THEORETICAL&APPLIED MECHANICS LETTERS2,022008(2011) Numerical simulation of pore-scale?ow in chemical?ooding process Xiaobo Li,1,a)Shuhong Wu,1Jie Song,1Hua Li,1and Shuping Wang2

1)Research Institute of Petroleum Exploration&Development of Petrochina,Beijing100083,China

2)Petroleum Exploration&Production Research Institute of Sinopec,Beijing100083,China

(Received11January2011;accepted26January2011;published online10March2011)

Abstract Chemical?ooding is one of the e?ective technologies to increase oil recovery of petroleum reservoirs after water?ooding.Above the scale of representative elementary volume(REV), phenomenological modeling and numerical simulations of chemical?ooding have been reported in literatures,but the studies alike are rarely conducted at the pore-scale,at which the e?ects of physicochemical hydrodynamics are hardly resolved either by experimental observations or by traditional continuum-based simulations.In this paper,dissipative particle dynamics(DPD),one of mesoscopic?uid particle methods,is introduced to simulate the pore-scale?ow in chemical?ooding processes.The theoretical background,mathematical formulation and numerical approach of DPD are presented.The plane Poiseuille?ow is used to illustrate the accuracy of the DPD simulation,and then the processes of polymer?ooding through an oil-wet throat and a water-wet throat are studies, respectively.The selected parameters of those simulations are given in details.These preliminary results show the potential of this novel method for modeling the physicochemical hydrodynamics at the pore scale in the area of chemical enhanced oil recovery.c 2011The Chinese Society of Theoretical and Applied Mechanics.[doi:10.1063/2.1102208]

Keywords chemical?ooding,pore-scale?ow,dissipative particle dynamics,mesoscopic simulation, enhanced oil recovery

Chemical?ooding,among the various enhanced oil recovery(EOR)techniques,is playing a dominating role in China.1The EOR mechanism of chemical?ooding is that addition of some chemical agents(e.g.alkaline, polymer,surfactant)to injected water makes higher sweep e?ciency and/or oil-displacement e?ciency.As the chemical EOR technique develops for some oil reser-voirs with low primary and water-?ooding oil recov-ery,some aspects of this technology need further stud-ies.One of the research focusing on chemical EOR lies on how to evaluate the possible performance of oil-displacement agents in reservoir.

Above representative elementary volume(REV), the phenomenological model formulation and numerical solution of chemical?ooding have been reported in some papers,2and the distribution of oil saturation and pres-sure in reservoir can be given by numerical simulations of chemical?ooding.Most of the phenomenological pa-rameters in chemical EOR models need to be obtained by laboratory experiments.To maximize the applica-tion potential of chemical?ooding and explore the po-tential high-performance chemical agents,the phenom-ena at the pore-scale must be studied.Both physico-chemical and hydrodynamic e?ects are of great impor-tance at the pore scale(～μm),which can hardly be resolved by experimental studies.Some novel theoreti-cal models and numerical simulation approaches should be searched for.

A bottom-up approach to model the?uid?ow through porous media is displayed in Fig.1.The continuum-based approaches modelling the macroscopic a)Corresponding author.Email:

lxb1980@http://www.doczj.com/doc/7bbaacc5482fb4daa48d4bc3.html.Fig.1.The bottom-up approach to model the?uid?ow through porous media

phenomena ignore fully the microscopic e?ects.Micro-scopic molecular dynamics,on the other hand,requires excessive times and e?orts before the macroscopic ef-fects become meaningful or make sense.It’s feasible to study the pore-scale?ow in chemical?ooding process by mesoscopic(between micro-and macro-)methods. Three of popular mesoscopic methods are Lattice Boltz-mann method(LBM),smoothed particle hydrodynam-ics(SPH)and dissipative particle dynamics(DPD).3 LBM can be regarded as the numerical realization of generalized Boltzmann equation,and SPH is the La-grangian formulation of macroscopic?uid dynamics on integral interpolants.LBM and SPH are mostly used by the researchers who are focussed more on the hydro-dynamics phenomena than on physicochemical ones.In the area of chemical EOR,some physicochemical phe-nomena(e.g.wettability)are essential for industrial