemical, rock mechanic and geophysics were carried out to characterize and map the unconventional reservoir shale hydrocarbon in Baong field, North Sumatera Basin, which is proven with the large potential hydrocarbon, particularly in the sand reservoir. The new challenge of this field is the present of thick shale layer, which is offering the new concept of an unconventional reservoir. The shale layer has the double role as source rock and reservoir. In this work, we performed geochemical analysis on the core data to determine the Total Organic Carbon (TOC), mineralogy, Tmax, and Kerogen type. In term of rock mechanic, the Rock Strength was calculated to determine the hardness and brittleness index. While for petrophysical analysis, we performed multi-linear regression of log data to estimate TOC relationship with the seismic attribute. In term of geophysics, we carried out seismic inversion to produce acoustic impedance, which is useful to map shale distribution. Our analysis shows that the target of shale layer has TOC range from 2 up to 3.5 wt.% with brittleness index of 0.48. Based on the predicted Tmax, this shale layer is categorized into early mature phase and classified into II Kerogen type, which means it has a potential to produce oil. The shale layer was indicated by the result of acoustic impedance inversion which has a value for over 25000 ft/s *g/cc and Rock Strength less than 3000 Psi.

Indonesia is known as the largest economy in South East Asia and as one of the emerging lower-middle-income countries. Before the pandemic Covid-19, Indonesia forecasted its GDP growth to increase to 5.5% in 2020. However, this never happened following the pandemic it decreased to 2.97% in the first quarter of 2020. This paper focuses on the renewable energy role in accelerating the economic recovery in Indonesia by emphasising the role of justice in the transition process. We conduct systematic reviews from different sources, both primary and secondary resources. We qualitatively analyse the energy regulation and energy road map in Indonesia as well as some academic research articles. Indonesia has developed its general energy plan related to the energy mix demand and supply, which includes a long-term plan on developing renewable energy sources and reducing the use of fossil fuels. As the fourth most populated country in the world, Indonesia still focusses on cheap energy supply a...

<p>The upper Triassic Streppenosa and Noto Formations are considered the main source rocks of the Hyblean Plateau in south-eastern Sicily, that represents the present-day deformed foreland of the Sicilian fold-and-thrust belt. This work focusses on the Upper Triassic Streppenosa and Noto Formations, penetrated by the Eureka 1 onshore well (south-eastern Sicily, Italy) in order to constrain the burial-thermal history of this basin of the western Tethys. According to previous paleogeographic reconstructions, starting from Norian, the palaeogeographic scenario consisted, moving from north to south, of a wide carbonate platform (Sciacca Fm.), adjacent to two different domains: the euxinic lagoon/basin of the Noto Formation, and, to the south, the basin of the Streppenosa Formation. Eureka 1 well is located in the inner portion of the platform-basin system and its Triassic succession consists of alternation of black shales and micritic, microbial dolomitic laminated limestones. A detailed description of the sedimentological facies from cores samples has been performed together with detailed organic petrography/Raman spectroscopy and clay mineralogy on fine grained sediments to assess thermal maturity of the Streppenosa and Noto Fms.<span> </span>The main facies consist of light-grey limestones (wackestone-mudstone) with scattered sub-angular intraclast, light grey finely laminated limestones, dark grey-black laminated mudstones, brownish undulated algal laminae saturated with bitumen. The cores are often bitumen saturated and interrupted by different sets of open microfractures, veins filled with calcite, and stylolites (parallel and vertical with respect to lamination) that may enhance and/or inhibit at places the fluid flow. Concerning thermal maturity, the studied interval falls in the lower-mid portion of the oil window, with robust agreement among the geothermometers derived from the three adopted techniques.</p>

A new regional paleogeography of the Kutai Basin during Tertiary is reconstructed based on the wealth of new field data and scattered updated publications to better understand the interaction amongst sedimentary provenance of different Tertiary basin substrate types, sedimentation styles, and stratigraphy architecture within the basin as a response to tectonic events. Data and information used are derived from published maps of gravity, magnetic, isopach, geologic, and significantly supported by outcrops and well information accompanied by biostratigraphic data. Kutai Basin is divided into Upper Kutai, Lower Kutai, and North Makassar Sub-basins. Their corresponding substrates are now perceived as the Northeast Schwaner Complex in the west, the North Meratus accreted mix continental-oceanic terrane in the middle, the North Makassar micro-continent in the east, and the Mangkaliat micro-continent in the northeast. The initial riftings of Kutai Basin were mostly the results of slab roll-back of the three subductions, e.g.: the northern continuation of Meratus subduction into the east of the Northeast Schwaner followed by docking of North Makassar micro-continent, the proto South China-Sea subduction into the Northeast Schwaner, and Banggai-Sula subduction into the North Makassar micro-continents. The timing of rifting was as early as Paleocene (60 Mya) and not later than Middle Eocene (45 Mya), depending of the relative position of the area within the basin to the respective plate interaction. There are five northeast-southwest trending highs and lows bounded by series of northwest-southeast transform faults making the architecture of overall Kutai Basin. The highs consist of: Teweh – Sampirang – Bangun Sari – Muyup Highs, Kahala – Kutai Lake – Kedang-Kepala Highs, Jonggon – Samarinda Highs, Balikappan – Mahakam High, and Makassar Highs. The first two highs have also been identified by several publications previously, but the last three highs are basically newly developed based on integrated method applied in this research. While during Middle to Late Eocene the Kutai basin experienced rifting and during Early Oligocene to early Late Oligocene the basins experienced sagging, paleogeography of the Upper and the Lower Kutai Sub-basins radically reshaped during late Late Oligocene to Early Miocene. Some the isolated highs were uplifted and formed the Kutai Island bounded by the marginal sea which separated it from the uplifted Paleogene sediments of the Upper Kutai Sub-basin. As consequences, sedimentologically, the provenance of the proto Mahakam Delta was derived from the Kutai Island, while the uplifted areas of the Embaluh and the Selangkai Groups and the Schwaner Complex were supplying sediment to the marginal seas in the Upper Kutai Sub-basin, surrounding the Kutai Island. During Middle Miocene to Late Miocene, the Kutai Island was connected to the Upper Kutai Sub-basin, allowing sediment supply from the Embaluh and the Selangkai Groups, the Schwaner Complex and the Meratus Suture deposited in the Middle to Late Miocene coast of the Lower Kutai Sub-basin. Several implication related to the unexplored hydrocarbon plays are: 1) the Paleocene syn rift play in North Makassar Sub-basin, 2) the Eocene syn rift play in the Upper Kutai Sub-basin, 3) the Oligocene reefal carbonates in the periphery of the Lower Kutai Sub-basin, 4) post rift shale gas on the western edge of the Lower Kutai Sub-basin, and 5) prograding Miocene deltas in the southern and northern borders of the basin.

The North Sumatra Basin is well known as a highly overpressured basin in Western Indonesia. Most of the sedimentary basins in western Indonesia, including the North Sumatra Basin, have similar histories of basin development. The basement of Paleozoic and Mesozoic sedimentary and metamorphic rocks is overlain by a syn-rift sequence, then a post-rift sequence associated with basin subsidence, and finally a sequence of shallow marine‐fluvial deposits. Overpressured strata are commonly encountered in the post-rift sequence because it is dominated by fine-grained sediments of low permeability. In the North Sumatra Basin, the post-rift sequence comprises the Baong

Detailed analysis of Modern Mahakam Delta sediments concentrated on identifying ichnological and sedimentological characteristics of four deltaic environments. These include: 1) distributary channel, which are typically low diversity and bioturbation index with displaying Psilonichnus, Skolithos, Ophiomorpha, Monocraterion, Teichichnus Arenicolites, Planolites, Thallasinoides, escaping traces, and Glossifungites ichnofacies; 2) estuarine tidal bar which are typically balanced diversity and bioturbation index with displaying Psilonichnus, Ophiomorpha, Arenicolites, Skolithos, Siponichnus, Monocraterion, Paleophycus, Helminthopsis, Teichichnus, Planolites, Chondrites, Paleodictyon, crawling traces, and vertebrate track; 3) interdistributary area which are typically medium diversity and high bioturbation index with displaying dominated Arenicolites, Ophiomorpha, Conichnus, Skolithos, Scaubcylindrichnus, Diplocraterion, Rosselia, Teichichnus, Chondrites; 4) mouth bar sediments are displ...

Sedimentological research in the Kutai Basin related to deltaic deposit has been studied since 1970s which lithofacies has been employed as central parameter. However, that has been contrary the fact that ichnofossil has been still paid regardless of fruitful parameter and used solely as attribute of depositional environment analysis by previous workers although they have to record it. This paper will establish the potential of ichnofossil data to explain the meaning of the cyclical and variability of fluvial influx and marine process based on outcrops studies in Kesejahteraan and Melati Roads, Samarinda City. The use of ichnofossil characteristics (e.g., bioturbation index, ichnodiversity, burrow diameter, burrow lining and penetration depth) as a proxy for the ascertaining the environmental conditions. The significant finding is that environment regularly might have been intruded by various intensities of fluvial influx, thereby fluctuating environmental conditions such as salinit...

This research is focused on studying the depositional system and petrographic characteristics of petroleum system that form in North Sumatera, Indonesia to reveal the diagenesis, metamorphism, alteration indicators related to reservoir and source rock potential. Field work was integrated with paleontology analysis and comprehensive petrographic study of selected thin sections. Paleozoic and Mesozoic Stratigraphy of North Sumatra can be divided into Tapanuli Group (Alas Fm, Kluet Fm, Bohorok Fm) and Peusangan Group (Pangururan Bryozoa Bed, Batumilmil Fm, Kaloi Fm, Kualu Fm). Pre-Tertiary Rocks were variously deposited in deep marine (ie: Sibaganding Limestone) with Radiolarian Limestone; shallow marine (ie: Batumilmil Fm, Kaloi Fm) with Limestone and dolomitic limestone; moraine glacier and till (ie: Bohorok Pebbly Mudstone); and shallow water (ie: Kualu Mudstone, Pangururan Bryozoa Bed). Batumilmil Fm can be divided into Dolomitic red limestone, Light-grey Limestone, Dark-grey Limes...