Volcanic rock distribution and gas abundance regularity in Xujiaweizi faulted depression, Songliao basin
松辽盆地北部徐家围子断陷火山岩分布及天然气富集规律

By a newly proposed band filter, second derivative by multiple upward and downward continuation, which utilizes continuation height and iteration number to modulate frequency and enhance target layer information, the aeromagnetic data of Xujiaweizi depression, the most highly studied area in Songliao Basin, are processed to extract volcanic anomalies. From a comparison with drilling data, the extracted aeromagnetic anomalies correspond well to the distribution of volcanic rocks. According to the aeromagnetic anomalies in combination with drilling and seismic data the plan distribution of three volcanic formations is predicted. It is shown that aeromagnetic gradient belts near or connected to hydrocarbon source are gas-abundant zones with well-developed volcanic reservoirs. This point of view will play an important guiding role in gas exploration deployment in Songliao Basin, and even benefit gas exploration in other areas in China.