Evaluating key parameters impacting asphaltene permeability reduction behavior in micro-pores during carbon dioxide injection

Abstract

Asphaltene is a heavy component of crude oil that can deposit in the pores of the formation and result in permeability reduction, and with time, pore plugging. Understanding the behavior of asphaltene and the mechanism by which it precipitates and deposits in the crude oil is vital in reducing asphaltene damage in the formation. Also, by evaluating asphaltene permeability reduction in the formation, we can predict the behavior of the asphaltene and determine the extent to which pore plugging will occur. This research studies the impact of carbon dioxide (CO2) pressure, temperature, and oil viscosity on asphaltene permeability reduction. These parameters were chosen in this study based on their proven significant impact on asphaltene instability in the crude oil. The research discusses the concept of Asphaltene Delayed Plugging Index, based on an observation of initial and secondary asphaltene plugging behavior. Although the impact of asphaltene pore plugging have been extensively studied, this research focuses on identifying the optimum time at which asphaltene mitigation must take place before severe damage occurs. It was found that asphaltene exhibited an initial permeability reduction which occurs rapidly. This initial permeability reduction did not completely cease oil production, but rather reduced flow. The initial pore plugging can be mitigated easily if detected early. If the secondary plugging occurs, complete cessation of production usually occurred, and it is very difficult to mitigate. Based on this, the research bridges between initial and secondary asphaltene pore plugging to determine the optimum time for asphaltene mitigation.