Search

This study was aims to demonstrate that bagasse as a waste can be use for enhanced oil recovery process. Bagasse has a lot of lignin content that can be processed as a sodium lignosulfonate surfactant. The use of bagasse for surfactants at the chemical flooding is an innovation in petroleum science. Synthesized bagasse to lignosulfonate was done by isolation process using sodium hydroxide as a reagent and sulfonation process using sodium bisulfite as a reagent. From FTIR test and NMR test, the surfactant synthesis from sugarcane waste, sodium lignosulfonate (SLS) consist of sulfonate groups (hydrophilic groups) and benzene (lipophilic groups). This SLS surfactant has value of 11.62 for HLB. The presence of hydrophilic and lipophilic components resulted in the stability of middle phase emulsion in the range of 5% - 10%. The core flood using that surfactant obtained recovery factor reaches 1.05% - 9.50%. HLB SLS surfactant from sugarcane bagasse shows the function of SLS surfactant as injection fluid in an oil / water emulsion system, which is indicated by the presence of an intermediate phase emulsion. Conclusion of this study indicate that the synthesized lignosulfonate of bagasse can use an injection fluid in O/W emulsion and bind oil and water to form microemulsions. The bagasse is a local raw material for sodium lignosulfonate (SLS) surfactants which can be useful for enhanced oil recovery. [ABSTRACT FROM AUTHOR]

KA oil field is located in Sumatera Basin. It has been producing oil since 1937. Because of its long production time, KA field can be classified as a mature field. From the primary production period (1937-1995), this field produced about 19.97 MMSTB (recovery factor of about 35%). Oil production is continued by water flooding since in 1996 until now. The Original Oil In Place (OOIP) calculated using the Material Balance method is nearly the same as the value calculated using the Volumetric method, if the entire reservoir area can be drained by existing production wells. KA field has been produced for a long time so that the wells drainage area proportionate to total reservoir area. This study aim is analyzing the relationship between the value resulted from MBE's straight line Havlena-Odeh method, the total drainage area, and the production time in OOIP estimation. Main conclution is the longer production time, the wider drainage area of the production wells, the closer the OOIP value resulted from MBE method to the value resulted from volumetric method. [ABSTRACT FROM AUTHOR]

Despite the slow growth of EOR development in Indonesia, CO2 EOR has recently gained its momentum due to its versatility to diverse reservoir systems in Indonesia. Optimizing CO2 Injection in EOR activity is a must, since no incentive or tax holiday is given in Indonesia for this activity, contrary to the majority of policies around the globe. This study offers an innovative approach of CO2 flooding injection rate determination using closed loop optimization in project economic evaluation. Particle Swarm Optimization (PSO) algorithm was implemented as a method of optimizing the injection rate of CO2. These novel algorithms are known and proven to be able to work with massive number of datasets, as well as identifying and separating bad dataset(s). The result is optimum injection rate that brings maximum economic value to the project. Utilization of this method increases the NPV of the project by 10.4% and 12% increase in RF. [ABSTRACT FROM AUTHOR]

Yogyakarta is one of the earthquake-prone areas because it lies near subduction area, the last recorded occurrence of high intensity earthquake activity on 2006, May 27th had a magnitude of 5.9 SR (Richter Scale) and suffered considerable damage. The Department of Social Affairs said that 6,234 people died, 36,299 people were injured and the earthquake displaced about 1.5 million people. The earthquake also caused damage to 616,458 residential building units in Yogyakarta and Central Java. Under the USGS, the epicenter of the earthquake is about 25 km southeast of Yogyakarta with a depth of 17.1 km mean sea level. Microtremor data with HVSR (Horizontal to Vertical Spectral Ratio) method can be used to determine the value of the predominant frequency spectrum (fo) and amplification factor (A) which describes the dynamic characteristics of the soil. The HVSR analysis method was developed to calculate the ratio of the Fourier spectrum of the microtremor signal to the horizontal component against its vertical component. Calculations regarding the value of soil vulnerability and analysis of subsurface structures are intended to determine the level of vulnerability of an area to earthquake hazards. In the Piyungan sub-district, the thickness of the sediment layer (H) ranges from 5 meters to 75 meters below the surface. The northern part of Piyungan sub-district tends to have a thick layer of sediment which is quite thick reaching 45 meters to 75 meters. While the value of the soil vulnerability index in most of the northern part of the study area has a land vulnerability index value that tends to be greater than 40 × 10-6 s2/cm with a maximum value of 78.62 × 10−6 s2/cm. Most of the study areas have soft soil types (Vs < 175 m/s), medium soils (175 m/s < Vs ≤ 350 m/s) and very dense soils and soft rocks (350 m/s < Vs ≤ 750 m/s). [ABSTRACT FROM AUTHOR]

The Ijen volcano was a Pleistocene volcano and is one of the stratovolcanoes which was active in East Java Province. This volcano erupts by magmatic and phreatic eruptions. This volcano has the largest natural lake in the world, measuring around 960 x 600 m. Embankments limited the morphology of the crater with heights between 2.145-2386 m. The lowest height of the western embankment was upstream from Banyupait River. The water volume of the crater lake of Ijen volcano is quite large and very acidic. The acidic water from the crater lake flows from upstream Banyupait River to the north to the lower direction of the Asembagus Situbondo area. The purpose of this research was to study the pH distribution of the Banyupait river flow from upstream to the coast. It was because that Banyupait river acid water was used by residents for daily life and agriculture. The methodology used in this research was conducting field survey and measurements. Field survey was carried out along the flow Asembagus river in Banyupait, which started from the village of Bantal to the river mouth in the Java Sea. In conducting a field survey pH measurements were also carried out from the river water of the Kali Banyupait. The observations showed that the river water upstream of Banyupait River had a pH of around 2-3, while the more towards the downstream the pH of the river water changed to an increase of around 3- 4. The acidic water of this river experienced dilution from several rivers in its area. Whereas in river estuaries, the river water mixes with the sea, so water has a pH of 4.2. Because river water is acidic (low pH), no biota along the Banyupait river was found. Besides that, the other characteristics of river water are brown. Rocks exposed to the river flow will be reddis, experiencing iron oxide. It was due to the interaction process of acid river water with rocks. However, the river water was used by residents around the river for agriculture and daily necessities. Consequently, the health of the population around Bantal village was low. [ABSTRACT FROM AUTHOR]

The tectonic mechanism is a mechanism that involves tectonic conditions in the area which affects the dynamics of poroelasticity. Elastic modulus in the porous medium will go through change along with fluid dynamics. The loading factor in the tectonic mechanism is followed by the tectonic forces. The aim of this study is to learn the impact of a tectonic mechanism on the coupling ratio during oil production and water injection. The objective zone of this study is a part of thrust fault regime, which is changed to be strike-slip fault regime. The sand reservoir of Z-600 is in the transition condition so that the dominance of SV and Shmin has a strong influence on a coupling ratio change. The fluid dynamics occurring during this period are oil production and water injection. Observations were made on mechanical properties and pore pressure changes. The coupling ratio estimation starting from 1994 until 2017 refers to a historical production matching, which demonstrates a rock strength response in the variation of existing tectonic regime position. Mohr diagram analysis was done, based on the Coulomb failure criterion. It reveals that pore pressure change is not always equal to the change in stress difference or deviatoric stress, due to the nature of irreversible porosity change during fluid dynamics. The horizontal stress might cause shear-tensile failure, it initiates a sanding problem potential. [ABSTRACT FROM AUTHOR]

PT. Pertamina Hulu Energi Ogan Komering (PHE OK) Water injection began in 1998, by injecting excess water in abandoned wells in Central ASD and continued in October 2000 and January 2002, and since May 2006 the injection rate was increased above 30,000 BWPD. From the analysis carried out, one of the obstacles in the injection water process at PHE OK is the main pipe capacity of the injection water which is getting smaller and the pressure drop along the pipe is very big. The pressure drop occurs due to the solid / deposition pile on the inside of the pipe, causing obstacles in the process of transferring injection water from the Block Station to the injection wells. From the laboratory analysis, the solid deposits inside the pipe wall is consist of more than 50% organic and hydrocarbon matters (paraffin, oils, and light asphaltene) often called as "Schmoo" deposit. Some pigging activities can not be done due to pipe size, pipe geometry that does not support, pipe construction that is not designed for pigging activities. To overcome the solid deposit problem, PHE OK carried out a field trial of Schmoo Remover Chemical to clean the pipe without using pipe pig. From the field trial result, the removal of the schmoo solid deposit resulted in a significant increase in water injection rates and decrease pipe pressure drop. [ABSTRACT FROM AUTHOR]

Kawengan Field has reached the peak of its production and currently is being developed an Enhanced Oil Recovery (EOR). In this research bio-surfactants will be used as substance that will be injected into reservoir. Bio- surfactants are as surfactant from microorganisms and can work to reduce interfacial tension (IFT) so that it can be applied in EOR. The other advantages of bio-surfactant are being able to reduce oil viscosity in reservoir temperatures, higher biodegradation rates and low toxicity. This research used Kawengan Field oil samples before and after being given bio-surfactants. In laboratory test, the viscosity and IFT will be measured. Viscosity shows the phase changes and IFT shows bio-surfactants can reduce IFT between water-oil.The aim of this research is to provide an overview of the application of bio-surfactants as a good and viable alternative to expensive chemical surfactants in increasing oil recovery. The addition of bio-surfactants can reduce oil viscosity from from 2,7 cp at 30°C to 0,37 cp at 80°C and IFT 3,91 at 2,5% bio-surfactants concentration. [ABSTRACT FROM AUTHOR]

High viscosity which is an inherent property of heavy oil would give an inconclusive result on a Pressure Drawdown Test. Some kind of thermal injection should be performed prior to implementing the operation of Pressure Drawdown Test, where the heat will reduce the viscosity of the reservoir fluid. The study was aimed to design a proper Pressure Drawdown Test for N-7 Well using a simulator. Since the well test was intended to reach radial flow regime then the viscosity should be reduced from 1069 cp to 66.5 cp for production time of 500 hours or to 24.8 cp for production time of 100 hours. Sensitivity test of several parameters namely viscosity, permeability, porosity, and shut-in time was conducted to analysis the effect of the parameters on the radius of investigation and radial flow time. This sensitivity would give various radius of investigation. Furthermore, the study was continued to correlate radius of investigation as a function of the parameters mentioned above. Permeability and shut-in time are directly proportional to radius of investigation. While porosity and viscosity are inversely proportional to the radius of investigation. [ABSTRACT FROM AUTHOR]

Liquid waste with a high amount of total suspended solids (TSS) is one of the significant environmental issues from coal mining activities in Kalimantan island under high precipitation in of an extensive zone of coverage. The TSS concentration with Nano-sized particle in mine drainage is caused by clay minerals which are dominated by montmorillonite type. Therefore, a vast chemical agent is usually used to treat TSS concentrations of liquid waste less than 300 mg/L based on government regulation. However, in this case, the chemical flocculant triggers the onset of secondary pollutant because of carcinogenic and non-biodegradable conditions. This study aims to observe specific fungi, Marasmius sp, as bio-flocculant for the treatment of mine drainage with extra high TSS. The fungi can produce a biodegradable polymer that precipitate the montmorillonite with two-mode action, namely bio-flocculant polymerization and mycelial trapping. A role model was performed in a laboratory-scale less than 1 L in several graduated/measuring cylinders under 22-30 °C. The results of clarity and flocculation rate tests indicated that the minerals in the mine drainage samples from PT.BC mining excavation area, had been precipitated rapidly. The clarity test by using spectrophotometer indicated that eighty six percent (86%) clarity value averagely in one-hour treatment, while the TSS concentration amount decreased down to 110.1 mg/L from original measured at 11,000 mg/L based on the flocculation rate test. [ABSTRACT FROM AUTHOR]

Rock slopes stability is important for personnel and equipment safety in the open-pit mine. Instability and failure of slope occur due to many factors such as unsuited slope geometry, geological discontinuities, weak slope material due to weather influences. External loads such as high rainfall and seismicity could play an essential role in slope failure. Consequently, a precise classification of rock mass is needed for the basis of determining technical policy. Rock slopes in open pit coal mining areas, especially in Indonesia, are characterized by applying various rock mass classification systems, such as Rock Mass Rating (RMR) and Geological Strength Index (GSI), because the study area comprises well-exposed rock formations. In the RMR system, there are five main parameters i.e. Rock Quality Designation (RQD), Uniaxial Compressive Strength (UCS) of rocks, discontinuity spacing, discontinuity and groundwater conditions were considered. Several rock mass classification systems developed for the assessment of rock slope stability were evaluated with the condition of rock slopes in the tropics, especially Indonesian region, particularly in sedimentary rocks in the open pit coal mining area in order to get the corrected GSI equation used to characterize rock slopes based on rock mass structure quantitative analysis and discontinuities surface conditions. This paper provides correlation between the GSI and RMR for sediment rock in coal mines. [ABSTRACT FROM AUTHOR]

Cinangka Village, Bogor, has been the center of the battery smelting industry since 1980. Thus, has resulted the soil contamination. The purpose of this study are 1) Calculate the percentage of reduction of lead (Pb) in soil after treated by Codyline fruticosa and Ipomea reptans Poir for 24 and 36 days; 2) Determine the Pb uptake by plants based on Pb concentration of plants and dry weight of plants; 3) Analize the efficiency of Pb absorpsion by plants to Pb polluted soil. The method used for this study are experimental method and laboratory analysis. The parameters tested were Pb in soil, Pb in Plant, dry weight of plant, and pH in soil. The efficieny of the plants was known by laboratory analysis using the Cordyline fruticosa and Ipomea reptans Poir within 24 and 36 days to remediate the soil with 10,032.84 ppm Pb as many as 12 samples. Percentage of reduction of Pb in the soil by the treatment of Cordyline fruticosa for 24 days was 36.58% and 97.99% after 36 days treatment. Reduction of Pb in the soil by treatment of Ipomea reptans Poir for 24 days was 39.98% and 97.80% after 36 days treatment. Pb uptake by Cordyline fruticosa was only 2,314.75x10-6 mg for 24 days treatment and 2,120.12x10−6 mg in 36 days treatment. Pb uptake by Ipomea reptans Poir is 22.26x10−6mg for 24 days treatment and 34.40x10−6.mg for 36 days treatment. The analysis showed that the efficiency of Pb absorption from soil contaminated by Cordyline fruticosa was only 3.72% and 2.08% by Ipomea reptans Poir after 24 days of treatment. The analysis showed that the efficiency of Pb absorption from soil contaminated by Cordyline fruticosa was only 4.31% and 3.79% by Ipomea reptans Poir after 36 days of treatment. Ipomea reptans Poir is not suitable as a phytoremediation agent of heavy metals because it is a food crop. Cordyline fruticosa as an ornamental plant is more recommended for planting around of battery smelting area. [ABSTRACT FROM AUTHOR]

Artisanal and Small-scale Gold Mining (ASGM) is an exciting issue in the developing world related to sustainable development goals in environmental topics. Mercury is one of the several focuses related to ASGM. The Minamata convention made to reduce and regulate mercury usage in ASGM practices. Indonesia, as a developing country with a quite significant number of ASGM miners, has been ratified and forced the implementation of the Minamata Convention since 2016. An ASGM operation located in Tobongon, East BolaangMongondow, North Sulawesi Province selected as a site of study. Tobongon is one of the few people's mining areas (Wilayah Pertambangan Rakyat – WPR) that has been verified by the Ministry of Energy and Mineral Resources (KementerianEnergidanSumberDaya Mineral – ESDM). This study covers several topics such as the current state of operation concerning mercury usage, legal status, and couples of activities that has been done for capacity building in the area. Descriptive analytics methodology was undertaken to finish this study. The result of this study will illustrate ASGM conditions in Indonesia with its complexity and challenges for improvement and development. [ABSTRACT FROM AUTHOR]

Mineralization of gold and other ore minerals in Arinem area and its surrounding was found in the quartz vein. The research area is in Arinem area and its surrounding, Garut Regency, West Java. Arinem and the vicinity was the location for early stage of research program of mineralization in Papandayan area. This area has good mineralization, and according to previous studies, is a low sulfidation area with the presence of pyrite, chalcopyrite, galena and sphalerite (Antam, 2014). The presence of galena and sphalerite mineral has suggested that instead of low sulfidation, the area may be in intermediate sulfidation zone state supported by other data such as quartz breccia, banded quartz and shear as control structure. Lithology in the area consists of breccia Quaternary and lava unit of Jampang formation in Miocene and unit of andesite and basaltic in Quaternary and intrusion of dacite, andesite and diorite. The alteration and mineralization of research area was classified as propylitic alteration zone with the presence of chlorite, epidote and calcite mineral, argillic alteration zone with montmorillonite, kaolinite mineral, silicic alteration zone with the presence of quartz-sericite, a bit of calcite mineral. Observed ore minerals are pyrite, chalcopyrite, galena, sphalerite. The geological structure was controlled by horizontal fault in almost north-south direction of N 170°-180° E and northeast – southwest horizontal fault in N 40° – 50° E, while the mineralization zone was controlled or following fault pattern of N 170° - 175° E. [ABSTRACT FROM AUTHOR]

The mining industries face significant uncertainties resulting in technical and financial risks. Ore reserve is the most critical technical risk. On the financial side, the price fluctuations shape financial risk. Since the commodity prices are hard to predict accurately, a risk assessment process is commonly performed. The Monte-Carlo simulation is a common approach to assess risks in the mineral industries, and requires reproduction of the correlation between the uncertain variables. When these correlations are non-linear, the problem becomes more complicated and require special attention. One way to incorporate non-linear relations into risk analysis is to utilize from copulas. Thus, this research objective is to model the financial risk based on its dependence pattern. As a result, it is found that the gold prices that are correlated with the oil prices follow Clayton copula model with the parameter (θ) of 4.11. [ABSTRACT FROM AUTHOR]

AST-04 well is a production well located in Riau, this well currently has two production Layers (SD_04 has oil reserve and SD_05 has gas reserve). Using commingle completion the oil production in this well is below expectation. This problem caused by SD_05 gas production with high pressure which through SD_04 perforation hamper the oil flow. Re-completion design using multiple completion become a solution to improve oil production. Oil from SD_04 will be flowed using short string, while gas from SD_05 using long string. By Vogel Equation, the redesign results production increase to 290 BOPD with natural flow using tubing size 2 7/8 inch. To utilize SD_05 gas production and increase SD_04 oil production, natural gas lift selected to assist oil lifting. Gas produces from SD_05 will be injected to short string (SD_04 perforation area) through an orifice. This method expected can increase oil production SD_04 layer to 406 BOPD with injection rate 1.367 MMSCFD. Using Craft, Holdden, & Graves equation, the orifice size 16/64 needed to flow the gas with injection rate desired. [ABSTRACT FROM AUTHOR]

Observation on the Tanjung Enim coal outcrops has been conducted to evaluate coal and cleat characteristics, particularly those occurring at Suban and Air Laya Putih (ALP) sites. Tectonically, the region is located in the South Palembang Sub-basin. In this region, there are four to five coal seams dipping to the SW direction. The dips of coal beds in ALP are commonly steeper than those in Suban, implying that the ALP seams had been more deformed tectonically and hence underwent more shortening. The samples analyzed reveal that the coals are medium in rank with the ash content relatively constant along strike, but distinctive vertically. Most seams have high values of inherent moisture, fixed carbon, and volatile matter. Deformation of the seams has resulted in two types of fractures known as face and butt cleats. The present study employed a scanline method to measure cleat attributes such as spacing, aperture, and bedding orientation. A total of 3,241 face and butt cleats were measured from 12 scanlines. The face cleats predominantly have NNE-SSW orientation, suggesting paleostress direction. The general trend of butt cleats is NW-SE, likely coincident with the releasing stresses. Face cleats have spacing and aperture more tightly than butt cleats. This suggests that face cleats developed in response to the maximum stresses, and butt cleats formed due to the minimum in situ stresses. Scanning Electron Microscope (SEM) analysis revealed that microcleats in seam show a number of apertures that were connected to form a network system within the analyzed samples. [ABSTRACT FROM AUTHOR]

The typical standard geothermal well-slotted liner is a 7", research on big hole slotted liner to increase steam production in geothermal fields. In the previous study, the potential of the geothermal field was 380 Mwe, while currently it has been produced at 39.79 Mwe so that the field geothermal is feasible to develop again. The current conditions there are 7 production wells with a standard hole (7 "liners) that have been proven to produce continuously in developing this production will simulate using the big-hole size slotted liner, starting at 8 5/8", 9 5/8 ", 10 ¾ ". With proven reservoir condition data, the geothermal field is feasible for production studies using big holes. The main parameters include Temperature, Pressure, mass flow, and steam quality.The conceptual model is an interpretation of the condition of the reservoir so that the reservoir conditions in the well can identify as data for the study. WellSim Simulator is used to predict pressure loss in the hole and bottom surface, and vice versa. The output is the pressure, mass flow rate, temperature, and steam quality of the wellhead so that various casing sizes can simulate with the condition of the reservoir. The optimal size of the production liner developed in the geothermal field is 9 5/8 ". [ABSTRACT FROM AUTHOR]

The mine drainage system can be a complicated process, although it has been done a lot of time. It depends on the conditions of the location and requirements of the dig with the purpose to get into the mine are not interfering with mining activity. This paper investigates and analyzes the costs of mine water management at the Pit B of PT Darma Henwa Bengalon site, using the variable costing method. Based on the study result, it founds that the cost of forming an open channel with the geometry of the upper width = 5.17 m, lower width = 2.6 m, channel height = 2.24 m, sloping channel length = 2.57 m, is Rp 36,808,096. The cost to make the Panels 1 and 2, Panels 2 and 4, and the Panel 3 Sumps that use PC1250 and HD465 are Rp 3,920,833,504. The costs for investment, the installation of pipes and pumps, and an operational cost at the beginning of mine dewatering is Rp 63,426,709,520. In the form of open channel cost sump formation, and pumping cost consists of components in the form of employee salaries, asset equipment costs, material costs, and indirect costs. Decision making with pump investment is more profitable than the rental concept because the mine life is over five years, but if the mine life is less than five years, the concept of rental is recommended. [ABSTRACT FROM AUTHOR]

The stability of tunnels in underground mines is an important factor in mining production which must be considered to ensure productivity and safety. At the Antam Underground Gold Mine, the production cycle begins with drilling an explosive hole and then filling the explosives. After that, the tunnel is blasted and ore is transported to the stockpile. The activities are continued by supporting the tunnel then return to the beginning of the cycle, which is drilling activity. Before this study was conducted, drilling was carried out using a 3 meter drilling rod. The blasting outcomes from the drilling were only about 2.0-2.3 m or less than 85% drilling depth. Among the various rock conditions that affect tunnel stability, the width and height dimensions are important design factors. This study aims to optimize drilling-blasting activities by considering Maximum Unsupported Span (MUS) using a Q system by replacing the diameter of drilling bit and lengthening the size of the drilling rod. By applying MUS analysis and operational considerations, MUS values were obtained that matched the characters in certain site. From data collection in the field, MUS values varied from 1.8 to 8 m depending on the characteristics of the rock mass. By observing the mining operation factor, the maximum range could be proposed in 4.2 m length and changed the drilling bit to 64 mm. Although the drilling time was longer but the outcomes of the forward meter of drilling blasting were more than 80%, which was 4 of 4.2 m. By utilizing MUS and considering mining factors, productivity could be improved and safety was guaranteed. [ABSTRACT FROM AUTHOR]

The population growth rate and economic growth that increase every year result in increased energy needs that are used to support human activities in daily life. Energy consumption in Indonesia comes from petroleum, coal, natural gas, renewable energy (EBT), and hydropower. Petroleum has the most significant portion of energy consumption in Indonesia where oil and gas in the upstream area activities, namely exploration and exploitation carried out to meet energy needs, have not been able to meet domestic energy needs. On the other hand, the economic downturn in the upstream oil and gas industry as a result of changes in world crude oil prices has resulted in reduced investment in this industry. By looking at the condition of non-renewable petroleum natural resources, while the need for oil and gas needs to continue to increase, on the other hand the availability and reserves of oil and gas tends to always decline, it is clear this will certainly have an impact on the upstream oil and gas industry in Indonesia. From the viewpoint of the Theory of Sustainability, were resources for current needs must be sought without compromising the needs of future generations, this can also be applied to the upstream oil and gas industry. Using the Artificial Neural Network method, with its ability to be used to obtain knowledge from complex or inaccurate data, and can also be used to extract patterns and detect trends that are too complex to be noticed either by humans or other computer engineering and the result is a model that can see the carrying capacity of oil and gas exploration and exploitation activities in Indonesia consisting of petroleum reserves, petroleum production rates, and investment. The level of trust shown through the results of the regression, which shows the results of the study how reliable the truth is 0.95. That means that the results of the study were 95% correct, is expected to be used as an alternative in making instruments to support the objectives sustainable development in the oil and gas industry in Indonesia. [ABSTRACT FROM AUTHOR]

Layer A on the X field has been produced since September 2007 until December 2016. This layer consists of 9 wells with current status: 1 production well (natural flow), five shut-in wells, and three dry-hole wells. The original oil in place of this layer is 28.113 MMSTB. The production data shows that cumulative oil production of this layer is 1.066 MMSTB, which means that the current recovery factor is 3.79 %. This number is tiny, and since there is a lot of hydrocarbon area that has not been produced, an integrated reservoir simulation study is done to determine the optimum scenario for this layer development. The study begins with data collecting and processing; model validation through initialization, history matching, and PI matching; remaining reserve determination, and,; simulation of field development scenarios. There are 5 scenarios simulated and until January 2043; Base Case (production of 1 existing well) gives 2.53 MMSTB or 9 % RF; Scenario 1 (Base Case+3 gas lift wells) gives 3.15 MMSTB or 11.21 % RF; Scenario 2 (Scenario 1 + 3 development wells) gives 6.49 MMSTB or 23.09 % RF; Scenario 3 (Scenario 1+6 development wells) gives 7.68 MMSTB or 27.32 % RF; and Scenario 4 (Scenario 1+9 development wells) gives 7.58 or 26.97 % RF. From the reservoir simulation result, the optimum development scenario for this layer is Scenario 3. [ABSTRACT FROM AUTHOR]

Gas lift has been successfully operated in many types of oil wells around the world. Many techniques have been derived to increase gas lift efficiency, not only from gas lift modeling but also technical designs of gas lift components have been tweaked to produce higher gas lift performance with less gas injected.Gas Lift Performance Curve currently holds as one of the most prominent evaluation method of gas lift performance. The method itself is derived as a subcomponent of Inflow Performance Relationship (IPR) curves that allows simple and robust GLP curve generation without having to perform procedural, iterative calculations. It is worth noting, however, that GLP curves cannot be held as a single culmination parameter in determining the efficiency of gas lift systems. This study introduces a new paradigm in modeling the performance of gas lifted wells by utilization of mechanistic fluid flow modeling. Mechanistic models, unlike conventional GLP curves, are generated from observations in full scale laboratory experiments, therefore complications in multiphase flow pattern, such as flow pattern transition can be fully acknowledged and incorporated into the calculations. Based on the previously stated hypothesis, this study offers a case study on marginal oil well where gas lift acts as the main extraction method. Observations done in the model has confirmed the functionality of Flow Pattern Map (FPM) derived from mechanistic modeling as a complementary check and balance tool for gas lift systems. It is also expected that the FPM will perform well in a multitude of gas lift case studies due to its versatility. [ABSTRACT FROM AUTHOR]

The Randu Kuning prospect is a part of the East Java Southern Mountain Zone, mostly occupied by both plutonic and volcanic igneous rocks, volcaniclastic, silisiclastic and carbonate rocks. Magmatism-volcanism products were indicated by the abundant of igneous and volcaniclastic rocks of Mandalika and Semilir Formation and many dioritic intrusive rocks of the Late Eocene-Early Miocene magmatism. Porphyry Cu-Au and intermediate sulphidation epithermal Au-base metals mineralization at Randu Kuning have strong genetic correlation with the magmatism-volcanism processes. The mineralized dioritic intrusive rocks at the area, are distributed at the center of the depression of an ancient volcanic crater. There are many intermediate sulphidation epithermal prospect area surrounding the Randu Kuning porphyry Cu-Au. Most mineralizations both porphyry and epithermal environments are associated with the presence of quartz-sulphides veins, but not all porphyry vein types contribute in copper and gold mineralization. The early quartz-magnetite veins (particularly A and M vein types) generally not contains Cu-Au or barren, while the later sulphide bearing veins such as quartz-sulphides (AB type) veins, chalcopyrite-pyrite (C type) veins, quartz-sulphides-carbonate (D type) veins are mineralized. Mineralization contains copper and gold deposits in range at about 0.66-5.7 g/t Au and 0.04-1.24 % Cu. Whereas the epithermal level, mineralization mostly related with the presence of pyrite+sphalerite+chalcopyrite+quartz+carbonate veins and hydrothermal breccias. The epithermal veins and breccia lead to the occurences of silver, zinc and lead mineralization, it commonly contains around 0.4-1.53 g/t Au, 0.8-8.5 g/t Ag, 0.17-0.39% Cu, 0.003-0.37% Zn, 00089-0.14% Pb. [ABSTRACT FROM AUTHOR]

One of the critical jobs in the mine planning and design is to optimize an open pit mine under many uncertain factors. This paper explains the incorporation process of the volatility of commodity price or market uncertainty into production phase design and ultimate pit limit using a maximum flow minimum cut algorithm. The Ornstein-Uhlenbeck (OU) mean-reversion process was used to generate 50-coal price simulations for 10-years ahead. For implementation, data from an Indonesian coal mining site was integrated into the method and resulted in 42% differences compared to a conventional way. [ABSTRACT FROM AUTHOR]

The field studied was an Oil Field with light oil reservoir characteristics. In order to increase oil production this field will be applied EOR method in the form of surfactant injection. In this study the type of surfactant that will be used is sodium lignosulfonate (SLS) surfactant using sodium oleate and EGBE formulations in various concentrations. The research carried out was a laboratory study with core flooding and wettability tests on various variations of SLS surfactant solution concentrations. The results of the core flooding test will provide the largest recovery factor of the various SLS surfactant concentrations tested. The same thing will be done in the wettability test. On changes in wettability, the contact angle of various surfactant concentrations that have been formulated will be observed. This study aims to determine the wettability changes of rocks that occur after the injection of SLS surfactants before and after the formulation. Furthermore, the formulations and concentrations of the surfactants which give a smaller contact angle will result in a greater recovery factor. [ABSTRACT FROM AUTHOR]

Several studies have been conducted on the benefits of bacteria to replace chemical reagents in the bioflotation process of copper sulfide minerals. Most of the processing of copper sulfide minerals is carried out by flotation by adding reagents. Flotation is one of the mineral processing processes to separate valuable minerals and their impurities by utilizing different mineral surface properties. In copper sulfide minerals there is a high sulfur content of pyrite impurities (FeS2) which must be separated or depressed (become more hydrophilic) to be separated with valuable minerals, while valuable minerals will remain hydrophobic (water-repellent). However, not all bacteria can survive at high sulfur concentrations. In this research, the interaction of biosurfactant-producing bacteria that can survive in environments with high sulfur content (Citrobacter sp. strain SKC-4) with pyrite minerals was characterized. The bacteria-pyrite interaction was observed by analyzing the elemental composition of mineral surface and the morphological changes of the sample with SEM-EDS (scanning electron microscope - energy dispersive spectroscopy). SEM observation showed the interaction of bacteria with pyrite minerals where the bacteria were able to stick and make mineral particles into complex aggregates. Moreover, the EDS results revealed that the presence of bacteria resulted in the change in the elemental composition of the pyrite mineral, which was dominated by iron (Fe), sulfur (S) and a small amount of carbon (C) which was the main element for microbial activity. Sampling for functional group testing (FT-IR Spectroscopy) was carried out on days 0,7,14, and 30 when bacteria interacted with minerals, showing a peak of C=O carbonyl bonds and carboxylic acid formation on the 7th day. The contact angle value of the pyrite decreased after 7 days of interaction with the bacteria, thus resulting in more hydrophilic pyrite minerals. From the results of the interaction characterization, the bacterium Citrobacter sp. strain SKC-4 has the potential as an alternative to a depressant reagent for a more environmentally friendly copper sulfide mineral bioflotation process. [ABSTRACT FROM AUTHOR]

Field X is an offshore field that is included in the deep-water area managed by an oil and gas company in Indonesia. From a number of tests conducted it was found that are presence of sand problems in this field especially in well G1 so that several studies were conducted. From the results of the study, it is determined that the use of Frac pack is one of the most appropriate ways, besides controlling sand problems, it also increases gas production on field X. The Frac pack method is a well stimulation by combining gravel pack to control the sand problems with hydraulic fracturing which is designed to have high conductivity to increase productivity over the well. In this paper, a calculation model is developed to find out the optimum fracture half length, fracture width and also the pumping schedule of the Frac pack with sensitivity of proppant concentration. Then the results will be compared with existing commercial software. The challenge faced in frac pack modeling for well G1 is large permeability so that the possibility of leakage occurring is greater and then handled by increasing the injection rate. Based on the calculations and analyzes that have been done, for the well G1 on field X it will be optimum to operate if frac pack is installed with the type of brady sand 20/40 proppant and dynafrac HT 30 as fracturing fluid, so that half fracture length, Xf 76.8 ft is obtained with fracture width, wf 0.4355 ft and 5 times fold of increase in the production. From this study it can be concluded that the calculation model made can be accepted and used commercially. [ABSTRACT FROM AUTHOR]

Drilling mud is the most important part in drilling activity. Drilling could work fluently, safely, and economically on fluency by system and condition of drilling mud. It means the mud system and the physical properties of the slurry conform to the required specifications. There are some kinds of drilling mud that can be used in oil and gas drilling operation, such as water base mud and oil base mud. In terms of economical objective, water base mud is usually used in drilling process. The purpose of this study is to conduct laboratory research of the effect of various temperatures on the characteristic of mud system of low solid mud by adding biopolymer and bentonite extender. This research uses roller oven method as a medium for simulation to condition the mud as close as possible to the condition in wellbore to see the change of physical properties of sludge at various temperatures. The result found is that the higher the temperature, the lower the drilling mud physical properties such as density, viscosity, plastic viscosity, yield point, dial reading 600 RPM, dial reading 300 RPM, and gel strength. However, it is found that not all the physical properties decrease. [ABSTRACT FROM AUTHOR]

The research aim of this study was to perform the engineering optimization tool diameter nozzle at the cement dust catcher fogging method. The research background is the amount of cement dust was still flying around the location of a cement plant in Tuban. The distribution of very fine cement dust in size have a negative impact on public health. It is necessary to control the spread of the cement dust from chimney cement plant with the flow of exhaust gases. This research was conducted in the laboratory and simulation using cement dust extraction equipment fogging method. Variables that are optimized sprayer nozzle diameter, while the other parameters were made permanent. The research result is optimal operating conditions dust extraction equipment fogging method on a variable nozzle diameter is 1.40 mm in diameter with an average efficiency of 70.79%. The conclusion is in such operating conditions, a tool for cement dust fogging method can capture the fine cement dust optimally. This can reduce the spread of cement dust into the environment so as to improve air quality. [ABSTRACT FROM AUTHOR]

Our understanding of the geological evolution of West Papua (or the Bird's Head Peninsula and Bird's Neck) predominantly stems from a systematic mapping campaign conducted by Indonesian and Australian geologists during the 1970's and 80's, together with the findings of mineral and hydrocarbon exploration by Dutch geologists in the early 1900's. Most of the research that has been conducted since these initial, but comprehensive studies have been associated with continued exploration for hydrocarbons (e.g., around the Salawati and Bintuni Basins) and precious metals (e.g., associated with Grasberg–Ertsburg). Here we present an overview of research conducted over the past five years that was largely funded by several oil exploration companies. Our research did not focus on oil exploration, but instead attempted to update our understanding of the age of magmatic, metamorphic and deformation events, and to improve our knowledge of the regional stratigraphy of West Papua. These new data have been used to develop new tectonic models and paleogeographic maps that provide a framework for future studies in the region to build upon. [ABSTRACT FROM AUTHOR]

Wonogiri Dam is one of the dams in Indonesia, located about 2 km south of the Wonogiri City, in the province of Central Java. Wonogiri Dam has a volume±400 million m3 with a surface area of 73,6 km2 which has many benefits such as for agriculture, tourism, and power plant. Wonogiri is a part of the East Java Southern Mountain Zone. Based on the geological map, there are many rocks types found at Wonogiri, such as volcanic breccias, andesite lavas, tuffs, and many igneous intrusive rocks. This research aimed to determine Ground Shear Strain (GSS) value along the main dam and the surrounding area and to predict phenomena based on GSS values. From the dominant period (TG) value, we can predict site class based on the classification of Zhao. The microtremor data was taken on 31 observation points which were divided from 14 observation points with 100 m spacing in the main dam and 17 observation points with 1.000 m spacing in the surrounding area from Wonogiri Dam. Microtremor data was analyzed using Horizontal to Verctical Spectral Ratio (HVSR) method to get the amplification factor and dominant frequency. Those data were used to determine the seismic vulnerability index (Kg). Kanai empirical equation was used to calculate Peak Ground Acceleration (PGA) value based on earthquake event on 27th of Mei, 2006 with a moment magnitude of 6,3 and 11,8 km depth. Seismic vulnerability index and peak ground acceleration value are used to determine the GSS value. The results of this research showed that GSS value in the research area was about 3,4 × 10−4 to 7,2 × 10−3. The phenomena that can happen were ground movement as the form of surface cracking and settlement. Seismic vulnerability index was below 20 (0,35 to 16,97) which means the surrounding area from Wonogiri Dam and main dam have low-risk, but the potential for damage to the building is still possible. Along the main dam area, we need to notice the point at 400m and 600m. The value of the dominant period in the research area ranged from 0.07 to 1.11 second. Based on the classification of Zhao, there are three classes of site class in the research area, that are site class I which consist of rock/ stiff soil, site class II which consist of hard soil, site class IV which consist of soft soil. [ABSTRACT FROM AUTHOR]

Geothermal energy utilizes steam from earth subsurface to drive turbines, which then produce electrical energy. The remaining brine from the process will return to the reservoir through injection wells. The brine basically can be utilized before injection, since it has high temperature, for other direct use. This paper aims to analyze the brine as a heat exchanger fluid, and calculate the energy requirements for meeting room heaters, and then determine the design of Heat Exchanger (HE). The meeting room has a 20-cm thick wooden wall, with dimensions of 20×10×3 m3. The room temperature will be set to be 21-27 °C. The geothermal source is at 300 m from meeting room and its elevation is 20 m below. The brine temperature that will be utilized is 100 °C, and it has 20 GPM and outdoor temperature is 14 °C. The result of the design is the fluid flow from the heat source to the output that warms the room. The flow is divided into four stages: at the pump, heat exchanger, air transmission and the room. The estimated cost of the heat exchanger is then calculated based on the design. [ABSTRACT FROM AUTHOR]

Jambakan is a village in Bayat District, Klaten Regency, Central Java Province, Indonesia. Brackishwater exists in the aquifers of study area, even though the location is ±30 km apart from the sea. In light of this, scientific discussion on where this water comes from is deemed necessary. The groundwater quality analysis at the local wells, detected brackishwater existence in shallow aquifers at the depths of 5-8 m. The geoelectrical method using the Schlumberger and dipole-dipole electrode configurations screened for any aquifers vertically and horizontally. The results showed that aquifers were distributed discontinuously, for which they were interpreted as fan alluvial deposits in shallow seas or molasses accumulations on the land. The interpretation also revealed that the brackishwater resulted from contacts with minerals in seawater sediments that composed the aquifers in this village. [ABSTRACT FROM AUTHOR]

Geological complexity Banyumas Basin becomes an attraction for geologists and geophysicist to conduct details research in this area. This research applies gravity and magnetic method to illustrate the subsurface geological structure patterns and basement configuration. The objective of this research is to analyze the depth of the basement from magnetic and describe the illustration of sedimentary rock. Interpretation of basement depth was processed from magnetic data, whereas geological structure and sedimentary patterns were analyzed using gravity data. Magnetic Anomaly pattern shows that low intensity of magnetic < 74nT (yellow-green) is disseminated at West-East of the map where a high intensity magnetic about > 190nT (red-purple) indicates basement rock or intrusive rock. Bouguer anomaly indicates that the area is dominated high anomaly 79.4 – 116 mgal (orange to purple) in west, north and southeast area, while low anomaly 49 – 79 mgal (blue-yellow) in the middle to the northwest of the area. Interpretation of magnetic data has guided gravity method in reconstruction basin model, especially in the basement and intrusive rock.Forward modeling of regional gravity map has pointed seven Formation with different densities, Tapak Formation; Upper Halang; Lower Halang; Pemali Formation; Gabon Formation; Karangsambung Formation and Basement rock. [ABSTRACT FROM AUTHOR]

The government's policy in the food sector is to achieve food self-sufficiency in the context of national food security, whose priority is in the form of partiality to farmers to improve welfare. This policy cannot be felt yet by the farmers who live in Tayuban village, Panjatan Sub district, Kulonprogo Regency, because there are still obstacles in its implementation. The problem faced by farmers in this village in increasing crop production is the lack of availability of water sources for irrigating secondary crops, especially in the dry season. The lack of water availability causes plant productivity lower, that impacts low income for the farmers. To overcome the problem of water shortages by finding ground water sources. The method in this paper is to conduct a surface geological survey to find out the distribution of sandstones as groundwater aquifers roughly and use topographic mapping data in the form of flow patterns, watershed boundaries and watershed forms. The results of this study can be concluded that Tayuban village is a syncline that can function as a reservoir of water [ABSTRACT FROM AUTHOR]

Three vein zones hosting gold mineralization have been outlined at the Poboya prospect, named as the River Reef Zone, the Hill Reef 1 Zone, and the Hill Reef 2 Zone. The vein zones were observed within metamorphic rocks leading to an issue regarding classification of the deposit type and exploration of the gold deposit. This paper aims to explain the deposit type of the Hill Reef 1 and Hill Reef 2 Zones according to the characteristics of their vein textures. Macroscopic observation on the considerable number of veins collected from the Hill Reef 1 and Hill Reef 2 Zones show that the vein textures consist of massive chalcedony, massive quartz, massive carbonate, banded chalcedony, colloform, crustiform, cockade, and lattice textures. These textures represent primary growth and replacement textural groups, which are similar to the vein textures observed at the River Reef Zone. Accordingly, the gold mineralization at the Hill Reef 1 and Hill Reef 2 Zones can be classified as a low-sulfidation epithermal deposit. Besides, the predominance of massive and lattice textures in the surface indicate that the veins analyzed in this study are from Chalcedonic Superzone and gold mineralization at the Hill Reef 1 and Hill Reef 2 Zones are well preserved. [ABSTRACT FROM AUTHOR]

The Ogan Komering Working Area has an area of 1,155 km2 located in the Ogan Komering Ulu District of South Sumatra Province. The Ogan Komering Working Area is currently operated by Pertamina Hulu Energi (PHE) Ogan Komering with a Gross Split Contract Agreement as of May 20, 2018. Waterflood project has implemented since 2006 in NEASD and GRH field. Ogan Komering Block has reached second peak production with 5,980 BOPD on early 2011. Because of plugging, the injection rate nowadays is only 16,000 BWPD when once it reached 40,000 BWPD. Remaining reserves in NEASD and GRH field is 4.04 MMBO based on updating GGR study in 2019. With enhancement injection rate, NEASD and GRH field are expected to increase 2-3 MMBO reserves. The further study about waterflood subsurface condition is conducted related to connectivity between injection well and production well also the injection performance in NEASD and GRH field to complete the target. From connectivity analysis supported with geophysic and geology interpretration, waterflooding in NEASD and GRH field consists of 4 areas which are A, B, C, and D. This analysis will be one of the guideline study for mature waterflood optimization. Connectivity the oil producer between water injection wells in carbonate reservoir NEASD & GRH field can concluded by tracer or injection-production wells performance plot. The reservoir connectivity's data in NEASD & GRH field will be used to validate the reservoir connectivity in GGR model to simulate the dynamic model for field application by adjustments the Voidage Replacement Ratio (VRR) target then observes the increment in oil producers wells. Wells connectivity data to support mature waterflood optimization project in NEASD & GRH field priorities to increase the water injection rate. [ABSTRACT FROM AUTHOR]

The settling pond is a reservoir that collects excess water from the mining area that carries solid material. It allows suspended materials to settle first before disposal, preventing pollution in the surrounding environments. In the research area, the settling pond dimension, however, cannot accommodate incoming water discharge during heavy rainfall. The overflows then directly enter the coastal waters, and without the settling or sedimentation process, they contaminate the coasts with solid material. This research was designed to examine the dimensions of the settling pond and identify erosion hazard level, along with the existing countermeasures. The mine drainage system was calculated through five analyses of rainfall data. (1) The maximum rainfall obtained from the recurrence interval analysis using the Gumbel method was 156.046 mm/day. (2) The intensity of rainfall was 28.73 mm/hour. (3) The areas of the catchment CA I, CA II, and CA III were 0.43 km2, 0.11 km2, and 0.43 km2, respectively. (4) The runoff discharges in CA I, CA II, and CA III were 2.36 m3/s, 0.79 m3/s, and 2.66 m3/s. (5) The total discharge of runoff water from the three catchments was 2.36 m3/s. From this discharge data and the settling rate of 0.000997 m/s, the settling pond area and volume were identified, i.e., 5839.5 m2 and 23,520 m3 with a depth of 4 m. This volume is higher than the actual size of the settling pond in the field. Aside from the inadequate capacity of the settling pond, the overflows are caused by the fast rate of erosion. In this case, the excess water flows directly into the settling pond without going through open channels, accelerating the water flow. The rate of erosion (A), calculated with the USLE equation, reached averagely (A) 540.5646 tons/ha/year and, therefore, fell into the category of severe or Class V (B). By replanting trees on the slope (revegetation) as countermeasures, the average rate of erosion (A) can be reduced to 172.98 tons/ha/year, which downgrades the erosion hazard level to Class III or moderate (S). Revegetation must be done immediately so that the erosion rate becomes even smaller [ABSTRACT FROM AUTHOR]

Several studies show that P-wave velocity are greatly affected by pore geometry and pore structure. Pore geometry and pore structure here are functions of pore attributes. Petrophysical properties of rocks such as porosity are the result of the sedimentation and diagenesis process so that porosity is strongly influence by pore geometry and pore structure. Thus the P-wave velocity should be predicted well by using porosity. This study was intended to apply the concept of critical porosity for P-wave velocity estimation. The data used in this study included porosity from log analysis and DT log data obtained from the Talang Akar formation for validation. By using this method, the P-wave velocity can be accurately predicted. [ABSTRACT FROM AUTHOR]

Java is an island which is considered to be quite disaster-prone. This terminology comes from the fact that along the island, we can find subduction tectonic activities which is also an epicenter. Some earthquake phenomena can be extremely destructive because of the existence of active fault as the vibration medium. Therefore, it is very important to do active fault mapping in Java island. In East Java province, there is an active fault which has been researched many times called Grindulu Fault. It is an active fault located in Pacitan Regency, East Java Province. It is a left-lateral fault. It is well exposed 500m alongside Grindulu river. However, the continuity of Grindulu northward is not well identified due to limitation of outcrop. This research was conducted to see how far the continuity of Grindulu northward. This research was started by satellite imagery survey to view areas where the existence of Grindulu fault may be found. Furthermore, field data acquisition was done on the marked areas. Field data obtained were in the form of fault slip data which were then analyzed using Wintensor software to see their kinematics. Based on the field data, the continuity of Grindulu fault can be found in three other areas which are Bakalan village, Wonogiri village; Pohijo village, Ponorogo regency; and Kruwe village, Megetan regency. Those exposed faults are strike-slip faults which are segments of massive NE-SW fault. This major fault is proposed with the name of Magetan-Pacitan active fault. The understanding of this active fault is expected to be reference for disaster mitigation in those areas. [ABSTRACT FROM AUTHOR]

Kedungwaru Village is a village in Karangsambung Subdistrict located at 109 ° 37'30 "- 109 ° 45'00" BT and 7 ° 30'00 '- 7 ° 37'30' 'LS. In the long dry season that occurs in the first half of 2018, residents in several areas of Kedungwaru Village complain of drought. Aquifers are a layer of water that can be used as a water source. The study was conducted using a single channel geoelectric instrument with the Vertical Electrical Sounding method with the aim to determine the distribution of aquifers based on the depth and thickness of the aquifer. The depth and thickness of aquifer data are then interpolated using IDW (Inverse Distance Weighted) method to produce depth maps and isopach maps. The results showed that there were two types of aquifers in Kedungwaru Village, namely unconfined aquifers and confined aquifers. The unconfined aquifer located at a depth of 1-3 m from the surface with a thickness varying up to 22 m, while the confined aquifer is at a depth of 13-30 m from the surface with thicknesses varying up to 20 m. [ABSTRACT FROM AUTHOR]

The new fiscal scheme in the upstream petroleum industry has been implemented in Indonesia since 2017. Furthermore, the combination split at each parameter is not reflective of the various economic conditions, with the difference between well-developed and new frontier offshore categories at two percent. However, the field size for the offshore new frontier areas should have significant larger reserves to justify the pipelines and other infrastructures capable of utilizing the well-developed offshore facilities. This study therefore analyzes the fiscal model calibration for the variable component of infrastructure in an offshore field, through its economic indicator. Sensitivity of infrastructure development is applied, which affects to the capital investment, the operating cost, and production scenario. The study found that the composition of the split is not reflective of the various development and economic conditions. It is suggests that a new gross split scheme be designed and applied to multiple levels of infrastructure in the same working area. [ABSTRACT FROM AUTHOR]

Proper and careful planning on the calculation of discharge in pipes in a system of three or more reservoirs are very important for the oil or the drinking water industry, as a collecting channel or as a fluid distribution. The discharge of fluid entering the pipe and coming out of the pipe can be calculated assuming the discharge flow is close to zero at the branching of the piping system. The debit calculation in this system can be done analytically and numerically, the numerical calculation will be faster than the analytical method. There are a number of analytical and numerical calculations that have been carried out by previous researchers, in this paper we do calculations by coding using other languages, namely Fortran. Calculations use data including elevation, length, diameter, roughness and friction factor from the pipe as well as Reynolds number data. Also uses the Moody Diagram, and the equations used are Bernoulli Equations, Continuity Equations, and Darcy-Weishbach Equations.In this paper numerical calculations using the Fortran program have been performed by displaying flow chart, coding, and the results of numerical calculations. The results obtained are quite in accordance with the results that have been calculated first, namely using the analytical method and linear interpolation by Streeter and numerical calculations that use Hardy Cross Method by Potter and Douglas. Deviation between our calculations with previous calculations, both analytically and numerically around 1%. So we conclude that our coding can be used for the calculation of debit in the three reservoir system planning. We present the numerical calculation results in the form of partial data while the complete data is presented in graphical form. This research can be continued to calculate a system of more than three reservoirs. [ABSTRACT FROM AUTHOR]

One of the main problems in open pit mining is the presence of water. Water in the mining area can disrupt mining operations and, in consequences, the production target will not be achieved. The mine drainage system is one part of the system used to overcome the presence of water. The rational method is the method most widely used by hydraulic engineers to estimate the discharge. The open channel dimension is designed based on the discharge estimation. Runoff coefficients are critical parameters for rational methods. There are several sources of literature determining the value of runoff coefficients, such as the approach of the American Society of Civil Engineering (ASCE), Schwab, Perry, and Gautama. In this paper, we examine the method selection effect of open channel dimension for determining the runoff coefficient value in the same conditions both of the rain catchment area and the rainfall intensity. The result is Gautama's coefficient value is the closest compare to real condition on the field. [ABSTRACT FROM AUTHOR]

Indonesia's geological conditions consisting of various geological formation units with different characteristics make it possible to meet the conditions of mixed soil-rock media. In the construction of the Sumedang toll road tunnel, the medium has an average value of Vp 2.0 km/sec relative low and the CF 1.1403 which are included in the soft rock category (category D II). The condition of the media can cause various problems of instability when doing tunnel excavations with the full face method. Especially collapse of the crown with a deformation value of 65.6 cm. Therefore, an initial reinforcement system is needed in the form of fore polling with fillers less than 5 meters in length and the distance between forepoling 0.5-0.8 m. This is done before excavation to increase the shear strength of the soil/rock in the crown so is not to collapse [ABSTRACT FROM AUTHOR]