The Method of Establishing Equivalent Q Value Model for Compensating Medium Absorption

Seismic resolution is a technical bottleneck restricting reservoir identification and description under thin interbed geological conditions in the Songliao Basin. Compensating for the absorption and attenuation effects of viscoelastic media along the wave field propagation path during pre-stack migration is an effective way to improve seismic resolution. Establishing an accurate Q value model is the key to achieving pre-stack time migration with viscoelastic media absorption compensation. This paper proposes a reasonable method for establishing equivalent Q-value model (Qe). Firstly, a pre-stack time migration algorithm based on viscoelastic media absorption compensation with constant Q values is derived to achieve fast migration scanning and obtain a set of pre-stack time migration profiles and gathers with different Q values for Qe pick up. To avoid the main frequency change caused by thin layer interference, the spectrum width is used to estimate the Qe of the control point. Noise level based on compensation results η, Determine its high cutoff frequency, and then adjust Qe based on the maximum frequency band width. Using the relationship between formation Q value and velocity, a three-dimensional Qe model is obtained from the migration velocity field. The availability of the method has been confirmed by the viscoelastic medium absorption compensation pre-stack time migration results of actual 3D seismic data, which greatly improves the resolution of seismic imaging.