An interwell connectivity inversion model for waterflooded multilayer reservoirs

Abstract

Abstract: In view of the limitations that the current connectivity model can only forecast the fluid production dynamic change, can't calculate the dynamics of oil and water phases, and can't analyze the connectivity between wells layer by layer, this study establishes a new interwell connectivity model for multilayer reservoirs which can simulate dynamics of oil and water between wells. The model hierarchically separates the reservoir system into a series of interwell connecting units characterized by parameters such as conductivity and control volume, and by using the material balance equation, the pressure and interwell flow at constant liquid production or constant pressure mode is calculated regarding the connecting unit as a simulation object, which are combined with the frontal advance theory to establish interwell saturation tracking calculation, and finally water production dynamics of every layer at well points can be worked out. On this basis, using simultaneous perturbation stochastic approximation method and gradient projection method, a model parameter inversion method is set up by dynamic fitting. The application cases show that the model has good dynamic fitting and prediction effect, inversed model parameters coincide with the actual geological parameters, verifing the validity of the method. Compared with the current connectivity method, it can obtain the real-time model of hierarchical interwell flow rate distribution coefficient, liquid production of single well and oil split coefficient and other information, and reflect the reservoir horizontal and vertical oil-water flow relation more accurately, providing guidance for production measure adjustment in oilfield. Key words: multilayer reservoir, interwell conectivity, inversion model, interwell connecting unit, interwell flow rate distribution coefficient, oil split coefficient