Technology Of Volcanic Rocks Recognition In Changde Area In Northern Songliao Basin

There are many big and small fault depressions in northern Songliao Basin, whose faults and formations are complicated. Where there are better conditions to give birth to gas reservoirs, the growing-oil horizons are thicker mud in Shahezi Group and the reservoirs are the volcanic and grit rocks. Changde lies between southeast depressions and centre fault upheaval in northern Songliao Basin, that is to say, which lies in the fault belts of complicated depressions in Xujiaweizi. The volcanic rocks lie in the low segment of Yingcheng Group dominantly, whose thickness is very thin and wideness is very extensive, including of thin-layer lava, eruptive volcanic rocks and tuff which are acidic or litmusless. The shapes of volcanoes are low and flat, and its cones are not evident. The frequency is between 20 and 25 Hz in seismic section, and the inner of volcanic rocks is low frequency and its seismic characteristics are not good continuum. The volcanic rocks can be recognized by seismic sections, plane and attribute slices, coherence and visualization firstly with the former experiences in deeply seismic interpretation, then which can be recognized and analyzed by the effective attributes of the volcanic gas reservoirs including density, hydrocarbon detection and divided frequency. At last, the advantaged gas reservoirs are provided. The reassuring science evidences are offered for the explorative layout of the deep-layer gas reservoirs in Songliao Basin.