EVALUATION OF AMPLITUDE VERSUS OFFSET (AVO) AND STOCHASTIC INVERSION SEISMIC METHODS TO MAP THE DISTRIBUTION OF HYDROCARBONS IN THE LOWER TALANG AKAR FORMATION (LTAF) IN THE

• Main Author: Ridho Pratama Zougira, Mohammad
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/86815
• Institution: Institut Teknologi Bandung

The "ZOUGIRA" Field is located in the Jabung Block, South Sumatra Basin, where the main reservoir of the "ZOUGIRA" Field comes from the LTAF Formation. The problem in this field is that there is a thin sandstone reservoir that results in a tuning effect, and a lot of coal intercalation in the sandstone reservoir interval that affects seismik reflectivity. Therefore, to overcome the tuning problem, it is necessary to carry out seismik enhancement and log blocky so that further analysis can be carried out. After the tuning problem was resolved, Amplitude Versus Offset (AVO) analysis was carried out to see the response of hydrocarbons in sandstone reservoirs that did not experience the tuning effect. Based on the results obtained, it shows that the classification of AVO in the study area is dominated by AVO class IV, and there is a difference in classification between seismik and wells in several wells. This is due to the presence of coal inserts in sandstone reservoirs which results in the AVO response to be class IV, so that the use of the AVO method to see the hydrocarbon response becomes ambiguous and some reservoirs cannot be analyzed AVO due to the tuning effect. Because the above problems have not been resolved, a stochastic inversion seismik method is carried out to overcome the problem of thin sandstone reservoirs and coal inserts. Before conducting stochastic inversion seismik analysis, first conduct a sensitivity analysis to find out the sensitive parameters in the research area. From the results of the sensitivity analysis, it was found that the crossplot between AI versus Density can separate between shale, sandstone and coal, and can separate between gas and oil zones. Based on the results, it is known that in the sand interval A was found GOC at a depth of 5250 ft and OWC at a depth of 5400 ft. At sand B intervals OWC was found at a depth of 5430 ft and at sand C no hydrocarbons were identified. Then from the results of the analysis of the facies of the meandering river is characterized by the number of sandstones that are visible, while the coastal plain is characterized by many coal inserts in the sandstone and shale layers.