论文详情
准噶尔盆地巨厚沙漠区地表沙丘起伏剧烈,低降速带巨厚,对地震波能量吸收衰减严重,地震资料采集激发接收困难,静校正处理问题突出。针对以上难点,开展了基于超深微测井的巨厚沙漠区表层特征调查分析,采用子波和Q值辅助分层方法,对近地表进行了准确分层,获得了准噶尔盆地巨厚沙漠区近地表特征新认识。在此基础上将地震波激发岩性由原来的降速层干沙层改为低速层湿沙层,通过理论和野外试验结合,优选了最佳多浅井组合激发方式及参数;通过检波器埋深试验,确定了20~40cm浅地表潮湿沙层埋置检波器的接收方式;对层析核函数进行剖析,推导出菲涅尔层析敏感核函数,形成了菲涅尔体层析反演高精度静校正技术;采用粘弹波动方程波场延拓近地表吸收衰减补偿技术,消除了巨厚沙漠区近地表吸收衰减的影响。在准噶尔盆地CH1J东、D2J北等多个区块的三维地震勘探中,上述技术的应用提高了地震资料的信噪比,提高了处理剖面的成像精度。
Thick deposits in desert areas of the Junggar Basin exhibit a dune-covered surface and a thick low-velocity layer.These characteristics cause a severe absorption attenuation of the seismic wave energy and a static correction problem.Besides,performing seismic excitation and reception is very difficult.Therefore,an investigation of the surface characteristics of the desert area has been carried out based on ultra-deep micro-logging stratigraphy.The stratigraphy of the shallowest layers was determined accurately using wavelet and Q-value techniques,and several new understandings have been obtained regarding the near-surface characteristics of the desert area of the Junggar Basin,which are listed as follows.1) The seismic excitation layer changes from being a deceleration layer in case of dry sand,into low-velocity layer in case of wet sand.The combination of the excitation parameters was optimized based on according to both experiments and theoretical considerations.2) By means of a receiving test,it was determined that the detectors should be buried into a shallow layer of wet sand,with a depth of 20-40 cm.3) The Fresnel tomographic sensitive kernel function has been derived through the analysis of the tomographic kernel function,so that a high-precision static correction technique based on the Fresnel tomography inversion has been obtained.4) A near-surface absorption attenuation compensation,based on the viscoelastic wave equation,has been utilized to eliminate the influence of near-surface absorption attenuation in the desert area with very thick low-velocity layer.These techniques were applied to the three-dimensional seismic exploration of several blocks such as the east CH1J and the north D2J in the Junggar basin,resulting in an improved signal-to-noise ratio of the seismic data,and in an increased imaging accuracy of the seismic profile.These achievements guided the improvement and the application of key technologies for seismic data acquisition and processing in the desert areas with very thick low-velocity layer.
中国石油化工股份有限公司科技攻关项目(JP17037和JP17039)资助。