From relative to absolute: A practical and robust workflow for low-frequency model building

Abstract

Because seismic data are band-limited and lack low-frequency components, estimation of elastic properties through seismic inversion requires the construction and incorporation of a low-frequency model (LFM). However, building a reliable LFM is often challenging. Consequently, seismic inversion results are sometimes interpreted in relative terms and are strongly influenced by thickness variations and contrasts in overburden and underburden properties. To address this limitation, I propose a simple and transparent workflow for constructing robust LFMs. The method begins with an initial background model (BGM) built from well data and interpreted seismic horizons, followed by correction of the BGM within the reservoir interval through a combination of seismic inversion results and wedge model-derived results. The workflow corrects thickness and background property effects without requiring explicit prior assumptions on reservoir properties such as net-to-gross ratio or fluid. Synthetic tests demonstrate that the method compensates for these effects and improves the prediction of absolute elastic properties by recovering the missing low-frequency component. Field application in the Northern North Sea demonstrates the practical value of the method, showing improved property predictions relative to commonly used deterministic LFM construction methods. Owing to its simplicity and transparency, the proposed workflow complements more complex inversion methods such as probabilistic inversion by offering a practical alternative during exploration and early appraisal stages, while also serving as a useful benchmark for quality control in probabilistic inversion during development and production stages.