DEVELOPMENT OF ULTRASONIC TOMOGRAPHY PROGRAM USING FRESNEL VOLUME APPROACH OF CORE PLUG IN SADEWA FIELD OF KUTAI BASIN, EAST KALIMANTAN BY

• Main Author: Naufal Aryan, Hafidz
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/62740
• Institution: Institut Teknologi Bandung

Tomography was a non-destructive method for investigating the internal structure of an object. In geophysics, tomography was used to find subsurface anomalies caused by differences in the physical parameters of rocks. The Fresnel volume tomography method was an alternative method for reconstructing the image of an object, where this method did not use ray path in its calculations. In calculating the fresnel zone, the finite difference method which was the solution to the equation of wave propagation was used. The frequency of the waves was also considered, where we used ultrasonic waves with a frequency of 1 MHz. The reconstruction algorithms used are Simultaneous Iterative Reconstruction Technique and Modified Simultaneous Iterative Reconstruction Technique. The program then created and tested with synthetic models and successfully reconstructed various P wave velocity anomaly models at anomaly sizes of 3 mm or more with good results. The sadewa well was a cored well from a gas reservoir field located in the Kutai Basin, East Kalimantan. The core plugs from this well were sedimentary rocks in the form of sandstone mixed with shale with various structure and velocities distribution. Three core plugs from Sadewa-2, Sadewa-4, and Sadewa-5st1 wells were used as research objects to calculate travel times using a P-wave transducer with a frequency of 1 MHz. Reconstruction of the anomaly models were carried out using fresnel volume tomography and succeeded in showing the presence of layer and laminate structures based on variations in velocity caused by differences in grain size of the core plugs