Research On Polymer Flooding Adaptability In The Yuan 13 West Block Indaqing Toutai

West of Yuan 13 of Toutai oilfield in Daqing is an oilfield with strong anisotropy and low permeability. During the period of water flooding development, the problem appeared that injection pressure increased quickly, casing damage was serious and formation pressure level was low and decreased quickly. In the condition of present well pattern, it was difficult to effectively employ the crude oil in the reservoir. It seriously restricted and influenced the development effect and economic benefit on the oilfield. Therefore, it is necessary to further excavate residual potential and the measure of enhancing oil recovery efficiency. Aiming at actual demand of oilfield, the research, theoretically guided by reservoir engineering, physical chemistry and analytical chemistry, by means of instrument test, chemical analysis and physical simulation, regarding displacement agent viscosity, molecular thread size, resistance factor and residual resistance factor and recovery efficiency as evaluation index, taking reservoir geology and fluids as research platform, the research on displacement agent screening and its adaptability with the reservoir was carried out. On this basis, physical simulation about displacement effect evaluation and the optimization of injection craft parameter was conducted. Reservoir rocks in the west of Yuan 13 area are sandstone with big pores and low permeability, which has the characteristic of small pore size, worse sorted behavior and water sensitivity and velocity sensitivity. When polymer flooding or polymer gel flooding was applied in target area, the adaptable polymer relative mass was no more than 800×104, and polymer concentration was no more than 900mg/L. Compared with polymer solution, the seepage resistance of Cr3+ gel was larger, and fluid steering capability was stronger. Compared with the sequent injection mode, the alternative injection mode of polymer solution or Cr3+ and water was adopted. It could not only weaken the negative effects caused by displacement flowing into low and medium permeable layer, enhance producing extent of the reservoir, but could save the displacement agent dosage and reduce the construction cost as well.