Analysis of improving oil recovery in polymer area by expanding swept volume

Abstract

In order to realize the development effect of the new K1 polymer flooding block in T oilfield, meet the recovery ratio not lower than that of the old test area and the small well spacing area, and reach or exceed the established development goal of the salt-resistant test area, it is necessary to expand the swept volume technology research. Through the research and application of a series of swept volume expansion technologies, such as high concentration and low speed stage parameters of different types of well groups, application of concentration reduction and speed increase, injection modification and deep profile control, the oil recovery is enhanced. At the stage of high concentration and low speed injection, the suitable injection concentrations of ABCD-IV wells are 1800mg/L-2100mg/L, 1500mg/L-1800mg/L, 1200mg/L-1500mg/L and 1200mg/L and below respectively. Based on the inflection point pressure of the indicator curve during water injection, after the pressure limit of concentration reduction and speed increase is determined to be 8.0MPa, the ratio of liquid absorption thickness before and after the measures and the relative liquid absorption of thin and poor layers show a trend of rising first and then falling; According to the pressure rising space, the injection pressure of all kinds of wells has decreased and the water absorption profile has been improved, and the effect of C and D wells is better than that of A and B; Seen from the drop of apparent water absorption index, the increase of liquid absorption thickness, the maximum water cut drop of connected production wells and the cumulative oil increase of single well, the effect of deep adjustment is the best in blank water drive period, followed by water cut drop period and poor in water cut recovery period.