The Colloidal Approach. A Promising Route for Asphaltene Deposition Modelling

It is now widely recognized that asphaltene exist in crude oils both as dissolved and particulate matter and that asphatenic crude oils behave as colloidal systems. The objective of this research work is to check if, in porous media and under dynamic conditions, asphaltene also behave as colloids. In this case, their deposition kinetic should obey the classical laws for colloid deposition in porous media. To achieve this, asphaltene deposition kinetics has been investigated as a function of the main controlling parameters such as flow rate, asphaltene aggregation state, resin content and crude origin. The study has been performed, first under well controlled condition using model fluids and porous media, and then under more representative conditions using actual crude oils and outcrop sandstones. The results confirmed that, indeed, the kinetics of asphaltene deposition in porous media obeys the general scaling low of colloid deposition. They allowed us to propose general scaling laws for the deposition kinetics in the form $\eta \propto A\gamma^{-s}$, η is the capture efficiency and γ the shear rate. The exponents s are universal exponents that are characteristic of the deposition regimes while the power law pre-factors A encompass all the specific features of the system considered (asphaltene and porous media). These kinetic laws show that the thickness of the deposit increases rapidly with decreasing shear rate. Accordingly and under favourable conditions, a thick deposit is expected to form during heavy oil extraction from high permeability formations and under low flow rate conditions. Such deposition could then have significant impact on the efficiency of heavy oil recovery. Therefore, its impact on permeability and on flow properties of reservoir fluids needs to be assessed as a part of process optimisation and evaluation. The Colloidal approach provides a new and promising route for asphaltene deposition and associated permeability damage modelling

Permeability Damage Due to Asphaltene Deposition : Experimental and Modeling Aspects

International audienceThe flow properties of several asphaltenic crudes were studied at reservoir temperature in rocks of different morphology and mineralogy. The experiments performed showed a progressive reduction in permeability to oil during injection, varying in rate according to the system considered. The existence of organic deposits was verified by Rock-Evalpyrolysis measurements made on sections of samples taken at the end of flow at different distances from the entry face. This technique enables the profile of the deposits to be quantified. The interpretation of the permeability damage experiments and their simulation are treated by comparing the asphaltenes in oil to colloidal particles in suspension, capable of being deposited at the surface of the pores and thus reducing the permeability of the porous medium. The first simulations were carried out using the PARISIFP particle damage model, which has recently been extended to the case of multi-layer deposition. A satisfactory qualitative agreement is observed with the experimental results

Permeability Damage Due to Asphaltene Deposition : Experimental and Modeling Aspects Endommagement d'un milieu poreux par dépôts d'asphaltènes : expériences et modélisation

The flow properties of several asphaltenic crudes were studied at reservoir temperature in rocks of different morphology and mineralogy. The experiments performed showed a progressive reduction in permeability to oil during injection, varying in rate according to the system considered. The existence of organic deposits was verified by Rock-Evalpyrolysis measurements made on sections of samples taken at the end of flow at different distances from the entry face. This technique enables the profile of the deposits to be quantified. The interpretation of the permeability damage experiments and their simulation are treated by comparing the asphaltenes in oil to colloidal particles in suspension, capable of being deposited at the surface of the pores and thus reducing the permeability of the porous medium. The first simulations were carried out using the PARISIFP particle damage model, which has recently been extended to the case of multi-layer deposition. A satisfactory qualitative agreement is observed with the experimental results. Les propriétés d'écoulement de plusieurs bruts asphalténiques ont été étudiées à la température du réservoir d'origine dans des roches de morphologie et minéralogie différentes. Les expériences réalisées mettent en évidence une réduction progressive de la perméabilité à l'huile au cours de l'injection, plus ou moins rapide selon les cas. L'existence de dépôts organiques a été vérifiée par des mesures de pyrolyse Rock-Evaleffectuées sur des sections d'échantillons prélevées en fin d'écoulement à différentes distances de la face d'entrée. Cette technique permet de quantifier le profil des dépôts. L'interprétation des expériences de colmatage et leur simulation sont traitées en assimilant les asphaltènes dans l'huile à des particules colloïdales en suspension, susceptibles de se déposer à la surface des pores et ainsi de réduire la perméabilité du milieu poreux. Les premières simulations ont été réalisées en utilisant le modèle IFP d'endommagement particulaire PARIS , qui a été récemment généralisé au cas de dépôt en multicouches. On observe un accord qualitatif satisfaisant avec les résultats expérimentaux

Permeability Damage Due to Asphaltene Deposition : Experimental and Modeling Aspects

The flow properties of several asphaltenic crudes were studied at reservoir temperature in rocks of different morphology and mineralogy. The experiments performed showed a progressive reduction in permeability to oil during injection, varying in rate according to the system considered. The existence of organic deposits was verified by Rock-Evalpyrolysis measurements made on sections of samples taken at the end of flow at different distances from the entry face. This technique enables the profile of the deposits to be quantified. The interpretation of the permeability damage experiments and their simulation are treated by comparing the asphaltenes in oil to colloidal particles in suspension, capable of being deposited at the surface of the pores and thus reducing the permeability of the porous medium. The first simulations were carried out using the PARISIFP particle damage model, which has recently been extended to the case of multi-layer deposition. A satisfactory qualitative agreement is observed with the experimental results

Cationic amino-containing N -isopropyl- acrylamide-styrene copolymer particles: 2-surface and colloidal characteristics

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Well injectivity decline for nonlinear filtration of injected suspension: Semi-analytical model

Injectivity decline due to injection of water with particles is a widespread phenomenon in waterflood projects. It happens due to particle capture by rocks and consequent permeability decline and also due to external cake formation on the sandface. Since offshore production environments become ever more complex, particularly in deep water fields, the risk associated with injectivity impairment due to injection of seawater or re-injection of produced water may increase to the point that production by conventional waterflood may cease to be viable. Therefore, it is becoming increasingly important to predict injectivity evolution under such circumstances. The work develops a semi-analytical model for injectivity impairment during a suspension injection for the case of filtration and formation damage coefficients being linear functions of retained particle concentration. The model exhibits limited retained particle accumulation, while the traditional model with a constant filtration coefficient predicts unlimited growth of retained particle concentration. The developed model also predicts the well index stabilization after the decline period.A. S. L. Vaz, P. Bedrikovetsky, C. J. A. Furtado and A. L. S. de Souz