Appliation Resarch Of Polymer Flooding In Class â…¡ Reservior Of The Sanan Oil Field Daqing

This paper studies the application of polymer flooding in class II reservoir of the Sanan oil field, Daqing. Polymer flooding enhanced oil recovery by improves water flood sweep efficiency. Polymer flooding has been widely used in major reservoirs, but it has never been used in classâ…¡reservoir of the Sanan oil field. This paper focuses on two aspects in the study: the scheme determination and design of numerical simulation on polymer flooding; the field test of polymer flooding.In the laboratory study of polymer flooding in classâ…¡reservoir, the optimization of injection parameters is carried out, namely polymer molecular weight; injection volume; polymer concentration; injection rate; injection mode. We adopt middle molecular weight polymer (12-16 million) in this polymer flooding test area. The injection volume is 0.64PV. The injection rate is 0.14PV/a. Polymer solution preparing and diluting with clean water. The injection concentration of single well is 850-1250 mg/L. The average injection concentration of the whole area is 1000mg/L. The viscosity of polymer is no less than 40mPa.s. It can forecast that polymer flooding will enhance recovery ratio 7.8% compare to water flooding in the entire area.The dynamic characteristics of the field test of polymer flooding in classâ…¡reservoir of Sanan oil field are list as following:the injection pressure increased while the apparent injectivity index decreased; the daily fluid production; liquid production index decrease and total water cut are decreased; the daily oil production increased. The center wells in the test area present significant effect of water decreasing and oil increasing and production indexes fairly close to the required target. The test results indicate that Saâ…¡7-14 formations are combined into a layer series. As injection-production well spacing is 175m, the controlling degree of polymer flooding is higher and it can meet the requirement of polymer flooding development in classâ…¡reservoir. The liquid accepting layers in classâ…¡reservoir are dominated by layers with net thickness over 1.0m. The layer that net thickness between 0.5m to 0.9m can be produced. As the heterogeneity of class II reservoir is strong, the injection parameters of each well should be designed and adjusted individually in order to solve the contradiction between layers and planes and improve the producing degree of deferent reserves. Layering and hydraulic fracturing are effective measures which can improve polymer flooding performance. Saâ…¡7-14 formations enhanced oil recovery is above 11% after polymer flood in Sanan oil field. The after tax financial internal rate of return is 47.96% in test area. It not only brings remarkable economical benefit but also has a wide popularization and application prospect. The field test and related researches of polymer flooding in classâ…¡reservoir will have positive effects on the development of Compound Flooding technology in Daqing oil field.