The Study On Polymer Flooding Mechanism Of The Middle Reservoirs In Different Geologic Model

Today, the polymer flooding is the enhance recovery technique that is used in the high water oil field.Since polymer flooding of main reservoirs has realized its commercial production in Daqing Oilfield, the related technologies, matched for polymer flooding, have been gradually developed and become more mature. But with development potential of polymer flooding in main reservoirs decreased, the technical studies on polymer flooding of middle reservoirs were conducted. The pilot test in the field showed, compared with main reservoirs, middle reservoirs have the characteristics of thin and multi-layers, low permeability, connectivity complicated and high diversity between layers in vertical direction. Therefore, the technologies used in main reservoirs can not be completely applied in middle reservoirs; it is necessary to develop the technologies to adapt to the geological characteristics of middle reservoirs.On the basis of field application, the concept of covering extent of polymer flooding is put forward and the relationship between covering extent and polymer injection parameter is established, which can determine the targets, suitable to use polymer flooding in middle reservoir, and optimize polymer injection parameter. Meanwhile the stimulations to boost production and injection as well as plugging measure have been also developed.The field experience indicates polymer flooding is feasible for middle reservoirs. The oil recovery by polymer flooding is 8% higher than that of water flooding. Combined with infilling well pattern, polymer flooding in middle reservoirs can improve oil recovery 12%OOIP. The related technologies matched for middle reservoirs have been popularized and applied in the north of Daqing Oilfield.