Microscopic seepage mechanism of initial high water cut of production wells in ultra-low permeability reservoir

Key words:  ultra-low permeability reservoir  microfracture  initial water cut  ^rarting pressure gradient  water lock effect  Jamin effect

Abstract:

The initial water cut of production wells in ultra-low permeability reservoirs is higher than that of in high permeability reseivolre, and the dropping trend of water cut will last for days in developing period. The analysis reaults of microscopic seepage mechanism show that oii flowes with drfficalty because of the water lock effect resulted from drilling; and iraciunng. Jamin effect, the open and close a￡ microfractiira, starting pressure gradient in reservoir result in high initial water cut. Because of thin throat of rocka, the initial water saluration is high, which results in the high initial water cut of production wells.