Seismic Imaging Tenhique Study On Complex Tectonic Structure In Thrust Fault Foreland Basin

There are some specific geological characteristics in Midwest foreland basin in China:①multistage development, severely in late phase;②multiphase slippage, complex tectonic deformation;③megathickness continental deposit filling, foreland sequence and non-foreland sequence alternation;④three sets of reservoir-seal assemblage bounded by regional slipping plane;⑤ordered hydrocarbon distribution. The above features make foreland basin become succeed petroleum exploration basin in the next years, even in the next decades. In recent 20 years, seismic exploration techniques and tectonic modeling theory in foreland basin has been developed continuously. The successful founding of Ke-la 2 gas field in Kuche depression in Tarim basin revealed a promising future for foreland basin petroleum exploration. Deepening geological study and strengthening seismic exploration technology development are necessary conditions to promote foreland basin hydrocarbon resources transformation.There are three kinds of difficulties in seismic imaging of thrust fault in foreland basin.①the complexity of near surface structure has increased not only the expense for seismic acquisition but also the difficulty of seismic static correction;②the extremely low signal to noise ratio has become a barrier to conventional seismic processing. An updated noise attenuating method needs to develop;③overthrust fault not only leads to severe vertical and lateral velocity variation, but also results in complicated faulting system and steep formation attitude. Static correction, noise attenuation, and imaging are three main factors that impact seismic imaging result badly.Based on above difficulties analysis, through 3 years study, an integrated method is proposed. This method combines static correcting and pre-stack imaging together. New techniques of static correction and pre-stack noise attenuation have been developed. These new processing approaches have been tested in 14 surveys in 6 Midwest basins. Based on the experiments of these new developed methods in different geological background, the processing strategy is put forward.