The wide azimuth seismic exploration technology for fractured reservoir and its application in deep buried hill exploration of BZ 19-6

Abstract

Bozhong sag is one of the most explored offshore depressions in China. Up to now, most of exploration achievements are located in Cenozoic strata with the depth above 3500 m, and the formations below 3500 m such as buried hill have not made a large-scale breakthrough. The Cenozoic sediments in this area are very thick, and multi-stage high-speed volcanic rocks are well developed, leading the seismic of buried hill has poor quality with low has low SNR, bad imaging. This is the main reason why the buried hill exploration failed to achieve a major breakthrough. On the other hand, early exploration showed that the type of buried hill’s reservoir is mainly fracture reservoir, which is completely different from sandstone reservoirs. The difficulty of effective reservoir prediction is also limits the deep buried hill exploration. To overcome the difficulties, it is of great significance for the research of wide azimuth seismic exploration. In this paper, taking Bozhong 19-6 buried hill structure in Bozhong sag as an example, the design of offshore wide azimuth seismic acquisition is carried out. What’s more, the key parameters of the observation system are demonstrated in detail to overcome the difficulties of large buried depth, high-speed volcanic rock shielding, strong heterogeneity of fracture reservoirs in buried hills. The practical application shows that the quality of the newly acquired seismic data is obviously improved, which lays a good foundation for the buried hill exploration. Note: This paper was accepted into the Technical Program but was not presented at IMAGE 2021 in Denver, Colorado.