Further study on oil/water relative permeability ratio model and waterflooding performance prediction model for high water cut oilfields sustainable development

The accuracy of predicting waterflooding performance is crucial in determining the scale of investment for oilfield development. However, existing common waterflooding prediction models often relies on assumptions that may not apply universally or lack theoretical derivation through statistical analysis. This has led to unsatisfactory prediction accuracy and multiple potential solutions. To address these limitations, it is proposed to incorporate the oil/water relative permeability ratio model into the derivation process of waterflooding prediction models. Initially, an evaluation of prevalent oil/water relative permeability ratio models is conducted, along with an analysis of their primary constraints. Additionally, the applicability of the analytical relative permeability model is thoroughly examined. Building upon the analytical relative permeability model and a modified Welge equation, a new waterflooding model is formulated, encompassing all pertinent physical coefficients. Notably, this model aligns seamlessly with the commonly used Arps’ decline curve, while extending its applicability to a broader range of conditions. Moreover, it can be simplified to generate typical water drive curves under suitable circumstances. The semi-log relationship between oil/water relative permeability ratio and water saturation is further simplified into a linear relationship or a multi-term formula. Compared with the traditional waterflooding model, the new model proposed in this research has a wider application range and can be applied to oilfield at high water cut. At the same time, the new model clarifies the coefficient of waterflooding curve A and the physical meaning of parameter 7.5 in Tong’s chart method for the first time. The new model proposed in this research further enriches the connotation of waterflooding theory and has certain application significance.