Water-flooded Zone Identifying And Water Flooding Law In Low Permeability Reservoirs

After 20 years of development,Wangyao and Xinghe have entered the medium and high water-cut stage.According to the statistics,the composite water-cut in Xinghe has exceeded 30.1%when Wangyao was 41.4%.For avoiding the strong flooded layer and reducing the water content of single well when developing reservoirs later,It is more and more important to provide an accurate perforation horizon for the well to accurately identify and evaluate the floodbed.The research is based on the analysis of core physical properties,the characteristics of real sandstone water flooding,the petrological characteristics of reservoirs,the change of physical properties,the change of wettability,the change of rock electrical and logging information,The characteristics of conventional well logging response are clarified,and then the water flooding layer is identified qualitatively and quantitatively by theoretical and experimental data,and the well interpretation model of water flooding zone is established.Acquired knowledge is as follows:1.The physical parameters and electrical parameters of the reservoir are flooded.After the reservoir is flooded,the porosity and permeability become better,The average porosity increased by about 5.97%,the baseline of the natural potential curve is shifted and the resistivity decreases first and then increases.2.Sedimentary facies and physical properties are the main factors influencing the distribution of flooded flooding.The sedimentary microfacies of underwater distributary is more susceptible to flooding in other areas where the other microfacies are more easily flooded and the hyperosmolar zone is better.Water flooding experiments show that different flooding levels are different types,reflecting the distribution of different oil and water and the remaining oil occurrence.3.Gray correlation analysis shows that it is more reasonable and accurate to identify the water flooded layer by RT and SP logging curves in the study area,and the criteria of qualitative identification of water flooding layer based on natural potential and resistivity curve are established.4.There are two kinds of reservoirs for identifying reservoirs in the chang-6 reservoirs of Xinghe Oilfield in Ansai Oilfield,and one is for the flooded reservoirs with low flooding reservoirs.The Archie formula model is used.For the middle and high flooding reservoir,the model of dilution coefficient was used to evaluate the reservoir.5.The sand bodies which has high watered out channels have the best physical properties,the highest water flooding efficiency,lower saturation of remaining oil.We suggest the intermittent injection-production and appropriate supplementation of a small amount of infill well.It is beneficial for the recovery of formation pressure and oil-water differentiationThe zones which the sand bodies are middle watered out have better physical properties,higher saturation of remaining oil,inlayers and interlayers have a large area of remaining oil distribution in space,we propose to adopt a segmentation-partitions injection-production,and perfect the injection-production system,At the same time,increase the density of infill well and perforating interval reasonably.The zones which the sand bodies are low watered out mainly have these characteristics below:the dense sand bodies have poor physical properties,the original oil saturation and oil volume is not high,It is need to perfect injection-production well pattern and form high displacement pressure difference.