Mechanisms and consequences of wettability alteration by crude oils

Reservoir wettability is controlled by crude oil/brine/rock interactions that have not been well understood. Studies using either model compounds or crude oil fractions have had only limited success in reproducing the wetting alteration that can occur in nature. In this study, the approach is first to identify the key features of interfacial activity unique to crude oils, then to design and conduct wetting alteration experiments—using both flat solids and porous media—that demonstrate the mechanisms by which alteration can occur. Components of crude oils that are interfacially active are found in the highest molecular weight, most polar fractions of the oil, the resins and asphaltenes. How these components affect wetting depends on the compositions of not only the oil, but also the mineral surfaces and the aqueous phase that is always present in oil reservoirs. Wettability altering interactions can occur by several mechanisms. In the absence of water, adsorption of polar species can create intermediately-wet surfaces. If the oil is a poor solvent for its asphaltene fraction, adsorption of large asphaltene aggregates can make surfaces fairly oil-wet. Adsorption can also occur because of ionic interactions between oppositely charged acidic and basic sites at the oil/water and solid/water interfaces. There may also be interactions between similarly charged sites, if ion binding can occur. All of these mechanisms have been documented for a range of crude oils with varying asphaltene fraction, solvency, acid number, and base number

Evaluation of Reservoir Wettability and Its Effect on Oil Recovery. Annual Report, February 1, 1996 to January 31, 1997

We report on the first year of the project, {open_quotes}Evaluation of Reservoir Wettability and its Effect on Oil Recovery.{close_quotes} The objectives of this five-year project are: (1) to achieve improved understanding of the surface and interfacial properties of crude oils and their interactions with mineral surfaces, (2) to apply the results of surface studies to improve predictions of oil production from laboratory measurements, and (3) to use the results of this research to recommend ways to improve oil recovery by waterflooding. During the first year of this project we have focused on understanding the interactions between crude oils and mineral surfaces that establish wetting in porous media. Mixed-wetting can occur in oil reservoirs as a consequence of the initial fluid distribution. Water existing as thick films on flat surfaces and as wedges in comers can prevent contact of oil and mineral. Water-wet pathways are thus preserved. Depending on the balance of surface forces-which depend on oil, solid, and brine compositions-thick water films can be either stable or unstable. Water film stability has important implications for subsequent alteration of wetting in a reservoir. On surfaces exposed to oil, the components that are likely to adsorb and alter wetting can divided into two main groups: those containing polar heteroatoms, especially organic acids and bases; and the asphaltenes, large molecules that aggregate in solution and precipitate upon addition of n-pentane and similar agents. In order to understand how crude oils interact with mineral surfaces, we must first gather information about both these classes of compounds in a crude oil. Test procedures used to assess the extent of wetting alteration include adhesion and adsorption on smooth surfaces and spontaneous imbibition into porous media. Part 1 of this project is devoted to determining the mechanisms by which crude oils alter wetting

Invasive neuroendocrine tumor of the kidney: a case report

Neuroendocrine tumors (NETs) involve the genitourinary system in less than 1% of cases, with primary renal carcinoids comprising only 19% of reported genitourinary NETs (56 cases worldwide). We report a case of a renal NET presenting as a large renal mass with extensive local invasion, requiring definitive radical en bloc resection via a thoracoabdominal approach

What do they know? Mapping the knowledge, attitudes, and practices of dog owners in the United States regarding dog training.

It has been suggested that dog training that utilizes a reward-based approach can promote a healthy relationship between dogs and their owners, but that aversive-based dog training methods may harm dog welfare and the human-animal bond. This study aimed to explore the factors influencing dog owners' decisions regarding dog training methods in the United States. A questionnaire was designed and implemented to assess dog owners’ training knowledge, perceptions, and practices. A convenience sample of 385 dog owners residing in the United States completed a survey promoted on social media. Descriptive analysis was performed for all data. Most respondents planned to or had already participated in training classes with their dogs. Most participants reported knowing enough to educate their dogs but would reach out for help with behavioral problems, advanced training, and puppy classes. The owners considered the stressfulness and reliability of training methods to be more important than how quickly the results were achieved. Participants preferred less stressful training methods, and the specific method used was most important when choosing a dog trainer or school. Dog owners indicated that the most important behaviors for their dogs to learn were recall, being calm at home alone, and good manners around people and other dogs. This study is the first assessment of dog owners in the United States and their knowledge, perceptions, and practices regarding dog training

Wettability and Prediction of Oil Recovery From Reservoirs Developed With Modern Drilling and Completion Fluids

Exposure to crude oil in the presence of an initial brine saturation can render rocks mixed-wet. Subsequent exposure to components of synthetic oil-based drilling fluids can alter the wetting toward less water-wet or more oil-wet conditions. Mixing of the non-aromatic base oils used in synthetic oil-based muds (SBM) with an asphaltic crude oil can destabilize asphaltenes and make cores less water-wet. Wetting changes can also occur due to contact with the surfactants used in SBM formulations to emulsify water and make the rock cuttings oil-wet. Reservoir cores drilled with SBMs, therefore, show wetting properties much different from the reservoir wetting conditions, invalidating laboratory core analysis using SBM contaminated cores. Core cleaning is required in order to remove all the drilling mud contaminants. In theory, core wettability can then be restored to reservoir wetting conditions by exposure to brine and crude oil. The efficiency of core cleaning of SBM contaminated cores has been explored in this study. A new core cleaning procedure was developed aimed to remove the adsorbed asphaltenes and emulsifiers from the contaminated Berea sandstone cores. Sodium hydroxide was introduced into the cleaning process in order to create a strongly alkaline condition. The high pH environment in the pore spaces changed the electrical charges of both basic and acidic functional groups, reducing the attractive interactions between adsorbing materials and the rock surface. In cores, flow-through and extraction methods were investigated. The effectiveness of the cleaning procedure was assessed by spontaneous imbibition tests and Amott wettability measurements. Test results indicating that introduction of sodium hydroxide played a key role in removing adsorbed materials were confirmed by contact angle measurements on similarly treated mica surfaces. Cleaning of the contaminated cores reversed their wettability from oil-wet to strongly water-wet as demonstrated by spontaneous imbibition rates and Amott wettability indices

Visual Advantage in Deaf Adults Linked to Retinal Changes

The altered sensory experience of profound early onset deafness provokes sometimes large scale neural reorganisations. In particular, auditory-visual cross-modal plasticity occurs, wherein redundant auditory cortex becomes recruited to vision. However, the effect of human deafness on neural structures involved in visual processing prior to the visual cortex has never been investigated, either in humans or animals. We investigated neural changes at the retina and optic nerve head in profoundly deaf (N = 14) and hearing (N = 15) adults using Optical Coherence Tomography (OCT), an in-vivo light interference method of quantifying retinal micro-structure. We compared retinal changes with behavioural results from the same deaf and hearing adults, measuring sensitivity in the peripheral visual field using Goldmann perimetry. Deaf adults had significantly larger neural rim areas, within the optic nerve head in comparison to hearing controls suggesting greater retinal ganglion cell number. Deaf adults also demonstrated significantly larger visual field areas (indicating greater peripheral sensitivity) than controls. Furthermore, neural rim area was significantly correlated with visual field area in both deaf and hearing adults. Deaf adults also showed a significantly different pattern of retinal nerve fibre layer (RNFL) distribution compared to controls. Significant correlations between the depth of the RNFL at the inferior-nasal peripapillary retina and the corresponding far temporal and superior temporal visual field areas (sensitivity) were found. Our results show that cross-modal plasticity after early onset deafness may not be limited to the sensory cortices, noting specific retinal adaptations in early onset deaf adults which are significantly correlated with peripheral vision sensitivity

SCA2003-01: EFFECT OF CRUDE OIL COMPOSITION ON WETTABILITY OF MICA

ABSTRACT While many factors are recognized as influencing reservoir wetting, they do so primarily by controlling the fate of components of the crude oil. Surface mineralogy, brine composition, temperature, pressure, and history of fluid occupation all are important variables, but if the oil does not contain species capable of adsorbing or depositing, reservoir rocks, the majority of which are initially water-wet, would remain in their original water-wet condition, while minerals that are naturally oil-wet would also be unchanged. In this study we focus on specific features of the composition of produced oil samples and relate them to the extent to which these oils alter the wetting of mica surfaces under controlled conditions. Wetting alteration tests were designed to control water film stability. The extent of wetting alteration was quantified by measurements of probe fluid contact angles. Oil properties were selected on the basis of previous studies that indicated the importance of ionizable species and asphaltene stability in the produced oil samples. Statistical tests between single variables and contact angles show little evidence of correlation, but more significant relationships were found using linear multivariate analyses and non-linear artificial neural networks