The Characteristics Of Deformation Band And The Evolution Of Fault In High Porosity Rock

The thesis,as the key anatomical objects of the micro-structural in Pleistocene-Holocene conglomerate of the southern margin of the Junggar basin,fracture coring sandstone of Xingshugang of Daqing placanticline,and glauconite quartz sandstone of Jiguan mountain in Qinhuangdao,combined with the published literatures,we system analysis the fracture deformation mechanism of the different nature of sandstone,the micro-structural types,characteristics and the formation of internal structure of fault zone,and it is of great significance on the study of fault sealing in the sandstone.Studies have shown that fracture of pure sandstone occurs in non-consolidated to semi-consolidated of diagenetic stage.Deformation mechanism of grain boundary frictional sliding,called 'particulate flow',results in particle rotating and rolling.fault rocks compared with the parent rock,only occurs particles rearrangement,And the formed micro-structure is disaggregation band,without significant decrease in porosity and permeability comparing with parent rock,it is the fluid channel for vertical migration.The fracture developed in the consolidation of diagenesis stage(porosity is greater than 15%)which deformation mechanism is cataclasis,and which fault rock is cataclastic rock.The formed micro-structure is Cataclastic band,with 1 to 3 orders of magnitude decrease in porosity and permeability comparing with parent rock.The form of cataclastic band is which result from strain hardening,from a single deformation bands to cluster cataclastic band.When cataclastic degree is high,withing strain softening effect,the slip surface may start to development,and fault develops.So the fault core and damage zone has certain sealing ability,slip surface for the oil and gas vertical migration channel.The fracture developed in consolidation stage(porosity less than 15%)which deformation mechanism is rupturing,and which fault rock is fault breccia,associated micro-structure type is fractures,and fault zone of a highly permeability.When the buried is deep,with a large numbers of fractures,produced cataclastic flow,fault core is cataclastic rocks,damage zone still has a large numbers of fractures.The deformation mechanism of consolidation sandstone is rupturing during the uplift process.It forms incoherent breccia,damage zone with a large numbers of fractures,and fault zone of a highly permeability.Quartz dissolution accelerates at 90?,depths greater than 3 km,the disaggregation band,cataclastic band formation solution and cementation band,and the pressure solution and cementation in deformation bands enhanced sealing ability.The fracture of impure sandstone occurs in non-consolidated to consolidated of diagenetic stage.Deformation mechanism are the mixing of layered silicate and sand particles,fault core is phyllosilicate-framework fault rocks,associated micro-structure type is phyllosilicate bands in damage zone,and the fault sealing ability is very strong.The types of deformation bands is disaggregation band,cataclastic band,solution and cementation band,phyllosilicate bands,disaggregation band with improve reservoir permeability,cataclastic band,solution and cementation band,and phyllosilicate bands are considered by many to baffle the flow of fluids.Field observations indicate that the fluid flow,not along the deformation bands,but around the deformation bands or along the fractures flow which around the deformation bands.This uderstanding to solve two key problems in petroleum geology:one is the multiple sets of reservoir which controlled by fault has the differenc of petroliferous,the fundamental reason lies in the difference of micro structure of fracture in different reservoir rocks,which the porosity higher,shale content is higher,the physical properties of cataclastic band,solution and cementation band,and phyllosilicate bands is lower,the density of oil and gas is bigger,oil and gas are more difficult to filling into.the reservoir,causing not all good physical properties of reservoir is oil reservoir.The other is that if the fault damage zone has cataclastic band,solution and cementation band,and phyllosilicate bands,will lead to the strong reservoir heterogeneity.It is difficult to exploitation the residual oil in the damage zone.When multi-target directional wells tapping the potential of residual oil along fault fracture zone,it is important to avoid the fault damage zone.