Mahakam Delta Research Articles

Understanding the murky history of the Coral Triangle: Miocene corals and reef habitats in East Kalimantan (Indonesia)

Studies on ancient coral communities living in marginal conditions, including low light, high turbidity, extreme temperatures, or high nutrients, are important to understand the current structure of reefs and how they could potentially respond to global changes. The main goal of this study was to document the rich and well-preserved fossil coral fauna preserved in Miocene exposures of the Kutai Basin in East Kalimantan, Indonesia. Our collections include almost forty thousand specimens collected from 47 outcrops. Seventy-nine genera and 234 species have been identified. Three different coral assemblages were found corresponding to small patch reefs that developed under the influence of high siliciclastic inputs from the Mahakam Delta. Coral assemblages vary in richness, structure, and composition. Platy coral assemblages were common until the Serravallian (Middle Miocene), while branching coral assemblages became dominant in the Tortonian (Late Miocene). By the late Tortonian massive coral assemblages dominated, similar to modern-style coral framework. Our results suggest that challenging habitats, such as the Miocene turbid habitats of East Kalimantan, might have played an important role during the early diversification of the Coral Triangle by hosting a pool of resilient species more likely to survive the environmental changes that have affected this region since the Cenozoic. Further research that integrates fossil and recent turbid habitats may provide a glimpse into the dynamics and future of coral reefs as “typical” clear-water reefs continue to decline in most regions.

Microbial domes and megaoncoids in Miocene reefs in the Mahakam Delta in East Kalimantan, Indonesia

Coral patch reefs in the Miocene Mahakam delta in East Kalimantan (Borneo, Indonesia) developed in shallow marine turbid waters. These reefs grew in delta front to prodelta environments under fluctuating siliciclastic input. Langhian patch reefs are well exposed in limestone quarries of the Air Putih area, near the city of Samarinda and include two different types of microbial carbonates in two sections, 2km apart. In the northern section, microbialites occur as low-relief domes, up to 2m wide and 0.5m high. The domes show internal lamination and coralline algae and encrusting foraminifers interlayered with microbial micrite. They developed around large coral fragments at the transition from reef deposits to fine-grained siliciclastics. Microbialites in the southern section formed decimetre- to metre-scale nodules (here termed “megaoncoids”) around nuclei of large coral fragments. Microbial micrite with laminated to digitate fabrics intergrew with coralline algae and encrusting foraminifers to form the thick covers of megaoncoids. Small nodules were bound together in larger ones, which are usually strongly asymmetric internally. Megaoncoids accumulated in a carbonate breccia laterally changing into coral boundstones. In both sections, microbialites grew on the flanks of shallow-water, low-relief patch reefs in poorly illuminated, low-energy conditions. Flat-domed microbialites formed on a nearly horizontal, stable seafloor seawards of the patch reef. The megaoncoids in the southern section formed as a result of downslope displacement of coral fragments coated by microbialite/coralline algal/encrusting foraminifer crusts. The slope of the patch reef's flank favoured the falling and rolling of encrusted corals, with the continued growth of microbial crusts on all sides of nodules. In contrast to Quaternary and recent occurrences of microbialites in Indo-Pacific and Caribbean reefs, the Samarinda microbialites are not components of the reef framework nor formed in deep water. Instead, they developed in shallow, turbid waters of the Miocene Mahakam delta in periods of arrested siliciclastic input.

STUDY ON DETERMINATION OF CATCH FISH AREA USING DISTRIBUTION PARAMETERS OF SEA SURFACE TEMPERATURE AND DISTRIBUTION OF CHLOROPHYLL-A AT MAHAKAM DELTA MARINE

As a maritime country , Indonesia has a comparative advantage in fisheries and marine resource potential . In 2010, the result of fish catches in Samarinda reached 9266.7 tons. Distribution of sea surface temperature and distribution of chlorophyll-a in the Mahakam Delta area required for mapping analysis of fishing grounds in order to maximize the potential of fish catches. The analysis using MODIS Terra satellite image with ATBD 19 MODIS algorithm to determine the concentration of chlorophyll -a and 25 MODIS ATBD algorithm to determine the sea surface temperature in the area of research. The Results of image data processing, sea surface temperatures in 2013 , 2014 and 2015 is dominated with temperatures ranging between 24°C to 28°C. In 2013 , the distribution of chlorophyll-a spread evenly. In 2014 , the waters were relatively less fertile due to the distribution of chlorophyll-a, identified less evenly. By 2015 , the waters were also less fertile. Chlorophyll-a was identified only slightly. Zone of fishing ground, in 2013, the distribution of many fish catches prediction zones spread along the coast north of the Mahakam Delta, the middle of Mahakam Delta and the middle of the Strait of Makassar.Distribution of little fish catches prediction zone were in the South Mahakam Delta. In 2014 , the many fish catches zone spread in the middle of Mahakam Delta and the little fish catches zone spread in north and south coast of the Mahakam Delta.In 2015, there were no many fish catches zones, just the little fish catches was indentified. The little fish catches zone spread in north and south coast of the Mahakam Delta.

Simulations of the flow in the Mahakam river–lake–delta system, Indonesia

Large rivers often present a river–lake–delta system, with a wide range of temporal and spatial scales of the flow due to the combined effects of human activities and various natural factors, e.g., river discharge, tides, climatic variability, droughts, floods. Numerical models that allow for simulating the flow in these river–lake–delta systems are essential to study them and predict their evolution under the impact of various forcings. This is because they provide information that cannot be easily measured with sufficient temporal and spatial detail. In this study, we combine one-dimensional sectional-averaged (1D) and two-dimensional depth-averaged (2D) models, in the framework of the finite element model SLIM, to simulate the flow in the Mahakam river–lake–delta system (Indonesia). The 1D model representing the Mahakam River and four tributaries is coupled to the 2D unstructured mesh model implemented on the Mahakam Delta, the adjacent Makassar Strait, and three lakes in the central part of the river catchment. Using observations of water elevation at five stations, the bottom friction for river and tributaries, lakes, delta, and adjacent coastal zone is calibrated. Next, the model is validated using another period of observations of water elevation, flow velocity, and water discharge at various stations. Several criteria are implemented to assess the quality of the simulations, and a good agreement between simulations and observations is achieved in both calibration and validation stages. Different aspects of the flow, i.e., the division of water at two bifurcations in the delta, the effects of the lakes on the flow in the lower part of the system, the area of tidal propagation, are also quantified and discussed.

Ecological Risk Assessment of Heavy Metal Pollution in Surface Sediment of Mahakam Delta, East Kalimantan

Spreading heavy metals in the water column may subsequently be accumulated in sediment because of low solubility then become sensitivity indicator for aquatic organism. Ecological risk is assessed through the heavy metals concentration in the surface sediment. Sediment samples were grabbed from 20 stations in Mahakam Delta. Hakanson method was used to identify ecological potential risk of heavy metals pollution. The results showed that Zn (70.63mg/kg), Cr (4.93mg/kg), Cd (0.11mg/kg) and Ni (33.48mg/kg) exceeded Threshold Effect Level. Furthermore Ni exceeded Probable Effect Level. Ecological potential risk of heavy metals sequence was Pb>As>Cd>Ni>Zn>Cr>Cu. The criteria of ecological risk on Pb and as were considerable risk (Eri Pb: 52.18 and Eri As: 50.00 and the others were low risk. Moreover, the potential ecological risk sequence of study were ST18> ST3> ST8> ST1> ST7> ST6> ST11> ST20> ST19> ST4> ST16> ST5> ST9> ST15> ST2> ST13> ST14> ST17> ST10> ST12. The criteria of ST 18, ST 3, ST 8, ST 1 and ST 7 belonged to considerable risk, ST 12 was low risk and others location were medium risk. Heavy metals input in Mahakam Delta are possibly caused by human activities such as industrial, mining, household activities, and from natural process by erosion and natural water flow.

Estimating Mean Tree Crown Diameter of Mangrove Stands Using Aerial Photo

Geostatistics was applied to estimate mean tree crown diameter using high spatial resolution aerial photo of three different mangrove forest structure in the Mahakam Delta, East Kalimantan, Indonesia. The variogram analysis of the aerial photo was succeeded to estimate mean tree crown diameter of mangrove forest of Mahakam Delta. The Range of variogram was used to predict mean tree crown diameter and came to result with the error about 6.19% or less than 0.5 m. Based on this study, green band looks promising but still need more exploration and further test especially for complex canopy structure such as lowland Dipterocarp forest which completely distinct to Mangrove forest. Despite of its successness, variogram was not succeed to estimate mean crown diameter of high density mangrove forest plantation sites. Close-spacing plantation suppressed tree crown growth and development. In the aerial photo, it produced smooth texture feature of tree crown with less edge of shadow. Consequently, tree crown became indistinguishable.

Distribution of Phytoplankton Diversity and Abundance in Mahakam Delta, East Kalimantan

The Mahakam Delta typically consisting of several ecosystems has been identified as one of biodiversity hotspot in Kalimantan Island. In order to provide phytoplankton distribution, diversity and abundance data, a research on 4 stations representing delta plain (ST1) and delta front (ST2, ST3, ST4) was performed. The studies describe phytoplankton community existing in this region and multivariate analysis using correspondent analysis (CA). There were 48 taxa phytoplankton belonging to Bacillariophyceae (35), Dinophyceae (6), Chlorophyceae (4), and Cyanophyceae (3). The highest taxa occurred in ST3 with diversity index of 2.09, followed by ST2 (1.95), ST1 (1.15), and ST4 (0.9). Diversity index of ST3, ST2, and ST1 delta was categorized as moderate stable community, while ST4 was categorized as unstable community. Bacillariophyceae was not only as the highest diversity class but also as the highest abundance, recorded in ST3. The abundance class ranged 1.4x105 cell/m3 to 2.2x106 cell/m3. Generally, phytoplankton diversity and abundance in delta front was higher than that in delta plain. Human activities and physical process likely influenced diversity and abundance of phytoplankton in Delta Mahakam.

Modelling fine-grained sediment transport in the Mahakam land–sea continuum, Indonesia

SLIM is an unstructured mesh, finite element model of environmental and geophysical fluid flows, which is being improved to simulate fine-grained sediment transport in riverine and marine water systems. A 2D depth-averaged version of the model is applied to the Mahakam Delta (Borneo, Indonesia), the adjacent ocean, and three lakes in the central part of the Mahakam River catchment. The 2D code is coupled to a 1D section-averaged model for the Mahakam River and four tributaries. The coupled 2D/1D model is mainly aimed at simulating fine-grained sediment transport in the riverine and marine water continuum of the Mahakam River system. Using the observations of suspended sediment concentration (SSC) at five locations in the computational domain, the modelling parameters are first determined in a calibration step, for a given period of time. A validation step is then performed using data related to another period of time. It is concluded that the coupled 2D/1D model reproduces very well the observed suspended sediment distribution within the delta. The spatial distribution of sediment concentration in the delta and its temporal variation are also discussed.

TEKNOLOGI EFISIENSI EKONOMI USAHA TAMBAK UDANG DI KECAMATAN MUARA JAWA KABUPATEN KUTAI KARTANEGARA

Delta Mahakam is one of the central representative aquaculture activities for Muara Jawa people that when this condition tend to be less technically efficient for production activities. The importances of this study through research objectives are (1) to analyze locative and economic efficiency achieved in the operations of farmers, (2) Measuring the use of production factors in optimal conditions to achieve a high economic efficiency level. The data in the second phase will be collected and then tabulated and analyzed, and to identify conditions and problems of shrimp farms by descriptive analysis. The results show on average the shrimp farmers in the study area have been technically efficient, but not locative and economically efficient. This is due to the excessive use of inputs that are less efficient. Increased production can increase the cost of production, so it is necessary to do the expansion of business scale in accordance with the recommendations allocative and economic efficiency. The shrimp fry price factor, the use of fertilizers and land depreciation expense does not significantly affect the cost of production so that if there is an increase in prices to a certain extent can be tolerated. The frontier analysis results showed most levels of price and economic efficiency of farms in the study area is relatively small or not efficient respectively 0.464 and 0.247, and the conditions of production factors are not the optimal conditions for below-average economic efficiency 0.664. Keywords : Economic Efficiency, Shrimp Farms, Muara Jawa

DATING BORNEO'S DELTAIC DELUGE: MIDDLE MIOCENE PROGRADATION OF THE MAHAKAM DELTA

Borneo's geologic and paleontological history remains poorly understood because of the lack of outcrops and difficulties with dating. Urban development around the city of Samarinda has produced over four kilometers of well-exposed stratigraphy depicting the progradation of the ancient Mahakam river delta across the Samarinda area, which includes slope, shelf, and deltaic deposits (clastic and carbonate). Previous studies have preliminarily dated the succession as middle Miocene, but reworking and the scarcity of diagnostic fossils make dating difficult. In this paper, an integrated stratigraphic age model has been constructed for the middle Miocene of the Samarinda region with a combination of magnetostratigraphy, sequence stratigraphy, and biostratigraphy (nannofossil, planktonic foraminifera, and larger benthic foraminifera). This age model provides improved temporal constraints for part of the Mahakam Delta succession. It also helps to place the pattern of biodiversity changes seen in Indonesian reef communities into a better time perspective, and permits more accurate sedimentation rates to be determined. It may also serve as a reference point to compare other Neogene sections in Southeast Asia. The two reef complexes at Samarinda, the Batu Putih and the Stadion section, are magnetostratigraphically dated at , 15 Ma and 11.6 Ma, respectively. The new chronology for the Samarinda succession shows that the Mahakam Delta went through a major phase of buildout and progradation during the middle and earliest late Miocene, during which time progradation across the former shelf break took place in the Samarinda area.

A DIVERSE PATCH REEF FROM TURBID HABITATS IN THE MIDDLE MIOCENE (EAST KALIMANTAN, INDONESIA)

The Kutai Basin (East Kalimantan, Indonesia) contains a rich and well-preserved Miocene fossil record of small patch reefs that developed under the influence of high siliciclastic input associated with the progradation of the Mahakam Delta. In this study, we reconstruct the biodiversity and paleoenvironments on one of these delta-front, mixed carbonate-siliciclastic systems that developed at the Serravallian–Tortonian boundary near the city of Samarinda. In two newly exposed sections, we analyzed the sedimentology and distribution of the main fossil biota including corals, foraminifers, coralline algae, and bryozoans. Seven facies are herein defined, including two dominated by platy corals and two by larger benthic foraminifera. Facies distributions were driven by changes in depth and variations in terrigenous input within a range of delta-front habitats. Despite the turbid conditions, fossil assemblages are highly diverse, including 69 coral species and 28 bryozoan species that occur in coral-dominated facies. Crustose coralline algae were mainly associated with the coral-dominated facies. Larger benthic foraminifera showed broader ecological tolerance within the range represented in the studied sections and thus are common in most facies. These diverse patch reef ecosystems were able to cope with high siliciclastic input during the early development of the Miocene coral reef biota.

Eutrophication of mangroves linked to depletion of foliar and soil base cations.

There is growing concern that increasing eutrophication causes degradation of coastal ecosystems. Studies in terrestrial ecosystems have shown that increasing the concentration of nitrogen in soils contributes to the acidification process, which leads to leaching of base cations. To test the effects of eutrophication on the availability of base cations in mangroves, we compared paired leaf and soil nutrient levels sampled in Nypa fruticans and Rhizophora spp. on a severely disturbed, i.e. nutrient loaded, site (Mahakam delta) with samples from an undisturbed, near-pristine site (Berau delta) in East Kalimantan, Indonesia. The findings indicate that under pristine conditions, the availability of base cations in mangrove soils is determined largely by salinity. Anthropogenic disturbances on the Mahakam site have resulted in eutrophication, which is related to lower levels of foliar and soil base cations. Path analysis suggests that increasing soil nitrogen reduces soil pH, which in turn reduces the levels of foliar and soil base cations in mangroves.

Analisis Sensitivitas Lingkungan OSCP (Oil Spill Contingency Plan) di Pesisir Selatan Delta Mahakam, Provinsi Kalimantan Timur

The research was one part of oil spill contingency plan (OSCP) developed for Delta Mahakam area, where oil & gas exploration and exploitation linked with rich biodiversity supporting coastal community livelihood. Environmental sensitivity analysis for OSCP only do two early stages of OSCP scope, which integrated with the dangers of coastal vulnerability. This analysis mapped environmental component from oil pollution become sensitivity rangking as an effort to support response development strategies and priorities for the coastal resources protection. The aims of this research were (1) to establish environment sensitivity rank and (2) to identify primary factor supporting the environmental sensitivity for OSCP in south Delta Mahakam area. The result of analysis showed environmenal sensitivity was 62.37% (517.52 km), its mean very high sensitivity. Then the high sensitivity criteria was 11.31% (94 km). The criteria of medium sensitivity was 11.92% (99 km). While for low sensitivity and very low sensitivity respectively were 1.78% (15 km) and 12.64% (105 km). Based on Principal Component Analysis (PCA), 36.01% variability was explained by axis of factor 1. The others variability 18.53% and 13.93% were explained by axis of the factor 2 and factor 3. Axis of factor 1 for coastal exposure (EK), oil residence index (OR), coastal type (TP), and biological resources (SH) had a quite large linear combinations coefficient, amounted to 0.94 (EK&OR), 0.83 (TP) and 0.75 (SH). This indicated a very high contribution for environmental sensitivity OSCP level drafting. On axis of factor 2, the linear coeffisien combinations for the resource utilization of port (PL) was 0.83 and settlement (PM) was 0.85. Axis of factor 3 contributed 0.75 and 0.66 on migas platform (PO) and placement of passive fishing gear/catchment area (AT). However, the utilization of coastal resources for PL, PM, PO and AT were on axis of factor 2 and factor 3 had a considerable distance with its SI variable. This possible caused by each variable percentage distribution which the value was very minor ranged 0.001-0.52%, so its not representated coastal resources elements closeness with SI variable in the study area. Keywords: Environmental Sensitivity, Oil Spill Contingency Plan, Mahakam Delta

VALUASI TOTAL EKONOMI HUTAN MANGROVE DI KAWASAN DELTA MAHAKAM KABUPATEN KUTAI KARTANEGARA KALIMANTAN TIMUR

Mangrove forest is a tropical coastal vegetation community. The purpose of this study are: to identify the types and functions of the ecosystem of the area of mangrove forest; calculate the total economic value generated by mangrove forests; examine the factors that affect the economic benefits gained at the Mahakam Delta mangrove forest, Kutai regency. Results of this study indicated that there were four dominant types of forests mangrove: rizhopora, avicennia, sonneratia and nypa. They have decreased due to reduced function of mangrove forest area. This result is supported by the calculation of total economic value (TEV) in 2012 which amounted to Rp503.071.398 869,2. Factor affecting the economic benefits of mangrove forests in order to remain sustainable in recreational value of travel cost, student employment, the number of dependent and age, while the factors that affect the existence of the mangrove forest are job and income, while the factor that affect the sustainability endemic bekantan are of the income, origin in the region and outside the region. Keywords: Mahakam delta, mangrove forest, TEV

Potency of Mahakam Delta in East Kalimantan, Indonesia

Normal 0 false false false IN X-NONE X-NONE Mahakam Delta is not only utilized for fishery activities but also for several industrial purposes such as coal and oil mining, shipping and timber. The objective of this paper is to provide information in term of the potency of Mahakam Delta located in East Kalimantan province, Indonesia. The study was conducted in Mahakam Delta, East Kalimantan Province, Indonesia. Participatory rural appraisal is a group of methods to collect information in a participatory fashion from rural communities. The method employed in this research was descriptive analysis describing the environmental potency found in Mahakam Delta. Massive conversion of mangrove forest particularly Nypa (Nypa fruticans) area into pond has driven conflict among related stakeholders on the utilization of natural resource and land which subsequently impacts on the fish and shrimp source regeneration, loss of ecological functions of mangrove forest for feeding, nursery and spawning ground of fish and other organisms. Besides of fisheries, oil and gas activity also exists in Mahakam Delta. Mahakam Delta is regarded as important area due to the largest producer of oil and gas mining. Thus, oil and gas industry is the most reliable sector that contributes to the economic development of Kutai Kartanegara district. As a resource provider, Mahakam Delta ecosystem provides various resources for livelihoods. As a life-support service provider, Mahakam Delta ecosystem provides habitat and ideal environment to support variety of living kinds. As a convenience provider, Mahakam Delta ecosystem provides unique and interesting recreation site. As a protector from natural disaster, Mahakam Delta ecosystem is able to protect human kinds from natural disaster threatening coastal area.

Dampak Degradasi Lingkungan Terhadap Potensi Pengembangan Ekowisata Berkelanjutan di Delta Mahakam: Suatu Tinjauan

<p class="Abstract">Tujuan penelitian ini adalah merumuskan konsep umum pengembangan ekowisata di wilayah kepesisiran Delta Mahakam berdasarkan fenomena degradasi lingkungan yang ada. Metode yang digunakan meliputi metode deskriptif analitis dengan menelaah secara kritis dan komprehensif dari berbagai penelitian yang telah dilakukan. Berbagai penelitian yang dilakukan bukan hanya terbatas pada pendekatan sains dan teknologi namun juga kebijakan pengembangan wilayah berbasis isu-isu strategis terkini. Hasil dari penelitian ini menyimpulkan bahwa fenomena degradasi lingkungan di Delta Mahakam telah berada pada tingkat yang sangat parah, yaitu hampir seluas 80 % dari 1000 Km<sup>2</sup>. Faktor utama degradasi lingkungan tersebut, yaitu konversi lahan, eksploitasi migas. Diperlukan upaya yang terpadu dan berkelanjutan untuk mengurangi dampak degradasi lingkungan yang salah satu upayanya adalah kegiatan pengembangan ekowisata. Kegiatan tersebut menekankan pada tiga prinsip penting, yaitu nilai konservasi, pelibatan masyarakat dan berkelanjutan. Berdasarkan pada tiga aspek tersebut maka pada penelitian ini menyimpulkan tiga konsep dasar dalam kegiatan pengembangan ekowisata kepesisiran. Terdapat beberapa indikator pada masing-masing konsep tersebut. Konsep tersebut meliputi konsep penataan kebijakan, konsep pengelolaan biogeofisik dan konsep pengelolaan ekowisata berkelanjutan.</p><strong></strong>

The Potential of Tiger Prawn Fry from Delta Mahakam, East Kalimantan Indonesia

Most of the life cycle of tiger prawns were estuarine (Delta Mahakam). In the juvenile stage life in estuarine and the adult stage in marine. The research objective is to assess the potential of the tiger prawn fry catches in the Mahakam Delta, as a source of tiger prawn fry in the Mahakam Delta area farms. Research using interviews and descriptive analysis through monitoring with fishermen. The results showed that the fry tiger prawn from the Delta Mahakam there on the beaches or the edge of the sea where the water is shallow and slightly brackish, as in the Delta Mahakam. Fry can be captured by using rumpon. Tiger prawns fry from Delta Mahakam durability is relatively higher than fry from the hatchery. However, the number and continuity of fry very limited because it depends on the season. Abundance of fry is determined by the number of larvae produced in the wild and their survival is greatly influenced by the availability of food. Doi: 10.12777/ijse.6.1.43-46 [How to cite this article: Suroso, B., Hutabarat, J., and Afiati, N. (2013). The Potential of Tiger Prawn Fry from Delta Mahakam, East Kalimantan Indonesia, International Journal of Science and Engineering, 6(1),43-46. Doi: 10.12777/ijse.6.1.43-46

Optimum Development in Mature Fields: Sanga-Sanga Assets, Indonesia

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 158716, ’Renewal Plan: Efficient Strategy for Optimum Development in Mature Fields - A Success Story From Sanga-Sanga Assets, Indonesia,’ Andre Wijanarko, Bambang Ismanto, and Robhy Permana, VICO Indonesia, and Italo Pizzolante, Eni, prepared for the 2012 SPE Asia Pacific Oil and Gas Conference and Exhibition, Perth, Australia, 22-24 October. The paper has not been peer reviewed. VICO Indonesia is the operator of the Sanga-Sanga production-sharing contract (PSC) in Indonesia. Against a backdrop of 46% annual base decline, VICO generated and implemented an integrated and aggressive work program called the Renewal Plan. This is an integrated approach between reservoir management and technology application. This plan proved to be an efficient example of better reservoir management for optimum development of mature assets. Introduction The Sanga-Sanga acreage is located onshore in the Mahakam delta, East Kalimantan, Indonesia. The acreage is located within the Kutai basin, which is characterized by the Samarinda anticlinorium, with a series of highly prolific anticlines. Hydrocarbon accumulations are most often located within a series of mid-Miocene upper-delta and delta-plain sandstone reservoirs, and are principally characterized by fourway dip closure or two-way structural/ stratigraphic traps. VICO Indonesia has been exploring and developing this PSC acreage actively since 1968. There are seven producing fields (Fig. 1): Badak, Nilam, Semberah, Mutiara, Beras, Pamaguan, and Lampake. These together produce 385 MMscf/D of gas and 14,500 B/D of liquids from 420 active wells, which have mixed wellbore completions (single, dual-selective, monobore, dual-monobore, and horizontal). The surface facilities supporting the production include four main production centers, 12 gathering stations, and more than 90 compressors. After 40 years of production, these fields have now reached a fairly mature stage; most of the penetrated reservoirs/ tanks have been depleted from original pressures. Coupled with the annual production decline, this condition has resulted in significant challenges to delivering a continuous economic and efficient field-development strategy while maximizing field production. Renewal Plan VICO carried out a reserves-reassessment study—an integrated approach involving reservoir management and technology applications conducted by a multidisciplinary team. The seven components of the Renewal Plan are described in the following subsections. Securing Base Production. Securing base production is one of the keys to achieving a production target. Well monitoring and surveillance are the primary methods by which base production is secured. Previously, VICO wells were monitored by frequent production tests, mostly depending on human surveillance. In the Renewal Plan, automated real- time monitoring well surveillance of wellhead-pressure and flow-rate data on each well was implemented. This real- time wellhead surveillance (RTWHS) transmits the data from the wellsite to the VICO server; then, it is stored in a database. Operators and production engineers could monitor the behavior of the well in real time. This system has proved to minimize well downtime, leading to aggressive well reactivation. This installation has also become standard for new wells. Currently, 90% of VICO’s active wells are equipped with RTWHS.

The ethological study of Glossifungites ichnofacies in the modern & Miocene Mahakam Delta, Indonesia

The ethological study of Glossifungites ichnofacies in the modern & Miocene Mahakam Delta, Indonesia

Shrimp pond effluent dominates foliar nitrogen in disturbed mangroves as mapped using hyperspectral imagery

Conversion of mangroves to shrimp ponds creates fragmentation and eutrophication. Detection of the spatial variation of foliar nitrogen is essential for understanding the effect of eutrophication on mangroves. We aim (i) to estimate nitrogen variability across mangrove landscapes of the Mahakam delta using airborne hyperspectral remote sensing (HyMap) and (ii) to investigate links between the variation of foliar nitrogen mapped and local environmental variables. In this study, multivariate prediction models achieved a higher level of accuracy than narrow-band vegetation indices, making multivariate modeling the best choice for mapping. The variation of foliar nitrogen concentration in mangroves was significantly influenced by the local environment: (1) position of mangroves (seaward/landward), (2) distance to the shrimp ponds, and (3) predominant mangrove species. The findings suggest that anthropogenic disturbances, in this case shrimp ponds, influence nitrogen variation in mangroves. Mangroves closer to the shrimp ponds had higher foliar nitrogen concentrations.