Enhanced liquid technique for narrow channel reservoirs under small difference between formation and bubble point pressure

The narrow channel oil reservoirs in Bohai area under small difference between formation and bubble point pressure have entered the stage of medium and high water cut, with rapid production decline and great difficulty in stable yield, while the big-pump enhanced liquid technique is an effective stimulation method. However, it is difficult to determine the reasonable enhanced liquid amplitude because the flow characteristics of narrow channel reservoir is different from the complete-structure reservoirs and it is easy to degas for small difference between the formation and bubble point pressure. Based on the flow percolation equation of narrow channel considering the influence of river boundary, the specific liquid recovery indexes of different water-cut stages were determined. According to IPR curve of gas phase, the reasonable production pressure difference under different formation pressure is determined. Combined with the specific liquid recovery index and reasonable production pressure difference, the reasonable liquid extraction range of this type oil reservoir at different water cut stages under different formation pressure was determined. This method is applied to field test which has resulted in good effects of increasing production and can provide theoretical guidance and production experiences for offshore narrow channel reservoirs.