Surface Seismic Data Processing Research Articles

Enhanced surface seismic data processing using simultaneous acquired DAS-VSP data

Distributed Acoustic Sensor (DAS) is increasingly recognized as a viable alternative to downhole geophone arrays for the acquisition of borehole seismic (VSP – Vertical Seismic Profile) or DAS-VSP data. When acquiring surface seismic data in the field, simultaneously acquired DAS-VSP data in an available well or wells can provide full well VSP imaging and significantly enhance surface seismic data processing. Borehole seismic data can provide higher resolution structural images around the borehole as the receivers are located inside a borehole and near the reservoir. In addition, the formation velocity, deconvolution operator, absorption, attenuation (Q value), anisotropy parameters and other reservoir formation information in a certain range around the wellbore can be obtained directly from the VSP data. These can be used to significantly enhance the surface 3D seismic data processing, such as velocity model calibration and modification, static correction, deconvolution, demultiple processing, high frequency restoration, anisotropic migration, and Q-compensation or Q-migration. In this project, Q-migration was conducted with the enhanced Q-field data volume obtained from the joint inversion of both the near surface 3D Q-field data volume from uphole data and the mid-deep layer Q-field data volume from VSP data. The Q-migration results show much sharper and more focused faults and fracture zones. A new 3D formation top structural model was built with much finer details based on the Q-migration data, and three new borehole locations were recommended to the client. The final drilling results on these three new boreholes are very successful with high volume of commercial oil flow.

Enhancement of Seismic reflectors by using VSP and Seismic Inversion in Sindbad oil field, south of Iraq

The purpose of this research is to enhance the methods of surface seismic data processing and interpretation operations by using the produced information of vertical seismic profile (measured velocity and corridor stack). Sindbad oil field (South of Iraq) is chosen to study goals and it's containing only one well with VSP survey (Snd2) that covering depth from Zubair to Sulaiy Formations and 2D seismic lines of Basrah Survey. The horizons were picked and used with low frequency contents from well data for the construction of low frequency model and it was used with high frequency of VSP to make the high frequency model that compensated to seismic main frequency through inversion process. Seismic inversion technique is performed on post stack of 2D seismic data (2Br2) through Hampson-Russell CGG program. The inversion model of low frequency shows 88.5% matching with relative seismic impedance while high frequency model 93.3% matching with lower error percent. The two impedance sections which resulted from inversion model were convoluted with best wavelet from VSP data to make a new seismic section. The LFM section was similar to original seismic section while the HFM section shows real enhancement of the Flatspot (DHI) feature and recoverable some missing reflectors.

Absorption related velocity dispersion below a possible gas hydrate geobody

ABSTRACTVelocity dispersion is not usually a problem in surface seismic data processing, as the seismic bandwidth is relatively narrow and thus for most Q values, dispersive effects are not noticeable. However, for highly absorptive bodies, such as the overpressured free gas accumulations associated with some gas hydrates or high‐porosity normally pressured gas sands, dispersive effects may be seen. In this work I analyse one such data set from the offshore north‐east coast of India. I demonstrate that the effect is measurable and that compensating for it in either data processing or migration can improve the wavelet character, as well as delivering an estimate of the effective Q values in the associated geobody. I also raise the question as to whether velocities derived using low‐frequency waveform inversion over such dispersive geobodies are wholly appropriate for migration of full seismic‐bandwidth data.