中-基性火山岩孔缝储集体形成控制因素——以准噶尔盆地金龙区块石炭系为例

以金龙区块石炭系中基性火山岩为例,综合岩心、薄片、测井、地震及分析化验资料,分析火山岩储集空间特征及形成过程：①火山喷发间隙期,火山旋回上部斜长石等矿物向方沸石、绿泥石蚀变,形成不稳定层;②石炭纪晚期构造运动造成断裂-裂缝发育及不整合面的形成,大气水沿着断裂-裂缝及旋回顶部不稳定层发生纵向及横向溶蚀,形成孔缝储集体雏形;③侏罗纪末期构造挤压再次形成断裂-裂缝,孔缝储集体被分割,储集空间基本定型。在断裂裂缝、古地貌及火山旋回界面控制下,孔缝储集体纵向上表现出分带性,横向上表现为古地貌高地储层厚、古斜坡储层薄的透镜状特征,整体表现出由裂缝、溶蚀孔及溶蚀缝构成的"多层楼式"复杂储集体。形成的孔缝型火山岩储层地质模型对火山岩储层预测及油气勘探提供有价值的参考。

Controlling factors for the formation of pore-fracture reservoirs in intermediate-basic volcanic rocks: A case study of the Carboniferous Jinlong Block,Junggar Basin

This paper analyzed the characteristics of volcanic reservoir space and its formation process in the case of intermediate-basic volcanic rock in the Carboniferous Jinlong Block,by integrating the core,thin section,logging,seismic and analytical data.The results show that:(1)feldspar and other minerals in the upper volcanic cycle altered to zeolite and chlorite and formed an unstable layer during the volcano eruption quiescent intervals;(2)tectonic movement at the Late Carboniferous developed fault-fracture and unconformity,and then meteoric freshwater could cause vertical and transverse dissolution along the fault-fracture and the unstable layer at the top of the cycle;(3)new fault-fracture formed through the tectonic activity of the La te Jurassic period,and the pore-fracture reservoir was compartmentalized and the accumulation space was basically finalized.Under the control of fault-fracture,palaeo-geomorphology and contact surfaces of the volcanic cycles,the reservoirs are characterized by zonation in the vertical direction and by lenticular geometry with greater thickness in the paleo high and losser thickness down the paleo-slope.As a whole,the reservoir is a complex"multi-zone overlapping"reservoir,composed of fractures,dissolved pores,and dissolved fractures.The geological model of pore-fracture volcanic reservoir is of great value for volcanic reservoir prediction and oil/gas exploration.