纳米颗粒吸附

SPE-181285-MSNanoparticles Adsorption, Straining and Detachment Behavior andits Effects on Permeability of Berea Cores: Analytical Model and LabExperiments

Wendong Wang, China University of Petroleum; Bin Yuan, University of Oklahoma; Yuliang Su, ChinaUniversity of Petroleum; Kai Wang, Coven Energy, LLC; Miaolun Jiang, China University of Petroleum; RouzbehGhanbarnezhad Moghanloo, University of Oklahoma; Zhenhua Rui, Independent Project Analysis, Inc.

Copyright 2016, Society of Petroleum EngineersThis paper was prepared for presentation at the SPE Annual Technical Conference and Exhibition held in Dubai, UAE, 26-28 September 2016.This paper was selected for presentation by an SPE program committee following review of information contained in an abstract submitted by the author(s). Contentsof the paper have not been reviewed by the Society of Petroleum Engineers and are subject to correction by the author(s). The material does not necessarily reflectany position of the Society of Petroleum Engineers, its officers, or members. Electronic reproduction, distribution, or storage of any part of this paper without the writtenconsent of the Society of Petroleum Engineers is prohibited. Permission to reproduce in print is restricted to an abstract of not more than 300 words; illustrations maynot be copied. The abstract must contain conspicuous acknowledgment of SPE copyright.

AbstractThe aim of this paper is to present both experimental and theoretical investigations on nanofluid flow withdynamic adsorption, detachment and straining behavior, and its associated formation damage. In this paper,we conduct core-flooding experiments on oil-wet Berea sandstone. Hydrophilic Nano-structure particles(NSP) is dispersed in the injected brine stream at 0.05, 0.2 and 0.5wt% concentrations. During the core-flooding of nanoparticles injection and post-flush of brine, the corresponding pressure drops across the coresand the effluent nanoparticles concentration are recorded. In order to quantify nanoparticles adsorption/detachment and straining behavior and associated effects on fluid flow, an analytical model is derivedusing method of characteristics. The interplay between nanoparticles and rocks is described by the coupledthe classical particles filtration theory and maximum adsorption concentration model. All the necessaryparameters, i.e., the maximum adsorption concentration, reversible or detachment adsorption concentration,nanoparticles adsorption and straining rates, and the corresponding formation damage coefficients, arecharacterized by matching analytical solutions with the effluent nanoparticles concentration history andreal-time pressure drop.The experimental results indicated that both adsorption and straining occur during the injection.The extent of adsorption and straining for Nano-structure particles (NSP), i.e., maximum adsorptionconcentration, particles adsorption rate and straining rates, increases along with the increase of nanoparticlesinjection concentration. As the results, the breakthrough time of nanoparticles injection is delayed, thesteady-state effluent concentration decreases, and the pressure drop increases more rapidly. The adsorptionamount of nanoparticles includes the reversible and irreversible adsorption. During the post-flush of brine,the reversible adsorbed nanoparticles detach from the already adsorption layers. With the increase ofnanoparticle injection concentration, the reversible or detachment of adsorbed nanoparticles also increase.In practice, this paper will contribute for the following applications 1) apply lab experiments to highlightthe importance of nanoparticles adsorption, straining and detachment behaviors on the formation damage.2) The analytical solution provides physical insights to quantify nanofluid flow performance, and can also2SPE-181285-MSbe used to optimize the usuage of nanofluids application while considering the loss caused nanoparticlesadsorption and straining.

IntroductionRecently, nanoparticle application has been widely reported in diverse potential applications in the oil andgas industry, including formation damage mitigation, assisted surfactant/alkaline/low salinity/gas flooding,and well treatment after fracturing in unconventional reservoirs. However, without enough dispersantstability passing through pore throats, nanoparticles could be adsorbed and plugged in pore-throats resultingin permeability impairment. A comprehensive study of nanoparticles adsorption/detachment behavior isessential for better understanding of nanofluid effects on permeability impairment, which provides essentialfoundation for the numerous benefits of nanoparticles in enhanced oil recovery. The EOR mechanisms ofnanofluid have been studied extensively, including wettability alteration, disjoining pressure, interfacialtension reduction, pore channels plugging and emulsification (Ogolo et al. 2012, Li et al., 2013, Li et al.,2014, Abdelrahman et al., 2015). It has been reported that the use of nanoparticles can change the wettabilityof a formation and affect oil recovery (Ju et al., 2006, Ju et al, 2009). The types of the nanoparticles wouldaffect the wettability alteration. During the injection, high concentration of nano-structure particle fluidcould block the pore throats and result in permeability impairment, while colloidal nanoparticles fluid hassmall effect on permeability reduction, both adsorption/desorption and transport behavior of nanoparticleswould significantly affect wettability alteration and formation permeability (Li et al., 2015a, Li et al. 2015b).Fines migration within reservoirs and subsequent permeability reduction have been regarded assignificant cause of well performance impairment (Sarkar, 1990). Core flooding experiments studyrecognized that fluid salinity, flow rate, pH, temperature, rock and fluid polarity could influence finesmigration within reservoirs (Ezeukwu, 1998). Numerous methods of fine immobilization by Low salinitywater flooding (LSWF) or nanoparticles injections are currently under intensive development. Low salinityof injection water is considered to be the most practical and effective way to achieve mobility controlcompared to other fines release factors, and the mechanisms for mobility control have been largely focusedon wettability, relative permeability, capillary pressure and residual oil saturation (Tang and Morrow, 1999,Rivet et al., 2010, Takahashi and Kovscek, 2010). Due to the unique electrical, chemical properties and verysmall sizes of nanoparticles (Patra, 2008), it can effectively reduce the double layer repulsive forces betweenfine particles and rock grains and maintain the integrity of rock texture without fines detachments (Huang,2008). Laboratory experiments have demonstrated that the equilibrium adsorption of silica nanoparticles onsandstone, limestone and dolomite are different, unique ability of nanoparticles can stabilizing formationfines in water flooding (Yu et al., 2012, Huang et al. 2015). However, many research have been limited tolaboratory experiments and phenomenon observation serving as proof of concept, while the evaluation ofmechanisms of nanoparticles adsorption and detachment is yet to be addressed. Less attention has been paidto the quantitative index on nanoparticles adsorption and transport mechanisms.The efficiency of nanofluid flow and transport for adsorption and desorption during water flooding hasbeen studied by means of mathematical reservoir modeling. Because of the very small sizes of nanoparticlescompared to pore-throat sizes (in order of μm), five forces and Brownian motion dominate the interactionsbetween nanoparticles and pore walls (Kartic et al., 1999). Since the dynamic balance process of adsorptionand desorption is controlled by the force between nanoparticles and pore walls, both phenomenon occurduring flow and transport through porous medium (Zhang et al., 2013). Several studies have also reportedsuccessful applications of method of characteristics for two phase three components flow in 1-D permeablemedium, which is considered to be the good approach to quantify nanoparticles transport and fines migration(Yuan et al., 2015; Yuan et al., 2016).The main objective of this paper is to present both experimental and mathematical investigationson nanofluid flow with dynamic adsorption/detachment behavior and its negative effects on formation