济阳坳陷中生界碎屑岩储层储集空间特征及控制因素

Characteristics and control factors of the reservoir space of the Mesozoic clastic reservoirs in Jiyang Depression

济阳坳陷中生界碎屑岩储层储集空间主要为溶解孔隙和裂缝,溶解物质主要为长石、岩屑等碎屑颗粒及碳酸盐胶结物;裂缝主要包括构造裂缝、压实裂缝和解理缝.构造裂缝主要形成于燕山期和喜山期,主要分布于不整合面附近的砂体中.碎屑岩储层储集性能主要受沉积作用、构造作用和成岩作用的控制,沉积作用是最重要的控制因素.其中三角洲砂体物性最好,河流砂体次之,冲积扇、扇三角洲及滨浅湖砂体物性较差.构造作用对储集物性的改造主要表现为断层活动和不整合,不整合面之下约100 m内储层裂缝和溶解孔隙最发育、物性明显提高.成岩作用对储层物性的影响受沉积作用和构造作用的控制,对储层的改造程度与沉积相带及距不整合面的距离有密切关系.中生界最有利的碎屑岩储层为不整合面之下约100 m内的河流或三角洲砂体.

Solution pores and fractures are main reservoir spaces of the Mesozoic clastic reservoirs in Jiyang Depression.The solution pores are formed by the solution of feldspar,lithic and carbonate cement.The fractures include structural fractures,compaction fractures and cleavage cracks,and the structural fractures are mainly formed during Yanshanian stage and Himalayan stage and developed in the sandbodies near unconformity.Sedimentation,tectonism and diagenesis control the porosity and permeability of the clastic reservoirs.The sedimentation is the most important control factor.The porosity and permeability of delta sandbody are the highest,that of fluvial sandbody takes the second place,and that of alluvial fan,fan delta and shore-shallow lake sandbodies is poor.The influence of tectonism on the porosity and permeability of the clastic reservoirs includes fault activities and unconformities.Fractures and solution pores are mostly developed and the porosity and permeability is obviously improved in the clastic reservoirs which are about 100 m under the unconformities.The influence of diagenesis on the porosity and permeability of the clastic reservoirs is controlled by both sedimentation and tectonism,and its improving effect on the porosity and permeability of the reservoirs is closely relative to sedimentary facies and the distance between the reservoirs and unconformities.The favorable clastic reservoirs in the studied area are the fluvial or delta.sandbodies which are about 100 m under unconformity interfaces.