Identification of geological structures by using ESA-MWT and MS-HDVD gravity data at Slawi, Central Java

It has been done of a geophysical measurement by Pertamina in the Slawi area of Central Java. The results of the seismic section show that there is an up dome in the field "M". The location of this area is in the mt. Slamet zone. So that the existence of an up-dome structure does not automatically provide the possibility of a hydrocarbon trap in the area. This study was conducted to characterize the existence of these structures using gravity data. The ESA-MWT (energy spectral analysis multi window test) and MS-HDVD (multi scale-horizontal derivative vertical derivative) methods of gravity data are applied in this study. The ESA-MWT method is able to map lateral rock variations very well, whereas MS-HDVD is more sensitive to vertical variations even though it is also good for identifying rock variations in both vertically and laterally. There are five horizons detected in the field. These five interfaces with density contrast extend over a depth range between 416 to 2112 meters. The horizons are identified as being associated with sediment rocks namely Formations of Tapak, Penosogan, Kumbang, Halang and Rambatan. The sediments are likely to be intruded by diorite stones (in up-dome form) which happened during the Late Miocene. The peak, or top, of the intrusion body is estimated at around 620 to 755 m depth on the Penosogan Formation.