四川盆地二叠系火山岩地震响应特征及分布规律

2018年底,川西南永探1井在二叠系钻遇火山岩储层,日产22. 5×104m3/d工业气流,使四川盆地火山岩成为目前重要的勘探接替领域。但由于钻井较少,研究程度低,火山岩厚度及岩相分布规律不清。充分利用地震信息,精细标定井下火山岩岩相与井旁地震响应特征,结合地震响应特征及层拉平剖面,建立了川西地区火山岩岩相地震识别模式。川西南地区有三种岩相,分别为火山岩喷溢相、火山岩溢流相和火山岩沉积相。通过对二、三维地震资料精细对比解释火山岩顶底界面,预测出川西地区火山岩岩相和厚度分布。综合顶部构造背景、火山岩相分布特征、钻井井下油气显示情况等因素,确定出川西南成都-简阳-三台地区火山岩油气勘探的有利区带,对于四川盆地火山岩油气勘探,提供了重要的支撑。

Seismic response Characteristics and Distribution of Permian Volcanic Rocks in Sichuan Basin

At the end of 2018, Yongtan-1 well produced 22.5x10_⁴m_³/d of industrial gas in volcanic rocks, which makes the Permian volcanic rocks in Sichuan Basin an important exploration succession area. However, there are few drilling wells, low exploration degree, and unclear volcanic rock thickness and lithofacies distribution. By Making full use of seismic information, accurately calibrating the seismic response characteristics of underground volcanic lithofacies and borehole side, combining with seismic response characteristics analysis and stratigraphic flattening, the seismic recognition model of volcanic lithofacies in Western Sichuan is established. There are three lithofacies in southwestern Sichuan, which are volcanic eruption facies, volcanic overflow facies and volcanic sedimentary facies.Through fine contrast and interpretation of the top and bottom interfaces of volcanic rocks from two-dimensional and three-dimensional seismic data, the distribution of volcanic lithofacies and thickness in Western Sichuan is predicted. Based on the top tectonic setting, volcanic facies distribution and oil and gas display in drilling wells, the favorable zones for volcanic oil and gas exploration in Chengdu-Jianyang-Santai area in southwestern Sichuan are determined, which provide important support for volcanic oil and gas exploration in Sichuan Basin.