| In the high water cut stage of oilfield development,effective and accurate evaluation of water flooded zone and its remaining oil saturation has become an inevitable important problem in some oilfields in China.Glutenite plays an important role in the exploration and development of oil and gas fields in China,Although there are some problems in this kind of reservoir,such as complex rock composition,large grain size variation,strong reservoir heterogeneity,complex pore structure,difficult injection production and so on,But the reserves are very considerable,so it is necessary to carry out qualitative discrimination and quantitative evaluation of remaining oil saturation for glutenite water flooded layer.Based on the relationship among lithology,physical property,oil bearing property and electrical property of the research area,the basic characteristics of reservoir in the study area are analyzed The reservoir is mainly composed of glutenite,with the characteristics of low porosity and permeability,and strong heterogeneity.Typical oil layers are characterized by high resistivity,obvious amplitude difference,high porosity,high acoustic time difference,low density and neutron,and low natural gamma.The typical water flooded layer has low natural gamma,high acoustic transit time and high resistivity,but the amplitude difference is not obvious,there is no envelope between C /O ratio and Si / Ca ratio,but the neutron counting rate curve decreases obviously and forms envelope with gamma counting rate curve.Based on these characteristics,the optimization of logging interpretation method for remaining oil saturation in the study area is established.By comparing the logging data of new and old wells in the development zone to study the change characteristics of logging curves after water flooding,the special response characteristics of spontaneous potential,natural gamma,acoustic time difference,resistivity,full spectrum logging and four neutron logging in water flooded zone are summarized,through the three porosity curve and resistivity crossplot method,the qualitative identification of water flooded layer is carried out,and the characteristics of oil,gas and water layer identification by neutron lifetime logging are summarized,The C/O,Si/Ca ratio curve and neutron gamma counting rate ratio curve are used to identify the water flooded zone qualitatively.The evaluation effect of the logging data of open hole well and the post casing saturation logging data on the qualitative identification method of the water flooded layer in the study block is analyzed.On this basis,the calculation models of reservoir parameters under different porosity and permeability conditions are established,the remaining oil evaluation methods of open hole logging data and saturation logging data are determined respectively.The saturation interpretation model of open hole logging data is established by using the multiple iteration method,and the dynamic evaluation of remaining oil saturation of glutenite water flooded layer is established by combining with the post casing saturation logging data.The cross plot of porosity and remaining oil saturation is used to divide the water flooded level.Combined with the well testing data,the accuracy of water flooded level judgment is verified,and a set of well logging interpretation and evaluation methods for glutenite water flooded layer are determined.In this paper,combined with the different geological characteristics of the study area,targeted to 13 wells in the study area for water flooded layer logging interpretation comprehensive evaluation,the coincidence rate was 82.6%.The comprehensive logging interpretation and evaluation method of glutenite water flooded zone is determined based on conventional logging data,combined with post casing saturation logging data and production performance data,which has certain guiding significance for logging quantitative evaluation of water flooded zone and tapping potential of old wells. |
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