A study on water-injection mode of low-permeability reservoirs

The reservoirs in the southern Dagang oil field are of low permeability with a large number of micro pores. After water injection, water cut in producing wells rose very fast and complicated the production operation. Through analysis of intermittent water injection theory and introducing domestic and international experiences, the super small intermittent water injection was applied in two pay zones, Nv20 and Nv34 in Shenvsi oil field in 1998. Later on the effect of different cyclic time and frequency and water cut on oil exploition was studied. The considerable numbers of experiences have proven that. (1) Super small cyclic flooding can take advantage of much more beds. (2) Super small cyclic water injection is suitable for water-injection wells; the corresponding production wells resulting in considerable reduction of associated water volume and stabilization of production water cut at 60% level. (3) The super small intermittent water injection is an effective economical method, especially in low permeability reservoirs.