Study On Sedimentary Microfacies And Reservoir Macro-heterogeneity Of Chang 6 In X13 Well Area Of Zhidan Oilfield,Qrdos Basin

Guided by geological theory,method and technology of multidisciplinary,this thesis probes into Chang 6 oil layer,Zhidan oil field in respect of stratum,structure,deposition,and reservoir,with the help of drilling data,geological logging data,geophysical well logging data,experimental analysis,well test and producing test,and related data.On the basis of cycle comparison method,Chang 6 oil layer is divided into four layers--Chang 6¹,Chang 6²,Chang6³,Chang 6⁴ so as to examine its top structure,sedimentary facies and distribution characteristic of the facies belt.This thesis explores heterogeneity of single sand layers,features of permeability parameters,types and distribution of the interlayers,interlamination differences,and distribution characteristics and functions of the sand layers and interlayers as it seeks to make clear geometric shapes,scales,continuity and connectivity of sand layers,two-dimensional distribution,interior porosity and plane changes of the sand bodies,and strong and weak heterogeneity of reservoir layers.The results show that the major sedimentary facies types of Chang 6 oil layer group in researched area is delta front subfacies,where small-sized nose structure develops.The sedimentary microfacies type of the river way,whose developing direction is NE-SW,mainly falls on underwater distributary channel,mouth bar,interdistributary and distal bar.The findings also reveal that the average porosity is 10.77%,relatively poor permeability is0.94×10^-3?m²,reservoir is ultra-low porosity and super-low permeability,interlayer density is between 1.4 and 2.2,interlayer frequency ranges from 0.166 to 0.224,the overall interlayer density is thin and its distribution is unstable.It demonstrates that the sandstone of Chang 6maintains the largest density—0.62,and the average density is 0.6,the interlayer widely develops in the researched area mainly with the form of mudstone,its frequency ranges from0.38 to 0.42,and the average frequency is 0.4.Besides,it presents that the thickness and width of the sand body develops in each period and continuously enlarges its scale.Thus,the continuity and connectivity of the sand body are relatively strong.With various stripped distribution,the direction of the sand body developing in researched area is NNE-SSW.The results suggest that the pore permeability of the four layers change at the plane,pore permeability correlates with permeability,and succession is exerted to low-value and high-value concentration.