川东龙会场—龙门地区二叠系火山岩分布特征及油气地质意义

Distribution characteristics and hydrocarbon geological significance of Permain volcanic rocks in Longhuichang-Longmen areas,eastern Sichuan Basin,SW China

四川盆地二叠系火山岩具有良好的勘探前景,而盆地东部地区多口钻井显示钻遇火山岩,但都没有展开相应的研究。基于测录井及地震等资料分析,对四川盆地东部龙会场-龙门地区二叠系火山岩识别模式及分布特征进行综合研究。结果表明:在地震剖面上,当龙潭组内部多形成一个波峰反射时,代表着火山岩发育;区内火山岩以溢流相玄武岩为主,少见凝灰岩;垂向上可划分为2个喷发期次,主要发育在龙潭组中下部;平面上火山岩分布受古地貌和基底断裂共同控制,在古地貌低洼处和基底断裂附近是火山岩主要堆积部位,厚度较大。

Permian volcanic rocks in the Sichuan Basin have good prospects for exploration.However,many wells in the eastern basin have showed volcanic rocks,but no corresponding research work has been carried out.Based on the analysis of drilling,logging and seismic data,a comprehensive study of the identification mode and distribution characteristics of Permian volcanic rocks in the Longhuichang-Longmen area in the eastern Sichuan Basin are examined.The results show that when one more peak reflection is formed on the seismic profile in the Longtan Formation,it represents the development of volcanic rocks;the volcanic rocks in the area are dominated by overflow facies basalts,but tuffs are rare.The vertical direction can be divided into two eruption periods,mainly developed in the middle and lower parts of the Longtan Formation;the distribution of volcanic rocks on the plane is controlled by the paleogeomorphology and basement faults.The depression of the paleogeomorphology and near the basement faults are the main accumulation parts of volcanic rocks with a large thickness.