Wettability Index Research Articles

Hydroxyl-functionalized silicate-based nanofluids for enhanced oil recovery

During the production life of the reservoir, wettability alteration from an oil-wet to a strongly water-wet condition and/or lowering the interfacial tension (IFT) between the water and oil phases is required at various stages to enhance oil recovery (EOR). Several chemical agents as potential wettability modifiers (e.g., surfactants and polymers) have been regarded and widely used in oil-wet systems. Recently, various nano-fluids, prepared by dispersing nanoparticles in brine solutions or solvents, have attracted attention as injecting fluid due to their unique properties. A large number of nanoparticles are being investigated for EOR applications either as stand-alone or in combination with surfactants and/or polymers. Because of its stability in brine even at low concentrations, totally or partially hydroxyl-functionalized nano-pyroxenes are capable of recovering additional oil after water flooding. However, the influence of their concentration on various parameters has not been previously investigated. Thus, in this study, we investigated the influence of nano-pyroxene on wettability, IFT and asphaltene aggregation. Wettability measurements were performed by contact angle measurements, imbibition experiments and wettability index to understand the underlying mechanisms. The interaction between nanopyroxene and asphaltene size distribution was investigated as a function of nanopyroxene concentration by dynamic light scattering (DLS) measurements. Results from the IFT measurements, contact angle, imbibition experiments and core flooding tests confirm that nanopyroxene affects oil recovery. Contact angle and wettability index measurements confirmed that adsorption of the nanoparticles on the rock surfaces alters the wettability from intermediate wet to stronger water-wet in the absence and presence of initial water films. In the presence of irreducible water saturation during wettability index measurements, depending on the brine composition and pH, initial alteration with aging resulted in a mixed or intermediate wet that changed to stronger water-wet as the nanopyroxene concentration increased. Moreover, increasing the concentration of nanopyroxene resulted in a noticeable IFT reduction but not an ultra-low range that can remobilize trapped oil due to higher capillary forces. Core flooding tests indicated that nanopyroxene-based nanofluid injection offers ~12–14.5% additional oil in addition to waterflooding.

Parallel plications may enhance surface function: physical properties of transparent tunics in colonial ascidians Clavelina cyclus and C. obesa

AbstractAn array of nano-scale protrusions, called the nipple array, is found on the body surface of various invertebrates, and this structure is believed to decrease light reflectance and water wettability on the surface in the terrestrial environment. However, its potential functions have not been well studied in aquatic environments. Clavelina spp. are colonial ascidians that have the nipple array on their integumentary matrix (i.e. tunic). We examined the physical properties on the surface of the tunic of C. cyclus and C. obesa, such as hardness, wettability and refractive indices, to evaluate the functional importance of this structure. The tunic cuticle of both species was covered with the nipple array, and the cuticle of C. cyclus was bent into folds forming parallel plications. The Clavelina tunic was very soft and had high bubble- and oil-repellency. The refractive-index deviation between the tunic and seawater was 0.07–0.095 for 589-nm light (D-line). Rigorous coupled wave analysis (RCWA) showed that the nipple array slightly reduced reflectance on the surface and the parallel plications reduced the reflectance still more. The nanoimprinted plates imitating the parallel plications have higher bubble repellency and lower reflectance than the flat plates. These findings support the functional importance of the plications as well as the nipple array.

Surface water storage characteristics of main herbaceous species in semiarid Loess Plateau of China

AbstractPlant surface water storage greatly affects rainfall interception in water‐limited environments. The storage characteristics of 55 common herbaceous species and their relationships with plant morphology, biomass‐related traits, and leaf wettability were examined using artificial wetting method in semiarid Loess Plateau. Results indicated that plant mass storage ranged from 0.12–1.26 g g−1, and Glycyrrhiza uralensis and Leymus secalinus had the highest and lowest values, respectively. Leaf storage ratio ranged from 40.2–93.2%, with the highest value in G. uralensis and the lowest in Chenopodium album. Fifty‐two species had higher storage capacities in leaves than that in stems. Gramineous and leguminous species had relatively lower mass storage and leaf storage ratio than compositae and rosaceae. Plant and leaf mass storage were negatively correlated with leaf adaxial/abaxial contact angles, and stem mass storage was negatively correlated with plant height. Storage capacities were closely related to morphological and biomass‐related traits, and leaf area was a better predictor of plant and leaf storage capacities, and stem fresh weight was a better predictor at the stem level. Path analysis revealed that leaf area and adaxial contact angle were two independent variables directly affecting plant and leaf storage capacities. Their ratio (i.e., wettability index) had higher correlations with storage capacities than other single trait and multiple regression models of these traits. Our results implied that high proportions of gramineous and leguminous species in grassland community would favour reducing interception loss, and wettability index can be an effective indicator for evaluating rainfall interception and vegetation hydrological benefits.

Fabrication of Hydrophilic Silica Coating Varnish on Pineapple Peel Fiber Based Biocomposite

In the last several years, the interest on hydrophobic and hydrophilic solid subtract was increased due to many applications in daily life, agriculture and industry. The continuous effort has been made to fabricate suitable material with more efficient fabrication method. In this research, physical blending method have been used by mixing four components of modifying agent with organic beeswax varnish at different weight percentage. Those modifying agents consists of decamethylcyclopentasiloxane (D5), Silica nanoparticles (R812S), Polydimethylsiloxane (BP-9400) and non-ionic surfactant (Triton X-100) were mixed in the mass ratio of 52:3:34:1. The modified varnish produced was coated on Pineapple peel fiber (PAPF) biocomposite and were characterized using Water Contact Angle (WCA) instrument, Fourier Transform Infrared (FTIR) and Scanning Electron Microscope (SEM). Based on the wettability index analysis; the value of water contact angle was reduced when increasing weight percent of modifying agents from 101.87 to 22.98°. The morphology of the surface was observed to have more silica nanoparticles, along with the increasing concentration of modifying agent. It also supported by FTIR which shows the presence of Si-O peak at 1030.88 cm-1. These results proved that the modifying agent and organic beeswax varnish had successfully produced hydrophilic coated on the PAPF surface.

Effects of the washing-enhanced nucleation process on the material properties and performance of perovskite solar cells

CH3NH3PbI3 (MAPbI3) perovskite thin films were fabricated by using the one-step spin-coating method with a washing-enhanced nucleation (WEN) process under various dropping times, and the resultant thin films were characterized through the reflected-type optical microscope, atomic force microscope, transmittance spectrometer, X-ray diffractometer, photoluminescence spectrometer and water droplet contact-angle imaging system. The experimental results show that the dropping time for the WEN process strongly influences the surface morphology, surface wettability, crystallinity and refractive index of the resultant MAPbI3 thin films, which dominates the contact at the hydrophilic MAPbI3/hydrophobic 6,6-phenyl C61 butyric acid methyl ester (PCBM) interface and thereby determines the photovoltaic performance. In addition, this investigation helps further understand the effects of the WEN process on the formation of a closely-packed MAPbI3 thin film.

Practical Approach to Derive Wettability Index by NMR in Core Analysis Experiments

Practical Approach to Derive Wettability Index by NMR in Core Analysis Experiments

Relative permeability measurement in carbonate rocks, the effects of conventional surfactants vs. Ionic liquid-based surfactants

In the present study, the effect of two different kinds of surfactants namely conventional (Sodium dodecyl benzene sulfonate (SDBS)) and ionic liquid (IL)-based surfactants are investigated on the tertiary oil recovery using relative permeability concept. In this way, besides the Amott wettability index measurement, unsteady state core flooding tests are performed to not only find the effect of surfactant injection on tertiary oil recovery, but also to investigate their effects on relative permeability of carbonate rocks. In addition, for more reliable conclusions regarding the possible mechanisms, interfacial tension (IFT), compatibility and emulsification tests are carried out as a function of concentration. According to the results obtained through the core flooding experiments, it can be concluded that the injection of SDBS which substantially reduces the IFT value leads to higher tertiary oil recovery (26% based on original oil in place (OOIP)) although the ILs revealed more compatibility at the presence of harsh salinity conditions at any examined IL concentration in this study. Finally, the results obtained by plotting the relative permeability data and mining into the cross points one can conclude that in the case of using ILs, the active mechanisms during the tertiary oil recovery is dominantly related to wettability alteration mechanism while in the case of SDBS, the IFT reduction is the active mechanism.

Experimental Investigation of Aluminosilicate Nanoparticles for Enhanced Recovery of Waxy Crude Oil

Recently, research on cost-effective nanoparticles for improved and enhanced oil recovery has attracted increasing attention. Most of the existing research activities on the effects of nanofluids were focused on the alteration of wettability and the reduction of interfacial tension. However, in those studies, the nanoparticle solutions were presumably composed of not only bare nanoparticles but also with stabilizers or surfactants. It becomes ambiguous which components in the nanoparticle solutions played a role. In this work, we used a waxy crude oil and aluminosilicate nanoparticle to resolve the ambiguity. The objective of this work is to investigate the oil displacement mechanism by nanofluid through the measurements of the wettability index and interfacial tension as well as through core-flooding experiments. These experimental results showed that aluminosilicate nanoparticles could alter the rock surface wettability from water-wet to stronger water-wet and decrease the interfacial tension between oi...

On the development of a relative permeability equation of state

Standard compositional simulators use composition-dependent cubic equations of state (EoS), but saturation-dependent relative permeability and capillary pressure. This discrepancy causes discontinuities, increasing computational time and reducing accuracy. In addition, commonly used empirical correlations, such as the Corey relative permeability model, show a sole dependence of relative permeability on phase saturation, lumping the effect of other pore-scale phenomena into one tuning exponent. To rectify this problem, relative permeability has been recently defined as a state function, so that it becomes compositional dependent and single valued. Such a form of the relative permeability EoS can significantly improve the convergence in compositional simulation for both two- and three-phase flows. This paper revisits the recently developed EoS for relative permeability by defining relevant state variables and deriving functional forms of the partial derivatives in the state function. The state variables include phase saturation, phase connectivity, wettability index, capillary number, and pore topology. The developed EoS is constrained to key physical boundary conditions. The model coefficients are estimated through linear regression on data collected from a pore-scale simulation study that estimates relative permeability based on micro-CT image analysis. The results show that a simple quadratic expression with few calibration coefficients gives an excellent match to two-phase flow simulation measurements from the literature. The goodness of fit, represented by the coefficient of determination (R2) value, is 0.97 for relative permeability at variable phase saturation and phase connectivity, and constant wettability, pore structure, and capillary number (∼ 10− 4). The quadratic response for relative permeability also shows excellent predictive capabilities.

Interspecific variations in the surface wettability and morphological traits of petals across 125 plant species

Petal wettability is an important characteristic of flowering plants, as excess surface water on a petal can cause color loss and collapse of shape. However, few studies have examined natural variations in the wettability and the related morphological traits of petals. The present study investigated these characteristics across 125 species from a warm temperate habitat (Tokyo, Japan) by evaluating the contact angles (CAs) of water droplets on the petal epidermis as an index of surface wettability and cell curvature (= cell height/width) and the presence of epicellular structures, such as cuticular folds and trichomes as an index of the petal surface roughness. We found that more than half of the species possessed convex epidermal cells with epicellular structures. In addition, the majority of species had petals with low wettability (CAs varying between 90 and 140°), and only 2.4% and 12% of species possessed super-hydrophobic and hydrophilic petals, respectively. This natural distribution of petal wettability was less variable than that of leaves. Among the less wettable petals (CA > 90°), there was also a significant correlation between cell curvature and CA, and this relationship differed between the adaxial and abaxial sides. To assess the ecological importance of petal wettability, its relationships with life form and flower direction were examined. This showed that herbaceous plants have more convex epidermal cells than woody plants, but no significant difference was detected in their CAs. Besides, among upward-facing flowers, the adaxial side had a more convex and less wettable epidermis compared to the abaxial side, which may protect sky-facing adaxial epidermis from wetting by raindrops. However, there was no significant difference in these features between the adaxial and abaxial sides of sideward- and downward-facing flowers. The less clear tendency of petal wettability was attributable to multiple functions of the petal surface.

In-situ detection based on the biofilm hydrophilicity for environmental biofilm formation

A biofilm has a unique structure composed of microorganisms, extracellular polymeric substances (EPSs), etc., and it is layered on a substrate in water. In material science, it is important to detect the biofilm formed on a surface to prevent biofouling. EPSs, the major component of the biofilm, mainly consist of polysaccharides, proteins, nucleic acids, and lipids. Because these biomolecules have a variety of hydrophilicities or hydrophobicities, the substrate covered with the biofilm shows different wettability from the initial state. To detect the biofilm formation, this study employed a liquid-squeezing-based wettability assessment method with a simple wettability index: the liquid-squeezed diameter of a smaller value indicates higher wettability. The method is based on the liquid-squeezing behaviour of a liquid that covers sample surfaces when an air-jet is applied. To form the biofilm, polystyrene surfaces were immersed and incubated in a water-circulated bioreactor that had collected microorganisms in ambient air. After the 14-d incubation, good formation of the biofilm on the surfaces was confirmed by staining with crystal violet. Although the contact angles of captive bubbles on the surfaces with the biofilm were unmeasurable, the liquid-squeezing method could distinguish between hydrophilic and hydrophobic initial surfaces with and without biofilm formation using the diameter of the liquid-squeezed area. The surface wettability is expected to be a promising property for in-situ detection of biofilm formation on a macroscopic scale.

The Impact of Nanoparticle Adsorption on Transport and Wettability Alteration in Water-Wet Berea Sandstone: An Experimental Study

Wettability alteration was proposed as one of the enhanced oil recovery (EOR) mechanisms for nanoparticle fluid (nanofluid) flooding. The effect of nanoparticle adsorption on wettability alteration was investigated by wettability index measurement of Berea sandstone core injected with nanofluids and by contact angle measurement of a glass surface treated with nanofluids. Nanoparticle adsorption was studied by single phase coreflooding with nanofluids in Berea sandstone. The adsorption isotherm and the impact of adsorption on the effective permeability were investigated by measuring the effluent nanoparticle concentration and differential pressure across the core. Results showed that hydrophilic nanoparticles (e.g. fumed silica) made the core slightly more water wet, and hydrophobic nanoparticles (e.g. silane modified fumed silica) delayed spontaneous imbibition but could not alter the original wettability. It was found that hydrophilic nanoparticles treatment reduced contact angle between oil and water by about 10 to 20 degree for a glass surface. Results also showed that different types of nanoparticle have different adsorption and desorption behavior and different ability to impair the permeability of Berea sandstones cores.

Effect of divalent cations in low salinity water flooding in sandstone reservoirs

The never ending challenge for petroleum engineers is to improve recovery from existing reservoirs. One promising and relatively low cost method for improving recovery is low salinity (LS) waterflooding. Previously [1], we studied the effects that divalent cations (Ca2+ and Mg2+) in formation water (FW) have on LS water EOR tests, and we found that higher concentrations of divalent cations generally and specifically Ca2+ in FW lowered the performance of LS water EOR. In this study, we probe the significance of the Ca2+ and Mg2+ concentrations in the injected LS water. We also measured the wettability index to investigate the wettability alteration resulted after changing the divalent cations concentrations. Berea sandstone cores were saturated with oil and connate FW. Each core was flooded with two pore volumes (PV) of FW followed by two PVs of various LS waters at reservoir temperature (90 °C). During flooding, aqueous samples of the effluent were analyzed for pH, Ca2+ and Mg2+ concentration. Six LS water flood cases were investigated: (a) 3× dilution of Ca2+ with original Ca2+ concentration; (b) 3× dilution of Mg2+ with original Mg2+; (c) 3× dilution of both Ca2+ and Mg2+; (d) 10× dilution of Ca2+ with original Ca2+ concentration; (e) 10× dilution of Mg2+ with original Mg2+; (f) 10× dilution of both Ca2+ and Mg2+. Overall, both Ca2+ dilution cases achieved a positive LS effect (higher incremental oil recovery), with the 10× Ca2+ dilution producing a larger effect than the 3× dilution. The Mg2+ dilution cases produced either zero or small LS effects. When both Ca2+ and Mg2+ were diluted, there was a positive LS effect but less than for just Ca2+. The presence of Mg2+ inhibited the full benefit of the Ca2+ dilution.

Impact of Initial Wettability and Injection Brine Chemistry on Mechanical Behaviour of Kansas Chalk

The injection of seawater-like brines alters stiffness, strength and time-dependent deformation rates for water-saturated chalks. This study deals with the mechanical effects and oil production upon brine injection through wettability-altered samples. The results from two test programs are presented: (a) ‘Wettability determination program’ and (b) ‘triaxial test program’. Kansas chalk samples were saturated by a mixture of oil and water and aged over time at 90 °C. The wettability index of the altered samples was estimated using chromatographic separation tests by co-injecting sulphate ions that adsorb on the water-wet mineral surfaces and non-affine tracer. A good repeatability was observed. In the triaxial test program, unaged water-wet and aged mixed-wet samples were hydrostatically loaded to 1.5 times yield stress so stiffness and strength could be determined. The samples were kept at the same stress level over time to monitor the volumetric creep. After a stagnant flow period of 15 days, MgCl2 brine and seawater were flushed through the samples so the oil production and ion concentration of the effluent water could be obtained. The combined observations of the bulk volume, oil volume and estimated solid volume (from effluent analyses) enabled us to calculate pore volume and thereby oil saturation with time. The mixed-wet samples were found to be stiffer and stronger than the water-wet samples, and when the stress was kept at 1.5 times yield the creep curves overlapped. During the flow-through period, the changes in ion composition are insensitive to the presence of oil, and ongoing water weakening for mixed-wet samples is the same as in the water-wet samples. Further, we found that oil was only produced during the first 2–3 pore volumes (PVs) injected. Afterwards, no oil was produced even though the chemical reactions took place and pore volume reduced.

Wettability characterization of low-permeability reservoirs using nuclear magnetic resonance: An experimental study

Influence of wettability to petrophysical responses in low permeability reservoirs is increasingly evident, but research of nuclear magnetic resonance (NMR) technology on wettability calibration in such reservoirs is very limited even though it has been used promisingly. The challenge is that the empirical interpretation model only applies to simple pore structure. It is urgent to develop a relatively simple, quick, and practicable model for wettability evaluation in low permeable reservoirs.This paper presents an experimental NMR study, integrating with Amott tests, X-ray diffraction, and scanning electron microscope (SEM) measurements, on wettability characterization of five typical core samples from different low-permeability reservoirs. NMR relaxation mechanisms and the effect of the aging were analyzed in detail. The study showed that all the core samples had a shift of T2 (spin-spin relaxation time) spectra between before and after aging. According to the shift characteristics, the core samples were divided into two types. The first type is that the wettability alteration relied on the aging and it displaced crude oil into original water-wet movable pore spaces to restore reservoir wettability. This type of formation is generated in distant-source reservoirs, which mainly involves fluid transport through buoyancy. Another type is that the wettability alteration was attributed to the natural oil-wet property of the rock matrix. This formation is mainly found in inner-source or near-source reservoirs, which may generate abundant oil-wet materials. Thus, the wettability alteration is the result of hydrocarbon accumulation modes. Based on the observations, a potential method for obtaining the wettability index was proposed. The method uses both the ratio of oil-wetted to water-wetted pore surface areas and diffusion-relaxation diagrams. The estimated results corresponded reasonably to the independent Amott tests. This study demonstrates that NMR relaxation is an effective solution to analyze and quantify wettability in low permeability reservoirs.

Encapsulation of curcumin in milk powders by spray-drying: Physicochemistry, rehydration properties, and stability during storage

Curcumin is a natural polyphenol that has strong antioxidant, anti-inflammatory and anti-carcinogenic properties, however, it is sensitive to light, oxygen and heat, and also presents very low solubility in water. Several studies have focused on curcumin preservation and bioavailability due to its health importance, especially by encapsulation. Milk may constitute a good matrix for the encapsulation of curcumin, because it contains a significant proportion of casein micelles which are amphiphilic and porous, making them suitable for carrying hydrophobic substances such as curcumin. This work aims at evaluating the efficiency of milk for encapsulating curcumin, releasing it in an aqueous medium during powder reconstitution, and improving its preservation during storage. Curcumin was encapsulated by spray-drying at pilot scale, extracted by different solvents, and quantified by UV/Vis. spectrophotometry. Physicochemical characteristics (particle size distribution, water content, water activity, and color) and rehydration properties (wettability, dispersibility, and solubility indices) of curcumin-loaded milk powder were characterized. A powder storage study was also conducted to evaluate the stability of curcumin over time at different temperatures (10, 25 and 50 °C). Drying conditions were set to obtain a product of water activity close to 0.2. A method for curcumin extraction and dosage was also validated using diethyl ether as extraction solvent. Milk powder loaded with curcumin showed no significant differences in most characteristics compared to raw milk powder, except that its wettability was decreased by the presence of curcumin. Moreover, the good encapsulation yields and the stability of curcumin antioxidant activity during storage showed the suitability of skim milk for curcumin encapsulation.

The role of ferrous clays in the interpretation of wettability – a case study

Clean sandstone, with minimal clay content, is expected to be strongly water wet once the rock has been through an effective cleaning process. Even samples containing significant clay minerals are usually expected to be water wet after appropriate cleaning. However, tests carried out on core samples from Fields in three different global locations show mixed indices, even for clean state samples where no aging with crude oil has taken place. A few hypotheses for this behaviour considered herein are: whether the cleaning method was adequate, whether wettability was altered by an external factor, or if wettability was due to mineral composition. This paper presents the results obtained from wettability studies on fresh, clean and restored state core plug samples from three different Fields. Wettability indices were obtained by using the combined Amott-USBM method. Petrography was performed on sample end-trims to investigate the possible presence of halite or barite in the clean state samples, thought to be from drilling fluid infiltration, which should have been removed by the methanol cleaning cycle. This showed no organic material or salt (halite), negating wetting change from inefficient cleaning. From a reactive clays [1] model perspective, these rock samples are considered clean-sand (i.e. illite/ smectites- as total clay content), determined by XRD analysis, are lower than 10%. SEM and XRD results showed the presence of grain-coating chlorite in one sample set and glauconite grains in the others. Only once the unusual wettability indices were obtained was the grain-coating chlorite identified as chamosite by SEM/EDX, which is an iron-rich form of chlorite. The presence of chamosite or glauconite appears to influence the wetting tendency. In summary, USBM vs Amott wettability indices of the analysed samples are consistent between both methods, showing a mixed to oil-wet tendency for all samples where chamosite was identified, regardless of the initial test condition. Samples with glauconite appeared to be more mixed wet after wettability restoration. The results suggest that iron rich clay/mineral content is the main contributor to the oil wet tendency of the evaluated rocks.

A laboratory scale approach to wettability restoration in chalk core samples

Wettability in chalk has been studied comprehensively to understand fluid flow mechanisms impacting coreflooding experiments. Wettability becomes paramount in understanding the parameters influencing chalk-fluid interactions. The main objective of this work is to evaluate as to which degree the wettability in chalk core samples can be controlled in the laboratory. Kansas chalk samples saturated with brine (1.1 M/64284 ppm NaCl) and an oil mixture (60% - 40% by volume of Heidrun oil and heptane) were aged at a constant temperature of 90oC with aging time as the laboratory control variable. A multimodal method incorporating contact angle measurements, wettability index via USBM test, and SEM-MLA analysis was applied in evaluating wettability. A systematic approach was applied with the three different methods to quantify the degree of uncertainty linked to a) wettability estimation and b) the aging procedure to control wettability alteration of Kansas chalk. With a comprehensive suite of samples, we were successfully able to alter the wettability of chalk cores.

Wettability of juvenile plumage as a major cause of mortality threatens endangered Barau's petrel

Seabirds spend most of their life at sea and have to possess a waterproof plumage to be able to sit on water for extended periods. We tracked juvenile Barau's petrels for the first time, when they leave their birth colony and found that half of the transmitters stopped soon after they first landed on the water off Réunion Island. We suspected from observation at sea that birds may have problems with the waterproofness of their plumage. Therefore during the next season we set up a simple protocol to assess waterproofness of the plumage of the birds just before they fledge. This protocol is based on the calculation of a wettability index expressed as the mass of water logged in the plumage after simulating the bird sitting on the sea surface. We found that at least one third of chicks ready to fledge gained more than 4 g of water in 20 s, indicating that plumage was not waterproof. Within a sample of birds having fledged and before reaching the sea surface, a similar proportion of birds had their plumage not waterproof. For the birds tracked, only those with an index indicating a waterproof plumage successfully dispersed after their first touch on the sea surface. We provide evidence of a possible major cause of mortality of juvenile seabirds that has not been described previously in wild seabirds, but could exist in other species. This issue may be a major cause of threat to the endangered Barau's petrel.

Spatially resolved wettability measurements using nmr wettability index

Wettability is a crucial petrophysical parameter for determining accurate production rates in oil and gas reservoirs. However, industry standard wettability measurements (Amott Test and USBM) are expensive and time consuming. It is known that NMR response varies as a function of wettability change in rock core plug samples. This information was used to develop an NMR wettability index (NWI) based on T2 distributions. This NWI is capable of measuring changes in wettability as a function of oil/water saturations unlike traditional methods which are based on measurements at Swi and Sor only. In addition, these oil/water saturations are determined without the aid of any special oil or brine, such as D2O. This allows the NMR method to nondestructively monitor changes in wettability in real time (i.e. during a flooding experiment or an aging procedure). In this work, we have coupled this T2-based NWI to spatially resolved T2 NMR measurements to monitor changes in wettability and saturation along rock core plugs. In order to derive an NMR wettability index, NMR T2 spectra of 100% brine saturated, 100% oil saturated, bulk oil and bulk brine are needed. These spectra are then mixed to give a predicted T2 spectrum which is compared (via a least squares fit) to a T2 spectrum recorded from a sample partially saturated with both water and oil and whose wettability is to be determined. For initial testing, three sandstone samples were employed along with 2% KCl brine and dodecane. To achieve sample states of mixed wettability, 100% brine saturated samples had dodecane pushed into them via centrifugation. Centrifugation at different speeds resulted in samples of varying bulk and spatial wettabilities from which NWI parameters and oil/water saturations were determined. The bulk wettabilities were compared to measurements done using the standard Amott test and oil/water saturations were confirmed by repeating experiments using NMR invisible D2O.