GSOC 2023 November Technical Talk

Advances in onshore FWI imaging

By Marianne Rauch

Abstract

Velocity model building for land data is challenging as the topography is not flat which then will introduce elevation differences between sources and receivers. Generally, land data suffers from poor spatial sampling and low signal to noise ratio and lacks usable low frequencies. Besides this, the heterogenous weathering layer can produce strong elastic scattering. Traditionally, near-surface velocity models are estimated using refracted arrivals, long wavelength corrections. Short wavelength statics are corrected through a residual static correction. This approach breaks down when the immediate geology below the weathering layer is complex and neither the long nor the short wavelength static corrections can resolve these issues. FWI can address some of these deficiencies and generate a more accurate velocity model that produces better migrated reflection images. Additionally, when FWI is run to higher frequencies, the normal derivative of the velocity model can be used to generate an FWI image (Wang et al, 2021). This presentation will address some of the challenges and addresses the current state of onshore FWI using various examples such as efforts to improve the data quality of the West Kermit 3D survey,

Bio for Marianne Rauch

Marianne Rauch has PhD in theoretical physics from the Karl Franzens Universitaet, Graz, Austria. She has an inquisitive mind and is involved in many technical aspects of the oil and gas industry worldwide. She has researched and developed geophysical technologies, advocates geological and geophysical integration during seismic processing, and interpretation, built and managed reservoir teams, mentored many students throughout her career and lately got involved in cybersecurity. She published a good number of technical articles and is a seasoned presenter. Marianne is very active in our societies such as being part of the technical committee of the URTeC and IMAGE, past 1^st VP of the GSH, organizing workshops and chairing numerous sessions at various conventions. Currently, she serves as 2^nd VP of the SEG. Besides geosciences, her passions include being a mother and being involved in volunteer activities where she is advocating for underprivileged children in her hometown Houston. She is employed by TGS in the role of Principal Technical Advisor and can be reached at Marianne.rauch@tgs.com and 832-641-2377.