Micro-scale investigation on the effect of waterflooding rate on oil recovery and residual oil distribution

Abstract

Waterflooding is currently one of the most common and mature oil and gas development methods. However, when oil and gas fields enters the medium or high water-cut period, there is still a large amount of residual oil remaining untapped while residual oil characteristics and distribution could be complicated. Micromodel method is considered as a novel experimental method for studying residual oil characteristics and waterflooding. Unlike conventional core flooding, visualization of the whole process can be realized through micromodels. In this work, three different flooding rates were used to simulate the waterflooding process via micromodels. Consequently, oil recovery rates and residual oil distribution were obtained. It was observed that higher waterflooding rate increased the oil recovery. When the flooding rate was large, dispersed residual oil was observed after waterflooding. When the rate was small, residual oil exhibited more complicated configurations. For the trapped residual oil in the dead end pores in hydrophilic rock matrix, increasing the flooding rate or the viscosity of displacing phase could be beneficial to dislodge the residual oil.