Physics/Geophysics

The influence of monsoonal wind to coastal upwelling mechanism which is generated by Ekman tranport was studied here by analyzing wind stress curl distribution over Java – Bali sea waters and its surrounding area. Surface wind data were used as input data to calculate curl of wind stress in a barotropic model. Confirmation with Corioli effect in the Southern Hemisphere, it could be known that negative curl value has relation with vertical motion of sea water as resulted by Ekman transport. Results of analysis showed that negative curl near coast over Java Sea which is stretching to Lombok Strait occurred in December to April when westerly wind of the NW Monsoon actives. It can be guidance and related with season of coastal upwelling in the region. Reversal condition, the occurrence of coastal upwelling in the south coast of Java island related with the negative value of wind stress curl that occurs since easterlies wind take place in May to August as a part of SE Monsoon episode. Generally, upwelling occurrence in the field of study is a response to the Monsoon circulation. This study with related data such as sea surface temperature, chlorophyll concentration, and mixed layer depth that derived from satellite imaging data (NOAA/AVHRR, Aqua/Modis and SeaWiFS) shows a magnificent confirmation pattern.  So applying wind stress curl to recognize upwelling zone is alternatively way as climatic approach to maps potential fertilizing of sea water in maritime-continent Indonesia.

The aim of this work is to study turbulent flow over two-dimensional hill using a simple isentropic model. The isentropic model is represented by applying the potential temperature θ, as the vertical coordinate and is conversed in adiabatic flow regimes. This implies a vanishing vertical wind in isentropic coordinates which reduces the three dimensional system to a stack of two dimensional θ –layers. The equations for each isentropic layer are formally identical with the shallow water equation. A computational scheme of centered finite differences is used to formulate an advective model. This work reviews a simple isentropic model application to investigate gravity wave and mountain wave phenomena regard to different experimental design of computation and topographic height.

... Supriyanto Suparno ( Website: http://supriyanto.fisika.ui.edu ) ( Email: supri@fisika.ui.ac.id atau supri92@gmail.com ) Edisi III Revisi terakhir tgl: 13 Oktober 2008 Departemen Fisika-FMIPA, Univeristas Indonesia Dipublikasikan pertama kali pada September 2007 Page 2. ...

Sibayak geothermal field is located about 65 km to the southwest of Medan in the North Sumatra Province, Indonesia. Starting from 1998, a small-scale geothermal power plant (2 MWe) has been installed in this area. Since electricity demand increases in the North Sumatra Province, Pertamina Geothermal Energy plans to increase the capacity to 20 MWe. Accordingly, detailed knowledge of the reservoir structure and its extension must be determined for a new production target. The mise-a-la-masse (MAM) surveys were carried out in this field using the exploration well SBY-1 and the production well SBY-4 to delineate a new production target for further field development. A conventional one-dimensional MAM data processing has been done to obtain lateral variation of subsurface resistivity. However, the result is not satisfied to image real condition of the geology on the subsurface. Therefore, we carried out an advanced 3-D MAM inversion based on the smoothness-constrained least-squares metho...

Summary Significant improvements in the magnetic survey, design, processing and most important, resolution of aeromagnetic data could provide detailed information on the spatial distribution, geometry, and structural style of faults and fracture systems. The magnetic data can easily integrate/merge and correlated with other available data (e.g. gravity, geology, seismic, topography). The integration of these data provides an excellent approach for structural system and evaluation of hydrocarbon plays in Esh El Mellaha area, Gulf of Suez. In this paper, enhancements and filtering of aeromagnetic data were implemented using band-pass filter and horizontal gradient technique. The results are compared with the available information; such as geologic map, drill-hole data, topographic data, and 2D seismic data in the northern part of the area. In general, the area is dissected by a system of faults most of them trending in the NW-SE (Red Sea trend) and NEE-SWW (Tethyan trend). Introduction:

DC Resistivity analysis was carried out in the Sibayak geothermal using Schlumberger Vertical Electrical Sounding (VES) during a preliminary study in 1990. The resistivity data has been processed conventionally using one-dimensional (1-D) inversion to estimate vertical variation of resistivity related to hydrothermal activity at shallow depths of less than 1 km. Subsequently, the inversion results were correlated to develop a 2-D resistivity section; afterwards, it was combined with the MT data processing result. However, the results of 1-D inversion of DC resistivity are not fully satisfactory for actual 3-D structures such as geothermal systems. Therefore, we have re-processed the same Schlumberger VES data set by performing a 2-D inversion based on ABIC least squares method. The 2-D inversion result shows a more realistic feature in terms of geological structure. Caldera boundaries and a dome-like structure of the low resistivity are clearly determined, indicating an up-flow zone...

Sibayak geothermal field is located about 65 km to the southwest of Medan in the North Sumatra Province, Indonesia. Starting from 1998, a small-scale geothermal power plant (2 MWe) has been installed in this area. Since electricity demand increases in the North Sumatra Province, Pertamina Geothermal Energy plans to increase the capacity to 20 MWe. Accordingly, detailed knowledge of the reservoir structure and its extension must be determined for a new production target. The mise-a-la-masse (MAM) surveys were carried out in this field using the exploration well SBY-1 and the production well SBY-4 to delineate a new production target for further field development. A conventional one-dimensional MAM data processing has been done to obtain lateral variation of subsurface resistivity. However, the result is not satisfied to image real condition of the geology on the subsurface. Therefore, we carried out an advanced 3-D MAM inversion based on the smoothness-constrained least-squares metho...

ABSTRACT Sibayak geothermal field is located about 65 km to the southwest of Medan in the North Sumatra Province, Indonesia. Recently, a small-scale geothermal power plant (2 MWe) has been installed in this area. Since electricity demand increases in the North Sumatra Province, Pertamina (Geothermal Division) plans to increase the capacity to 20 MWe in the year 2005. Accordingly, detailed knowledge of the reservoir structure and its extension must be determined. The mise-a-la-masse (MAM) surveys were carried out in this field using the exploration well SBY-1 and the production well SBY-4 to delineate a new production target for further field development. Interpretation of the MAM data was done to correlate the results with formation temperatures and lost circulation zones and finally to image a promising reservoir zone. This interpretation result of MAM data indicates that reservoir zones trends to the north-northeast direction of the study area and shows a good correlation with formation temperature and lost circulation zone. This fact leads us to propose that the best production target for the development of the Sibayak area is characterized by the high temperature, high permeability and high well productivity region marked by the dome-shaped resistivity zone below the conductive cap rocks.