Kefeng Xin

3D Prestack Beam Migration with Compensation for Frequency Dependent Absorption and Dispersion

Spatial variations in the transmission properties of the overburden cause seismic amplitude attenuation, wavelet phase distortion and seismic resolution reduction on deeper horizons. This poses problems for the seismic interpretation, tying of migration images with well-log data and AVO analysis. We developed an efficient prestack beam Q migration approach to compensate for the frequency dependent dissipation effects in the migration process. A 3D tomographic amplitude inversion approach may be used for the estimation of absorption model. Examples show that the method can mitigate these frequency dependent dissipation effects caused by transmission anomalies and should be considered as one of the processes for amplitude preserving processing that is important for AVO analysis when transmission anomalies are present.

3‐D tomographic Q inversion for compensating frequency dependent attenuation and dispersion

Following our previous work on Amplitude Tomography that deals with amplitudes alone, we extend our effort to include the compensation of bandwidth and phase of seismic signals that are distorted by seismic attenuation. Our new approach involves utilizing tomographic inversion for estimating the quality factor (Q) from prestack depth migrated common image gathers. By filtering the seismic data into different frequency bands and measuring the effect of attenuation on amplitudes in each band, the frequency dependent effect, which was ignored in our previous work, of attenuation is fully taken into account, allowing Q to be estimated from our tomographic method. By using the estimated Q volume in one of the migration methods that incorporates Q in the traveltime computation, we demonstrate, through examples, that our workflow provides an optimal compensation solution that resolves amplitude and bandwidth distortions due to seismic attenuation.

3D prestack depth migration with compensation for frequency dependent absorption and dispersion

Spatial variations in the transmission properties of the overburden cause seismic amplitude attenuation, wavelet phase distortion and seismic resolution reduction on deeper horizons. This poses problems for the seismic interpretation, tying of migration images with well-log data and AVO analysis. We developed a prestack depth Q migration approach to compensate for the frequency dependent dissipation effects in the migration process. A 3D tomographic amplitude inversion approach may be used for the estimation of absorption model. Examples show that the method can mitigate these frequency dependent dissipation effects caused by transmission anomalies and should be considered as one of the processes for amplitude preserving processing that is important for AVO analysis when transmission anomalies are present.

3-D Tomographic Amplitude Inversion for Compensating Transmission Losses in the Overburden

A tomographic inversion approach using prestack depth migrated common image gathers is utilized to compensate reflection data for amplitude loss caused by transmission anomalies in the overburden. The approach has the advantage of estimating transmission losses from anywhere within the overburden using the actual seismic raypaths. Examples show that the method can mitigate amplitude attenuation caused by transmission anomalies and should be considered as one of the processes for amplitude preserving processing that is important for AVO analysis when transmission anomalies are present.

Robust seismic reflection Q tomography through adaptive measurement of spectral features

In this paper, we describe a robust Q tomographic inversion approach for estimating the subsurface volumetric Q field by using reflection seismic data. The inversion process involves two key stages: adaptively extracting dissipation time information from the change of spectral features of the seismic data in the presence of noise, and integrating the picked dissipation time information from both pre-migration CDP gathers and post-migration CIGs into a ray-based grid tomography for Q model building. This approach can be used together with the Q-PSDM technique to provide better images by honouring the actual wave-paths in both Q estimation and Q compensation. The Q-PSDM results show the reliability of this approach when using it to perform Q estimation in both conventional and broadband seismic data processing.

3D tomographic amplitude inversion for compensating amplitude attenuation

Introduction Spatial variations in the transmission properties of the overburden cause seismic amplitude distortions on deeper horizons and hence pose problems to the AVO analysis. One of the common causes of these transmission anomalies is gas within shallow sediment. This induces anomalous amplitude decay in zones beneath the gas anomaly, often making the identification and interpretation of deeper reflectors difficult. This in turn affects the ability to accurately predict reservoir properties. Thus, there is a need to compensate the amplitude loss caused by this kind of transmission anomalies.

3‐D tomographic amplitude inversion for compensating amplitude attenuation due to shallow gas

A tomographic inversion approach using prestack depth migrated common image gathers is utilized to compensate reflection data for amplitude loss caused by transmission anomalies, such as shallow gas, in the overburden. The approach has the advantage of estimating transmission losses from anywhere within the overburden using the actual seismic raypaths. Examples show that the method can mitigate amplitude attenuation caused by transmission anomalies and should be considered as one of the processes for amplitude preserving processing that is important for AVO analysis when transmission anomalies are present.