ANALYSIS OF CARBONATE DEPOSITION AND ITS FLUID CONTENT IN ‘JAMHARI” FIELD, EAST JAVA BASIN BY USING INTEGRATED ANALYSIS OF SEISMIC STRATIGRAPHY, ATTRIBUTES, AND AI INVERSION

• Main Author: Adnan Aziz, Ryzal
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/52894
• Institution: Institut Teknologi Bandung

One of the basins as the backbone of hydrocarbon production in Indonesia is the East Java basin, one of which is the Cepu Block. A unique field that has not been widely interpreted and yet produced is the "Jamhari" Field. The objective of this research is to characterize and determine the distribution of the Oligocene carbonate formation gas reservoirs. The carbonate rock formation is quite unique both laterally and vertically. Reservoir quality is more influenced by the postdeposition process. Both of these are challenges in this research. The data used are 3D seismic PSDM (Post-Stack Depth Migration) in the time domain and one well log. First, a well log analysis is carried out to determine the character of the target zone. So that the reservoir is divided into two based on the log of total gas, gas-1 with a concentration below 100 units and gas-2 with a concentration of 300 units. Sensitivity analysis was carried out to determine whether the log data had specific data distribution characteristics. So, it is used to parameterize the P-Impedance (AI) inversion process. Simultaneously, running seismic attributes for seismic stratigraphic analysis. The results are used for the TCE and BCE picking horizons. Horizons are used for the inversion guiding process. Model based inversion is applied because it is quite efficient and quite representative. Raw seismic analysis and variance attributes found extensional tectonic features that influence the buildup geometry. The presence of gas is mapped with the instantaneous frequency and amplitude envelope attributes. From the analysis of the reflector character, geological features, and buildup geometry, Jamhari Field is divided into several facies, fore-reef, reef-core and back-reef. The results of the AI inversion were extracted into other physical properties and to determine the distribution of these parameters. The reconstruction of the depositional environment was carried out without biostratigraphic data or age logs that were specifically accurate. So, the depositional environment approach was analyzed with each of the data: log data, seismic data, and relative sea level curves. Furthermore, the analysis results are integrated to obtain a depositional environment scheme. The integration of structural and stratigraphic analysis is also carried out to obtain a comprehensive image. Finally, that the gas-1 reservoir is associated with the transgressive depositional environment at the end of the build-up growth and the gas-2 reservoir is correlated with the thick build-up interpreted as exposed carbonate.