Enhancement of Heavy Oil Recovery with High CO2 Injection Rates in Silica Nanochannel

Shuo Zhang,Xiaofei Sun,Yanyu Zhang

doi:10.2113/2021/3363280

Abstract

Abstract CO2 injection enhanced oil recovery has become one of the most important approaches to develop heavy oil from reservoirs. However, the microscopic displacement behavior of heavy oil in the nanochannel is still not fully understood. In this paper, we use CO2 as the displacing agent to investigate the displacement of heavy oil molecules confined between the hydroxylated silica nanochannel by nonequilibrium molecular dynamics simulations. We find that for heavy oil molecules, it requires more much higher displacing speed to fully dissipate the residual oil which is found related to the decreased CO2 adsorption on the silica nanochannel. A faster CO2 gas injection rate will lower the CO2 adsorption inside the nanochannel, and more CO2 will participate in the displacement of the heavy oil. The results from this work will enhance our understanding of the CO2 gas displacing heavy oil recovery and design guidelines for heavy oil recovery applications.

Highlights

Enhanced oil recovery [1,2,3,4,5,6,7,8,9] is critical for the petroleum industry to recover the residual oil
Since heavy oil molecules are more likely to be staying onto the surface, numerous studies have investigated the adsorption of heavy oils on the silica surface, such as Wu et al [28], who investigated the sorption, diffusion, and distribution of heavy oil on the silica surface using molecular dynamics simulation in 2013, and they later evaluate the diffusion and partitioning of SARA fractions of heavy oil on the soil organic mattercoated quartz surface
Due to the large interactions between asphaltene molecules, the asphaltene molecules tend to aggregate during the entire displacement process and higher pushing speed results in smaller asphaltene molecule distribution near the silica surface and faster decaying interaction with each other

Summary

Introduction

Enhanced oil recovery [1,2,3,4,5,6,7,8,9] is critical for the petroleum industry to recover the residual oil. Yan et al [24] studied the oil inside a nanopore throat transport phenomenon employing molecular dynamics simulation They revealed the different roles of scCO2 slug and water slug in CO2 WAG injection and investigated CO2 WAG injection-based enhanced oil recovery (EOR) mechanism. Fang et al [25] in 2019 studied oil displacement in CO2/N2 slug flooding at the molecular and atomic levels and they proposed that the key factors for oil exploitation are the CO2 swelling effect and N2 propelling effect. They have further calculated the mass transfer process [26]. Zhong et al [29] investigated the adsorption behavior of decane and other components of heavy oil as different polarity components in heavy oil on the water-wet silica surface

Methods

Results

Conclusion