The Complete Bouguer Anomaly (CBA) map from 1997 gravity survey at Karaha-Telaga Bodas, West Java, Indonesia is used to make a model of the subsurface geothermal system. A two-dimensional cross-section of the system i...
The Complete Bouguer Anomaly (CBA) map from 1997 gravity survey at Karaha-Telaga Bodas, West Java, Indonesia is used to make a model of the subsurface geothermal system. A two-dimensional cross-section of the system is produced using a 2.5-D forward modeling. Initially, the print CBA maps of the Karaha-Telaga Bodas geothermal system is digitized. Next, the digital map is separated by using the moving average and spectral filtering methods, so a regional and residual anomaly maps are obtained. The subsurface modelling is made based on geological information of the area to produce a model that can represents the real condition as similar as possible. The line chosen for modelling has a North - South orientation, passing through Karaha and Telaga Bodas to foresee both of the geothermal system in one cross-section. Subsurface model interpretation shows that there are two separate granodiorite intrusion body with density contrast of 0.5 g/cc below Karaha - Telaga Bodas. This conclusion coincides with the intrusion body found during drilling operation. The intrusion body is possibly the heat source of the system. The reservoir of this system is interpreted as volcanic breccia with thickness of two kilometres in Telaga Bodas and keeps thinning towards Karaha. The fluids of the Karaha-Telaga Bodas Geothermal System are estimated to come from acid sulphate water and meteoric water entering from Telaga Bodas, as well as meteoric water entering from Karaha. There is an upflow in the South, Telaga Bodas.
In hydrology context, sediment can be interpreted as inorganic and organic material that is transported by, suspended in, or deposited by streams. It is important to know the function of soil, stream discharge, land-c...
In hydrology context, sediment can be interpreted as inorganic and organic material that is transported by, suspended in, or deposited by streams. It is important to know the function of soil, stream discharge, land-cover features, weather conditions and land-use activities. Sediment load carried by streams and rivers can be composed either of fine materials, mostly silts, and clays, or coarse materials such as sand. One product of sediment is dissolved load consists of indistinct material in solution moving downstream. It is produced by chemical weathering processes and does not move out of the water. To investigate the dissolved sediment, we have applied the floating of Time Domain Electromagnetic (TDEM) method. The acquisition of TDEM data has been performed use tires and small ship as innovation measurements. The calculated data model using Occam and Marquardt Algorithms. The responses of data show the sedimentation has less resistive compare the surrounding structures. This innovation is very helpful to know the environmental condition, especially in the water.
TDEM (Time Domain Electromagnetic) method is a sounding geophysical method using electromagnetic wave generated by the electrical current source to image cross section of earth's subsurface. TDEM using galvanic so...
TDEM (Time Domain Electromagnetic) method is a sounding geophysical method using electromagnetic wave generated by the electrical current source to image cross section of earth's subsurface. TDEM using galvanic source (grounded wire) is one of TDEM acquisition technique which has flexible properties for the complex topography of measurement area. Three-dimensional forward and inversion modeling technique of TDEM with galvanic source still develops until now. Three-dimensional modeling is required because three-dimentional structure can influence TDEM signal which has a dimension of z-axis direction only. In this paper, We have been developing a 3D forward modeling program applying finite difference time domain method for 3D subsurface models. We can assess a distribution of TDEM synthetic data affected by 3D model. Using this 3D TDEM modeling program synthetic data has been generated as the function of transmitter and receiver position in 3D model space. Furthermore, this program can be used to simulate a conductivity change of reservoir model as consideration of reservoir monitoring implementation.
Underground cavities or voids detection is essential especially when it comes to building construction. By knowing the presence of void lying underground, one could consider whether the subsidence is likely to be prev...
Underground cavities or voids detection is essential especially when it comes to building construction. By knowing the presence of void lying underground, one could consider whether the subsidence is likely to be prevented or not. Ground penetrating radar is a high-frequency electromagnetic sounding technique that has been developed to investigate the shallow subsurface using the contrast of dielectric properties. This geophysical method is suitable to be used to detect and locate voids beneath the surface especially those that lie in shallow depth. This research focused on how GPR could be implemented as void detector using model simulation or forward modelling. The models applied in the forward modelling process are to be made as similar as the real condition in the case study location which took place in Tahura Japan Cave, Bandung, Indonesia. Forward modelling needs to be done so in the future, we might use the modelling results as the references in measuring real GPR data in the location. We used three models that we considered fairly representative to prove that GPR is capable of detecting and locating voids underneath the ground. This research resulted in the different amplitude region around the considerably homogeneous region. The different amplitude region is characterized having an arc shape and is considered to be air which is known as the key component of voids.
The joint inversion of geophysical data can reduce the ambiguity of model parameters. Joint Inversion of Magnetotelluric (MT) and Transient Electromagnetic (TEM) data was performed to get detailed information of subsu...
The joint inversion of geophysical data can reduce the ambiguity of model parameters. Joint Inversion of Magnetotelluric (MT) and Transient Electromagnetic (TEM) data was performed to get detailed information of subsurface structure. Whereas TEM data is sensitive to describe in the shallow structure, while the deeper structure is related to MT data. We derived the joint inversion scheme from the second order of Marquardt algorithm using singular value decomposition (SVD). The detailed analyses of the model parameters are performed by damping factors, V-matrix, damped error bounds and importances value. The joint models parameters with damping factor and importances value above 0.9 indicate that the associated eigen parameters are well-resolved.
Indonesia has 40% of the world's potential geothermal resources with estimated capacity of 28,910 MW. Generally, the characteristic of the geothermal system in Indonesia is liquid-dominated systems, which driven b...
Indonesia has 40% of the world's potential geothermal resources with estimated capacity of 28,910 MW. Generally, the characteristic of the geothermal system in Indonesia is liquid-dominated systems, which driven by volcanic activities. In geothermal exploration, electromagnetic methods are used to map structures that could host potential reservoirs and source rocks. We want to know the responses of a geothermal system using synthetic data of Audio-magnetotelluric (AMT) and Magnetotelluric (MT). Due to frequency range, AMT and MT data can resolve the shallow and deeper structure, respectively. 1-D models have been performed using AMT and MT data. The results indicate that AMT and MT data give detailed conductivity distribution of geothermal structure.
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