IDENTIFICATION OF CO2 DISTRIBUTION USING AVO ANALYSIS METHOD AND FAR-ANGLE SEISMIC ENHANCEMENT IN THE LOWER TALANG AKAR FORMATION (LTAF) IN FIELD

• Main Author: Reza Perdana, Muhammad
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/81064
• Institution: Institut Teknologi Bandung

The "G" field has evolved into an oil and gas field that is currently and will be developed in the future, located precisely in the Jabung Block southeast of Jambi City. CO2 content in this field, particularly in the Lower Talang Akar Formation (LTAF) interval, is frequently encountered in all gas sandstone samples. Thus, CO2 content can be identified using the Amplitude Versus Offset (AVO) analysis method, allowing an examination of its influence on CO2 presence percentages. The AVO method to be employed covers a wide-angle range, approximately 0o-45o; however, at the far-angle range, seismic data relatively does not exhibit a sufficiently robust AVO response. Therefore, seismic enhancement methods are necessary. Seismic enhancement results in seismic data with excellent vertical resolution (thin layers) and lateral amplitude consistency. Gradient analysis using enhanced seismic data has corrected vertical and lateral amplitude inconsistencies, particularly at far angles (30o-45o), maintaining consistent crossplot patterns, and increasing the correlation coefficient values from AVO modeling gradient analysis of well sample data. Results obtained through this AVO method, following AVO modeling on well data and gradient analysis on seismic data, indicate an average AVO response of class 4 within the LTAF interval. AVO analysis of CO2 presence reveals that reservoir intervals containing CO2 demonstrate a class 4 AVO response, with an increase in fluid content percentage resulting in a more positive intercept and a more negative gradient (towards class 1 AVO). In mapping CO2 distribution, the best attribute used is AVO volume blending with intercept weight 2.62, gradient 2.62, product 2.31, amplitude-weighted 2.47, with an AVO blending correlation value of 0.89. The influence of CO2 can lead to similar changes in AVO attributes across compartments, flooding surface sequence intervals, and facies, as well as the distribution of class 4 AVO anomalies with CO2 content exhibiting a pattern consistent with the facies distribution obtained from well data correlation