Analysis of water breakthrough rules of oil-well in low permeability reservoir

In this article,the injection-production pattern is subdivided into triangular computing unit with a point-fountain and a point-converge.Based on non-Darcy tube differential element method of low permeability reservoir,general formula for water breakthrough time in production well is achieved.The article studied the effects of well pattern,reservoir heterogeneity,and fracture development on water breakthrough time.An empirical formula on water breakthrough time and different factors is also given in this article taking X oil field in Ordos Basin.Based on the statistic regression analysis,an empirical expression for half length fraction and water breakthrough time of oil wells is suggested.Conclusion shows that reservoir heterogeneity and fracture size have the most severe effect,but pattern of well spacing has the least effects on water breakthrough time of oil well.In irregular wells or oil wells where the smallest triangle well pattern units are obviously different,water breakthrough has a stepping up law,water breakthrough time and fraction half length show decreasing power exponent relationship.