RESERVOIR SPACE EVOLUTION OF VOLCANIC ROCKS IN THE YINGCHENG FORMATION OF THE XUJIAWEIZI FAULT DEPRESSION, THE SONGLIAO BASIN

Commercial gas streams were obtained from volcanic rocks in the Yingcheng Formation of the Xujiaweizi Fault Depression, the Songliao Basin, but the output of each well was different. It was not only related to the distribution of volcanic rocks, but also related to the developing degree of accumulating spaces in volcanic rock reservoirs. The study of core, thin section and scanning electron microscope data showed that the main accumulating rock types of the study area were various volcanic lava and volcanic breccia, and the accumulating spaces included primary and secondary two kines. Though the primary accumulating spaces took the small proportion, they provided fovorable conditions for paulopost reconstruction. The development and evolution of volcanic rock accumulating spaces can be divided into four stages. The first is the forming stage of primary accumulationg spaces, and the secondary is weathering and leaching stage. These two stages are dominated by construction. The third is shallow-burying and structural fracture developing stage, with coexisting of construction and destruction, but dominated by construction. The fourth is deep-burying stage, which is dominated by destruction.