Identification Of Dominant Seepage Channels And Optimization Of Plugging,Profile Control And Flooding Parameters After Polymer Flooding In Putaohua Reservoir In Beiyi District

There are 13 polymer flooding blocks in the first-class oil layer in the Sazhong Development Zone,all of which have entered the follow-up water flooding.The geological reserves are 20799×10~4t,the remaining reserves are 9838×10~4t,and the average recovery degree is 52.7%.After the polymer flooding,the oil layer has a high recovery degree.,the difficulty of producing the remaining reserves,etc.,relying on the original well pattern for subsequent water flooding to enhance the recovery factor is limited,and the cost is high and the efficiency is low.Therefore,it is necessary to carry out a new round of detailed description and qualitative assessment of geological reserves and dominant seepage channels,in order to formulate comprehensive adjustment measures and lay the foundation for continuous and stable oil production.Using fine geological modeling as a means and reservoir numerical simulation as a method,this paper studies the distribution law of remaining oil in the reservoir after polymer flooding and the classification of dominant seepage channel types,combining the rhythm characteristics of the reservoir after polymer flooding and the advantages of the reservoir after polymer flooding.Based on the distribution law of seepage channels,a new classification method of dominant seepage channels in reservoirs after polymer flooding is established based on the combination of dynamic and static methods.Based on the numerical simulation of the reservoir,combined with the classification results,carry out the optimization of the blockage and control and flooding parameters of the dominant seepage channels in the reservoir after polymer flooding.Combined with the on-site development performance,a targeted adjustment plan is designed for different types of difficult injection wells,and the post polymer flooding is further improved.The method of plugging and adjusting dominant seepage channels in reservoirs.The research results show that:there is a large amount of remaining oil distribution in the target area after the Putaohua reservoir in the Beiyi area.On the plane,the remaining oil is mostly affected by geological factors,rhythm characteristics and well pattern factors,and is distributed in blocks.Therefore,the plane residual oil is divided into six types according to its influencing factors:micro-amplitude structural type,intralayer gradient type,interlayer interference type,plane heterogeneity type,plane phase transformation type and uncontrollable well pattern type.At the same time,the calculation of the remaining oil reserves of each vertical sublayer and the remaining oil reserves of each sedimentary facies in the plane was completed,and the recovery degree of each sublayer was determined.In terms of dominant seepage channels:Based on the distribution law of remaining oil after polymer flooding in the target area and the results of streamline numerical simulation,the development characteristics of dominant seepage channels were determined,and the dominant seepage channels after polymer flooding were combined with logging curves,sedimentary microfacies characteristics and inter-well connectivity.The channels are divided into three types:strip-shaped dominant seepage channels,branch-shaped dominant seepage channels,and planar dominant seepage channels.Vertically,combined with dynamic saturation changes and the comparison of static factors of single-well layers,the vertical dominant channel horizons are obtained,and statistics are calculated.The direction and number of each type of dominant seepage channel are shown.Based on the fuzzy comprehensive evaluation method,a scoring system was established to carry out quantitative identification and analysis of dominant seepage channels.Based on the score level,the 66wells in the test area were divided into key plugging wells,sub-key plugging wells and wells requiring plugging control,respectively.The profile control position,profile control thickness and radius,and injection speed of different types of well groups are optimized.At the same time,for different types of injection-difficult wells,a targeted adjustment plan is designed,the potential tapping effect of different types of remaining oil and the plugging control methods of advantageous seepage channels are comprehensively evaluated,the plugging control measures for advantageous seepage channels are summarized,and a comprehensive adjustment plan is prepared.