A New Relative Permeability Characterization Method Considering High Waterflooding Pore Volume

Abstract

In the process of waterflooding development, high waterflooding PVs will make the fluid percolation in the reservoir more complicated, resulting in lower efficiency of waterflooding. High waterflooding PVs will affect the relative permeability and change the seepage law of oil–water two-phase flow in a high water-cut period. In this study, we performed high waterflooding PVs relative permeability experiments using nine natural cores. The unsteady measurement method is used to test the relative permeability curve. The results show that: (1) the relative permeability is affected by the waterflooding PVs, the recovery efficiency of 2000 waterflooding PVs is 10.72% higher than that of 50 waterflooding PVs on the core scale; (2) it makes water mobility increase sharply, while oil phase flow capacity remains low and decreases at high water cut stage. A new relative permeability characterization method considering high waterflooding PVs is established, which is applied to the numerical simulator. It shows that the remaining oil saturation of the high-permeability belt is higher than the calculation results of the traditional numerical simulator. It means that the injected water does not diffuse much into the low-permeability zone of the formation. The modified simulator is validated with the actual China offshore oilfield model. The numerical saturation of the key section of the passing well is in good agreement with the actual logging interpretation results, and the water cut curve fits better in the whole area. The modified simulator could predict oil production accurately after high waterflooding PVs treatment.

Effect of Displacement Pressure Gradient on Oil–Water Relative Permeability: Experiment, Correction Method, and Numerical Simulation

“…Additionally, many scholars have studied the impact of reservoir development dynamic parameters, including waterflooding pore volume [31][32][33], displacement pressure gradient [34,35], and flow velocity [21,[36][37][38]. Unlike the static parameters, there is no generally accepted understanding of the effects of dynamic parameters on relative permeability, especially displacement pressure gradient and flow velocity.…”

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

“…However, with the continuous development of water flooding, when the reservoir enters the ultra-high water cut stage, the semi-log relationship between oil-water relative permeability ratio and water saturation is no longer completely linear, and the curve will bend downward (Bondar and Blasingame 2002;Jian 2013;Zhaojie and Fengpeng 2013;Chunlei 2014;Cao et al 2021). Besides, a large number of oilfield practices have shown that the water flooding characteristic curve will also occur upward warping (Zhaojie and Fengpeng 2013;Baohong 2015;Chuanzhi and Duanping 2015;Cuo 2017;Hongen and Sibo 2019;Qi et al 2022), which results in the application of conventional water flooding characteristic curve to predict the development indexes will have a non-negligible error.…”