Fluvial Reservoir Heterogeneity Of Guantao Formation In Kongdian Oilfield

The reservoir of Guantao Formation in Kongdian Oilfield has strong heterogeneity and the distribution characteristics and connections of sand bodies and the interlayer are complicated.The control factor affecting fluid distribution is not clear and the distribution of remaining oil is complex.In this paper,with the comprehensive utilization of core,well logging,seismic and production data,the research of sedimentary facies and reservoir heterogeneity is carried out,then analyze the effect of reservoir heterogeneity on the development and distribution of remaining oil,and the following results and knowledge have been achieved.According to seismic data,well loggings and cores available in study area,applying the theory of high-resolution stratigraphic sequence of continental deposit to divide objective intervals Guantao Formation into 3 oil formations,10 small layers and 22 single sand layers.The sediment provenance of fluvial facies of Guantao Formation in Kongdian Oilfield is mainly from the southwest Cangxian Uplift.Guan 2 oil formation mainly develops single banding meandering river and interlaced banding meandering river,and Guan 1 and Guan 3 oil formation mainly develop single banding braided river and interlaced banding braided river,then combining the example of modern fluvial deposits of Rakaia River in New Zealand four kinds of rivers' depositional models are established.The reservoir heterogeneity is strong,and the interlayer between oil formation and small layer is more stable compared with the interlayer between the stable single sand layers.There are large differences in particle size,physical properties and fluid viscosity between oil formations.Also,there are big differences in physical properties,oil-bearing ability and producing degree among single sand layers.The shape of composite channel sand in the plane can be divided into three types.There are disjoint banding,interlaced banding,split jointed banding.The development of interlayer in meandering river reservoirs is relatively low,and it is mainly distributed in point bar by indented form.The development of interlayer in braided river reservoirs is well developed,and it is mainly distributed in channel bar by flat-plate form.The intra-layer heterogeneity is from medium to poor.The reservoir heterogeneity is mainly influenced by the aspects of deposition,structure and waterflooding extractionThe reservoir heterogeneity have great effects on oil and gas distribution,water absorption status and liquid producing situation and then affects the remaining oil distribution.Interbed remaining oil mainly distributes on non-major reservoirs of low producing extent and main layers with poor physical properties.Plane remaining oil mainly distributes in main facies belts of low exploitation degree,such as channel bar and point bar of single channel.The remaining oil in meandering river reservoir is mainly concentrate in lateral accretion sandbodies blocked by echelon dissection and uncontrolled by injection-production well pattern,while in braided river reservoir it is located in the lower part of interlayers in channel bar.