Research And Application Of Key Technologies For Earthquakes In A Well-free Area In Deep Waters In The Northern South China Sea

This article is mainly focusing on seismic exploration technical problems in northern of the South China Sea deepwater area without wells.The key technology of deepwater seismic data processing was initially proposed.The combination of generalized 3DSRME(3D Surface Related Multiple Attenuation)and DMA(Diffraction Multiple Attenuation)technology,which is fitting for complex diffraction wave attenuation,3DCRS(3D Common refection Surface Stack)technology that improves the low SNR of middle and deep strata and high precision and speed pickup combination technology which meets the large lateral speed variation are developed.On the basis of good outcome of seismic data and taking the analysis of surrounding wells AA21-1-1 as the starting point,impedance inversion under the constraint of post-stack speed trend was developed.The final results are low energy matching and high-band impedance inversion results,reaching the purpose of more accurate reservoir forecasting.For fluid detection,the application of AVO inversion and scalar Poisson's ratio inversion combination method could distinguish the gas reservoir types effectively.Meanwhile,the inversion results of pre-stack and post-stack could be verified by each other for the correctness of reservoir prediction and hydrocarbon detection.The northern South China Sea deepwater area without wells was selected here as the research target region.Combining with the actual geological conditions of the target region,the new processing and inversion technology was combined to improve prediction accuracy and reduce the risk of exploration and development.Finally,after summary of application and law of target region,a series of seismic exploration methods for the northern South China Sea deepwater area without wells were developed.The research results as follows:(1)Combination of complex diffraction multiples attenuationThe key of deepwater seismic data imaging is to suppress the multiple waves in low SNR region under the rugged seabed.In this paper,the new method of combination of the generalized 3DSRME,blind adaptive signal subtraction and DMA successfully suppressed the deepwater complex diffracted multiples.(2)Inversion without wellsThe target region in northern South China Sea deepwater area without wells,and directly logging information is not available.In this paper,by referring to neighboring wells,statistics of petrophysical characteristics in the target region are obtained.After extraction virtual wells,inversion parameters were tested.Through the combination of low and high-band impedance inversion results,the energy matching weights were adjusted.The final result provides fine guidance for the goals of exploration and development in work area.