四川盆地高石梯地区灯影组四段顶岩溶古地貌、古水系特征与刻画

四川盆地灯影组白云岩岩溶孔洞储层发育,在四川盆地威远、资阳及高石梯-磨溪地区发现了大型气田。但是该套储层非均质强,储层预测困难,需要进一步从岩溶地质理论出发,恢复岩溶古地貌、古水系,从而掌握该套储层发育分布规律,指导进一步勘探开发。本文选用印模法恢复了高石梯地区灯四顶岩溶古地貌,并结合现代岩溶学和岩溶动力学理论,划分了岩溶台地、岩溶缓坡地和岩溶盆地3类二级地貌单元。应用现代岩溶分类方法,根据微地貌组合形态,对二级地貌作精细刻画,划分了6种三级地貌单元,最后根据岩溶动力学、岩溶水文地质学在高石梯地区刻画出北部、西部和东南部三大水系。认为岩溶缓坡,位于径流区,水动力条件最强,孔洞最发育,是储层勘探方向。精细的古地貌、古水系的刻画对促进高石梯地区灯影组油气勘探开发具有重要实际意义。

Characterization of karst paleo-geomorphology and the paleo-water system on the top of the 4th member of the Dengying formation in the Gaoshiti area, Sichuan basin

Karst pore-cave reservoirs of the Dengying formation developed well in the Weiyuan, Ziyang and Gaoshiti-Moxi areas in the Sichuan basin, which are heterogeneous, thus making reservoir prediction difficult. One of possible approaches to solve this problem is recover the karst paleo-geomorphology and paleo-water system from the karst geological theory, so as to reveal the development and distribution of the reservoirs to guide exploration. In this paper, the karst paleotopography in the Gaoshiti area is restored by the impression method. Combined with the modern karst and karst dynamics theory, paleogeomorphology （second-class）are divided unto three types of the third class:karst platform, karst gentle slope and karst basin. Based on the modern karst classification method, according to the micro-geomorphic combination form, the second-class paleogeomorphology is finely characterized, and six kinds of third-class paleogeomorphology units are divided. Finally, according to karst dynamics and karst hydrogeology, The three major water systems, i.e. the north, west and southeast are depicted in the Gaoshiti area. It is considered that different geomorphological locations have different hydrodynamic conditions, and there are differences in the developmental characteristics of different types of karst paleogeomorphology, runoffs in ancient water systems, excretion and reservoir development, and filling characteristics. The fine paleogeomorphology and the depiction of the ancient water system have great importance for advancing oil and gas exploration and development of the Dengying formation in the Gaoshiti area.