The Studies On Liquid Production Of Subsequent Water Flooding Of Polymer Flooding

Liquid production rate occupies an important place in the oilfield development. The index is an important criteria for development effect evaluation, development planning and design. the level of liquid production should be studied before studying liquid production rate changes. So far many effective methods have been gained which can evaluate liquid production. However, these methods expose some weaknesses. For this reason, this paper studies liquid production in two ways: liquid production index and pressure drawdown, analyses calculation methods of liquid production index and pressure drawdown. And a concept model has been set up to verify the feasibility of the formula.By means of porous flow mechanics and reservoir engineering method, liquid production index calculation formula of water-flooding, polymer flooding and subsequent water-flooding were derived. And this paper analyses changes of reservoir physical property and seepage brought by flow medium variation. This paper discovered that dimensionless liquid production index depends on mean viscosity of formation fluid. By using the formula and field data of integrated reservoirs, this paper analyses influences factors including relative permeability curve, viscosity ratio, water cut and formation thickness in vertical direction. Through regression analysis of liquid production index, empirical equations of dimensionless liquid production index of four types of integrated reservoirs have been obtained. Finally, the feasibility and effectiveness of the method with some instances are proved.As the pressure drawdown increases, oil production increases first and then decreases. Through investigation, the reason for turning point and minimum bottom hole pressure calculation are analyzed. Based on the existing method and the curve of viscosity changed with the pressure, the relation of viscosity and pressure has been obtained by using subsection regression method. Then it is substituted in Darcy law and is integrated. Given viscosity influences, the paper deduces the calculation of minimum bottom hole pressure. This paper offers some cases to indicate that the improved method can better reflect the oil production changes with pressure drawdown.