气烟囱是由于天然气(或流体)垂向运移在地震剖面上形成的异常反射,是气藏超压、构造低应力和泥页岩封隔层综合作用而形成。气烟囱在形成过程中携带大量富含甲烷气的流体向上运移到天然气水合物稳定带,其形成之后仍可作为后期活动的油气向上运移的特殊通道。在中中新世后,气烟囱是琼东南盆地气体向上运移的通道。地震识别出的似海底反射(BSR)分布区存在大量的气烟囱构造,通过速度、泥岩含量、流体势等属性参数及钻井资料,判断该烟囱构造为有机成因的泥底辟型烟囱构造。
Gas chimney is one of seismic anomalies resulting from vertical gas or fluid migration. It is formed by the combined action of overpressure, low stress and mud shale sealed reservoir. During the formation of gas chimney, large scale methane-rich fluid migrates into gas hydrate stability zone along with it. After it is formed, gas chimney is still a special migration pathway to the later action of fluid and petroleum. Gas chimney is the main pathway for gas migration in Qiongdongnan basin after middle Miocene. Many gas chimneys were found in the distribution zone of bottom simulating reflector (BSR) identified from seismic data. The characteristics of gas chimney are biogenetic mud diapirs by analyzing the parameters of interval velocity, fluid potential,mud content and well data.