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EAGE-HAGI 1st Asia Pacific Meeting on Near Surface Geoscience and Engineering
- Conference date: April 9-13, 2018
- Location: Yogyakarta, Indonesia
- Published: 09 April 2018
1 - 20 of 115 results
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Case Studies: Identification of Subsidence Problem Using Electrical Resistivity Imaging
Authors N. Yunus, M.H. Arifin and K.I. Abdul RahimSummaryThe settlement problem can cause a major damage to the building foundation thus could probably causing harm to the surrounding area. Therefore, three locations has been chosen to discuss this matter which located at Batu Pahat, Johor, Shah Alam, Selangor and Sungai Siput, Perak. Electrical Resistivity Imaging (ERI) method has been chosen to measure the resistivity of subsurface materials and identify the causing factor of subsidence at these locations. The instrument used is ABEM Terrameter SAS 4000 System. Resistivity profiles showing the subsurface condition of the study area which indicated various factors that causing the subsidence at these areas. Remediation process must considered several factors including suitability of proposed method including the causing factors, lithology and severity of the damage.
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Travel-Time Tomography Imaging around Sinabung Volcano during 2010–2017 Eruption Period
Authors A.T. Sasmi and W. SuryantoSummarySinabung Volcano, which never shown any certain volcanic activities since its last eruption in 16th century, suddenly errupted at August 29, 2010. The disaster has not just stopped. Sinabung eruption repeatedly occurred at 2013, 2014, 2016, and 2017, with unstable change of eruption statuses. This research is aimed to identify relationship between Sinabung Volcano recent erruption activities, with distribution of P-wave anomaly around Sinabung Volcano.
Seismic velocity values are derivative form of travel time value. Some factors which influence a seismic velocity condition are lithology type, rock density distribution, rock porosity, rock depth and pressure condition, also fluids saturation in study area. This research was implemented using earthquake travel time data of January 2010-May 2017 period, from Indonesian agency of Meteorology, Climatology and Geophysics (BMKG) earthquake catalog. Data processing was done by Simulps14 program to create distribution map of Vp anomaly from the targeted area.
The result showed that vertical variety of P-wave velocity beneath Sinabung Volcano indicates relation with partial melting zone and fracture which were formed at the end of 2013. This features led Sinabung into big eruption at January 2014.
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The Application of Magnetic Resonance for Formation Pressure Tester and Stimulation Optimization in Produced Carbonate Reservoir
Authors Cahyo Nugroho, Viet Le, Al-Turkey Shaikha and Mohammed Ali Al-IbrahimSummaryA producer well with tight carbonate reservoir was planned for stimulation with objective of production improvement. The strategy for the stimulation was hydraulic fracturing in a fishbone completion. Magnetic resonance and formation pressure tester were used to evaluate fluid content, rock quality and formation pressure of the reservoir. The magnetic resonance had helped to identify the formation pressure tester points and resulted all good test in tight carbonate. The magnetic resonance had delivered remaining oil saturation and rock quality in regards to porosity and permeability. The oil saturation and rock quality were integrated to choose the sidetracking intervals of fishbone completion. The fishbone completion was to be stimulated with hydraulic fracturing to connect the good oil saturation and rock quality intervals, and to enhance permeability of fair rock quality. This application is first use of magnetic resonance in a revisited producer well of tight carbonate reservoir.
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Identification of Heat Source and Alteration Zone of Parangwedang Geothermal System using Magnetic Method
More LessSummaryResearch using magnetic method has been done on geothermal area located in Parangtritis, Yogyakarta. This geothermal system is often called Parangwedang geothermal system. This research aims to map alteration zones and predict the existence of heat source in Parangwedang geothermal system. The research was conducted by acquiring magnetic method data on 2x1 km2 area around the manifestation of parangwedang hot water with measuring point in the form of uniform grid with the number of 174 points of measurement and spacing between the points 100 m. The result of the magnetic method is a total magnetic field anomaly map that will be analyzed qualitatively to determine the extent of the alteration zone and the predicted presence of heat source. The alteration zone is mapped to a low magnetic anomaly located in the southwest of the research area. The existence of heat source is suspected to be in a high magnetic anomaly located just below the manifestation of hot water parangwedang.
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Evaluating problematic landslide-risked site using hydrogeophysics, isotope and conventional hydrological techniques
SummarySlope failures, landslide and settlement of foundation (subsidence) typically do not occur spontaneously. In this context, the task of predicting the exact failure is difficult, as the point of ultimate failure is dependent on a number of factors ranging from geologic structures of the area to land use change. The first stage in any assessment of a landslide-risked area is the establishment of a reliable conceptual model of the subsurface conditions. Here we present initially results from a study conducted at Bukit Tinggi National Secondary School, Pahang, Malaysia prior to the likely occurrence of landslide activities. Our focus is to evaluate problematic subsurface of a natural landslide-risked using integrated geophysical, isotopic hydrology and conventional hydrological techniques. In this preliminary stage of the study, field screening began with minimally intrusive techniques: electrical resistivity tomography and seismic refraction surveys. The results of geophysical techniques are supported by the isotopic signature which may give a direct insight into the origin and distribution process within the hydrological system. It can be concluded that these techniques complement the conventional hydrological and hydrogeological methods employed in problematic site assessment and their use should be encouraged.
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Geotourism Development Planning in Paleobotany Park Merangin
Authors A. F. Bobbybuana, S. Dwiputri, M. I. Pribadi, R. A. Puteri, I. Azizah, A. M. Fath, B. Ansori, A. Sidik and D. SaputraSummaryGeopark Merangin Jambi located in the Jambi Province administratively. The total area of Geopark Merangin Jambi is 20.360 km2. Currently, Geopark Merangin Jambi is in the process of being certified as Global Geopark by GGN-UNESCO. The Paleobotany Park Merangin with whole area of 1.551 km2 is present as a core region and is situated in the southern part of Merangin Regency, typically along and in flood plains of the Merangin and Mengkarang Rivers. The main obstacles found in Paleobotany Park Merangin based on Author’s observation results are poor accessibility to geosite locations and inadequate management. This constraint is due to the lack of attention from the government and the public awareness to preserve geosites even though Geopark Merangin Jambi is currently in the process of being certified as Global Geopark. Therefore it is necessary to plan the development of geotourism in Geopark Merangin Jambi, especially in Paleobotany Park Merangin as a core region of Geopark Merangin so that constraints can be overcome. The aim of this paper is to introduce as well as publication media to increase local income and in addition it can be used by the Government to develop the Paleobotany Park Merangin in the future.
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Audiomagnetotelluric Survey to Characterize the Geological Features of Merren Valley Site, Papua, Indonesia
Authors S. Arjuna, A. Pringgoprawiro and A. SyukriSummaryA drilling plan is quite important to minimize errors during drilling. Information on subsurface geological aspects will helpful in providing supporting information for drilling plan. An audiomagnetotelluric (AMT) survey has been successfully characterized the Merren valley site which is located East of Grasberg mine area, Papua, Indonesia. The AMT survey is aiming to characterize the lithological features and delineate the EESS west fault at the depth as part of wells monitoring drilling program. A total of 57 stations were collected by using Zonge equipment system with dipole 50 m, 25 m spacing between stations, and L shaped configuration. The Zonge software used to produces the 2D electrical resistivity profiles. According to the AMT survey results and comparing with known geological condition of study area shows the near surface layer interpreted as glacial till formation that characterized by a moderately resistivity response about hundreds ohm-m. Meanwhile, the deeper layer that has resistivity response about thousands ohm-m indicated as limestone rock. The EESS west fault zone (lower resistivity) indicated more steeply than fault inferred by conceptual model. The resistivity inversion model appears agree with the geological condition of Merren valley site that can be used for making decision in drilling plan program.
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Damage Zone Map Due to Earthquake on May, 27th 2006 in the Area of the Opak River, Yogyakarta Based on MMI Scale
Authors P. Nurhayati, A.S. Banuzaki, B.S. Simorangkir, I. Ilmawan and D.P.E. PutraSummaryJava island has been known to be frequently affected by earthquake. On the other side, the management of earthquake disaster mitigation is still lack of disasters anticipation and mitigation plan. It can be proven by the absence of detail damage-zonation maps of earthquake. The damage-zonation maps of earthquake are needed to assess the impact of future earthquake. Based on the 5.9 richter scale Yogyakarta earthquake on May 27, 2006, the worst affected region was around the Opak River. Therefore, the damage zonation map of earthquake in Opak River is absolutely needed to mitigate the future earthquake cases. The investigation was conducted by interviewing the earthquake witnesses scaterred in 82 locations along Opak River. The results of interview were classified based on MMI (modified mercalli intensity). By apply spatial analysis in GIS, the MMI data were interpolation and extrapolation to damage-zonation map of MMI. Reveal the result the biggest MMI classes was obtained along the Opak River and controlled by fault continuity, earthquake magnitude, distance from epicentrum, litology thickness and litology type.
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Two-dimensional Magnetotelluric Modeling Based on Bi-tree Mesh
Authors M. Li, Z.Y. Zhang, M. Xin and S.P. XieSummaryIn order to improve FEM forward modeling efficiency and precision of the 2D magnetotelluric problem, this paper focuses on calculating the response of a two dimensional MT model considering the conductivity and permeability variations simultaneously. These secondary fields method used to solve the secondary variations problems parallel to strike like Wannamaker. A model discrete method based on the bi-tree structure was developed and applied.
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Geothermal Control System with Estimated Distribution of Resistivity Value Using AMT Method in Ungaran Area
Authors A. Gilang, A.T. Yuliwardana and A.I. AssidhiqieSummaryGeothermal prospect area of Mount Ungaran is located approximately 30 km southwest of the capital of Central Java, Semarang. The area is physiographically located in the North Serayu Mountains formed by the lifting of the Miocene. This mountain was active between the late Pliocene and the Late Pleistocene. In the area, there is a geothermal prospect located on the southern slope of Mount Ungaran, namely in Gedongsongo area.
Several geothermal manifestations around Mount Ungaran include: fumarole in Gedongsongo area, hot springs in Banaran, Diwak, Kaliulo and Nglimut areas, and altered rocks are found in Gedongsongo and Kendalisodo. From existing research, a geothermal prospect in this area is dominated by water, which is structurally controlled by Ungaran caldera structure. From interpretation AMT, the heat source is thought to be a diorite intrusion with range value resistivity are 2.8–4.0 ohm.m. Cracked volcanic rocks of Lower and Tertiary Quarterly are thought to function as reservoir rocks with range value resistivity are 1.5–1.4 ohm.m. The impermeable upper quartile volcanic rocks are thought to function as cap rocks with range value resistivity are 2.8–4.0 ohm.m. Based on geothermometry on fumarole found in Gedongsongo area, reservoir temperature is estimated to reach 230°C.
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Geology and Geophysisc to Discover Cu-Zn Mineralization in Purwohardjo Area, Wonogiri Regency, Central Java
Authors V. P. Harefa, R. A. Hidayah, B. B. Prabowo, D. Aminulloh, R. A. M. Yudha and B. D. DiliantoSummaryThe research is located in Central Java Province, Wonogiri Regency, Karangtengah-Purwohardjo Area. The lithology unit in the research area consists of volcanic breccia units, which are intruded sequentially by the pyroxene andesite, and the dacite. The geological structure of the shear and fracture faults participates in controlling the mineralization in the research area. Based on interconnected relationships in the field, the dacite is interpreted as a mineralization-bearing intrusion. Hydrothermal alteration includes argillic and propylitic alteration. The argillic alteration zones are characterized by the presence of sericite minerals, chlorite and clay minerals, which are generally intensively formed on pyroxene andesite and dacite. The propylitic alteration zones are characterized by the presence of chlorite, epidote and calcite minerals, which are commonly found in volcanic and partly andesitic breccias. Hydothermal alteration is strongly associated with ore mineralization. The copper ore sulfide minerals are chalcopyrite, bornite with a bit of kalkosit and kovelit.
In Induced Polarization profiles the Trend value of high chargeability appears to be related to the presence of metal sulphide minerals in andesite and dacite rocks. Based on the characteristics of alteration and mineralization and from Geophysiscs interpretation, the research area is included in High Sulfidation Epithermal related to Porphiry type.
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Application of the bilateral filter to improve derivative based lineaments enhancement approaches
Authors J Wang and X. H. MengSummaryIn the work discussed in this paper, we have applied the bilateral filter to improve the derivative based lineaments enhancement method of gravity and magnetic data. The method was tested using the gravity responses of a combined density model. A comprehensive comparisons indicated that the bilateral filter can effectively smooth the original field data without disturbing the sharpness edges. Filtered data obtained from the bilateral filter can be further used for edge detection stably without losing of useful boundary information.
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Lithology and Petrophysic Variations of Carbonate Reservoir Using Rock Typing: Analogue Study in Ponjong, Yogyakarta
Authors I. Ramadhan, A. R. Perdana, P. Herianto and R. HidayatSummaryResearch area shows 3 distinct rock types, RT 1, RT 2, and RT 3 (lacks of data). RT 1 has the highest permeability, compared to RT 2, and RT 3 (lowest). The permeability is very dependent on pores, which has strong relations to diagenetic environment.
Diagenetic processes have implications on pores and cement forming. Cement formed by diagenetic process are bladed isopachous (calcite), formed in fresh water phreatic environment and fibrous isopachous (aragonite), formed in marine phreatic environment. Pore formed by dissolution shows vadose zone
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Geology and Hydrothermal Alteration of Cibeber Prospect, Lebak, Banten: a preliminary study of Au-Ag-base metal sulfide deposit and implication to exploration
Authors C. D. P. Dana, A. Idrus, S. D. Masti, F. Yuniardi and I. A. MeakSummaryThe research area is located in Neglasari, Cibeber, Lebak, Banten. As we know that western Java has a big potential in mineral deposits especially epithermal deposits and one of them was found in this studied area. This study aims to understand the geological and hydrothermal alteration as well as the mineralization characteristic in studied area. Surface geological mapping is used to know the geological condition including lithologies and structural geology also hydrothermal alteration distribution. Five representative ore vein samples were analyzed using FA-AAS method to determine the grade of precious and base metal contents. The lithologies found in this area can be divided into 3 unit stratigraphically that is sandstone unit, tuff breccia unit and andesitic lava unit while the structural geology are strike slip fault, normal fault and some joints. There are 4 alteration zone that is silification zone, clay-silica zone, clay zone and chlorite-epidote zone. The mineralization mostly found as hydrothermal veins which can be divided into two type that is precious metal bearing vein or usually called as low sulfidation type and base metal bearing vein or usually called as intermediate sulfidation.
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CSAMT investigation for geological structures in a HLRW preselected site
More LessSummaryThis paper discusses the use of Controlled Source Audio-frequency Magnetotelluric method (CSAMT) in geological structure exploration at an area preselected for high level radioactive waste (HLRW) in northwest China. The survey objective is to evaluate the rock mass quality and find the weak geological structures which will cause damage to the safety and stability of underground repository. We conducted a dense CSAMT survey, combined with borehole information to delineate the local weak geological structures. The study was conducted in NW China in 2014. The comparison between the interpreted results and geologic information shows that both are in agreement. The preliminary results offer detailed information about the electrical structures of Nuorigong rock mass from the surface to 1400 m deep, so the interrelationship between the target rock mass and its surroundings were analyzed to show their shapes. In conclusion, CSAMT results are helpful in exploring the subsurface for geological structures and competent rock mass. It can also provide the reliable geophysical evidence and scientific reference for complete and consistent evaluation of the deep geological structures, and aid in comprehensive assessment of preselected sites for HLRW disposal, such as further study in the design and construction of an underground man-made repository.
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Site investigation using resistivity survey to investigate possible slime deposit in ex- tin mining area
Authors H. Hussin, M.H. Ariffin and T.A. JamaluddinSummaryResistivity is a well-known method to detect rock resistance value in the subsurface. Its ability to penetrate deep into rock mass have been utilized in various field. In this study, resistivity tomography survey was conducted to identify the present of slime layer in ex-tin mining area which conducted at Kampar, Perak, Malaysia. Slime was a residual material mostly comprise sandy and clayey material. Slime was consider as weak material and can cause problems especially ground settlement. A total of five resistivity survey lines was carried out to cover entire proposed area ( Figure 1 ). Geologically, the study area is underlain by sedimentary and metamorphic rocks which is part of Kinta Formation. Resistivity interpretation shown four different anomalies which are soft layer, compact layer (soil), slime and rock boulder. The present of slime material is deposited 25m below surface.
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Geomagnetic Investigation to Delineate Heat Source of Geothermal Potential in Jambi Sub-Basin
Authors A. F. Bobbybuana, F. Randitama and V. AfrionalSummaryPandan Sejahtera Village, Geragai, East Tanjung Jabung, Jambi, is an object study area to make observations, because the discovery of geothermal manifestations in the form of hot springs with a temperature of about 60 degrees Celcius. The study area is located in back-arc basin which is far away from subduction zone and active volcanoes. In geothermal exploration, Geomagnetic Method used to identify the type of rock that is the source of heat. Interpretation of geomagnetic data is done by using Reduce to Pole and Upward Continuation as filters. In order to calculate those filters, Fast Fourier Transform (FFT) was applied to the geomagnetic data by using Oasis Montaj software. Based on the Upward Continuation filter results the Author interpret that distribution of shallow and deep anomalous zone are respectively associated with residual and regional anomaly magnetic. Deep anomaly in the East - Northeast direction is interpreted to be associated with a heat source because it has a low magnetic anomaly value owned by demagnetized rocks due to high temperatures.
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Determination of Peak Ground Velocity Observation as Geohazards Parameter in North Sulawesi
Authors R. Priadi, D.A. Pratama and R.B. KurniawanSummaryNorth Sulawesi’s activities are mostly done by triple junction between Eurasian, Philippine and Pacific plates causing seismic activity in the north Sulawesi region. In addition to PGA data there is also one parameter that can be used to characterize the ground response during a earthquake that is PGV (peak ground velocity). PGV is the most frequent value in an area within a given time period due to an earthquake. The result of PGV observation value is obtained if the largest PGV value is 0.25667215 cm/s at the earthquake event of Northern Molucca Sea M 4.8 dated 19 November 2016. Then for the smallest PGV value of 0.000187953 cm/s at event Molusca sea M 4.8 dated 5 May 2016 which recorded maximum at north-south component at TMSI station. The average PGV observation value in North Sulawesi is 0.056756952 cm/s. Areas with large observational PGV values are Bitung, Bolaang Uki, and Kotamobagu districts. PGV values are only good for accurately representing intensity and state of the station for earthquake magnitude below M 6.0. For earthquakes with magnitude M 6.0 or greater it is recommended to keep using PGA to represent ground shaking when an earthquake happend.
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2-D time-domain waveform inversion using Gauss-Newton methodology in elastic media, case study: complex marmousi2 model
Authors B.I. Hardi and T.A. SannySummaryFull-Waveform Inversion (FWI) can be defined as an iterative fitting data procedure for obtaining physical properties of the Earth based on the full wave-field data simulation. Hence, FWI is widely known as a comprehensive way to solve the complex structure below the earth surface, it performed a high-resolution image, and very powerful when it combined with the good prior model.
In this research, we especially focusing on how we worked with the 2-D Full-Waveform Inversion (FWI) using Gauss-Newton approach in elastic media. The steps included the forward modeling problem based on the finite-difference and staggered grid scheme that bounded by free-surface boundary condition (on the top of model) and Perfectly Matched Layer (PML) for the rest, also, we applied the Gauss-Newton inversion that exploit the approximate-Hessian into this methodology. For the result, we tested the inversion modeling in simple layer cake model and complex marmousi2 model, both of those models are located in the shallow area.
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