Wettability alteration is an important method to increase oil recovery from oil-wet carbonate reservoirs. Chemical agents are used as wettability modifiers in carbonate systems; however, the role of Nanoparticles in this field is still in its infancy and consequently has attracted the attention of many researchers in the last decade. In this work, the impact of SiO 2 Nanoparticles on the wettability of a carbonate reservoir rock was experimentally studied. The impact of these Nanoparticles on the wettability of carbonate systems is still in its infancy. For this purpose, the effect of Nanofluid's concentration on wettability and interfacial tension were investigated to determine the optimum concentration of Nanofluid for injection into core samples. The result suggests that a concentration of 4 g/L of Nanofluid could significantly alter the wettability of the rock from a strongly oil-wet to a strongly water-wet condition. Moreover, we studied the Nanofluids' potential in enhanced oil recovery of oil-wet core plugs. The results show that a considerable amount of oil can be recovered right after start of water injection to the aged core plug with Nano fluid.

New technologies are emerging oil industry to afford the need for increasing oil recovery from oilfields, one of which is Nanotechnology. This paper experimentally investigates a special type of Nanoparticles named Polysilicon ones which are very promising materials to be used in near future for enhanced oil recovery. There are three types of Polysilicon Nanoparticles which can be used according the reservoir wettability conditions. In this paper, hydrophobic and lipophilic polysilicon (HLP) and naturally wet polysilicon (NWP) are investigated as EOR agents in water-wet sandstone rocks. These two Nanoparticles recover additional oil through major mechanisms of interfacial tension reduction and wettability alteration. The impact of these two Nanoparticle types on water-oil interfacial tension and the contact angle developed between oil and the rock surface in presence of water phase were investigated. Then, several coreflood experiments were conducted to study their impacts directly on recoveries. Furthermore, optimum pore-volume injection of each Nano-fluid was determined according the pressure drop across the core samples. The results show a change toward less water-wet condition and a drastic decrease in oil-water interfacial tension from 26.3 mN/m to 1.75 mN/m and 2.55 mN/m after application of HLP and NWP Nano-fluids respectively. As a result, oil recoveries increase by 32.2% and 28.57% when a 4 gr/lit concentration of HLP and NWP Nano fluids are injected into the core samples respectively. According the differential pressure data, two and three pore-volume injections of NWP and HLP Nano-fluids are the best injection volumes respectively. Finally, HLP and NWP Nanoparticles improve oil recovery without inducing any formation damage according the oil recovery and pressure drop data.

Regarding the most reservoirs around the world are experiencing their second half of life, the need for an appropriate EOR method utilizing efficient new technologies gets more important. Nanotechnology is an advanced technology finding its place in EOR processes as it provides a high potential for oil and gas recovery. In this study, a special type of polysilicon nanoparticle (HLP, Hydrophobic and Lipophilic Polysilicon) is investigated as an EOR agent during different water injection scenarios. The water-wet sandstone core samples are employed. Injection of HLP nanoparticle dispersed in a carrier fluid can improve oil recovery through two mechanisms: reduction of interfacial tension and wettability alteration. Reduction of interfacial tension improves pore-scale displacement efficiency. In addition, wettability alteration towards less water-wet condition provides an ideal wetting state increasing oil recovery. Three scenarios of HLP nanofluid injections are applied. First, the nanofluid is injected after waterflooding at ultimate oil saturation. Second, 3 porevolume water injection is applied after the sequence of water and HLP nanofluid injections. Third, HLP nanofluid is injected from beginning. HLP nanofluid application lowers the oil-water interfacial tension by a factor of ten as well as changing the contact angle from 123° to 99°indicating less water wet condition. The experienced oil recoveries and pressure drops during the experiments are reported for each scenario. In all scenarios, the most of oil recovered through the first injected pore volume. According to oil recoveries, nanofluid injection from the beginning can enhance oil production considerably in compare to the other ones. Moreover, pressure drop data indicate severe permeability impairment after three pore-volume injection of nanofluids. Experimentally, nanotechnology has proved its potential to enhance oil recovery however many aspects are still in progress to be known.

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Prevention of asphaltene formation in reservoir rocks can result in resolving a severe long-lasting issue in petroleum production. The present research addresses the issue in the context of exploring the potential effect of nickel oxide (NiO) nanoparticles in destabilizing asphaltene deposition in porous media, in the presence of carbon dioxide. To ensure proper distribution within the system and to retain future field-scale applicability, the NiO nanoparticles were exposed to the in situ oil via injection gas stream, in which they had been uniformly dispersed using polydimethylsiloxane (PDMS). The experimental results, established under miscible CO 2 state, indicate a considerable improvement in permeability/porosity reduction of core, as well as less asphaltene accumulation in porous media and increased oil recovery factor after applying NiO nanoparticles.