| The 402 block of TZ4 oil field is situated in the center of the Taklamakan Desert,Tarim Basin,lying on the central fault-uplift belt of Tazhong central uplift belt.Lots of geological research work has been done in the area,but there still left some problems to be well solved:with increasing number of drilling wells in the oil field and the continuously collection of well logging data,the explanation model of reservoir parameters should be modified.the research on vertical and horizontal distribution characteristics of the insulating layers and interlayers in TZ4 oil field with present data is not in-depth enough.the research on heterogeneity of conglomeratic sandstone sections in the macroscopic and microscopic aspects remains to be improved.though many achievements have been made in the comprehensive well logging evaluation of conglomeratic sandstone reservoir,little research work has been done in the homogeneous sandstone reservoir beneath the CIII oil group.The research work on 402 block of TZ4 oil field in this paper includes the four-property relationship study of reservoir,quantitative exploration of reservoir parameters,the identification and distribution of insulating layers and interlayers,the heterogeneity and comprehensive evaluation of reservoir.Some achievements were obtained:The main lithology of the CIII oil group in the study area is fine sandstone;the physical properties of reservoirs are dominated by mid-porosity and mid-permeability in the conglomeratic sandstone section(an average porosity of 12.37%,an average permeability of 258.83×10-3?m2);And they are dominated by mid-porosity and mid-to-high permeability in the homogeneous sandstone section(an average porosity of 18%,an average permeability of 349.93×10-3?m2);The percentage of oil-immersing level is the highest.The correlation of four-property is preferable,and behaved as the more coarse the lithology is,the higher of the oil level and the better of the physical properties.By placing the core data and standardizing the logging curves,later an nonlinear artificial neural network is brought in to respectively make a secondary interpretation to porosity and permeability of the conglomeritic and homogeneous sandstone sections.The result of interpretation is obviously improved compared with that of the predecessors.According to the core and physical property data,the insulating layers and interlayers in the study area could be classified as argillaceous interlayer,calcareous interlayer and cal-argillaceous interlayer.Carrying on the research from the vertical,horizontal,and plane aspects of the interlayers to find the distribution properties,the result shows that it is easiest for the existence of interlayers in the northwest,middle and southeast part of the area,and there exist more argillaceous interlayers which are widely distributed in the whole CIII oil group.The cal-argillaceous interlayers are relatively less,which are mainly distributed in layer 5 to layer 7.The calcareous interlayers are the least,and are mainly distributed in layer 9 to layer 12.The continuity in the lateral of the interval interlayers is preferable.A key research is carried on at macro level of the CIII oil group in 402 block from inner and plane parts as well as between the layers.The conclusion is,there is a middle extent of heterogeneity in layer 1,a strong extent in layer 2 to layer 5,and the strongest is in layer 3.The lower limit of porosity and permeability are respectively confirmed by the method of smallest radius of the pore throat,statistics and oil testing in the conglomeritic and homogeneous sandstone sections of CIII oil group.The results show that the lower limit of porosity and permeability in conglomeritic sandstone section are6.03%and 1×10-3?m2;and are respectively 8.93%and 3.63×10-3?m2 in homogeneous sandstone section.Choosing the parameters of porosity,permeability and pore-throat structure,the reservoirs are classified into three types through the classification research of reservoirs in study area,and a standard of reservoir classification is determined.Based on the standard of classification evaluation,the individual well reservoir is comprehensively classified and evaluated,after that,the vertical and horizontal distribution features are analyzed.The main reservoir types in conglomeritic sandstone section are type II and type III,type I is in low development.The main reservoir type in homogeneous sandstone section is type I,with large reservoir thickness,and high average porosity and permeability are the typical characteristics in this section. |
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