Velocity Model Building Based on the Buried Hill Surface and Its Application for the Carbonate Reservoir in Tarim

The carbonate reservoirs in Tarim mainly include limestone fracture-cave reservoir and dolomite remnant buried hill reservoirs. The insider of the buried hill has complex structure and abundant fractures, and at the same time igneous rock is widely spread, not only inside the buried hill but also in shallow layers. These factors lead to strong lateral velocity variation. Therefore the accurate velocity model building technology is demanded to solve the imaging of the buried hill and the identification for the igneous rock and the carbonate rock. In this paper, a new velocity model building method based on the buried hill surface has been put forward, which uses different modelling strategy to handle with the overburden and underlying parts of the buried hill surface. Specifically, we use a quantitative description technique for modelling of overburden igneous rock, and grid-based tomography for modelling of underlying formations. When we have applied this method into the real seismic data and use the multi-well constrained PSDM technology at the same time, the key issues, such as the imaging of the buried hill and the identification for the igneous rock as well as the carbonate rock, can be solved very well.