Numerical Simulation Study Of Horizontal Well Acidizing

In horizontal well drilling and completion process, the drilling and completion fluids willinevitably contact with the oil and gas layer for large area and long time, which formed alager-scale pollution area and increased the flow resistance of fluid in the fluid, it is moreserious pollution than vertical wells, combined with low permeability reservoir capacity verylow, therefore, the horizontal wells face the same problems of deluging the pollutionformation surrounding wellbore、dredging the fluid channel of the near wellbore、improvingand restoring the capacity of oil and gas wells. The acidification can improve formationpermeability around the wellbore, thereby improving the seepage force around the wellbore.Compared to vertical wells, the matrix acidizing of the horizontal wells is more complex,dueto the different well horizontal sections with different soaking time in the working fluid andthe variable mass flow of horizontal section itself.In this paper, based on the analysis of influencing factors and characteristics ofhorizontal wells, numerical model of horizontal wells damage has been established;According to the mass and momentum conservation of the acid flow in the wellbore, wellboreflow model has been established in the acidification process; Based on the cumulative processof acid flow along the wellbore wall into the formation around the wellbore, reservoir flowmodel has been established in the acidification process; According to the acid flow volumerelationship in the reservoir formation, wormhole model has been established. Coupling theabove models, it solves the rate of acid flow in the formation and the distribution of wellborepressure by numerical methods, and analysis the influence of the reservoir parameters andacid injection rate. It can provide a theoretical basis for acidizing.