Abstract:

Observation and electronscanning of rock slices and core samples in 8th district,Karamay oilfield,have the following characters:1.Complicated petrofabric——coarse and fine matrices,five kinds of grainsupported framworks and four types of grain contact.2.Violent mechanical compaction——grain deformation,intra-grain fissures and false matrices.3.Well developed authigenic minerals——three series of zeolites,calcites and chlorites.Based on the occurrence and origin of the authigenic minerals,the relationship between pore evolution and diagenesis processes,the conglomerate are in immatured and semi-matured diagenesis,mechanical and chemical compaction greatly decreased primary porosity,but the de-analcitization resulted in a large amount of secondary corrosion pores,and then,the chlorite grown inpores apparently blocked the throats,thus reduced the permeability of the conglomerate.Two diagenesis processes are discriminated:the ductile tuffaceous clastic conglomerate with a few secondary corrosion evolved into nonreservoir,where as conglomerates composed of compression-resistant neutral and acidic lava clastics with much more secondary pores,developed into effective reservoir.