Abstract:

To meet the demands of seismic exploration acquisition and near-surface velocity modeling in deep exploration in China, surface survey was carried out in 2D exploration area of eastern Huludao in western Liaoning. The topography of this region is undulating, surface structure is complex, the thickness and speed of low-velocity layer and slow-down-velocity layer is unstable, leading to a prominent static correction problem. Therefore, it is a key problem to complete the job of nearsurface modeling in this region. By comparing the different results from a variety of methods, we choose following surface survey methods. Uphole survey method is given priority; then refraction method, which costs lower, in the region that meets the refraction surface conditions; at last, as a complement, lithology log method at production well reserved for uphole survey. With these methods, we analyze the difficulty and countermeasure of surface survey and determine the parameters of field construction. In this surface survey, along the profile of 16.9 km, 8 loggings is laid out. According to the micro log interpretation results, the near surface is of two or three layers; low-velocity layer thickness is 1.68-4.33 m with a speed about 350-1 000 m/s; the thickness of low velocity zone is about 5-12 m, whose speed ranges from 1 000 to 2 800 m/s; the high speed layer is pyknotic granite, whose speed is 2 800-4 900 m/s. According to the results of micro logging and the coefficiency similarity between each layer, the authors establish a near-surface model, suggest the depth of shot hole, and obtain the statics data. These works effectively guide the design of field seismic acquisition, provide the reliable basis for data processing, and supply a reference to the surface survey in other region.

Key words: uphole survey, surface survey, near-surface modeling, seismic exploration, western Liaoning Province