Volcanic craters are favorable targets in gas exploration and development, because surrounding these craters there exists the superimposition of various types and facies of volcanic rocks which are characterized by relatively remarkable reservoir thickness, large reservoir porosity and fairly good reservoir properties. The determination of volcanic craters is hence very important in gas exploration and development. Using thin section X-ray diffraction techniques, his paper identified arfvedsonite in volcanic rocks from Songliao Basin, and thus confirmed that the volcanic rocks are composed of pantellerite. As the late evolutionary stage product of alkali-rich magma, pantellerite is always accumulated near the volcanic crater due to its high viscosity and poor mobility. As pantellerite can be used as important evidence for the existence of crater, it has an important significance in improving the efficiency of gas exploration and development in volcanic rock areas.%火山口附近是多种岩性、岩相叠合的地区,堆积厚度大、储层孔隙度大、储层物性好,是天然气勘探开发的有利目标区.火山口位置的确定对天然气的勘探开发部署具有特殊意义.利用岩石薄片X衍射技术,在松辽盆地深层富碱酸性火山岩中识别出特征的碱性暗色矿物--钠铁闪石,从而确定其为碱流岩.碱流岩是富碱岩浆演化晚期的产物,岩浆喷发到地表时粘度大,流动性差,往往堆积在火山口附近.碱流岩可以作为确定火山口存在的重要标志之一,它的确定对提高深层火山岩天然气勘探开发的效率具有重要的指示意义.
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