济阳坳陷深层砂岩成岩作用及孔隙演化

济阳坳陷深层发育的三角洲相、扇三角洲相及冲积扇相砂岩,是以填隙物微孔隙和粒间孔为主的低孔低渗、中孔低渗型储层。从总体上讲,压实作用使粒间孔隙随深度的增加而减少,但三角洲相砂岩抗压实作用强,利于粒间孔隙的保存;石英次生加大、绿泥石和高岭石的充填、铁方解石和铁白云石等的胶结使粒间孔隙减少,溶解作用可以随深度的增加产生大量有机酸,在喷出岩屑中形成大量的岩屑溶蚀孔,利于深部储层次生孔隙的形成。次生孔隙和微孔隙成为深部储层的主要储集空间类型。晚成岩A亚期有机酸大量排出,形成长石和岩屑等溶蚀孔,使溶蚀孔、粒间孔和微孔隙并存;B亚期有机酸与CH₄、CO₂ 并存,绿泥石占据了孔隙,阻止了碳酸盐的沉淀,使微孔隙和溶蚀孔得以保存;C亚期有机酸减少,CH₄、CO₂ 增加,利于构造、成岩裂缝形成,保存大量微孔隙,改善了储集性能。

DIAGENESIS AND PORE EVOLUTION OF DEEP SANDSTONES IN JIYANG DEPRESSION

The deep sandstone of delta,fan delta and fluvial fan facies are low porosity low permeability or mid porosity low permeability reservoirs with filling micropores and intragranular pores.In general,the intragranular porosity decreased with the increasing of sandstone burial depth;the secondary enlargement of quartz,the filling of chlorite and kaolinite,the cementation of iron calcite and iron dolomite reduced the porstiy;solution in deep strata resulted in large amount of eroded pores.Late diagenesis could be divided into A,B and C diagenetic substages.Considerable organic acids in A substage caused solution pores in feldspar and debris;in the B substage,CH\-4 and CO\-2 existed,chlorite filled the pores,thus preserved micropores and solution pores;in the C substage,organic acids decreased and CH\-4,CO\-2 increased,thus forming fractures and improving reservoir property.