The Iterative Processing Technology and Effect of Seismic Data in the Kelasu Tectonic Belt

The seismic and geological conditions in the Kelasu structural belt of the Tarim Basin are rather complex. On the surface, the mountains are high and the slopes are steep, gullies crisscross everywhere, and there are numerous cliffs. The terrain undulates drastically, with an elevation difference exceeding 2,000 m in some areas, and the surface structure is complex and changeable. Underground, the upper, middle and lower layers of the three-layer structure are quite different. The shallow structures are high and steep, the salt layers are extremely thick and change rapidly, and the subsalt structures are characterized by thrust imbrication. The thickness of the salt layer exceeds 5,000 m in some places. The dual complexity of the surface and underground makes it difficult to build a high-precision velocity model for the area and to obtain accurate imaging of the subsalt structures. The seismic and geological conditions in the Kelasu structural belt of the Tarim Basin are rather complex. On the surface, the terrain undulates drastically, with an elevation difference exceeding 2,000 m in some areas. And the surface structure is complex and changeable. Underground, the upper, middle and lower layers of the three-layer structure are quite different. The shallow structures are high and steep, the salt layers are extremely thick and change rapidly, and the sub-salt structures are characterized by thrust imbrication. The thickness of the salt layer exceeds 5,000 m in some places. The dual complexity of the surface and underground makes it difficult to build a high-precision velocity model for the area and to obtain accurate imaging of the sub-salt structures. In order to improve the imaging precision of seismic data and quickly support exploration and development, on the basis of the seismic processing with four procedures, we strengthened the iterative work of velocity modeling and depth migration. As a result, the imaging precision of the target area has been improved, and the imaging quality and precision of the target area have been significantly enhanced, which has helped the oilfield achieve new breakthroughs in the Kelasu structural transition zone. Meanwhile, the advantages of the seismic processing divided into procedures have been fully exploited, reducing repetitive work such as surface modeling and static correction, signal processing and stacking, shortening the processing cycle and saving processing costs. All this strongly demonstrates the correctness and effectiveness of this research idea, which can be applied to the geophysical exploration work of other oilfields.