Analysis of water breakthrough features in Ansai Oilfield and production increase technology for medium-high water cut wells

Ansai Oilfield is a matured oilfield of low pressure, low permeability and low production which has been developed for 30 years; a large number of oil wells are now in medium-high water cut development stage, so it is very difficult to maintain stable production only by conventional production increasing technologies. At present, it is still prudent to stimulate the medium-high water cut oil wells, there is still blind spot in optional technology under different water breakthrough types, and the direction of reducing water cut and increasing oil production is not yet clear. In view of the different development features of medium-high water cut oil wells and different water breakthrough types in Ansai Oilfield, some aggressive measures were implemented such as fracturing by changing relative permeability and water-plugging fracturing as well as maintenance measures like chemical water plugging and the second cementing, etc. The practice shows that various technologies are different in adaptability to different water breakthrough types, and there is no one technology which can solve the problem of reducing water cut and increasing oil production under different water breakthrough features. So selecting the proper technology which suits the actual conditions can achieve the satisfactory results.