Improved Seismic Imaging with Multi-Azimuth PSDM Processing: A Case History South China Sea

Abstract

With the deepening of exploration and development, exploration in the south China sea is faced with increasingly complex geological targets, including complex fault blocks, lithological targets, middle and deep strata, small scales and more subtle and complex exploration targets. At present, the internationally recognized best seismic solution is "two wide and one high" acquisition and processing, namely wide azimuth, broadband, high-density field observation system and targeted processing. In the aspect of wide azimuth acquisition and processing, domestic land acquisition has also developed greatly, and in the past few years, there has also been a heated debate on the advantages and disadvantages of wide and narrow azimuth acquisition in complex areas. However, in the aspect of offshore acquisition, wide-azimuth acquisition is rarely carried out. The main reason is that the construction cost and difficulty are higher. With the primary 3d coverage of some mature areas on the sea, it is still unable to meet the exploration needs. In the past, the seismic observation system design was mostly based on the seismic acquisition and survey lines in accordance with the direction of vertical structure strike, so as to facilitate the accurate imaging of the main structure or the construction along the long axis of the work area according to the cost of offshore acquisition. However, in fact, the fault strike in the tectonic development area is complex and changeable, and there is no uniform rule. Some small faults that control the trap are completely perpendicular to the large structural strike, so the old 3d will lead to some poor fault imaging. According to the practical test data analysis, found that the different line direction observed data imaging effect is different, therefore some recently in the south China sea area for the secondary multi-dimensional three-dimensional attempt at sea to achieve multiple acquisition costs are relatively low, and the construction is convenient, but if you want to achieve benefit maximization, must consider the joint use of composite materials. Compared with the factors that need to be considered in collection and processing, it is much more complex, and the development of processing is relatively lagging behind. The main anisotropy is not fully considered, and relatively simple superposition is often difficult to reflect the effect of multi-direction.