Abstract:

Volcanic rocks, facies belts of volcanic edifices, reservoir prediction and hydrocarbon detection of Xujiaweizi fault depression are analyzed by using of full 3-D seismic data, and the detail description of the volcanic gas pools is made . According to eruptive types, the volcanic rocks of Xujiaweizi fault depression are classified into fissured type, central type and compound type. The volcanic rocks of fissured type have wedge outer shape with strong amplitude, low frequency and bad continuum. However, its inner characteristics are bad continuous reflection, middle-strong amplitude, paralleldiagonal structure. The volcanic rocks of central and compound type have mound outer shape with strong amplitude, low frequency and bad continuum. And their inner characteristics are blankchaotic reflection. Volcanic edifices are divided into crater-near crater facies belts(CNCF), proxy facies belt(PF), distal faceis belt(DF) and volcanic-sedimentary facies belt(VSF). The CNCF has mound shape and chaotic reflection. The PF has bed reflection. The DF has bed shape and good continuum. The VSF has filling structure and good continuum. And volcanic facies belts can be recognized by using of coherence cube technique. According to the results of well-seismic integrated reservoirs inversion and hydrocarbon detection of attenuation attributes ,the relative errors between reservoirs prediction results and new-well is decreased to 17.0%(the average value is 10.2%). The accuracy of hydrocarbon detection is increased to 75%. All above provide foundation for exploration of volcanic gas pools.

Key words: Songliao basin, Yingcheng Formation, volcanic rocks, gas pool, reservoirs, hydrocarbon detection