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Journal ArticleDOI

Effect of transverse forces on velocity of nanoparticles through a single fracture in a fractured petroleum reservoir

29 Jun 2016-International Journal of Oil, Gas and Coal Technology (Inderscience Publishers (IEL))-Vol. 12, Iss: 4, pp 379
TL;DR: In this paper, the effect of van der Waals and gravity force on the velocity of nanoparticles through a single fracture was studied. And the particle size limit was identified as the size beyond which the nanoparticles have negligible velocity through the fracture.
Abstract: The present experimental and numerical study aims to study the effect of transverse forces on the velocity of nanoparticles through a single fracture. The velocity of nanoparticles is computed with the effect of van der Waals and gravity force through a single fracture based on the parallel plate model for a fixed half fracture aperture and temperature, a selected nanofluid (type of nanoparticles and dispersing medium) over a range of particles sizes. Particle size limit is identified as the particle size beyond which the nanoparticles have negligible velocity through the fracture. Effect of half fracture aperture and temperature on particle size limit is studied. Finally, the numerical model is applied to experimental data obtained for a range of silane coated silica and alumina nanofluids prepared in distilled water and formation water of an Indian carbonate reservoir to screen the nanofluids for flooding applications. [Received: July 31, 2014; Accepted: March 2, 2015]
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Journal ArticleDOI
TL;DR: Estimates of the surface forces confirmed that nanoparticle–mineral interaction is less attractive in LSW as compared to SSW and DIW, and indicated a reduction in the adsorption rate with increasing nanoparticle concentration in L SW.
Abstract: This study addresses the kinetics of silica nanoparticle adsorption on calcite from a solution at three salinities: deionized water (DIW), synthetic seawater (SSW), and low salinity water (LSW). The nanoparticle adsorption mechanisms and the effects on calcite dissolution are addressed. It was shown that nanoparticle adsorption was best described with the second-order-kinetic model and that silica nanoparticle adsorption reduced calcite dissolution. This was confirmed by measuring the Ca2+ ion concentration, the pH, and by estimating the amount of calcite dissolved. This is an important conclusion of this work, especially as LSW as an enhanced oil recovery technique is a candidate for use in chalk fields. Less formation damage/dissolution of chalk when silica nanoparticles are combined with LSW can lower the risk of reservoir subsidence. Intraparticle diffusion and the pseudo-second-order models, indicated a reduction in the adsorption rate with increasing nanoparticle concentration in LSW. This is explained by possible repulsive forces among the nanoparticles as they diffuse from the bulk fluid onto the calcite surface. Ion charges reduce the repulsion among the nanoparticles through shielding. However, an increasing nanoparticle concentration reduces the shielding efficiency by the ions. Estimates of the surface forces confirmed that nanoparticle–mineral interaction is less attractive in LSW as compared to SSW and DIW.

19 citations

Journal ArticleDOI
TL;DR: In this article, the adsorption of silica nanoparticles (NPs) dispersed in different brines on chalk surfaces and their effect on fluid/rock interaction was addressed.
Abstract: The main objective of this work is to address the adsorption of Silica nanoparticles (NPs) dispersed in different brines on chalk surfaces and their effect on fluid/rock interaction. Isothermal static and dynamic adsorption on chalk are addressed here. Isothermal static adsorption showed increased adsorption of NPs at higher salinity. The tests were performed to cover wide range of injection scenarios with synthetic seawater (SSW) and low salinity water (LSW). The selected LSW composition here is based on 1:10 diluted SSW, which has shown to have superior performance compared to other ion compositions. The dynamic adsorption tests of NPs showed reduction of calcite dissolution of about 30% compared to LSW alone. That is, silica nanofluid hinders calcite dissolution i.e., has less effect on chalk matrix integrity which is a major concern in chalk reservoir, if low salinity is employed for enhanced oil recovery. Both scanning electron microscope images and pressure drop across the core during nanofluid injection indicated no throat blockage. Based on ion tracking and the monitored pH, the mechanism(s) for NP adsorption/desorption are suggested. The results from this study suggests a synergy wherein adding relatively small amount of silica NPs can improve the performance of low salinity floods.

18 citations

Journal ArticleDOI
27 Oct 2018-Water
TL;DR: In this article, a numerical model was developed to investigate the influence of gravity on the transport of colloids in a single horizontal fracture-matrix system, and prominence was given to study the mass flux at the fracture and colloid penetration within the rock matrix.
Abstract: A numerical model was developed to investigate the influence of gravitational force on the transport of colloids in a single horizontal fracture–matrix system. Along with major transport phenomena, prominence was given to study the mass flux at the fracture–matrix interface, and colloid penetration within the rock matrix. Results suggest that the gravitational force significantly alters and controls the velocity of colloids in the fracture. Further, it was shown that the colloid density and size play a vital part in determining the extent that gravity may influence the transport of colloids in both fracture and rock matrix. The mass flux transfer across the fracture–matrix interface is predominantly dependent on the colloidal size. As large as 80% reduction in penetration of colloids in the rock matrix was observed when the size of the colloid was increased from 50–600 nm. Similarly, the farther the density of colloid from that of the fluid in the fracture (water), then the higher the mitigation of colloids in the fracture and the rock matrix. Finally, a non-dimensional parameter “Rock Saturation Factor” has been presented in the present study, which can offer a straightforward approach for evaluating the extent of penetration of colloids within the rock matrix.

10 citations

Journal ArticleDOI
TL;DR: In this article, the impact of different concentrations of nanofluids on the displacement of oil from a thin gap and to understand the behavior of the interfaces by studying the interfaces on both macro and micro scales, and by examining variation in the relative permeabilities, mobility ratios and capillary numbers.

4 citations

MonographDOI
01 Mar 2020
TL;DR: In this paper, the authors investigated the adsorption mechanisms of silica NPs and their effect on fluid/rock interactions during nanofluid injection, and showed that the adorption process on quartz and calcite was best fitted to pseudo second order kinetic model.
Abstract: Conventional oil production from petroleum reservoirs generally leaves more that 50% of the original oil in place unrecovered. This residual oil is the target of various enhanced oil recovery (EOR) techniques that involve fluid injection into the reservoir which supplements oil recovery by interacting with the rockoil-brine system. Silica nanofluids have emerged as a promising fluid for EOR. Nanofluids are colloidal suspensions of nanoparticles (NP) dispersed in a suitable fluid. Over the past decade, a lot of research has focused on investigating silica nanofluids for EOR applications. This thesis addresses the mechanisms for silica NP adsorption and fluid/rock interactions during nanofluid injection. Understanding these processes would aid efficient design of nanofluid floods. In chapter 1 of the thesis, a brief background of the research conducted into silica nanofluids for EOR is discussed. Wettability alteration, interfacial tensionreduction and structural disjoining pressure due to NP wedge formation are the major mechanisms attributed to incremental oil recovery by silica NPs. However, the adsorption mechanisms of silica NPs and their effect on fluid/rock interactions are not well understood. This thesis focusses on the adsorption of silica NPs for sandstone and chalks mineral surfaces and their effect on fluid/rock interactions. The materials and methods used in this study are presented in chapter 3. Chapter 4 addresses the surface modification of berea sandstone by the in-house silica nanofluids. Fines migration during water injection, especially in the case of low salinity, is a potential problem in sandstone reservoirs. It is shown that adsorption of silica NPs in berea sandstone reduces production and migration of fines. This is due to reduction of direct contact between the flooding fluid and rock minerals. The reduction of the fines was indicated by the reduced pressure drop, i.e. reduce the flow resistance of the fluid during the post flush of the NPs’ slug. In addition, it was shown that the adsorption of silica NPs modify sandstone surface and make the interaction between the modified surface and the fine particles more attractive. So, modified surface acts as a “collector” for the fines. The in-house silica nanofluids show limited stability of the dispersed NPs. To proceed with the objectives of this work, it was decided, then, to acquire a more stable commercial silica nanofluid (DP9711 from Nyacol Nano technologies). The nanofluids’ stability was confirmed at our laboratory. Two types ofadsorption experiments were performed: (1) static adsorption of silica NPs on minerals and (2) dynamic adsorption of silica NPs injected into sandstone and chalk cores. The kinetic aspects of silica NP adsorption were also addressed. The static adsorption was done to address the silica NPs adsorption affinity to the different minerals (calcite, quartz and kaolinite) and the kinetics of the adsorption process (chapter 5). The dynamic adsorption of the injected silica NPs was performed to address the extent of the fluid/rock (sandstone and chalk) interactions in chapter 6. Fluid/rock interactions during oil recovery by continuous injection of silica nanofluids are addressed in chapter 7. Silica NPs shows high adsorption affinity towards calcite mineral followed by quartz, and the lowest adsorption affinity towards kaolinite. The scanning electron microscopy (SEM) images did not show pore throat blockage. This was also confirmed by the improved injectivity during nanofluids injection. Silica NPs’ adsorption process on quartz and calcite was best fitted to pseudo second order kinetic model. Both the rate of adsorption and the level of equilibrium adsorption increases with the salinity. The adsorption of NPs is largely influenced by the fluid pH for chalk and sandstones. Increased alkalinity during low salinity flooding favours NP desorption. However, dynamic adsorption of NPs injected into chalk and sandstone core showed high irreversible adsorption at elevated salinity (synthetic seawater: SSW). It is interesting to see that in the limited oil recovery experiments; mineral dissolution, suppression of the ion exchange process and loss of cementing minerals caused by low salinity injection, were reduced by silica nanofluids. It is also shown that the silica NPs modifies the mineral surface and made the interaction energy between the fines and the mineral surface more attractive for both LSW and SSW. In other words, the silica nanofluids reduce the probability for formation damage associated with low salinity water injection in sandstone reservoirs. Some incremental oil recovery was observed with silica NPs. However, limited experiments were performed on oil recovery, hence the recovery by nanofluids has not been optimized in this work. NP adsorption on chalk significantly reduced calcite dissolution by about 30%. That is the silica nanofluid reduced the detrimental effect of low salinity flooding on chalk matrix integrity which is one of the major concerns in chalk reservoirs. As mentioned earlier oil recovery optimization was not performed. The results from this work identified that silica nanofluids can potentially increase oil recovery from chalks as compared to low salinity injection alone. The main outcome of this work suggests a synergy between silica NPs and low salinity flooding technique for EOR wherein, addition of silica NPs to low salinity water can reduce formation damage in sandstone reservoirs and reduce the risk of reservoir subsidence due to calcite dissolution in chalk reservoirs. The results from this work identified that silica nanofluids can potentially increase oil recovery from chalks as compared to low salinity injection alone. The main outcome of this work suggests a synergy between silica NPs and low salinity flooding technique for EOR wherein, addition of silica NPs to low salinity water can reduce formation damage in sandstone reservoirs and reduce the risk of reservoir subsidence due to calcite dissolution in chalk reservoirs.

3 citations