Research On The Microscopic Pore Structure And Polymer Flooding Compatibility Of The First Type Reservoir In Sanan Development Area

Sanan development area of Daqing oilfield was placed on production in 1964,and it has started the tertiary oil recovery since 1999.Polymer flooding,as a kind of tertiary oil recovery technology which has been widely used in Sanan development area has achieved satisfactory production-increasing results.Until now,as the scale of polymer flooding in the major reservoir is getting larger,the development situation of each block is different.Therefore,the research of reservoir microscopic pore structure characteristic should be carried out,and the compatibility scheme between polymer flooding and oil reservoir should be made to guide the block to be developed efficiently and properly.This article calculate the mineral rock characteristic,pore space types and characteristics of the first type reservoir in Sanan development area by manipulating the core mercury penetration and the SEM pictures.The unified standard was made according to the parameter characteristics of different pore structure to divide the pore types into the first type to the fifth type and the macroscopic property characteristics of each type were summarized.The microscopic pore structure parameters were divided into the main parameters and the secondary parameters on the basis of analyzing the relativity between each microscopic pore structure parameter and permeability.The relationship model between the median pore radius and the air-permeability of coring wells as well as the log interpretation effective permeability and air-permeability were set up.The models were verified by the mercury injection experiment data,and they are in accordance with the regulation.The distribution characteristics of porosity,permeability and oil/water relative permeability were analyzed.The impact of deposition and diagenesis on the characteristics of reservoir pore structure were analyzed respectively.The types of sedimentary microfacies in the research area were summarized.The poroperm characteristics,pore throat distribution and microscopic pore structure characteristics of each sedimentary microface were studied.The types and characteristics of diagenesis in the research area were summarized and its impact on the physical property,anisotropy as well as oiliness of the reservoir were analyzed.The compatibility between the pore structure and polymer flooding was studied.The compatibility plate was made by comparing the field production condition theoretical analysis computation as well as the indoor experimental results.After analyzing the actual polymer injection situation in oilfields,it can be infered that the time range of polymer flooding wells becoming effective of different oil layers is 90 to 210 days,the average pressure gradientcorresponding to the stable average injection-production pressure is 0.13MPa/m,the corresponding polymer seepage velocity is 0.3 meters per day.The feasible injection standard of the formation was determined by analyzing the correspondence between the effective swing radius of polymer molecule,the median pore radius and permeability.The indoor experiment of polymer flooding injection effect was carried out.The polymer solution of different molecular weight were made up by clear water and it was diluted into different concentration by sewage.The polymer solutions were injected into the core with different penetration level in constant voltage.The compatibility plate between pore structure and polymer flooding parameters was made by analyzing the seepage velocity value to divide the compatibility standard.The compatibility standard will direct the actual production to some extent.