bluuebunny/crossref_metadata_2025 huggingface dataset:
Photon blockade in a double-cavity optomechanical system with nonreciprocal coupling
Authors: Wang Dong-Yang , Bai Cheng-Hua , Liu Shutian , Zhang Shou , Wang Hong-Fu
Published: July 2020

Photon blockade is an effective way to generate single photon, which is of great significance in quantum state preparation and quantum information processing. Here we investigate the statistical properties of photons in a double-cavity optomechanical system with nonreciprocal coupling, and explore the photon blockade in the weak and strong coupling regions respectively. To achieve the strong photon blockade, we give the optimal parameter relations under different blockade mechanisms. Moreover, we find that the photon blockades under their respective mechanisms exhibit completely different behaviors with the change of nonreciprocal coupling, and the perfect photon blockade can be achieved without an excessively large optomechanical coupling, i.e., the optomechanical coupling is much smaller than the mechanical frequency, which breaks the traditional cognition. Our proposal provides a feasible and flexible platform for the realization of single-photon source.
Orthogonal Optimization Design of Scour Protection Device with Flexible Material for Pile Foundation
Authors: Wang Tianying , Zhou Yanjun , Tang Honglin , Tian Haiqing
Published: July 2020

To apply the scour protection device with the flexible material developed by the author to engineering practice, orthogonal optimization design of the device for a fixed offshore platform in Chengdao Oilfield as a case study was presented. The influences of main design parameters, such as pile diameter, thickness of flexible material and elastic modulus of flexible material on the protective effect of the device were studied by two-way fluid-solid interaction numerical simulation based on ANSYS workbench platform. Then, the optimal design plan of the scour protection device with flexible material was determined. Furthermore, by comparing and contrasting the results of the flow field calculation for the pile legs with versus without protective devices were compared and analysed, the device’s good effective protection effect functionality was demonstrated. The research results will shed light on the practical engineering design of the flexible energy dissipation guiding antiscour device.
Permeability of A Composite Seawall: Effect of the Orientation of Gaps in the Structure
Authors: Dabir Vaishnavi , Deki Sonam , Agarwal Kunal , Ranjan Ashish , Khare Kanchan
Published: July 2020

A Seawall requires reflecting and dissipating entire wave energy with zero transmission. The permeability would significantly affect its hydraulic stability under wave loads. Thus, the permeability of a structure changes with the material and consequently a variation in the composite structure may give a different perspective on the hydraulic performance of a seawall altogether. As a first step towards establishing the composite seawall, a comprehensive permeability test is performed as a preliminary assessment of hydraulic conductivity. In the current research, a bag made of non-woven geotextile polymer filled with sand and a roll of non-woven needle punched coir geotextile is investigated. A total number of 20 model tests were performed by varying the orientation and positions of the material composites and thereby the gaps in the structure. The results are noted and future research possibilities into the design and development of a composite seawall as an alternative to traditional seawall are thus presented.
Dynamic Response Computation of Single-Point Mooring of Product Tanker Based on AQWA
Authors: Zhang Xuan , Hu Jinpeng , Hong Bo
Published: July 2020

This paper took the product tanker at sea and its mooring positioning system as the research object and used the time-frequency domain method to calculate the movement of the product tanker. In the three-dimensional potential flow theory, a single-point mooring system was established as a numerical model in the ANSYS Workbench. The frequency-domain computing module was to analyze the hydrodynamic response of the tanker under the unit regular waves, the dynamic response amplitude operators (RAOs) of the tanker, and the motion conditions under different frequency distributions. The time-domain computing module was to analyze the response of a single-point mooring system under the actions of wind, wave, and current. Setting the mooring point, pretension, layout, mooring radius, and other parameters, of the mooring product tanker was calculated lasted 1 hour for the time-domain coupling analysis under the extreme offshore environment. The tension of each cable was compared with the minimum breaking strength of the mooring cable to determine its safety.
Study on Design Strategies About Single-sided Natural Ventilation in Residential Buildings
Authors: Lei Jingbo , Chen Hong , Song Risheng
Published: July 2020

Natural ventilation is an effective measure to reduce energy consumption and improve indoor environment. The enlargement of the depth of high-rise residential buildings allows only single-sided natural ventilation, which makes the problem of poor natural ventilation itself more serious. In this study, CFD numerical analysis was used to verify the optimal design strategy of one-sided ventilation residence in a practical case, and the results showed that the design strategy could improve the ventilation effect of one-sided ventilation houses [1].
Pore type characterization of kais carbonate reservoir using differential effective medium
Authors: Prananda A , Rosid M S , Widodo R W
Published: July 2020

The Kais Formation is a hydrocarbon reservoir that produces in the Salawati Basin. However, the success in drilling has diminished so a new concept of exploration is needed to characterizing the pore type. Carbonate reservoirs are classified into three pore types based on pore geometry, namely interparticle pore, stiff pore, and crack pore. The pore geometry of carbonate reservoir is very complicated which is compared to siliciclastic rock. The process has greatly affects heterogeneity and pore geometry complexity are cementation, dissolution, and fracturing. These processes modify the pore geometry which correlates with rock porosity. The modification of pore geometry will change the rock elastic properties. It can be identified from the P-wave velocity (Vp). The change in P-wave velocity (Vp) has an effect of 40 %, as a result of modification of the pore geometry. Therefore, studies of rock physical properties that take into account the complexity of pore geometry are very important in characterizing carbonate rocks. Differential Effective Medium (DEM) is one of the elastic rock modeling methods which calculates the geometry aspect of the pore by including porosity into the parent material. The aim of this study is to characterize pore type using DEM in the three different wells; MEI-1 well, MEI-2 well, and APR-1 well. The result of this study shows that MEI-1 and APR-1 well is dominated by interparticle and crack pore, while MEI-2 well is dominated by interparticle and stiff pore.
Estimating shear wave velocity (Vs30) of East Java, Indonesia, using ambient noise inversion of horizontal to vertical spectral ratio (HVSR)
Authors: Tawakal M I , Haris A , Martha A A
Published: July 2020

The shear wave velocity on average to a depth of 30 m (Vs30) is an important parameter for seismic hazard assessment. Vs30 can identify soil dynamic characteristics that can be used to seismic hazards mitigation efforts. East Java is one of the provinces in Indonesia that has high geological disaster potential. Therefore, a study of earthquake risk mitigation strategies must be carried out as a disaster mitigation effort. One of the ways to determine soil characteristics is to estimate the shear wave velocity. This study aims to determine the average shear wave velocity (Vs30) to obtain information on the vulnerability of soil conditions in East Java. we use stationary seismograph data from Indonesian Agency for Meteorology, Climatology, and Geophysics (BMKG), German Research Centre for Geosciences (GFZ) temporary seismograph and secondary data from seismic waveform portable seismographs installed independently in East Java. This study uses the horizontal and vertical ambient noise inversion method. One-dimensional wave velocity models are obtained from Monte Carlo simulations based on the best misfit values. Vs30 East Java values ranged from 168–788 m/s with sediment thickness ranging from 10 meters to more than 200 meters. Based on the classification of soil types, in the northern part of East Java is dominated by the type of soft soil (SE) to hard soil (SC). In the southern part of eastern Java is dominated by medium soil (SD) to hard rock (SA). The northern part of East Java, especially in the Kendeng zone is dominated by low shear wave velocity. Lowest Vs30 can be seen in Sidoarjo, Surabaya, Mojokerto, Jombang, Gresik, Lamongan, Nganjuk, Madiun, Ngawi, Bojonegoro, Probolinggo and the southern part of the Madura Island. The low shear wave velocity (Vs30) is associated with sediment layers and high shear wave velocity (Vs30) is associated with hilly areas and transition zones.
Monitoring agroforestry for REDD+ implementation using remote sensing data and geographic information system: A case study of Repong Damar, Pesisir Barat Lampung
Authors: Laura C T , Darmawan A
Published: July 2020

Repong Damar is a unique practice of agroforestry found in Lampung that has a canopy structure nearly similar to that of natural forest. Apart from its uniqueness and important roles, effort to map and timely monitor the condition over Repong Damar is very limited. This research aims to analyze the most appropriate and accurate method for detecting Repong Damar using satellite images and to understand the historical change of Repong Damar cover. We tried to relate this effort to REDD+ potential implementation through agroforestry by estimating the forest reference level (FRL) of Repong Damar. Three methods of detection were used i.e. Object Oriented Classification (OOC), Maximum Likelihood Classification (MLC) and Vegetation Indices Classification (VIC). The most accurate method for detecting Repong Damar was the OOC. By using this method, time-series change of Repong Damar from 1990 to 2018 was determined. FRL was established by multiplying carbon stock of Repong Damar and the time-series average coverage area of Repong Damar from 1990 to 2015, i.e. 33,187,752 tC/yr. The emission performance of Repong Damar in 2018 was calculated from the total carbon stock of Repong Damar in 2018 against FRL. Repong Damar has emitted 1,485,378 tons of carbon in 2018.
Characteristics of primary tin mineralization in the Central and West Bangka Island
Authors: Aditya R , Setiawan I , Nugraheni R D , Sihombing F M H , Indra T L
Published: July 2020

Bangka Island is an important tin producer in Indonesia, mostly from the secondary tin deposits. However, the secondary tin deposit is depleting, causing further exploration shifted to the primary tin mineral. The purpose of this study is to make a mineralization model of primary tin deposit in Bangka Island. Methods that implemented in this study are petrographic analysis, mineragraphic analysis, XRD (X-Ray Diffraction), and XRF (X-Ray Fluorescence) analysis. The studied rock samples that consisted of granite, meta-sandstone, and sandstone. Some of the rocks are altered rocks with varying intensity. Petrographic and mineragraphic analysis show the presence of minerals that indicate the primary tin deposits, such as cassiterite, tourmaline, topaz, sericite, pyrite, and sphalerite. XRF analysis shows data about the value of Sn elements so that they can be classified into two classes, very high grade (> 800 ppm), and low grade (100–200 ppm). XRD analysis is necessary to do to determine the type and intensity of alterations that occur in the study area. The results of each analysis will provide supporting information regarding the primary tin mineralization process in Bangka Island.
Characteristics of surface hydrothermal alteration around Gunung Pancar area, West Java, Indonesia
Authors: Yoga D A , Sahdarani D N , Sihombing F M H , Grandis G , Supriyanto  , Kadja G T M
Published: July 2020

Hydrothermal alteration is an interaction between rock and hydrothermal fluid by means changing the mineralogical composition of the rock. This process is controlled by permeability, chemical composition, temperature, pressure, and duration of the hydrothermal alteration. Gunung Pancar, located in West Java, is considered an outflow for Gunung Gede Geothermal System. Typical geothermal surface manifestations found around Gunung Pancar are hot springs, warm ground and surface alteration. Basic geological mapping was conducted followed by water and altered rock sampling. Petrographic and diffraction methods are completed to confirm altered protolith. Water analyses were conducted to determine water type and origin. Alteration zonation is then inferred based on the water type, intensity of alteration and then cross referenced with indication of structural geological features. Zonation reveals that the intensity of alteration gets weaker as it moves away from the apparent faults. The result suggested that the permeability of the host rock affects thermal fluid movement around Gunung Pancar and subsequently the local geothermal conceptual model.
Identification of basement and subsurface structure of Depok City by using ESA-MWT gravity data
Authors: Hamonangan R A , Rosid M S
Published: July 2020

Basement is a hard layer which has a high-density contrast compare to the above it layer. In geotechnics, this layer is useful for the basement installation of high-rise buildings and other heavy buildings. Rock density contrast is sensitive physical parameter to be detected using gravity data. The study conducted in Depok City is aimed to identify the presence and the depth of the basement. Gravity data has been collected from 87 stations throughout the city of Depok. The average density value of rocks in the study area is 1.73 g/cc which was obtained by using the Parasnis method. The shallow basement layer is mapped using the Energy Spectrum Analysis - Multi Window Test (ESA-MWT) method. This method works by windowing test points from Complete Bouger Anomaly (CBA) values to get the interface depth for each test point. The fault structure can be identified through a residual anomaly map and by the Multi Scale - Second Vertical Derivative (MS-SVD) method whose results correlate with each other. The basement layer was successfully identified among the 3 other horizon layers and was at a depth of 0 - 68 m below the subsurface. Fault structures were also identified in the study area in the North and South part of the study area, where its fault identified as a normal fault.
A trend of surface solar radiation in Chiang Mai, Thailand
Authors: Promplin S , Charoentrakulpeeti W
Published: July 2020

The solar radiation passing through the atmosphere to the earth surface has varied in both increasing and decreasing directions. The decreasing direction caused mainly by aerosols, which its properties can absorb and reflect solar radiation. The emission sources of aerosol are primarily from human activities. This study aims to delineate a trend of surface solar radiation in Chiang Mai by using data from 7 air quality monitoring stations, recording during 1995–2017 in urban and rural areas. According to the Mann Kendal Sen’s Slope analysis, the results show that surface solar radiation in Chiang Mai has presented the decreasing trends in 5 stations which located in urban areas while the other 2 stations located in rural areas have presented increasing trends. This could be basically explained that the difference and intensity of activities between urban and rural areas has affected the variation of surface solar radiation.
Comparison of two rapid DNA extraction for DNA based identification from fish fillet products
Authors: Khoirunnisa V , Andayani N , Maryanto A E
Published: July 2020

Efficiency and quality on the result of DNA extraction determined the success of species identification using DNA. High concentration and good purity of DNA are the basic principle for choosing the appropriate extraction method. The objective of this research is to find an effective and efficient method from two different rapid DNA extractions, KAPA Express Extract Kit (KAPA Biosystem) and Chelex® 100 (Biorad). We used each method to extract 44 fish fillet samples from Jabotabek (Jakarta, Bogor, Tangerang, Bekasi) modern retail and traditional markets. We found the KAPA Express Extract Kit (KAPA Biosystem) had fast extraction time approximately 15 minutes for PCR-ready DNA faster than 20 minutes using the Chelex® 100 (Biorad) method. All the PCR-ready DNA are visualized with gel electrophoresis and both method resulted in positive DNA bands. We propose the use of KAPA Express Extract Kit (KAPA Biosystem) than the Chelex® 100 (Biorad) method because the fast and easily to use for the next analyses such as PCR and DNA sequencing.
A depositional setting variation and its effect to the coal quality of Warukin formation in Satui Area, South Kalimantan: Insight from maceral, biostratigraphy, electrofacies and lithofacies analyses
Authors: Haidiati F C , Sihombing F M H , Indra T L
Published: July 2020

Warukin Formation is one of the coal bearing formation in Kalimantan that has significant coal resource. The formation as Middle Miocene Age and deposited in generally regression stage. In addition to coal, it is composed of mudstone and sandstone with siderite nodule, with some coal seams also have parting of carbonaceous mudstone. Coal from Warukin has various quality that possibly related to the changes in depositional environment. This study attempted to understand the relation between depositional environment and the coal quality. To do that, coal is sampled from coal seams that can be found in study area. After collected, the sample then analyzed using lithofacies, electrofacies, biostratigraphy, and maceral analysis. These various analyses would uncover the slight variation on depositional setting between each seam in study area. Later, the result then correlated with the coal quality analyses that have been done before. From the study, it is concluded that some coal sample has higher Sulphur content that related with deposition with more seawater influence. Biostratigraphy analyses indicate that the interburden deposited in shallow marine setting, thus indicate that the depositional interchanged between transitional setting to shallow marine. Electrofacies also indicate that there were progradation and retrogradation process in the depositional activities. Maceral studies also indicate different type of maceral component that reflect the depositional variation within the seam.
Petrography characteristics of Quaternary volcanoes in Rawa Danau Caldera, Banten Province
Authors: Adani S , Indra T L , Syahputra R
Published: July 2020

The caldera from volcano eruptions often been found in Indonesia. However, the caldera which has swamp and lake such as Rawa Danau, Serang, Banten is rare in Indonesia. It encompasses with a swamp at the outer part and lake on the central part. The caldera surrounded by five Quaternary volcanoes, which are Mount Karang, Mount Parakasak, Mount Aseupan at the south, and Mount Tukung-Gede along with Mount Marikangen at the north side of the swamp. The Rawa Danau location is about 50 km to the East of Krakatau Volcano, so it might have been some linkage to its rock properties. This similarity can be seen from the textures and mineral compositions of their thin sections. Most of the volcano material resulted from different volcanoes. The challenging work was how to differentiate their sources eruption in the field because the weathering rate is high. Thus, this paper aims to differentiate the products of each young volcanoes in Rawa Danau using petrography analysis. In general, young volcanoes in Rawa Danau have trachytic and porphyritic textures, with plagioclase, pyroxene, and opaque as the phenocryst and microlite plagioclase as the matrix. The plagioclase can be found around 15–30 % as the phenocryst, microlite plagioclase as the matrix. The plagioclase type is around An55 compared with Krakatau which has An58. The magma characteristics of these young volcanoes might have a similarity with the magma of Krakatau Volcano.
Feasibility study of thermal anomaly detection for earthquake: A case study from 2014 Mae Lao earthquake, Thailand
Authors: Wongpornchai P , Suwanprasit C
Published: July 2020

Earthquake is the natural disaster which causes damage to human lives and their properties, domestic animals and buildings in the areas near the epicentre. The ability to predict the earthquake can greatly reduce in catastrophic damages, but nowadays, earthquake prediction is still the unsolvable problem. However, the earthquake prediction is still an interesting topic for scientists all over the world. One of the important earthquakes precursors in earthquake preparatory phase is thermal anomaly. The thermal region data from remote sensing have been employed recently based on the concept of stress accumulation in the active plate tectonics region, which can be transformed as temperature variation prior event. Moderate Resolution Imaging Spectroradiometer (MODIS) Land Surface Temperature (LST) data have been commonly used to locate thermal anomalies prior to occurrence of earthquake event. In Thailand, 2014 Mae Lao Earthquake, the largest earthquake in the Thailand historical record with magnitude Mw 6.1, shook the area of Mae Lao District, Chiang Rai Province on 5thMay 2014. To locate possibility of thermal anomalies, the daily data of MODIS MYD11A1 product for 30 days before and after the earthquake were processed and analysed. Average LST before and after earthquake events were used for removing background temperature in the area and comparative method was performed to detect the thermal anomalies. The result found that this simple technique detected the thermal anomaly occurrence during 12-23 days prior to the earthquake and 9-28 days after the earthquake. Nevertheless, in order to understand furthermore about earthquake mechanism, it is necessity of discovered thermal precursors.
Estimation of reservoir lithology in field “A” using modeling of anisotropy parameter
Authors: Ramadhan M F F , Rosid M S , Purba H
Published: July 2020

The heterogeneity and anisotropy of rocks in the field is a necessity. Moreover, the existence of clay and carbonate sediment in Indonesia almost dominate the existing oil and gas reservoir. Ironically, the processing of seismic data is still much done by treating reservoir rocks as an isotropic homogeneous medium. Inaccuracies of results, therefore, always haunt the failure of exploration. Hockey stick phenomenon is the result of anisotropic medium that often appears on the far offset. Demand for the implementation of an anisotropic rock medium is now increasing and more important amid the exhaustive oil and gas reserves. NMO correction by using hyperbolic travel time on anisotropic media still displays the phenomenon of hockey stick at the remote offset. Usually this phenomenon will be muted on the processing of seismic data with the approach of isotropic earth models. This will result in the loss of some lithologic information. Therefore, this study was conducted using anisotropic approach to reduce residual moveout for data which has a very long offset. The method is to calculate the anisotropy parameter model of η which is controlled by core data. The results of this study showed that the Alkhalifah and Tsvankin method of non-hyperbolic travel time was better in the NMO correction for anisotropy medium with a long offset compared to the method of hyperbolic travel time. In addition, Alkhalifah and Tsvankin method can also estimate the lithology of a reservoir. The value of anisotropy parameter η from the equation itself has the same pattern as the gamma ray log. In reservoir, the sand has negative η value and shale has positive η value.
Variation on the coastal deposit in Nusa Tenggara Islands based on the mineralogy and petrographic analysis
Authors: Savira D , Sihombing F M H , Indra T L
Published: July 2020

Sand as part of sedimentary material can be consisted of single mineral fragments, rock fragments, or even biogenic materials. Nusa Tenggara is an archipelago that was formed due to the meeting of the Indian Ocean Plate and the Eurasian Plate which supported by other geological processes. The stratigraphy of these islands is dominated by carbonate rocks, volcanic rocks, coastal deposits and alluvium. Due to the variation of the rock composition, there is a large possibility that mineralogy sediment material found in the coastal area will be different from one place to other. This study aims to analyse variations on coastal deposits in a number of specific locations in the Nusa Tenggara Islands. This study was carried out by mineralogical and petrographic analysis of sand samples from six coastal areas in Nusa Tenggara Islands. The mineral composition of coastal sand was identified using hand loupe to give general understanding. After that, the petrographic analyses were implemented to give detailed mineralogical analyses of each sand. Mineralogical studies are specialized in study of the physical structure and chemical composition of each mineral, while petrographic studies can support the details of every physical information obtained through macroscopic observations. Data are retrieved by taking sand samples directly in the research field in a certain amount. This sample is separated then for macroscopic analysis while the other parts are made in a thin section. The thin section will be used for petrographic analysis under a polarization microscope. The analysis result shows that there are variations in coastal sediment components and it most likely does to different rock found around such area.
3D broadband seismic inversion: Case study of exploration cretaceous sandstone, North Arafura Basin
Authors: Sofyadi A , Haris A , Riyanto A , Sutha I M
Published: July 2020

This paper presents applications of Absolute and Relative Acoustic Impedance of seismic inversion for qualitative and quantitative seismic interpretation from 3D Broadband PSDM Post-stack Seismic data. A case study from the exploration area of Late Cretaceous – Early Cretaceous Clastics in Arafura Sea, eastern Indonesia has been perform in this work, where inside the study area have no well information for seismic inversion at all. The present work shows the promising contribution of applying 3D Broadband Seismic Velocity for background trend of 3D Post-Stack Model Based Seismic Inversion and perform interpretation from 3D Broadband Relative Acoustic Impedance to reduce the uncertainty associated with the seismic interpretation, to recognize the porous sand section (as an indication of hydrocarbon reservoirs) and to understand the distribution of the reservoir based on seismic data-driven, to later for define the high certainty location of exploration well.
Identification of geological structures by using ESA-MWT and MS-HDVD gravity data at Slawi, Central Java
Authors: Rosid M S , Christanto M
Published: July 2020

It has been done of a geophysical measurement by Pertamina in the Slawi area of Central Java. The results of the seismic section show that there is an up dome in the field “M”. The location of this area is in the mt. Slamet zone. So that the existence of an up-dome structure does not automatically provide the possibility of a hydrocarbon trap in the area. This study was conducted to characterize the existence of these structures using gravity data. The ESA-MWT (energy spectral analysis multi window test) and MS-HDVD (multi scale-horizontal derivative vertical derivative) methods of gravity data are applied in this study. The ESA-MWT method is able to map lateral rock variations very well, whereas MS-HDVD is more sensitive to vertical variations even though it is also good for identifying rock variations in both vertically and laterally. There are five horizons detected in the field. These five interfaces with density contrast extend over a depth range between 416 to 2112 meters. The horizons are identified as being associated with sediment rocks namely Formations of Tapak, Penosogan, Kumbang, Halang and Rambatan. The sediments are likely to be intruded by diorite stones (in up-dome form) which happened during the Late Miocene. The peak, or top, of the intrusion body is estimated at around 620 to 755 m depth on the Penosogan Formation.
Geostatistics analysis as a tool to create the distribution model of Rawa Danau volcano deposits, Banten Province
Authors: Mulyo M J W , Syahputra R , Indra T L
Published: July 2020

The eruption of an ancient volcano at the early Pleistocene had deposited volcanic material evenly, especially in the western part of Rawa Danau. Many smaller mountains emerged around Rawa Danau volcano as the Pleistocene volcano erupted. Then, at the end of the Pleistocene, the ancient volcano erupted for the second time with a very large force that destroyed most of the mountain and created a caldera. The volcanic material from the second eruption was distributed to evenly around the ancient volcano. We used geostatistical analysis with Inverse Distance Weighted (IDW) method to interpolate the spreading of volcanic deposits both in the first and second eruption. The objective of this research is to predict the volcanic deposits in the area which has not been researched yet and it is possible to have more eruptions in the future since geothermal manifestations such as hot springs are found in the research area. We used the outcrop data from geological mapping to interpolate the data. The output of this paper would be the interpolation map of facies deposits in Rawa Danau.
Palynological analysis to infer environmental dynamics of Muarajambi Temple compound
Authors: Sihombing F M H , Sirait S , Purnomo A , Sulistiowati D , Indra T L
Published: July 2020

Muarajambi Temple Compound situated in the side of a river in Jambi Province, Indonesia. Due to its vicinity to the river, the compound has experienced various geological event associated to the river sedimentation, such as river flood and alluvial sedimentation. We have collected two soil sample from beneath an excavated human-made structure in the sideway of a river. The first sample was collected right in bottom of the structure, while the second sample was collected around 20cm beneath the structure. Taking sample right beneath the structure is ideal for the analyses because this would avoid contamination after the temple construction. The pollen and spore content from these samples were analysed to understand its variation. From the analyses, we found that the first younger sample has larger AP (arboreal pollen) percentage but smaller NAP (non-arboreal pollen) compared to the second sample. This indicate that the vegetation is less dense in the first sample. This study might indicate the environmental changes due to human activities, particularly human activities around the temple compound which led to the construction of the temple compound itself.
Integrated analysis of spectral-decomposition, AI inversion and RMS amplitude attribute for determining sandstone reservoir distribution: A case study of ‘X’ field in Central Sumatera Basin
Authors: Suwondo  , Haris A , Riyanto A , Wiyono J
Published: July 2020

The Sand A reservoir distribution in Bekasap Formation, ‘X’ Field, Central Sumatera Basin had been delineated using spectral decomposition, AI inversion, and RMS Amplitude attributes. There are onlapping feature of Bekasap Formation to the Basement High. The aim of this study is to identify the existence of oil reservoir in Bekasap Formation. The uncertainty of the subsurface model will be reduced with the integrated analysis. Spectral decomposition used frequencies of 20 Hz, 50 Hz, and 70 Hz. High amplitude with low frequency anomaly is showed by the 20 Hz frequency map and this anomaly considered as the reservoir zone. However, the amplitude anomalies are not showed by the two other frequency maps. This unique anomaly was verified by well data. The distribution of Top A reservoir was showed based on AI inversion, spectral decomposition of 20 Hz, and RMS attribute has direction of northeast-southwest on onlapping zone to the Basement High. This study concluded that combination of spectral decomposition, RMS Amplitude, and AI inversion analysis had been successful to delineate the sandstone reservoir.
Subsurface structure identification of ‘X’ geothermal prospect area based on gravity and magnetotelluric data
Authors: Sugiyo E W , Daud Y
Published: July 2020

Exploration stage has the highest risk, due to discover the interest reservoir zone include high temperature and pressure, middle to high permeability, and non-acidic fluid. Permeability is one of the most difficult parameters to be determined in this stage. Fault zone could be able to control and provide fluid flow within reservoir. It is usually related to high permeability zone. Fault identification become an important and interesting parameter in to be explore. The aim of this research is identified subsurface structure to build up a conceptual model of geothermal system. The methods include magnetotelluric data analysis and 3D MT structure interpretation together with first horizontal derivative and second vertical derivative analysis of gravity data. Geochemistry and geology data are used as supporting data. There are structure types of normal and reverse fault identified in the research area. MT and gravity interpretation show that structures are direct to northeast-southwest and northwest-southeast. Up-flow zone is predicted between TPP-TPB manifestations. Structures supposed to highly contribute in providing permeability zone in the research area. Manifestations fluid have the characteristics of meteoric and magmatic fluid (volcano-hydrothermal system). The clay cap thickness average is predicted between 500–700 m. The reservoir thickness average is predicted between 1500–2000 m. Temperature estimation of the reservoir is 240–280 °C. Heat source might be located between TPB and TPP manifestations. Subsurface structure analysis might be useful to increase success ratio in drilling.
The effect of volcanism to the source rock maturity in Gunung Endut area: Insight for subvolcanic hydrocarbon exploration
Authors: Risman C , Setyowati T P , Febiansyah N , Sahdarani D N , Sihombing F M H , Aditiyo R , Supriyanto  , Indra T L
Published: July 2020

Banten region is known to have subvolcanic hydrocarbon system but no proven play despite oil seeps and the potential source rock have been identified in this area. A Geochemical analysis of source rock have been done on Gunung Endut, Banten Province. There are four coaly shale sample from Genteng Formation and Bojongmanik Formation collected and analysed in this study. The purpose of this study is to understand the influence of volcanic environment towards the quality, quantity and maturity of source rock based on TOC, pyrolysis, and vitrinite reflectance analyses. The result obtained showed TOC value between 8–18 wt% which indicated excellent petroleum potential from the source rock. In addition, Pyrolysis data showed S1 value between 0.05–0.19, S2 value between 1.52–11.53, S3 value between 4.10–7.57 and Tmax 414.8–523.2 °C. From both analyses, TOC and Pyrolysis, the source rock is categorized as Type 3 Kerogen producing gas and Type 4. Based on its maturity, three sample are categorized as immature while one specimen is categorized as postmature. Furthermore, Vitrinite Reflectance analysis result shows Ro value between 0.27–0.63 that support the result of pyrolysis analysis. Maturity anomaly found in the sample is presumed to be caused by intrusion that have been identified by the geological mapping in the same region. The condition on the surface may also reflect the source rock in the subsurface. A number of source rock in Banten region may be matured due to intrusion that related to volcanic activities. Subsurface zone with abundance igneous bodies will have different maturity compare to other area. Hence, it is important for petroleum exploration activities in Banten region or other volcanic area to properly identify the distribution of subsurface igneous body due to its effect to the source rock maturity.
Reservoir simulation of Ulumbu geothermal field using TOUGH2 and ITOUGH2 simulator
Authors: Yuono R T , Daud Y
Published: July 2020

Ulumbu geothermal field is classified as a natural two-phase geothermal system, located in the south of Mandosawu - Ranakah Old volcanics and Pocoleok, Flores Island. This field produces 4 x 2.5 MW electric power in 2014 until now with temperature between 230–240 °C. This study aims to perform reservoir simulation in the Ulumbu field. The reservoir simulation method aims to determine the reservoir characteristics of the geothermal field. This research used TOUGH2 and ITOUGH2 simulator to simulate the reservoir. The work concept from TOUGH2 is forward modeling while ITOUGH2 is inverse modeling. Both of methods will produce an output. The output of this research is natural state model that was validated by three wells of the actual measurement (pressure and temperature) and heat flow from the conceptual model. A pressure and temperature profiles are very representative with the data in the three wells. The reservoir location is between Poco Leok and Poco Rii (upflow zone) and continues to the southwest (outflow zone) with an average area of 10.5 km2. The top reservoir is at an elevation of 500 m, while the depth is up to -2000 m. Reservoir rock has a permeability value of around 10−14–10−15 m2, porosity value of 8–10 %, density value of 2500 kg/m3, and specific heat capacity value of 900 J/kgK. Temperature distribution results of the natural state model show the hydrogeological profile of the Ulumbu geothermal system. The natural state model is then used to help undertake a geothermal field development scenario, that is, to calculate resource reserves and to make recommendations for subsequent drilling zones.
Identification characteristics of volcanic deposits in Cimarga, Southeast Banten
Authors: Yekini M A , Sitorus F , Jabbar G A , Supriyanto
Published: July 2020

Volcanic eruption(s) in the past occurred around rawa danau volcanic complex is marked by the presence of a caldera and widespread volcanic deposits in the Banten Province as Tuff Banten. This study aims to determine the possible mechanism of the eruption based on volcanic deposits. Moreover, this study will also present the prolonged research process to understand the dynamics of volcanic deposits in Banten. Field study and sampling of volcanic deposits were completed followed by thorough petrographic analysis. There are three outcrops all with different characteristics. There are 6 layers in outcrop 1. Out of six layers, layer 1 (P1) until layer 5 (P5) appear similar, consisting of pumice rich (as fragment) and lapilli layer, while layer 6 (P6) consists of massive ash. In outcrop 2, there are 5 layers, which show cross and parallel laminations in each layer. Outcrop 3 contains 3 layers with the top and bottom layers consisting of lithic and pumice lapilli that are medium in size. Based on grain size from each outcrop, grain size from outcrop 1 until outcrop 2 progress into finer grains. From these characteristics outcrops 1 indicated flow deposits, outcrop 2 indicated surge deposits, and outcrop 3 indicated flow deposits. Therefore the facies from all three outcrops lean towards medial to distal with outcrop 3 as a distal facies.
Reducing residual normal moveout by globally optimized generalized moveout approximation in vertically transverse isotropy (VTI) media
Authors: Kertanah  , Rosid M S , Purba H
Published: July 2020

The anisotropic phenomenon in wave propagation has been widely recognized on various scales. Knowledge of anisotropic effects is essential for interpretation and processing of seismic data. The existence of anisotropy leads to the moveout of nonhyperbolic even in a homogenous layer. A transversely isotropic medium with a vertical symmetry axis (VTI) is a reasonable approximation of horizontally layered anisotropic medium. The approximation of travel time is important for reducing the residual normal moveout of layered VTI media. The aim of this study is to develop globally optimized generalized moveout approximation in reducing residual normal moveout in VTI media. A comparative analysis was carried out to recent method for given an ellipticity parameter (0 ≤ η ≥ 0.5 ) and wide offset depth to ratio (0 to 4). The result shows that the globally optimized generalized moveout approximation is better in reducing residual moveout at large offsets with a stronger anellipticity parameter than existing methods. This is essential for reducing the accumulation of error especially for deeper substructures.
Evaluation of shale hydrocarbon potential in upper Talang Akar formation based on laboratory geochemical data analysis and Total Organic Carbon (TOC) modelling
Authors: Azizah S G N , Haris A , Julikah
Published: July 2020

In shale hydrocarbon exploration, shale acts as the source rock and reservoir rock. This study aims to evaluate the potentional of shale hydrocarbons based on the laboratory geochemical data and TOC (Total Organic Carbon) modelling. Evaluation of shale hydrocarbons in sthe study field was carried out on two wells, X-1 and X-3 wells with a target in the upper part of Talang Akar formation as a source rock. Geochemical data is needed for evaluating the quality of the source rock by looking at the total organic carbon content, the maturity, and the hydrocarbon produced by the source rock. Analysis of the laboratory geochemical data resulted that the shale of upper Talang Akar formation had enough potential and mature organic material and also will generate the hydrocarbon in oil form. One of the main parameters for the success of shale hydrocarbons exploration is to know the amount of organic material of the source rock. TOC obtained from laboratory geochemical data is discrete data. Therefore, TOC modelling is carried out to obtain prediction of continuous TOC in upper Talang Akar formation in both wells. This prediction uses three different methods, those are Passey, multiple linear regression, and neural network. Based on those three methods, neural network produces the best data. The correlation obtained from X-1 well and X-3 well using neural network method are 0.96 and 0.84 respectively.
Coast effects on 3-D inversion of magnetotelluric data for geothermal exploration in East Flores, Indonesia
Authors: Arafat Y , Daud Y
Published: July 2020

Nowadays geothermal exploration in Indonesia is beginning to reach small islands, most of which have a prospect in the coastal area. This has influences on the MT data modelling due to the distortion of the electric field component caused by the extreme contrast of resistivity between land and sea. In these conditions, it is necessary to apply the correction of the coast effects. The seawater resistivity (0.3 Ωm) must be included in the 3-D MT modelling. A simulation was conducted to observe coast effects on 3-D MT modelling. Forward 3-D MT modelling is done to obtain synthetic data to compare homogeneous model and coast effects model. The simulation results show that the presence of seawater affects all MT data frequencies, but the most significant distortion occurs in the low frequency. The affected frequency range correlates with the distance between the MT station and seawater. If the distance of MT station to the sea is getting closer, then the disturbed frequency range is greater, and vice versa. The results of 3-D inversion of MT real data with the coast effects model are used to construct a conceptual model for geothermal systems in East Flores. The interpretation shows that the geothermal prospect area in the field is around Mount Anging. This research is expected to be a consideration for drilling recommendations and further development.
Identification of flood potential in Rawa Danau, Banten Province based morphometry and satellite image analysis
Authors: Haidiati F C , Syahputra R , Indra T L
Published: July 2020

The Quaternary Volcanic Rawa Danau, Banten Province has a unique characteristic. Their deformed morphology reflects those unique characteristics. A physical characteristic of deformed morphology is able to describe the morphometry parameters of a subwatershed. It also can be analyzed using the Digital Elevation Model (DEM) obtained from satellite imagery. The lineament of geological structure can be observed from satellite images through their colour, shape, texture, and pattern. Subwatershed characteristic data can be used to calculate the flood discharge using morphometry. Some morphometry parameters can be used are river dimension, an azimuth of river segment, an azimuth of terrain lineament, river length, drainage density, and bifurcation ratio. This research can be used to identify flood potential at Rawa Danau–Banten Province. The result of the research shows that the value of Rb is less than 3, it means all of the subwatershed has deformed. At the Cidano, Ci Kaduan, Ci Bulakbaru, Ci Tawing, Ci Cangkepan, Ci Pasauran, Ci Sangkuy, Ci Carung value of Rb increased so it indicates that the deformation is quite substantial and also potentially flood.
Interpretation of surface geological conditions based on Landsat-8 data, DEM and field geological data in the Tulehu geothermal prospect area, Maluku Province
Authors: Kurniawan A , Daud Y , Tifani M A , Latuconsina N , Maulana F
Published: July 2020

Tulehu is in the eastern part of the island of Ambon, Maluku. The research area is in some village; Suli, Tial, Tulehu, and Waai, Salahutu District, Maluku Province with a research area size of approximately 10 x 10 km2. It is an area with a high geothermal prospect. Much research has been carried out here to study the geological, geochemical and geophysical conditions of it. The reservoir is estimated to reach more than 230 °C based on geochemistry. This study will focus on discussing the surface geological conditions of the Tulehu area based on the interpretation of satellite imagery and field observations data that have been carried out in the form of structure and rock unit data. This research image of satellite imagery data consists of Landsat 8, and DEM processed using ArcGIS 10.2.1 software. The results show that the study area is composed of 4 rock units which are sequentially from the oldest to the youngest namely Lava Flow (early Pliocene-middle Pliocene), Pyroclastic Flow (middle Pliocene-late Pliocene), Limestone (Pleistocene-Holocene), and Alluvium (Holocene). The structure that works in the study area has NE-SW and NW-SE directions with two main faults that form like basins in parts N and S of Mount Eriwakang. The results of this study are displayed in a surface geological map and are equipped with a geological cross section.