Genesis of Differential Bonding Between Zeolite Cements and Clastic Particles in Sandy Conglomerates in Shawan Sag,Junggar Basin
Through thin section and scanning electron microscopy(SEM)observations and energy spectrum analysis,the types and charac-teristics of zeolite cements in the Permian sandy conglomerate reservoirs in the Shawan sag of Junggar basin were identified,and the mecha-nism of differential bonding between zeolite cements and clastic particles was clarified.The results show that in the Upper Permian upper Wuerhe reservoirs,the plastic deformation of rock fragments and alkaline formation water result in strong bonding between laumontites and clastic particles and in the Lower Permian Fengcheng reservoirs,laumontites are lowly bonded with clastic particles under the conditions of abnormally high pressure,and acidic fluids,while heulandites are highly bonded with clastic particles due to their crystal characteristics.The differential bonding between zeolite cements and clastic particles in the upper Wuerhe and Fengcheng reservoirs are mainly related to rock composition,abnormal pressure,mineral type,crystal structure,and the degree of late diagenetic fluid alteration.