Perpustakaan Digital ITB

A study area has been selected for seismic attribute analysis and re-interpretation of the Ngimbang Formation in Madura island North East Java Basin (NEJB). The study area is located at the north-west part of Madura island, where there are 2D seismic lines and three drillholes X-1, Y-1, and Z-1. The purpose of this research is to identify hydrocarbon prospective areas through seismic attribute analysis and re-interpretation. The data sets for this project were obtained from PT Pertamina Indonesia, They include a set of 2D seismic data over Madura island in SEGY format, sets of log data, and some well reports in Power Point, and PDF format. However, the research only used some parts of the data that occurred within the study area. The early interpretation analysis of the study area was obtained by importing the horizon and faults that existing from an early analysis by Pertamina. The top of Ngimbang in the study area forms an elevated structure trending in an east-west direction, with slopes in the north and south parts forming a major wrench fault system trending in an east-west direction. Some minor local faults surround the major fault system. Selected seismic attributes were extracted from the near top of Ngimbang horizon from 2D seismic data. The seismic attributes generated were energy, instantaneous amplitude, instantaneous frequency and instantaneous cosine phase. From these attributes, the most appropriate one was re-interpreted to derive anomalous target area that can be further explored and may lead to hydrocarbon discovery. iii From the generated seismic attributes, the energy attribute was chosen as the best one to be re-interpreted. The re-interpretation result showed high energy anomalies which was the first one that has the greater value, near the Y-1 and Z-1 wells. These high energy anomalies were the result of high value amplitude in the 2D seismic data of the near top of the Ngimbang Formation. The energy anomaly is a response attribute that returns the energy of a trace segment, and useful for seismic object detection (e.g. chimney detection). This anomaly may caused by acoustic impedance contrast, bright spot, sequence boundary, gas accumulation, tuning effect, lithology changes, depositional environment changes, faults, etc. The Gravity method and analysis ran in the same study area and used to compare the result of the re-interpretation from the Seismic Attribute, in purpose it can increase the quality of the re-interpretation and get the best result in re-interpreting the Ngimbang formation in Madura island. It is suggested that more detailed studies should be carried out in the Madura data to validate the results of this study. Also a further re-processing stage is strongly recommended to increase the quality of the 2D seismic data in the Madura island, especially in the study area, so any exploration and research carried out in this area an the hydrocarbon occurrences are not overlooked. The use of 3D seismic surveying in the most prospective areas in Madura island is recommended following attribute analysis and re-interpretation of the entire Madura 2D data sets. The purpose of this research is to identify hydrocarbon prospective areas through seismic attribute analysis and re-interpretation. Selected seismic attributes were extracted from the near top of Ngimbang horizon from 2D seismic data. The seismic attributes generated were energy, instantaneous amplitude, instantaneous frequency and instantaneous cosine phase. From these attributes, the most appropriate one was re-interpreted to derive anomalous target area that can be further explored and may lead to hydrocarbon discovery.