Borehole electrical imaging logs were used to interpret volcanic reservoirs in the Yingcheng Formation in China. The logs helped identify different types of volcanic rocks and structures, such as rhyolite, basalt, and volcanic breccia. By analyzing the images, researchers determined various volcanic facies, including sedimentary, effusive, and explosive facies. They also found layered structures in weathered volcanic crusts at the top of the formation. The direction of maximum stress in the area was identified, along with different sets of tectonic fractures. Overall, the study provides diagnostic criteria for interpreting volcanic reservoirs, which can be useful in similar geological settings.