基于层序地层学的时频分析技术识别有利砂体——以涠洲A构造湖底扇为例

Time-frequency analysis method of fusing sequence stratigraphy identifies favorable sand bodies:taking Weizhou A tectonic lake bottom fan as an example

针对油气勘探面临的圈闭规模小,地质沉积相变快等复杂情形,如果受地震分辨率不足的制约,可以通过时频分析技术在时间域和频率域上进行精细的地震信号聚焦,以达到提高识别小型油气目标精度的目的.本文在阐述时频分析技术原理的基础上,与层序地层学分析有机结合,确立了湖底扇有利砂体的能量团随频率变化的方向性及其响应强度等时频特征,揭示了湖底扇砂体由于岩性、物性或孔隙流体性质变化所导致的时频特征的差异.研究结果表明,以湖底扇频率响应分布特征为前提,利用时频分析技术将涠洲A湖底扇各朵叶体甜点的瞬时频率变化特征类比能反映湖底扇有利砂体的优势频率变化的规律,可以定性地预测湖底扇各朵叶储层甜点的岩性组合信息,从而降低朵叶体甜点岩性解释的多解性,为有利砂岩的发现及油气开发提供了技术支撑.

Aimed at the complicated situations faced by oil-gas exploration,such as small size of traps and fast geological sedimentary phase transitions.It is urgent to research by insufficient seismic resolution,time-frequency analysis technology can be used to focus fine seismic signals in the time and frequency domains,in order to improve the accuracy of identifying small oil-gas targets.On the basis of explaining the principle of time-frequency analysis technology and organically combining it with sequence stratigraphy analysis,this article establishes the directionality and response intensity of the energy cluster of favorable sand bodies in the lake bottom fan with frequency changes,and reveals the differences in time-frequency characteristics caused by changes in lithology,physical properties,or pore fluid properties of the sand bodies in the lake bottom fan.The research results show that based on the frequency response distribution characteristics of the lake bottom fan,using time-frequency analysis technology to analogize the instantaneous frequency change characteristics of sweet spots in each lobe of the A lake bottom fan in Weizhou that can reflect the dominant frequency change pattern of favorable sand bodies in the lake bottom fan,and can qualitatively predict the lithological combination information of sweet spots in each lobe reservoir of the lake bottom fan.In addition,it can reduced the ambiguity of lithological interpretation of sweet spots in the lobe,which provided technical supports for the discovery of favorable sandstones and oil-gas development.