In Jurassic of Yili Basin,coal measure strata were well developed and had the characteristics of strong seismic reflected energy and better continuity,the comparative tracking for sand bodies could be carried out in the whole area.However,due to the low-velocity of the coal measure strata and high-velocity of the surrounding rocks,the reflection coefficient was higher and complex reflected wave was created between the bottom of overlying Cretaceous and surface.Because of the complexity of multi-reflected wave,it was difficult for multiple reflected wave compression and it severely influenced the reliability of seismic data.Therefore,during the seismic data acquisition and processing,the characteristics of the multi-reflected wave should be analyzed in the operation area for obtaining a proper compressed multiple reflected wave.At present the method of data acquisition was to increase the number of overlying and array length for data compression,thus the signal-noise ratio of deep-layer seismic data was raised negative influence was induced.That is why proper acquisition parameters in seismic observation systems must be carefully selected.Through forward simulation,the seismic record of single shot can be acquired.Based on stacking effect,reasonable parameters in observation systems can be selected.Therefore,the geologic model of backbone lines can be established to optimize acquisition parameters,thus the quality of seismic data is improved.

The exploration of oil and gas in Baiqiu Area of Nanyang Depression was to search for lithologic and structural reservoirs,the lateral resolution and the signal-to-noise ratio of seismic data were highly required.By theoretical research on the seismic wave propagation property under the complex media conditions,and guiding by wave equation and others new design technologic theory,a 3-D observation system with high accuracy was quantitatively evaluated,and based on the geological requirements,it was designed accurately and the parameters were demonstrated.Under complex media conditions,an observation system is designed according to the wave equation forward simulation and the surface demonstration,which could meet the requirements of the pre-stack migration treatment and lithologic interpretation at the initial stage of data acquisition design for a high precision of 3D seismic exploration in the area.The acquisition footprint is reduced for the purpose of improving imaging precision.Seeing from the data acquisition profile in the area,the wave combination property is obvious,fault plain is clear high signal-to-noise ratio and the new acquisition data can meet the research demands of the structures of the fault block groups.

There existed 2 sets of coal seams on the top of Jurassic sedimentary strata in Yining Depression of Yili Basin,where multiples were well developed and interfered each other with underlying reflection planes.It greatly impacted the quality of the target zones.Based on forward modeling,it presented a new design method of seismic acquisition geometry to suppress multiple wave interference.It could improve the energy of seismic wave and the signal-to-noise ratio of the deep reflection.The result shows that changing the acquisition parameters,i.e.reducing the receiver interval,increasing the spread length and improving the fold are favorable for suppressing the time difference between the primaries and multiples and improving signal to noise ratio of deep reflection.

Based on the condition of seismic geology in lower He III Member in Biyang Sag and the demand of geologic model and prestack migration,associating with seismic wave equation and lighting analysis,high accuracy 3D seismic acquisiton method is fully demonstrated and studied.Its application results show that seismic data quality re-acquired is better than the former,that is,fracture position image is clear,features of target layer and other reflection layers above it are clear and reliable,resolution and signal-to-noise ratio are all improved and section effect is obvious,which achieves the objective for acquisiton of high accuracy seismic.