Influence of threshold pressure gradient on development indicators in heavy oil
The existence of the starting pressure gradient of heavy oil aggravates the resistance of heavy oil seepage,which causes certain difficulties in the development of heavy oil.In order to solve this problem,a mechanistic model was constructed using the NRSNL non-linear flow simulation software to investigate the effects of the presence or absence of threshold pressure gradient on residual oil distribution and water saturation under different reservoir rhythms,permeability ratio,and crude oil viscosities.The research findings demonstrate that the presence of the threshold pressure gradient reduces the extent of oil recovery and accelerates water breakthrough in the wells.After 20 years of exploitation,the recovery rate decreases by 1.72%to 3.09%,and the water con-tent increases by 1.31%to 2.78%.Under the same initial pressure gradient conditions,the recovery efficiency of anti-rhythmic res-ervoirs is lower than that of rhythmic and compound rhythmic reservoirs.When the viscosity of crude oil and the permeability ratio are larger,the impact of the initial pressure gradient on the recovery efficiency is greater.
threshold pressure gradient of heavy oilresidual oil distributionrhythmpermeability ratiocrude oil viscosity