Derivation of water flooding characteristic curve for offshore low-amplitude structural reservoir with strong bottom water

Abstract

The water flooding characteristic curve method is one of the essential techniques to predict recoverable reserves. However, the recoverable reserves indicated by the existing water flooding characteristic curves of low-amplitude reservoirs with strong bottom water increase gradually, and the current local recovery degree of some areas has exceeded the predicted recovery rate. The applicability of the existing water flooding characteristic curves in low-amplitude reservoirs with strong bottom water is lacking, which affects the accurate prediction of development performance. By analyzing the derivation process of the conventional water flooding characteristic curve method, this manuscript finds out the reasons for the poor applicability of the existing water flooding characteristic curve in low-amplitude reservoir with strong bottom water and corrects the existing water flooding characteristic curve according to the actual situation of the oilfield and obtains the improvement method of water flooding characteristic curve in low-amplitude reservoir with strong bottom water. After correction, the correlation coefficient between $$\frac{{k_{ro} }}{{k_{rw} }}$$ k ro k rw and $$S_{w}$$ S w is 95.92%. According to the comparison between the actual data and the calculated data, in 2021/3, the actual water cut is 97.29%, the water cut predicted by the formula is 97.27%, the actual cumulative oil production is 31.19 × 104t, and the predicted cumulative oil production is 31.31 × 104t. The predicted value is consistent with the actual value. It provides a more reliable method for predicting low-amplitude reservoirs' recoverable ability with strong bottom water and guides the oilfield's subsequent decision-making.

A new water flooding characteristic curve at ultra-high water cut stage

“…Based on the phenomenon, some experts derived the water flooding characteristic curve suitable for the ultra-high water cut stage by the method of reverse or fractal theory (Guan and Wen-rui 2019; Andersen et al 2020;Liu et al 2021). And most scholars proposed some special mathematical expression forms based on the conventional water flooding characteristic curve expression, such as polynomial function term (Zhaojie and Fengpeng 2013;Feng et al 2014;Xiaolin and Zhiping 2015;Zhinbin 2015) or exponential function term (Dekang 2017;Jianwei and Yigen 2020).…”