Wahyu Triyoso
Global Geophysics Group, Institut Teknologi Bandung

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Seismic Data Processing and Seismic Inversion in The Ray Parameter Domain: Common Reflection Point (CRP) Stack and Ray Impedance Wahyu Triyoso; Edycakra Immanuel Sinaga; Madaniya Oktariena
Scientific Contributions Oil and Gas Vol 47 No 2 (2024)
Publisher : Testing Center for Oil and Gas LEMIGAS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29017/SCOG.47.2.1621

Abstract

Reservoir characterization can be enhanced by integrating lateral and vertical perspectives from seismic surveys and well logging, respectively. Seismic impedance is a crucial parameter, calculated by multiplying the rock density by the primary (P) wave velocity. While acoustic impedance solely considers these two factors, elastic impedance incorporates additional angular measurements and secondary (S) wave velocity data. Elastic impedance, however, equates the incident angle with the transmission angle in disregard of Snell's law; therefore, it provides a simplified representation of seismic impedance. This study explores an alternative approach to seismic impedance, known as ray impedance. We calculated ray impedance by tracing the impedance variation along the path of a seismic ray, considering its changing velocity and angle as it traveled through different subsurface strata. We transformed the seismic information from the offset space to the ray parameter space, to achieve ray parameter stacking. Unlike the traditional angle domain inversion, which uses near-angle, mid-angle, and far-angle seismic stack data, the ray-impedance inversion utilized segments of ray data: near-ray, mid-ray, and far-ray. We compared the common depth point stack, ray stack, and angle stack methods to infer the acoustic, elastic, and ray impedance characteristics. Challenges with gas cloud interference in seismic data imaging were present. We developed a ray parameter strategy to address these imaging difficulties. The comparison of different stacking techniques indicated that ray stacking could offer an alternative for imaging in the presence of gas cloud effects. Furthermore, impedance cross-plotting demonstrated that ray impedance provided a more discernible separation of low-clay-content zones than elastic impedance did. Overall, data processing in the ray parameter domain yielded positive imaging outcomes in the presence of gas clouds, suggesting that ray impedance is a practical method for lithological differentiation
The use of the Common Offset of the Common Reflection Surface (CO-CRS) for Velocity Analysis and Data Preconditioning Wahyu Triyoso; Fernando Lawrens Hutapea
Scientific Contributions Oil and Gas Vol 48 No 4 (2025)
Publisher : Testing Center for Oil and Gas LEMIGAS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29017/scog.v48i4.1935

Abstract

This study introduces a Common Offset (CO) extension of the Common Reflection Surface (CRS) method to address seismic imaging challenges in complex geological settings and with noisy data. This CO-CRS approach aims to enhance the signal-to-noise ratio and overcome the limitations of conventional preconditioning techniques that rely on accurate parameterization. Building upon established work on zero-offset CRS (ZO-CRS), the CO method generates regularized prestack data suitable for both time- and depth-domain processing by interpolating missing offsets using a local hyperbolic approximation. Ultimately, this study utilizes CO-CRS for enhanced velocity analysis and data preconditioning prior to performing prestack time migration (PSTM). In this study, the CO-CRS is then used for velocity analysis and prestack time migration. The results show that prestack CO-CRS data yield improved time-migrated seismic images, and we suggest extending the application to the depth domain. To achieve a reliable velocity model for imaging, recursive seismic inversion (RSI) is applied to derive the velocity model using the PSTM stack and a velocity interval time, based on CRS semblance velocity analysis. Furthermore, the prestack depth migration (PSDM) is then tested. The depth-imaging results are reliable, and it can be concluded that combining the benefits of the CRS noise-reduction feature with more accurate velocity analysis and prestack migration can provide enhanced capabilities.