松辽盆地徐家围子断陷主要断裂对气藏的控制作用

Controlling effect of major faults on the gas reservoirs in the Xujiaweizi fault depression,Songliao Basin

解剖松辽盆地徐家围子断陷气藏控藏要素对将来火山岩复杂气藏的勘探具有重要的指导意义。为此,在精细解释徐家围子断陷三维地震资料的基础上,绘制了基底断裂与火山岩、气藏分布叠合图,并精细解剖了该区的火山机构。结果认为,徐家围子断陷火山岩天然气藏主要受控于深层断裂系统,基底断裂在火山岩发育、储层改造、高强度气源充注等成藏关键要素中都发挥了重要作用:平面上,火山沿基岩断裂走向成串珠状排列,断裂分叉或转折点为火山重要通道;纵向上,多期火山结构叠置;火山活动后期,深层酸性流体沿断裂上涌,并顺着不整合面扩展,形成了具有良好次生孔隙的优质储层;在断裂通道附近,按火山岩相发育部位,离断裂近的火山岩侵出相、喷溢相上部亚相和空落亚相是气藏形成最有利的部位。

To explain how the major faults affect the gas reservoirs in the Xujiaweizi fault depression is of great significance to the exploration of complex volcanic gas reservoirs.In view of this,based on the 3Dseismic data of fine interpretation of the Xujiaweizi fault depression,the biplot of the distribution of basement faults,volcanic rocks and gas reservoirs is drawn and the volcanic structures are explained in detail.The conclusions are drawn as follows.（1） The volcanic gas reservoirs in the Xujiaweizi fault depression are mainly controlled by the deep fault system and basement faults play important roles in the development of volcanic rocks,reservoir stimulation,and charging with high-intensity gas source.（2） On the plane,the volcanoes are in the beaded distribution along the bedrock fracture trending and the bifurcation or turning points are the important panels of volcanoes;while from the vertical profile,multi-stage volcanic structures are overlapped.（3） At the later period of volcanic activity,the deep acid fluids upsurged along the fracture and extended along the unconformity surface to form quality reservoirs with favorable secondary pores.（4） From the locations of well-developed volcanic facies,the eroded facies,the upper overflow subfacies,and spatiall fading subfacies all close to the fracture are favorable places for the forming of volcanic gas reservoirs.