Northeast Java Research Articles

In Situ Stress and Stress Regime in the Onshore Part of the Northeast Java Basin

In situ stress is importance in the petroleum industry because it will significantly enhance our understanding of present-day deformation in a sedimentary basin. The Northeast Java Basin is an example of a tectonically active basin in Indonesia. However, the in situ stress in this basin is still little known. This study attempts to analyze the regional in situ stress (i.e., vertical stress, minimum and maximum horizontal stresses) magnitude and orientation, and stress regime in the onshore part of the Northeast Java Basin based on twelve wells data, consist of density log, direct/indirect pressure test, and leak-off test (LOT) data. The magnitude of vertical ( and minimum horizontal ( stresses were determined using density log and LOT data, respectively. Meanwhile, the orientation of maximum horizontal stress ( was determined using image log data, while its magnitude was determined based on pore pressure, mudweight, and the vertical and minimum horizontal stresses. The stress regime was simply analyzed based on the magnitude of in situ stress using Anderson’s faulting theory. The results show that the vertical stress ( ) in wells that experienced less erosion can be determined using the following equation: , where is in psi, and z is in ft. However, wells that experienced severe erosion have vertical stress gradients higher than one psi/ft ( . The minimum horizontal stress ( ) in the hydrostatic zone can be estimated as, while in the overpressured zone, . The maximum horizontal stress ( ) in the shallow and deep hydrostatic zones can be estimated using equations: and , respectively. While in the overpressured zone, . The orientation of is ~NE-SW, with a strike-slip faulting stress regime.

Leading Condition Of Small Pelagic Resources Based On Data In The State Fisheries Management Area Of The Republic Of Indonesia (Wppnri) 712 And 573 Year 1990 - 2017 East Java Province For Sustainable Management

Pelagic fish resources have a very important role in regional economic development. The assumption that fish resources are common property so that everyone is free to catch (open access) is a problem with overfishing in East Java waters. The purpose of this study is to determine the superior commodity of small pelagic fish, the status of exploitation of superior fish resources and to compile a scenario of sustainable management of superior resources. The method in this research is quantitative descriptive method with data analysis used including Location Quotient (LQ), Schaefer (1954), Fox (1970), Walter Hilborn, and programming STELLA (System Thinking, Experimental Learning Laboratory with Animation). The research result of the superior species in the province in the south of East Java) is sardin, while the superior fish in the regency is s Rainbow runner. The status of fisheries at the level of superior fisheries exploitation in South East Java, the level of exploitation of ssrdin fish is 240% with the status of Depleted. Finally, the level of exploitation for s Rainbow runner fish is 689%, which means that they are included in depleted. The scenario of sustainable management of pelagic fisheries for the next 10 years, namely 2018 - 2027 for lemuru fish, the highest biomass reserves will be obtained in 2027, using a fixed effort allocation which has biomass reserves of 179% and the potential value of sustainable reserves of 8,438.48 tonnes. The results showed that the superior commodities of small pelagic fish in North East Java were mackerel fish. The superior fish commodity in the Regency / City is obtained by Finny scad fish. The level of exploitation for mackerel is 127% with the status of Over Exploited, and the level of exploitation for Finny scad is 131% with the status of Over Exploited. The scenario for the management of the superior mackerel commodity, the highest biomass reserve in 2027 is the allowable fishing effort allocation (fJTB) of 129%. Key Words: STELLA ,Superior commodity, Fishery status, Sustainable potential

Pasting Properties of Selected Rice Varieties from Several Provinces in Indonesia

Pasting properties play an important role in determining the quality of cooked rice, or other related food products. These attributes of several rice varieties from North Sumatera, West Sumatera, South Sumatera, Banten, West Java, Central Java, Yogyakarta, East Java, and South Sulawesi were measured, using Brookfield viscometer DV-II+Pro. Popular brands are believed to leverage the potentials, in order to possibly predict customer’s preference. Pasting temperature, peak viscosity, viscosity after 10 minutes at 93.5°C, break down intensity, viscosity at 50°C, and degree of setback, were subsequently evaluated. The extent of breakdown and setback situations were instrumental in characterizing paste stability as well as the retrograde tendency, after cooling. Furthermore, Anak Daro (West Sumatera) demonstrated optimal paste stability, with very minimal breakdown value (231cP). This estimate was significantly lower, compared to most samples, with exception to Ceredek, IR 42 (West Sumatera), Jago Pelung, Pandan Wangi (West Java), Pandan Wangi (East Java), and Memberamo (South Sulawesi). Conversely, Berlian (East Java) showed the greatest retrograde tendency, with maximum setback value (3865 cP). However, the evaluation was more extensively, than other varieties, excluding Ramos Kembang, Ramos Walet (Banten), and C4 (Central Java).

In Situ Stress and Stress Regime in the Onshore Part of the Northeast Java Basin

In situ stress is importance in the petroleum industry because it will significantly enhance our understanding of present-day deformation in a sedimentary basin. The Northeast Java Basin is an example of a tectonically active basin in Indonesia. However, the in situ stress in this basin is still little known. This study attempts to analyze the regional in situ stress (i.e., vertical stress, minimum and maximum horizontal stresses) magnitude and orientation, and stress regime in the onshore part of the Northeast Java Basin based on twelve wells data, consist of density log, direct/indirect pressure test, and leak-off test (LOT) data. The magnitude of vertical ( and minimum horizontal ( stresses were determined using density log and LOT data, respectively. Meanwhile, the orientation of maximum horizontal stress ( was determined using image log data, while its magnitude was determined based on pore pressure, mudweight, and the vertical and minimum horizontal stresses. The stress regime was simply analyzed based on the magnitude of in situ stress using Anderson’s faulting theory. The results show that the vertical stress ( ) in wells that experienced less erosion can be determined using the following equation: , where is in psi, and z is in ft. However, wells that experienced severe erosion have vertical stress gradients higher than one psi/ft ( . The minimum horizontal stress ( ) in the hydrostatic zone can be estimated as, while in the overpressured zone, . The maximum horizontal stress ( ) in the shallow and deep hydrostatic zones can be estimated using equations: and , respectively. While in the overpressured zone, . The orientation of is ~NE-SW, with a strike-slip faulting stress regime.

Mapping study using the unsupervised learning clustering approach

The aim of this research is to analyze the number of criminal cases in Indonesia by utilizing unsupervised learning techniques. The unsupervised learning technique used is data mining by mapping clusters of regions in Indonesia. Sources of data were obtained from the Operations Control Bureau, National Police Headquarters of the Republic of Indonesia through processed data from the Central Statistics Agency (abbreviated as BPS) with data url: https://www.bps.go.id. The data mining method used to map the form of calcter is k-medoid. The data used is data on the number of crimes according to the regional police (2017-2019) which consists of 34 records. The attribute used is the number of crimes in the past three years based on the regional police for each province. The mapping label used is the high cluster (D1) and the low cluster (D2) on the number of criminal acts in Indonesia. The mapping analysis process uses the help of Rapid Miner software. In determining the amount of calcter (k = 2) is done using the Davies Bouldin Index (DBI) parameter with a value of 0.876 (the smaller the better). The results showed that six provinces were in the high cluster (D1) and twenty-eight provinces were in the low cluster (D2). The final centroid in each cluster is 16,008; 21,498; 21,616 (cluster_0 / D1) and 6,994; 7,311; 6,785 (cluster_1 / D2). The six provinces in the high cluster of criminal cases are North Sumatra, South Sumatra, Metro Jaya, West Java, East Java and South Sulawesi. The results of the research are expected to provide information for the government to reduce the number of criminal acts in Indonesia based on the number of clusters that exist.

Sediment and Crustal Structure Beneath East Kalimantan and East Java, Indonesia From Receiver Function

We investigate the sediment and Earth’s crustal structure beneath the East Kalimantan and East Java by modelling the stacked receiver function from six seismic broadband stations belong to the Meteorology, Climatology and Geophysics Agency of Indonesia (BMKG). The calculation of receiver functions from 60 teleseismic earthquake events using iterative time-domain deconvolution method. Inversion result shows a significant variation in the sediment layer thickness from 1 km to 4 km beneath East Java. It is correlated with the South East Java basinal area (station KRK) and the North East Java Basin (station GRJI and BWJI). The sediment layer of about 5 to 10 km beneath East Kalimantan is associated with the Kutai Basin (station SGKI, SMKI, and BKB). Average Sediment layer shear velocity (Vs) beneath all station is observed to be less than 2.31 km/s. Crustal thickness beneath East Java varies between 20 to 40 km and 34 to 50 km beneath East Kalimantan, with average crustal shear wave velocity, Vs 4.60 km/s.

Islamic Financial Literacy: Developing Instruments

The purpose of this study was to analyze the efficiency of local government expenditure based on Islamic Human Development Index (I-HDI) in Local Government at the Indonesian’s Province using Data Envelopment Analysis (DEA). DEA is a non parametic method that was developed to measure the level of efficiency compared to the Decision Making Unit (DMU). This method can measure the efficiency of a government entity by using multi-input and multi-output. DEA result also can be used to identify wich input or output must be increased by Decision Making Unit (DMU) to reach optimum efficiency. The result from this study showed that the average of efficiency score in local government at Indonesian’s Province is increasing from 2015 until 2018. This study also indicates that North Sumatera, East Java, and Yogyakarta’s government spending were efficient in 4 years. While Bangka Belitung and West Papua achieve the lowest efficiency score, and should optimize input and increase the number of output to improve the efficiency. Morever, the main source of inefficiency is in Life birth rate indicators.

Granulometry analysis of Ngrayong sandstone, Tempuran Area, Rembang Zone, North East Java Basin

The study area is located near Tempuran Village, Rembang Zone, North-East Java. Ngrayong sandstone is a famous reservoir in north-east Java, mainly composed of sandstones which are exposed along east-west trending along the southern flank of Pakel Anticline. Eighteen samples from four different facies from eight outcrops conducted for granulometry analysis. The objective of this paper is to predict the reservoir potential base on granulometry analysis especially grain size and sorting. The study area is still needs to confirm about reservoir quality. Ngrayong Formation consists of laminated to thin bedded sandstone facies, thick bedded to massive sandstone facies, calcareous sandstone facies and cross-bedded sandstone facies. According to the analytical results, sandstone facies are composed of very fine to fine, poorly sorted to very well sorted sandstones. Base on the results of analyzed samples, Ngrayong sandstone have good porosity and permeability, thus Tempuran area can be considered as a prospective reservoir.

Recent magmatism drives hydrocarbon generation in north-east Java, Indonesia

Conventional studies of petroleum basins associate oil generation with the gradual burial of organic-rich sediments. These classical models rely on the interplay between pressure, temperature, and the time required for organic matter transformation to oil and gas. These processes usually occur over geological timescales, but may be accelerated by rapid reactions when carbon-rich sediments are exposed to migrating magmatic fluids. The spectacular Lusi eruption (north-east Java, Indonesia) is the surface expression of the present-day deep interaction between volcanic and sedimentary domains. Here we report the ongoing generation of large amounts of hydrocarbons induced by a recent magmatic intrusion from the neighbouring Arjuno-Welirang volcanic complex. We have investigated a unique suite of oil and clast samples, and developed a detailed conceptual model for the complex hydrocarbon migration history in this part of the basin by integrating multidisciplinary techniques. Our results show that palynology, organic petrology, and chlorite microthermometry are the most sensitive geothermometers for basins affected by recent magmatic activity. These findings further our understanding of the driving mechanisms fueling the world’s largest active mud eruption and provide a unique dataset to investigate modern hydrocarbon generation processes.

ESTIMASI NILAI POROSITAS DAN PERMEABILITAS DENGAN PENDEKATAN DIGITAL ROCK PHYSICS (DRP) PADA SAMPEL BATUPASIR FORMASI NGRAYONG, CEKUNGAN JAWA TIMUR BAGIAN UTARA

Reservoir rock permeability and porosity are physical properties of rocks that control reservoir quality. Conventionally, rock porosity and permeability values are obtained from measurements in the laboratory or through well logs. At present, calculation of porosity and permeability can be calculated using digital image processing / Digital Rock Physics (DRP). Core data samples are processed by X-ray diffraction using CT-micro-tomography scan. The result is an image model of the core sample, 2D and 3D images. The combination of theoretical processing and digital images can be obtained from the value of porosity and permeability of rock samples. In this study, we calculated porosity and permeability values using the Digital Rock Physics (DRP) approach in sandstone samples from the Ngrayong Formation, North East Java Basin. The results of the digital image simulation and processing on the Ngrayong Formation sandstone samples ranged in value from 33.50% and permeability around 1267.02 mDarcy.

Facies Classification Using Stochastic Inversion Method for Carbonate Oligo-Miocene in Pangkah, North East Java Basin

The offshore Northeast Java Basin is one of the largest basins in Indonesia and one that contains complete hydrocarbon systems from Middle Miocene Tuban formations to Pre Tertiary basement formatio...

Depositional and diagenetic history of limestones and dolostones of the Oligo‐Miocene Kujung Formation in the Northeast Java Basin, Indonesia

AbstractLithological and geochemical features of platformal carbonates record the signatures of the global climates and the regional environmental settings and also reconstruct the diagenetic history and porosity evolution, which are essential to evaluate the potential of hydrocarbon reservoirs. This study investigates the platformal carbonates of the Oligo‐Miocene Krunji Formation of North East Java Basin, which are potentially significant hydrocarbon reservoirs. The carbonate sequence in a 283 m thick section at Kranji in East Java is subdivided into three lithological units: limestone unit 1, dolostone unit 2, and limestone unit 3, in ascending order. The strontium‐isotope ratios of well‐preserved calcite samples indicate the depositional period from Chattian (late Oligocene) to Burdigalian (early Miocene), which is consistent with ages of the foraminifer assemblages. Unit 1 consists of low‐porosity limestone, in which two horizons of subaerial exposure are recognized by the occurrence of red‐colored matrix and lower δ13C values. Unit 2 consists of dolomitic rock and exhibits coarse‐grained calcitic grains and cross‐stratified structure. Considering that this unit has been subject to dolomitization, the sediment of unit 2 was initially permeable and was likely deposited in a shoal setting. The overlying unit 3 of Aquitanian–Burdigalian age is characterized by a highly granular texture. High porosity and uniformly low δ13C and δ18O values indicate that Unit 3 was subjected to more intense meteoric diagenesis than the Chattian unit 1. This was likely a consequence of the Antarctic ice‐sheet expansion during the Oligocene/Miocene transition, which amplified sea level change. The unit 2 dolomite has high δ13C and δ18O values and a high 87Sr/86Sr ratio which resulted from the reflux of seawater into permeable the sediment body in middle‐late Miocene (Burdigalian Tortonian) following the deposition of unit 3. The porosity and permeability of the Kujung Formation were initially controlled by sedimentological processes, but largely modified by later diagenetic processes.

PENERAPAN DATA MINING PADA JUMLAH PELANGGAN PERUSAHAAN AIR BERSIH MENURUT PROVINSI MENGGUNAKAN METODE K-MEANS CLUSTERING

Water is one of the primary needs for humans so that everyone has the right to get clean water for their daily needs. Along with increasing population, the need for water will increase. So with that the PDAM must sell clean / decent water to its customers, clean water becomes the focus of attention and has the greatest power compared to other problems. Because water is a basic necessity, most of the companies impose rates that can be reached by the community and prices are adjusted to the growth in demand. The purpose of this research is to get a grouping of the number of customers of clean water companies in all provinces using the K-Means Algorithm, K-Means is a method for grouping data into a cluster by calculating the closest distance from a data to a centroid point. Clusters used are high level clusters (C1), medium level clusters (C2), and for low level clusters (C3). Centroid data obtained is for high-level clusters (C1) which are as many as 7710154, for medium-level clusters as much as 929586, and for low-level clusters as much as 112462. Based on the calculated data obtained high-level results, namely the province of Indonesia, for the medium level namely province North Sumatra, DKI Jakarta, West Java, Central Java and East Java, and other provinces are low levels. So that this result can be a support for the company in order to increase water needs.

Penerapan Data Mining Dalam Mengelompokkanm Jumlah Usaha Berdasarkan Provinsi Menggunakan K-Means Clustering

Industrial revolution 4.0 is an era where technology in the IT field is growing very rapidly, it can also be said a new era for entrepreneurs in Indonesia that must be a golden opportunity to improve business performance and opportunities for millennials to enter the business or business world. In this era people are expected to be able to compete especially in the business world. This study discusses the Application of Data Mining in Grouping the Number of Enterprises by Province Using K-Means Clustering. The source of this research data is collected based on the information documents of the number of businesses in Indonesia produced by the National Statistics Agency. The data used in this study are provincial data consisting of 34 provinces. Data will be processed by clustering in 3 clusters, namely cluster of high number of businesses, cluster of medium number of businesses and cluster of low number of businesses. The results obtained from the assessment process are based on the index of the number of businesses with 4 provinces, the number of high businesses, namely North Sumatra, West Java, Central Java, and East Java, 13 Provinces, the number of medium enterprises and 17 other provinces, including low business numbers. This can be used as input to the community, especially in provinces where the number of businesses is low so they can compete in the business world and input for the government to provide facilities and infrastructure to support entrepreneurs in Indonesia.

THE ANALYSIS OF FACTORS THAT AFFECT LABOR ABSORPTION IN NATURAL RUBBER PLANTATION

The study aimed to analyze several indicators that exist in the rubber industry and their influence on labor absorption in particular provinces in Indonesia from 2012-2015. The provinces consisted of North Sumatera, Riau, South Sumatera, Lampung, West Kalimantan, Central Kalimantan, South Kalimantan, West Java, Aceh, and East Java. The factors that the writer used in this research were rubber production, the size of rubber plantation, provincial minimum wage, and the number of company. In this research, the writer used panel data regression as the analyzing tool and random effect model as the best model to describe the relationship between independent and dependent variables. The result of the result shows that the provincial minimum wage and the number of company had significant effect on labor absorption while the other two, rubber production and the size of rubber plantation area did not have significant effect on labor absorption.

Elastic Properties Modeling for Identification of Prospective Reservoir Zones in the Carbonate Reservoir, MRD Field in the North East Java Basin

“MRD” field is an oil and gas field which located in Rembang Zone. One of the hydrocarbon zones in this fieldlies in Ngimbang Formation. Reservoir in this field has a lifespan of Middle Eocene to Early Oligocene. Reservoir of this formation is carbonate rocks and dominated by calcite and dolomite minerals. One of the uniqueness of this kind of reservoir is the pore shape which quite complex. In this study, reservoir characterization which performed on this field is based on elastic properties modelling. Elastic Properties modelling which was conducted in this field can provide an output of the pore shape, aspect ratio, and the fraction of each respective poresforms that exist in this field’s reservoir zone. Therefore the primary data such as petrophysical data, XRD (X-Ray Diffraction), and the data of other reservoir parameters are needed for more accurate resultsobtained with real conditions. The result of this modelling shows that the shape of the pores in the reservoir zone at any depth can be predicted. Distribution of pore shapes that exist in the two wells can be used as a reference for prospective determination of hydrocarbon zones in “MRD” field.

Integrated Subsurface Temperature Modeling beneath Mt. Lawu and Mt. Muriah in The Northeast Java Basin, Indonesia

Abstract The subsurface temperature has many impacts on geological phenomena such as hydrocarbon generation, geothermal energy, mineralization, and geological hazards. The Northeast Java Basin has various interesting phenomena, such as many oil fields, active faults, mud eruptions, and some active and dormant volcanoes. We measured temperature data from tens of wells along a 130 km survey line with an average spacing of 5 km. We also measured the thermal conductivity of rocks of various lithologies along the survey line to provide geothermal heat flow data. We propose integrated modeling for profiling the subsurface temperature beneath the survey line from Mt. Lawu to Mt. Muriah in the Northeast Java Basin. The modeling of subsurface temperature integrates various input data such as a thermal conductivity model, surface temperature, gradient temperature, a geological model, and geothermal heat flow. The thermal conductivity model considers the subsurface geological model. The temperature modeling uses the finite difference of Fourier’s law, with an input subsurface thermal conductivity model, geothermal heat flow, and surface temperature. The subsurface temperature profile along with survey line shows some interesting anomalies which correlate with either subsurface volcanic activity or the impact of fault activity.

Studi Lingkungan Pengendapan dan Diagenesis Batuan Berdasarkan Analisis Petrografi di Daerah Sukolilo, Pati, Jawa-Tengah

Sandstones of Ngrayong Formation are an important reservoir in the north-east Java basin while the Bulu Formation generally functions as an aquifer in the study area. The quality of aquifers and reservoirs in the form of porosity and permeability can be influenced by the diagenesis process. This study aims to determine the depositional environment and diagenesis processes that occur in rocks of Ngrayong Formation and Bulu Formation. Sandstones as sedimentary rocks generally undergo diagenetic processes consisting of compaction, cementation, and dissolution, while carbonate rocks diagenesis processes are very varied but the most important is the process of dissolving and fracturing as forming porosity. From the results of the petrographic analysis, it can be seen that the depositional environment of the Ngrayong Formation is inner-neritic to middle-neritic while the Bulu Formation is deposited in the inner shelf environment. The diagenesis process that occurs is compaction, cementation, dissolution and micritization.

ONSHORE-OFFSHORE FACIES CHANGE OF NGRAYONG SANDSTONE IN MADURA AREAINDONESIA

Ngrayong sandstone composes a siliciclastic reservoir that produces oil for more than a century in North East Java Basin of Indonesia. Clean sand facies makes the best reservoir in western part of the basin, onshore East Java Island. Meanwhile, sand quality decreases eastward to Madura Island. In Madura, rock gradually changes to be more calcareous and shaly, due to the change of depositional environment. In offshore of Madura, the depositional environment is still questionable. This study is aimed to reveal differences between onshore and offshore facies of Ngrayong sandstone in Madura as their distribution is not well known and oil potential of Madura Strait is not well identified. Study methods consisted of geological field work, well correlation, and petrophysical analysis from several well data. The results show that Ngrayong sandstone was deposited during Middle Miocene, composed by interbedding of thickly bedded sandstone and alternating thinly bedded sandstoneshale. The succession is commonly intercalated by mudstone and thinly bedded limestone. At Madura Island, Ngrayong sandstone overlies the Early-Middle Miocene Tawun Formation, which both represent the Megasequence (MS) 3 interval. Due to regional subsidence and transgression during Late Miocene, Ngrayong sandstone and other equivalent rocks were overlain by monotonous mudstone and calcareous sandstone of Wonocolo Formation. The Ngrayong sandstone is evenly distributed in whole surface area of Madura Island and it spreads further 25-50 Km to the south and 100-125 Km to eastern part of offshore Madura Strait. Sandstone distribution is roughly depleted from the gross thickness hundreds of meters in northern part to only few centimeters in southeast part of study area. The facies changes to be more calcareous to the east, while the southward facies is shaly due to a deeper depositional environment. Despite of facies changing into shales or carbonate facies, Ngrayong sandstone potential in offshore Madura Strait needs to be considered as upside potential due to its distribution is wider than initial estimation, and its petrology and petrophysic data support it as a clastic reservoir.

The DutchMogharaer,ArabicMuḥarrar,and Javanese Law Books: A VOC Experiment with Muslim Law in Java, 1747–1767

This article examines the claims of Dutch East India Company (VOC) officials in the mid-eighteenth century regarding the Islamic source of a legal code prepared for the local population in Semarang, northeast Java. Although the VOC had encountered local legal cultures in Indonesia since the mid-seventeenth century, it preferred to circumvent those in favour of European laws whenever possible. But in the eighteenth century, VOC officials addressed indigenous legal systems more directly when the company sought possibilities for direct control. This resulted in the production of many codes on the legal status of Muslim and Chinese subjects of Indonesia. In the process of codification, some officials claimed to have consulted Islamic legal texts and Muslim jurists. One criminal code that came out of the effort supposedly took its rulings accurately from theMugharrar,which is possibly theMuḥarrarwritten by the Islamic jurist ʿAbd al-Karīm al-Rāfiʿī (d. 1226). I argue that this assertion is baseless, and demonstrate that the very pretense is part of a larger colonial project that sought legitimacy from the indigenous subjects at a time of political and economic crises.