Research On Near-surface Modeling Techniques For Gravel Areas Of Mountain Front Belts In Western China

The mountain front belts in Tuha basin which abuts against Turpan hydrocarbon depression is one of the areas with the most oil and gas exploration potential in Tuha basin . Due to the complex terrain and complicated subsurface geological conditions, impacts, the previous seismic data in the areas was so poor that couldn't satisfy the oil and gas exploration demands. Otherwise, for the mountain front belt is mainly covered with huge thick gravel, with the alluvial fan development, and its near-surface character representing as continuous media, there are always long-wavelength static correction problems, that affects the actualization of nice structure and conditions the oil and gas exploration course in the area. In this article, based on the analysis of surface particularity, we researched into the surveys such as refraction with long spread, Deep up-hole logging, up-hole and refraction joint methods and so on, provided the foundation for exactly actualization of surface structure;we also provided an effective method for resolving continuous media velocity via researching the heavy hammer excitation and multiple coverage of LVL geometry. Eventually based on the fruits of the both aspects above, we developed the lateral varying T-D curve modeling method, which brought prominent improvement to the section character, achieved anticipative researching effects. By contrast between sections we gained the following four understandings:1)The optimized surface layer researching methods can solve the thickness problems of super-thick layer. 2) The multiple coverage shallow refraction tomographic inversion technique effectively solved the surface layer velocity problems in areas covered with gravel. 3) The lateral varying T-D curve modeling method effectively solved long wave static correction problems that may caused by gravel alluvial fan. 4) There primarily formed a series of surface layer static correction technology that is fit for the super-thick gravel areas of the mountain front belt in Tuha basin, and this provided timely and dependable technology guarantee for prospecting exploitation to oil fields.