| Summary: | Volcanic rocks were widely developed in sedimentary basins in China. The Songliao, Junggar and Sichuan basins have got great research successes and exploration discoveries in igneous reservoirs, which have become one of the important fields for oil and gas exploration in China. In the Changling Fault Depression of Songliao Basin, volcanic rocks are widespread in the Huoshiling and Yingcheng formations, which have a good potential for reserve and production increase. However, the results of exploration were directly dependent on the technical level of identification and characterization of volcanic traps. The conditions of hydrocarbon accumulation in volcanic traps are more severe than those in clastic traps. The physical property of reservoir and sealing effectiveness of surrounding rocks are the key factors for the effectiveness of volcanic rock traps. Based on systematically analyzing the discovered volcanic reservoirs, it was pointed out that the characterization of volcanic rock mass and volcanic reservoir were the key points for the identification of volcanic traps. In this study, taking the volcanic lithologic trap as an example, a "five-step processing" for the identification and description of volcanic lithologic trap was proposed and applied to the Longfengshan nose structural belt in practice. The drilling results showed that the characteristics of volcanic traps were consistent with the research results before drilling, which confirmed the effectiveness and reliability of traps. It also verified that the identification and description methods of volcanic traps were effective for the Changling Fault Depression and had certain guiding application value in volcanic exploration in other basins of China.
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