Asphaltene Deposition in Carbonate Rocks: Experimental Investigation and Numerical Simulation

Oil production from asphaltenic oil reservoirs has always encountered difficulties, such as plugging and unpredictable fluid properties. To physically recognize the aspects of asphaltene deposition, several dynamic and static asphaltene deposition tests were designed and performed on one of the giant south Iranian oil reservoirs using dead and live crude oil and real core samples. Moreover, the effects of fluid velocity on the extent of damage were investigated. It was found that surface deposition of asphaltene particles is the main source of formation damages in the porous media and the resulting permeability impairment obeys an exponential behavior. All of the experiments confirm that pore-throat plugging causes permeability reduction of the cores linearly with time until a new mechanism of pore-throat opening comes into effect. Decreasing fluid velocity, i.e., approaching the stagnant condition, extensively raises the asphaltene uptake, indicating that the amount of asphaltene existing for deposition increases and approaches the initial amount of precipitation. A three-phase, four-component black-oil simulator was developed and coupled with a deposition model. Subsequently, the simulator was verified by the experimental results and used for evaluation of different asphaltene deposition parameters. It was found that the pore-throat plugging mechanism is not properly included in the models, and therefore, the ability of current deposition models is under question. The results of this work elucidate some less addressed shadows of the asphaltene-related issues in porous media and could be a better framework for developing new models of deposition in porous media.