Study On Fault Zones And Characteristics For Oil-gas Reservoir Forming Of Carboniferous Volcanic Rocks In Chunfeng Oilfield

The carboniferous volcanic rocks in research area mainly consist of andesite?basalt?tuff and few mudstone.Since the density of the rocks and the worse porosity and permeability of the volcanic matrix,it is difficult to form an effective reservoir space.According to the oiliness of selected core,all the oil-bearing segments are located in fault broken zone.Fault striation oil immersion and oil patch appeared in various directions in broken core.The interspace of rocks in fault broken zone is the main reservoir space.Thus,fault broken zone is the effective location of carboniferous hydrocarbon accumulation,which need more attention to be studied.The paper defined the development characteristics,realized the spatially distributing features and established the recognition model of fault broken zone based on coring,well logging and seismic data.Furthermore,the fault broken zone was classified into different types,the influences of fault and lithology are cleared,and the hydrocarbon reservoir forming characteristics are analyzed based on the various association characteristics.According to the observation and analyzation of core,the development characteristics which consists of the occurrences of broken rocks and fracture on both sides.The data of core and imaging of fault broken zone were calibrated into the conventional well logging curve so that the distribution of fault broken zone in the wells can be effectively identified through identification chart and discriminant function,which established by intersection graph method and Fisher discriminant method.Calibrating the fault broken zone which was quantitative identified into seismic data,combining with the development feature of the fault in research area,the seismic reflection characteristics of fault broken zone can be realized.Based on that,we can further traced the spatial distribution characteristics and analyzed it through 3D seismic data.The paper classified the fault broken zone which was distinguished based on the differences of size and compound mode.Comparing with the different types of fault broken zone and the relationship of the fault and lithology,the paper analyzed the influences of the fault and lithology to fault broken zone.Large-scale fault broken zones are more easily forming in the wells which closed to the big fault and has the bigger development intensity.Fragile basalt and andesite are more easily formed large-scale fault broken zone than the plastic tuff.According to the identification and spatial distribution prediction of fault broken zone and the data of core and well logging,we assessed the broken rocks and induced fractures which have the possibility to develop effective reservoir space and compared the physical properties of fault broken zones of different types.As a result of that,we concluded that the breccia type has the best physical properties.Based on the previous research results and the reservoir forming background of research area,the paper proposed the conception of fault broken zone hydrocarbon reservoir and defined the reservoir forming characteristics of volcanic-rock fault broken zone.