| The southern steep zone in Biyang Depression is a very dificult area for seimic acquisition due to its complex seismogological conditions, where there are various complex reservoirs derived from fault zone such as lithology plus structure, delta fans, subwater fans, basement buried hills, traps within basement and so on. It surface conditions are also complicated which are bare rock area, riffle area, hilly area and farmland area from south to north. What the main features of deep formations are that the cross section of the large fault is highly steep (around 40degrees) which probably are fractures assembly, and the differences in formation velocity from the both walls of fault are great, and downdip faults and sanbodies are developed. Through secondary acquisition and new method research, the acquisition technique is optimized; the shooting conditions are studied to decide the shooting lithology and the type of dynamite also be selected by test.The selection of shooting conditions is determined by different surface zones. In bare rocks area, how to solve the drilling problem is to shoot within high-speed rock under weathering layer by optimizing hole's position and penetrating the weathering layer; therefore, the better shooting result can be achieved after the dynamite is loaded with the high-speed rock by using high explosives. In mountain area, the shooting positions are optimized through the"four dodging and four moving methods", i.e, dodging thick LVL and moving from higher places to the lower ones, dodging softer places and moving to harder ones, dodging steeper places and moving to flatter ones, and dodging dryer places and moving to wetter ones. In the valley of Sajiahe Rive, what is the importance is how to build the holes in loosen layers and ensue shooting under the weathering layer. In hilly area, the powerful rigs are equipped to penetrate the gravel interlayer to better shooting lithology to ensure shooting in high-speed velocity layer.The special recording method is acquisition technique in water areas. There are many water bodies in the operation areas, such as Sanjiahe River basin, some water reservoirs and pools. Some geophones have to be planted in the water and many problems are solved so that the seismic information recorded in water could be used effectively, such as the insulation, stabilization and wave consistency against the one from the land.The design method to stimulate and optimize 3D field geometry based on ray tracing model can guarantee there are more receiving lines within a template and more overlaid receiving lines between adjacent templates; and also can reach the requirements for small size bins, harmony between crossline and inline fold, and imaging migration upon fracture surfaces with large stratigraphic dip. It also help to solve the shooting difficulty in complex seismogological conditions, wherever for deep formation and in complex surfaces such as river, ancient watercourse or mountains. This technique will provide good experience for future secondary acquisition or precise survey in Beiyang Depression or other areas with similar conditions.The application of this technique to Shuanghe-Changqiao 3D high-precise seismic project has achieved good geological effects. The quality of single shots is much improved especially in difficult areas such as mountains and riffle areas, from which the reflection from strata and fault panels was shown clearly. The seismic profiles can complete display the geological features of the southern steep zone in Biyang Depression. On the whole, field processing section is clear and actual with clean background, well continuous event, high S/N ratio and high frequency. There are obvious structure shows from the structure section with clear breakpoint, pinchout and Low-Amplitude Structure. S/N ratio and resolution of the field is improved remarkably, especially below Eh3 section. The S/N ratio from middle-deep Strata is improved most and the quality of the data from shallow-middle strata is much better.
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