Applying Seismic Interpretation Technology To Recognize And Describe The Carboniferous Volcanic Rocks In The Wucaiwan Area Of Junggar Basin

Wucaiwan area is located in Wucaiwan hydrocarbon depression of Eastern uplift of Junggar Basin, and the surface of Carboniferous formation is a huge nosed structure which plunges to the west. The Pingfengshan fault crosses the bridge of the back to form the Wucaiwan broken nose and at the same time, a number of north-south faults split it into many local broken nose structures.In Wucaiwan area, more than 20 drills uncover Carboniferous formation. The main types of volcanic rock are andesite and volcanic breccia, and the reservoir physical property is primarily dominated by the pores and fractures. Carboniferous volcanic rock weathering crust at the top of Carboniferous formation having the better reservoir physical property, which makes up the better regional reservoirs and seals combination with overlying large sets of the mudstones of Permian Jiangjunmiao formation, is the important prospecting target. However, restricted by the quality of seismic data, hydrocarbon reservoir characteristics and enrichment regularities are not yet clear, which restricted the exploration process of this area.Through target-oriented carrying out research on the integrated exploration of acquisition, processing and interpretation, the quality of seismic data of Carboniferous formation is significantly improved and enhanced, which laid the foundation for anatomying and understanding the features of the Carboniferous reservoirs systemly.The volcanic apparatus in Wucaiwan area have the characteristics of typical layered volcanos. Four typical seismic response characteristic profiles for the vary lithological combinations are founded by using of the cores, geology logging data, log and seismic data comprehensively. At the same time, volcanic facies planar distribution are predicted by using the time and coherent cube slices, and interlayer root-mean-square amplitude. Volcanic sequence division and litho-facies study methods are summarized innovatively in this paper.Carboniferous reservoir is more complex. Oil-gas distribution is controlled by the structures and the lithologies. By analyzing, there are three possible reservoir types. Enriching along the weathering crust is the features of Oil-gas distribution in this area. Through analyzing the relationship between oil layers and seismic attributes in the vicinity of the Carboniferous weathering crust, that strong root-mean-square amplitude area is the possible hydrocarbon potential area. The result of post-stack seismic inversion shows that the characteristic of the andesite interbedded with the volcanic breccia is very obvious in Upper Bashan formation and the three cap rock's low impedance feature is obvious too. This is a more reliable way to predict the vertical and lateral distribution of volcanic rocks. At the same time, the paper carries out exploratoryly research of the pre-stack seismic attribute and pre-stack inversion. The Top boundary of the gas reservoir mainly show the IV-class AVO characteristic. Through the interactive analysis between the acoustic impedance and elastic impedance, we can predict the possible gas reservoir area. Studied comprehensively the geological research with the analysis of the known hydrocarbon reservoirs, the paper select out 4 favorable targets and propose 3 well sites.The paper form the technologies and methods for the volcanic facies prediction successfully by applying seismic technology, and gropes the technologies and methods for the lithology and hydrocarbon prediction initially about the special reservoir of volcanic rock. The paper has laid the technological foundation about the further study for the volcanic gas reservoir in this area and the other similar areas.