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Seismic Technique and Application of Tiaohu Formation Volcanic Traps in Santanghu Basin, West of China

Zhi, Fengqin
Petrochina Hangzhou Reseach Institute of Geology, Hangzhou, China.

As a kind of special reservoir, the volcanic reservoir is still difficult in study and in prediction. Here, there are two effective methods for the exploration of volcanic traps. One is the study of seismic facies, the other is the techniques of seismic attributes. Seismic facies analysis is a traditional and effective method: according to petrologic lithofacies analysis, we can build the relationship between lithology and seismic facies in the same sequence through well calibration, and we can also get the plane map of the volcanic. The seismic attributes include coherency attributes, root-mean-square amplitude attributes, in both seismic section and slicing. Volcanic edifice is usually divided into four facies belts, which are crater facies, near crater facies, proximal facies and distal facies. Volcanic crater is the heart of volcanic activity. We can effectively judge the position of the volcanic crater by coherency slices, combining with time slice. The combination of the two methods, we can get the plane map of the volcanic.

Looking for effective reservoir is the purpose of our exploration. Volcanic facies decide to lithology and reservoir distribution. The necessary dissolution and fracture treatment is the key of forming and effective reservoir. When we got the plane maps of the volcanic facies, Combing with the degree of fracture, unconformity and the palaeostructure distribution, we can identify effective reservoir distribution.

Through the above work, we suggest that the volcanic traps are mainly distributed in the near-middle crater facies, the range between the initial eroding line and pinchout line is the weathering crust reservoirs area. The long-term inherited ancient tectonic is benefit to the migration and accumulation of oil and gas. Where there are appropriat cooperationed between reservoirs, ancient structure and fracture are the goals of we are looking for.

 

AAPG Search and Discovery Article #90155©2012 AAPG International Conference & Exhibition, Singapore, 16-19 September 2012