ROCK PHYSICS ANALYSIS AND EXTENDED ELASTIC IMPEDANCE INVERSION (EEI) FOR CHARACTERIZATION CARBONATE RESERVOIR ON “X” FIELD, UPPER KUTAI BASIN

• Main Author: Hasanah, Uswatun
• Format: Theses
• Language: Indonesia
• Subjects: Teknik (Rekayasa, enjinering dan kegiatan berkaitan)
• Online Access: https://digilib.itb.ac.id/gdl/view/66686
• Institution: Institut Teknologi Bandung

Carbonate is one of the main reservoir rocks in hydrocarbon exploration and production. Carbonate reservoirs produce nearly 60% of the world's hydrocarbon reserves. However, carbonate rocks are not easy to characterize compared to clastic reservoirs because of the diagenetic process that changes the rock properties to be very heterogeneous. A very important rock property in carbonate rocks is the variation of the pore type which is approximated by the aspect ratio parameter. Seismic data processing is also involved in this study to observe the distribution of anomalies so that the reservoir can be characterized properly. Along with the development of technology, various methods were developed, one of which was the Extended Elastic Impedance Inversion (EEI) to provide significant information on the separation of the lithological anomaly and the carbonate reservoir fluid in "X" Field, Upper Kutai Basin. The research was conducted at Field "X", Upper Kutai Basin, Central Kalimantan, Indonesia. The research stage began with processing well data to analyze sensitive elastic parameters in separating lithological anomalies and fluids in the target zone. The sensitivity analysis of the well data shows that the Mu-Rho parameter is sensitive in separating the porous and tight carbonate lithology, while the Lamda- Rho is sensitive to the presence of gas filling the reservoir in the target zone. Then look for the optimal correlation angle or chi angle for each sensitive parameter. Rock physics analysis was also carried out on well data to estimate the aspect ratio with a modified method by Kumar and Han (2005) by determining the boundaries of the Hashin Shtrikman approach to upper-lower bound and Wyllie time average equation as the reference pore. In estimating the aspect ratio, the elastic modulus of minerals is needed which is obtained by using several other approaches such as the Dvorkin Model (2008) and Krief (1990). Then, the Toksoz cluster modeling was carried out to approach the predetermined boundary values for each pore type being modeled. The results of the modeling will be obtained for the aspect ratio value for all target zone intervals. Furthermore, seismic data processing is carried out by extracting rp and rs using the Ursenbach-Stewart equation (2008) so that the EEI reflectivity volume (chi) can be found for each sensitive parameter at the optimal chi angle. The result of rock physics analysis shows that the aspect ratio is low, which is about 0.1, which indicates that the pore type of the carbonate reservoir in the "X" field is relatively flat. Meanwhile, the inversion results provide information on low Mu- Rho anomaly which shows the lithology of the porous carbonate reservoir and the low Lamda-Rho as a pore filling fluid anomaly in the form of gas up to 80 ms below the Horizon Upper. Carbonate. Based on these two results, it was found that the prospect zone in the carbonate reservoir has a flat pore shape which is associated with a relatively good porosity value. The distribution of this prospect zone is indicated by the results of the EEI inversion (80) with a low Mu-Rho value of 16- 54 GPa * g / cc which is a porous carbonate lithology and EEI (330) with a low Lamda -Rho 40-81 GPa * g / cc which sensitive to gas liquids up to 80ms below Horizon Upper Carbonate.