Deposition of colloidal asphaltene in capillary flow: Experiments and mesoscopic simulation

Edo S. Boek*, Hemant K. Ladva, John P. Crawshaw, Johan T. Padding

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

63 Citations (Scopus)

Abstract

The aggregation and deposition of colloidal asphaltene in reservoir rock is a significant problem in the oil industry. To obtain a fundamental understanding of this phenomenon, we have studied the deposition and aggregation of colloidal asphaltene in capillary flow by experiment and simulation. For the simulation, we have used the stochastic rotation dynamics (SRD) method, in which the solvent hydrodynamic emerges from the collisions between the solvent particles, while the Brownian motion emerges naturally from the interactions between the colloidal asphaltene particles and the solvent. The asphaltene colloids interact through a screened Coulomb potential. We vary the well depth εcc and the flow rate v to obtain Peflow ≫ 1 (hydrodynamic interactions dominate) and Re ≪ 1 (Stokes flow). In the simulations, we impose a pressure drop over the capillary length and measure the corresponding solvent flow rate. We observe that the transient solvent flow rate decreases when the asphaltene particles become more "sticky". For a well depth εcc = 2kBT, a monolayer deposits on the capillary wall. With an increasing well depth, the capillary becomes totally blocked. The clogging is transient for εcc = 5kBT, but appears to be permanent for εcc = 10-20kBT. We compare our simulation results with flow experiments in glass capillaries, where we use extracted asphaltenes in toluene, reprecipitated with n-heptane. In the experiments, the dynamics of asphaltene precipitation and deposition were monitored in a slot capillary using optical microscopy under flow conditions similar to those used in the simulation. Maintaining a constant flow rate of 5 μL min-1, we found that the pressure drop across the capillary first increased slowly, followed by a sharp increase, corresponding to a complete local blockage of the capillary. Doubling the flow rate to 10 μL min-1, we observe that the initial deposition occurs faster but the deposits are subsequently entrained by the flow. We calculate the change in the dimensionless permeability as a function of time for both experiment and simulation. By matching the experimental and simulation results, we obtain information about (1) the interaction potential well depth for the particular asphaltenes used in the experiments and (2) the flow conditions associated with the asphaltene deposition process.

Original languageEnglish
Pages (from-to)805-813
Number of pages9
JournalEnergy and Fuels
Volume22
Issue number2
DOIs
Publication statusPublished - Mar 2008

Fingerprint

Dive into the research topics of 'Deposition of colloidal asphaltene in capillary flow: Experiments and mesoscopic simulation'. Together they form a unique fingerprint.

Cite this