Dynamic law and method of judging effective time of early polymer flooding in Bohai Oilfield

Key words:  Bohai Oilfield  polymers  polymer injection time  water cut change shape  dimensioniess effective time

Abstract:

A typical model was constructed based on data in Bohai Oilfield, and the variation laws of water cut and oil production rate with different polymer injection time were studied. The definition of dimensioniess effective time was proposed to judge the effective time of early polymer flooding. And the influences of polymer injection time, coefficient of variation and mobility ratio on the dimensioniess effective time were analyzed. The judgement standard of effective time for polymer flooding with different polymer injection time was proposed. The results show that early polymer flooding exists a critical injection time, and if injection time is greater than the critical value, water cut curve would have significant decrease funnel, if less, it would not show decrease funnel. So the appearance of decrease funnel could not be the only standard to determine the effective time. The model was tested based on the available production data, and the relative error is about less than 10% , which can meet the engineering precision demands.