Oil Layer Thickness Research Articles

EVALUATION OF OLEOPHILIC SKIMMER PERFORMANCE IN DIMINISHING OIL SLICK THICKNESSES

ABSTRACT 2017-086 ASTM F2709-15 “Standard Test Method for Determining a Measured Nameplate Recovery Rate of Stationary Oil Skimmer Systems” has become the standard for testing the performance of stationary skimmers. This standard specifies testing the skimmer in “ideal conditions” in order to measure a skimming system’s maximum performance. These ideal conditions are created by testing the skimmer in calm conditions and allowing the skimmer to recover either in pure oil or in a thick layer of oil on water. When testing the skimmer in oil and water, the skimmer recovers oil in a starting oil thickness of 75mm and continues recovery until the oil thickness reaches 50mm. Performance values obtained from this test include measured nameplate recovery rate (NRR) which is the maximum rate at which the skimmer system can recover and process oil under ideal conditions, and the recovery efficiency (RE) which is the percentage of oil collected to total fluid collected. In actual oil spills it cannot be assumed that a skimmer will encounter enough oil to continuously conduct recovery operations in 50–75mm of oil. As these performance values are becoming a tool used by regulators to verify the capabilities of response equipment listed in oil spill response contingency plans, it is important to understand if and how a skimmer’s performance will vary as oil slick thickness changes. To explore this question, the Bureau of Safety and Environmental Enforcement (BSEE) and Ohmsett - The National Oil Spill Response Research and Renewable Energy Test Facility, recently conducted independent performance testing of two oleophilic skimming systems to better understand the relationship between oil recovery rate, recovery efficiency, and different oil slick thicknesses. Skimmers were tested in various oil slick thicknesses ranging from 75mm down to 6mm at the Ohmsett facility. Skimmers were tested in a type I refined test oil as defined by the ASTM F631-15 “Standard Guide for Collecting Skimmer Performance Data in Controlled Environments.” Testing results suggest that reduced oil thicknesses do indeed have a significant impact on the measured recovery capabilities of a skimmer. This paper outlines the final testing results, and discusses the potential implications of using ASTM F2709-15 performance values in conjunction with various oil spill response planning standards for mechanical oil recovery equipment.

Experiments at Sea with Herders and In Situ Burning (HISB)

ABSTRACT A series of experiments involving herders and ISB (designated HISB) were conducted at sea on 14th – 15th June 2016, near the Frigg Field in the North Sea. The primary objective of the experiments described in this paper was to demonstrate, at near-full scale, the use of herders followed by in situ burning (ISB) in open water conditions and validate the findings of an earlier field study of herders in conjunction with ISB. Two experimental releases of 6 m3 (approximately 40 barrels) and one of 4 m3 of Grane Blend crude oil were undertaken. The released oil spread out differently on the sea surface in each of the slicks due to slight variations in release conditions and prevailing wind conditions. Herder (ThickSlick 6535) was applied around two of the slicks by spraying from a small boat; a third slick was not herded before ignition. In the first test, approximately 80% of the total amount of thick oil was herded to form a coherent slick with an average oil layer thickness of approximately 3 mm to 5 mm. The second herded slick accounted for 40% of the amount of oil released and resulted in an average layer thickness of approximately 2 mm to 3 mm present as several discrete areas of thick oil. The average oil layer thickness in the non-herded slick was 2.5 mm to 3 mm (under very calm weather conditions) and this slick had also been broken up into several discrete areas of thick oil. Ignition with gelled gasoline igniters was carried out approximately one hour after oil release. All three slicks were successfully ignited. Approximately 3.4 m3 of the available oil in the first herded slick was consumed in three distinct burns, while the second herded slick consumed 0.8 m3 of oil in only one burn. The remaining test involving an unherded slick consumed approximately 1.2 m3 of oil in three burns.

Experimental Investigation of Sand Jets Passing Through Immiscible Fluids

Laboratory experiments were conducted to study the dynamics of sand jets passing through two immiscible fluids. Different oil layer thicknesses, nozzle diameters, and sand masses were employed. Evolution of oily sand jets with time was investigated using image processing and boundary visualization techniques. Different shapes of the frontal head and trailing wave section were observed and cloud formation was classified into different categories based on Reynolds number, normalized oil layer thickness, and evolution time. It was found that the effect of Reynolds number on evolution of oily sand jets was more significant than the other parameters. Width and frontal velocity of oily sand jets were measured at different times. It was observed that oily sand jets became unstable after a distance of ten times larger than the nozzle diameter. Instability of oily sand jets caused intense spreading with a spreading rate of 0.4. The thin layer of oil encapsulated sand cluster was ruptured due to excess shear stress and caused bursting of the frontal head into a cloud of sand particles. Three different bursting mechanisms were observed and a correlation was found between the densimetric Froude number and the normalized bursting time. Data mining and boundary visualization techniques were used to model oily sand jets. Model trees were developed to classify and predict the growth of oily sand jets at different conditions. Modeling results indicated that the Model tree can predict the growth of sand jets with an uncertainty of ±8.2%, ±6.8%, and ±8.7% for width, velocity, and distance, respectively.

Lithology and oil-bearing properties of tight sandstone reservoirs: Chang 7 member of Upper Triassic Yanchang Formation, southwestern Ordos Basin, China

Using core, well logging, geological analysis, production, and test data, this study characterizes a method of well logging for identifying lithology, oil or water layers, and thickness of oil layers of tight sandstone reservoir in the Chang 7 member of the Upper Triassic Yanchang Formation, southwestern Ordos Basin, China. This reservoir consists of two rock types: fine sandstone and siltstone. The fine sandstone has distinct oil traces and flecks, which strongly indicate the presence of oil, and this rock is therefore the superior reservoir. The siltstone exhibits essentially no oil shows and thus is an unproductive layer. A method of density and neutron curve normalization and overlay was used to identify the tight fine sandstone, tight siltstone, mudstone, and shale. The criteria for identifying the tight fine sandstone are a natural gamma value of less than 93 API (American Petroleum Institute units) and a difference between the normalized curves exceeding 0.05. A resistivity-porosity plot was used to identify oil or water layers relatively effectively. The criteria for identifying the tight oil layers are (1) a resistivity exceeding 28 Ω·m and a porosity exceeding 9.5% or (2) a resistivity between 20 and 28 Ω·m, a porosity exceeding 9.5%, and an oil saturation exceeding 65%. Based on the lithologic identification via normalization and overlay of the density and neutron curves and the criteria for distinguishing the tight oil layers, the thickness of the tight fine sandstone oil reservoir was accurately determined by overlaying the normalized difference curve on the resistivity curve.

Effect of asymmetric elliptical shapes of the sealing ring sliding surface on the main parameters of the oil film

This article discusses the results of simulation studies of the effect of selected sealing ring sets with asymmetrical elliptical sliding surfaces on the oil layer thickness distribution over the whole operating range of an internal combustion engine. The problem of calculating the sliding surface coverage with visco-elastic oil film as well as in mixed friction conditions is discussed. The effect of asymmetrical elliptical sliding surfaces particularly on the dimensionless slip and squeeze indicators was determined, defining these surfaces ability to produce an oil film. The research results presented in this article show that there exists a real possibility of friction loss re-duction in the cylinder and sealing rings contact area, while maintaining the oil film continuity between the sliding surfaces.

Reproducing kernel method for numerical simulation of downhole temperature distribution

This paper research downhole temperature distribution in oil production and water injection using reproducing kernel Hilbert space method (RKHSM) for the first time. The aim of this paper is that using the highly accurate RKHSM can solve downhole temperature problems effectively. According to 2-D mathematical models of downhole temperature distribution, the analytical solution was given in a series expansion form and the approximate solution was expressed by n-term summation of reproducing kernel functions which initial and boundary conditions were selected properly. Numerical results of downhole temperature distribution with multiple pay zones, in which different radial distance and different injection–production conditions (such as injection rate, injection temperature, injection time, oil layer thickness), were carried out by mathematical 7.0, and numerical results correspond to general knowledge and show that use RKHSM to research downhole temperature distribution is feasible and effective.

Dynamics of a bubble bouncing at a liquid/liquid/gas interface

We study the dynamics of an air bubble bouncing at a liquid/liquid/gas interface, which we refer to as a compound interface. When a bubble interacts with a thin layer of oil on top of bulk water, the oil layer modifies the interfacial properties and thus the entire process of bouncing and bubble bursting. The influence on the bubble motion is experimentally and numerically investigated. Based on the coefficient of restitution and the damping rate of the bubble velocity profile, the damping increases with the oil layer thickness and viscosity. In addition, the effect of the oil layer thickness is more prominent for high-viscosity oil. Furthermore, a reduced-order mass–spring–damper model is proposed to describe the bubble bouncing at the compound interface, which predicts the time of the first contact of the bubble with the interface and agrees well with the experimental results. Such a model also captures the general experimental trends of the coefficient of restitution for the multiphase system. Our work contributes to a further understanding of the collision and coalescence of bubbles with a compound interface.

The problems of piston skirt microgeometry in combustion engines

Geometry of the slot between piston bearing surface and cylinder bore affects the friction losses of the IC engine to the far extent. It appears that these losses depend more on the area covered with oil than the thickness of oil layer separating collaborating parts. Barrel-shaped or stepwise piston bearing surface is the way to reduce the oil covered area. Turns out that the referred to friction losses contributes more to area covered by the oil film than the film thickness of the separation elements cooperating. The method to reduce the area covered by the oil film is a modification of the bearing surface of the piston by adjusting the profile. This paper presents the results of simulation leading to the reduction in friction losses and abrasive wear of piston bearing surface and cylinder bore. Covering the piston bearing surface with a thin layer of graphite one can get an extremely advantageous tribological properties of the piston assembly which means the expected parameters of oil film and in a case of film rupture-an ignorable abrasive wear of the graphite layer and/or cylinder bore.

THE PROBLEMS OF HYDRODYNAMIC NON-ISOTHERMAL LUBRICATION

The classical hydrodynamic theory of slide bearing lubrication has been constituted on the assumption of constant pressure and viscosity perpendicular to the thin oil layer thickness. These fundamental assumptions are in contradiction to contemporary achievements connected with new devices such as micro-bearing, nano-bearing, magnetic bearings, artificial joints in humanoid robots, micro-motors. Therefore, new methods of measurements and calculations using AFM and a new mathematical computer programs are needed. Energy conservation equations after boundary layer simplifications confirm the fact that temperature gradient variations across the film thickness have the same order of magnitude as the variations in longitudinal or circumferential directions. The fact that temperature gradient variations across the bearing gap height can be significantly large are evident, despite the temperature differences across the film thickness that are negligibly small. This statement cannot be compliant with the assumption of a constant viscosity value in the gap height direction. It has been proven that hydrodynamic pressure is not constant across the film thickness for non-Newtonian oils with Rivlin Erickson constitutive equations. For pseudo-plastic non-Newtonian oils, the apparent dynamic viscosity significantly decreases with shear rate increases. However, for pseudo-plastic oils, the shear rate increments during the oil flow are strictly connected with the average flow velocity increments. Therefore, the apparent dynamic viscosity depends strongly on the oil velocity gradients. It is evident that flow velocity gradients across the film thickness have intensive variations, particularly in regions where gap height attains the least value. In these places, the dynamic viscosity attains the largest variations in gap height directions. If gap height in micro-bearing is smaller than one micrometre, than the largest oil dynamic viscosity increments caused by the velocity variations across the film thickness are located near the superficial layer of the movable journal surfaces in the case of the hydrodynamic lubrication by rotation, but in the neighbourhood where each of two come near lubricated surfaces during the squeezing. Hence, in these places, dynamic viscosity increases across the film thickness and attains the local maximum values. A gap height smaller than one micrometre has the largest oil dynamic viscosity increments caused by the adhesion force variations across the film thickness located near the motionless sleeve surfaces. In a similar manner, the influences on the viscosity variations caused by the cluster points of concentrations of nano particles as oil inhibitors or oil additives smaller than 5 nm occurring in micro-bearing gaps and the cluster concentration regions of collagen fibres occurring in human joint gap are observed. This paper describes and comments on the above-mentioned problem of oil viscosity changes in the gap height direction, and it presents the apparent dynamic viscosity functions for Newtonian and non-Newtonian oils as well indicates the largest viscosity variations in bearing gap height direction and gives examples of initial calculation results.

Fine study on single sand body and measures for tapping the potential of residual oil during polymer flooding in Pubei reservoir of Daqing

In order to effectively guide the narrow channel sand body oil fields to exploit, according to the sand body distribution characteristics and geological genesis of narrow channel sand body oil fields, the type of single sand body is clarified. By means of identification of logging curves and correlation of well-tie profile, the internal structure of single sand body is recognized. and then the remaining oil genesis, distribution characteristics and the potential areas for polymer flooding are clarified by combining numerical simulation technology and dynamic analysis technology, and the remaining oil potential tapping method is designed by taking into consideration various factors including the characteristics of the remaining oil, reservoir property and product dynamic character. The result shows that the single sand body is divided into five types including multiphase channel superposition, distributary channel, single channel, sheet sand and lenticular sand. Potential remaining oil mainly are distributed in thick oil layers of multiphase channel superposition type and distributary channel type in which channel sands were developed and sedimentary environment are stable inner front facies and lake regressive inner front facies. The remaining oil is developed by optimizing the parameters of polymer flooding and combining many different measures. The study provides technical support for the efficient exploration for polymer flooding.

How oil properties and layer thickness determine the entrainment of spilled surface oil

Viscosity plays an important role in dispersion of spilled surface oil, so does adding chemical dispersants.For seven different oil grades, entrainment rate and initial droplet size distribution were investigated using a plunging jet apparatus with coupled camera equipment and subsequent image analysis.We found that amount of oil entrained is proportional to layer thickness and largely independent of oil properties: A dispersant dose of 1:200 did not result in a significantly different entrainment rate compared to no dispersants. Oil viscosity had a minor to no influence on entrainment rate, until a certain threshold above which entrainment was impeded.The mean droplet size scales with the modified Weber number as described by Johansen. The obtained results can help improve dispersion algorithms in oil spill fate and transport models, to aid making an informed decision about application of dispersants.

Experimental study of burning behavior of large-scale crude oil fires in ice cavities

In situ burning (ISB) on open water can remove more than 85–90% of spilled oil making it a promising technology for an efficient oil spill response. The current study examines the burning behavior of an oil spill in the presence of ice, comparable to the Arctic environment. Alaska North Slope (ANS) crude oil with initial thickness varied from 0.5 to 1.5cm in ice cavities with effective diameters of 28 and 110cm and depths of 10–25cm are studied. The experiments show that, overall, the average burning rate in an ice cavity is greater than that of a similar sized vessel or a pan. However, overall efficiency is much lower compared with ISB on open water. This is because of oil layer penetration horizontally into the ice, forming a pocket or a lateral cavity. Depending on initial conditions such as ullage, geometry of cavity and thickness of oil layer, 7–23% of the oil is trapped within the lateral cavity and thereby un-recoverable. The broader implications of the experimental results towards ISB in the Arctic are discussed.

Bonding performance and fracture morphology of a hybrid multiscale epoxy adhesive on oil‐covered substrates

ABSTRACTA hybrid multiscale epoxy adhesive reinforced with a combination of short carbon fibers and rubber nanoparticles was prepared for bonding oil‐covered aluminum substrates. The shear performance of the bonded joints was investigated as a function of the oil layer thickness. Scanning electron microscopy and energy‐dispersive X‐ray analysis studies were carried out to evaluate the oil‐diffusion behavior near the substrate–adhesive interface. The results show that the shear strength decreased, whereas the distribution range of the testing results increased as the oil layer thickness increased. When the oil layer was thinner than 10 μm, the oil‐accommodating adhesive could be used directly without degreasing, whereas over 96% of the bonding strength could be retained with almost no change in the failure probability. The analysis of Weibull distribution indicated that the shear strength and Weibull modulus were 18.89 MPa and 13.503, respectively. By analyzing the relationship between the shear strength results and the failure model of the fracture surface, we found a correlation. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 42898.

Splash behaviour and oily marine aerosol production by raindrops impacting oil slicks

The high-speed impact of a droplet on a bulk fluid at high Weber number (We) is not well understood but is relevant to the production of marine aerosol by raindrop impact on the sea surface. These splashes produce a subsurface cavity and a crown which closes into a bubble canopy, but a floating layer of immiscible oil, such as a crude oil slick, alters the splash dynamics. The effects of oil layer fluid properties and thickness, droplet size and impact speed are examined by high-speed visualization. Oil layer rupture and crown behaviour are classified by dimensional scaling. The subsurface cavity volume for impact on thick layers is shown to depend on the Reynolds number (Re), although canopy formation at highReintroduces a competingWeeffect since rapid canopy closure is found to retard cavity expansion. Time-resolved kinematic measurements show that thin crude oil slicks similarly alter crown closure and cavity growth. The size and spatial distributions of airborne droplets are examined using high-speed holographic microscopy. The droplets have a bimodal distribution with peaks at 50 and$225~{\rm\mu}\text{m}$and are clustered by size at different elevation angles. Small droplets ($50~{\rm\mu}\text{m}$) are ejected primarily at shallow angles, indicating production by splashing within the first$100~{\rm\mu}\text{s}$and by breakup of microligaments. Larger droplets ($225~{\rm\mu}\text{m}$) are found at steeper elevation angles, indicating later production by capillary instability acting on large ligaments protruding upward from the crown. Intermittent droplet release while the ligaments grow and sweep upward is thought to contribute to the size-dependent spatial ordering. Greater numbers of small droplets are produced at high elevation angles when a crude oil layer is present, indicating satellite droplet formation from ligament breakup. A crude oil layer also increases the target fluid Ohnesorge number, leading to creation of an intact ejecta sheet, which then ruptures to form aerosolized oil droplets.

Quantification of the effect of oil layer thickness on entrainment of surface oil

This study quantifies the effect of oil layer thickness on entrainment and dispersion of oil into seawater, using a plunging jet with a camera system. In contrast to what is generally assumed, we revealed that for the low viscosity “surrogate MC252 oil” we used, entrainment rate is directly proportional to layer thickness. Furthermore, the volume of stably suspended small oil droplets increases with energy input (plunge height) and is mostly proportional to layer thickness. Oil pre-treated with dispersants (dispersant-oil ratio ranges from 1:50 to 1:300) is greatly entrained in such large amounts of small droplets that quantification was impossible with the camera system. Very low interfacial tension causes entrainment by even minor secondary surface disturbances. Our results indicate that the effect of oil layer thickness should be included in oil entrainment and dispersion modelling.

Novel Gel with Controllable Strength for In-Depth Conformance Control: Bulk Gelation Performance and Propagation Properties in Porous Media

Polymer gel has been widely used to control excessive water production in mature oilfields. However, in view of reservoir conditions characterized by serious heterogeneous thick oil layers, high strength and in-depth propagation are required of polymer gel to achieve good treatment efficiency. Based on the concept of in-depth conformance control, a novel gel with controllable strength composed of polymer, resorcinol/hexamethylenetetramine (HMTA), acetic acid and gel strength modifier was developed. The effects of component concentrations on bulk gelation properties were investigated. The microstructures of conventional gel and novel gel at different aging time were studied by scanning electron microscopy (SEM), which can provide insight into the mechanism of controllable gel strength. Moreover, sandpack flow experiments were carried out on sandpacks (Φ2.5 × 100 cm) with multi-point pressure taps to investigate whether the novel gel can propagate in porous media. Compared with the conventional gel, SEM results showed that the three-dimensional network structure of novel gel was weakened more seriously, resulting in the decrease of gel strength. Due to decreased gel strength at different aging time, the novel gel can propagate in porous media to achieve in-depth conformance control.

Measurement System for Oil-Water-Air Interface Position and Oil Layer Thickness

The measurement system adopts linear CCD as photographic element. Through the optical amplification system, the images of oil-water and oil-air interfaces were clearly imaged onto CCD chip. CCD transforms optical signals into electronically signals, and then submits data to PC through USB channel. After Savitzky-Golay smoothing on light intensity data, the software analyzes the data and calculate out the positions of oil-water-air interfaces. By calculating the difference between two positions, the oil layer thickness is gotten. The experiment results that the measurement system given in this paper is reasonable, stable, effective and accurate. This measurement system has wide application in the physical and chemical industry field.

Detection and quantification of oil under sea ice: The view from below

Traditional measures for detecting oil spills in the open-ocean are both difficult to apply and less effective in ice-covered seas. In view of the increasing levels of commercial activity in the Arctic, there is a growing gap between the potential need to respond to an oil spill in Arctic ice-covered waters and the capability to do so. In particular, there is no robust operational capability to remotely locate oil spilt under or encapsulated within sea ice. To date, most research approaches the problem from on or above the sea ice, and thus they suffer from the need to ‘see’ through the ice and overlying snow. Here we present results from a large-scale tank experiment which demonstrate the detection of oil beneath sea ice, and the quantification of the oil layer thickness is achievable through the combined use of an upward-looking camera and sonar deployed in the water column below a covering of sea ice. This approach using acoustic and visible measurements from below is simple and effective, and potentially transformative with respect to the operational response to oil spills in the Arctic marine environment. These results open up a new direction of research into oil detection in ice-covered seas, as well as describing a new and important role for underwater vehicles as platforms for oil-detecting sensors under Arctic sea ice.

Instability of equilibrium of the liquid dielectric surface and formation of regular cellular structures in the field of a corona discharge

It has been established experimentally that the equilibrium of the plane surface of transformer oil under a corona electrode (needle) becomes unstable when the critical voltage, which increases with the oil layer thickness, is attained at the corona point. When the voltage at the needle exceeds the critical value, regular static cells are formed on the oil surface with characteristic sizes decreasing upon an increase in voltage. The theoretically estimated parameters of the experiment are found to be close to the experimental data. Comparison of the parameters corresponding to the occurrence of instability in the equilibrium of the oil surface in the field of the corona discharge with the parameters of instability in the equilibrium of the charged surface of liquid helium in a uniform electric field [7] demonstrates the similarity of the effects.

DETECTION AND MAPPING OF FLOATING OIL EMULSIONS WITH SYNTHETIC APERTURE RADAR (SAR) IMAGERY

Detection of floating oil on the ocean surface, and particularly thick layers, is crucial for emergency response to accidental oil discharges. While detection of oil presence on the ocean surface is relatively easy under most conditions with a variety of remote sensing techniques, estimation of the thickness of oil layers is technically challenging. In this paper we use Synthetic Aperture Radar (SAR) imagery collected during the DeepWater Horizon (DWH) oil spill and the Texture Classifier Neural Network Algorithm (TCNNA) to identify SAR image signatures that may correspond to regions of very thick emulsified oil. These locations were generally consistent with sea level observations and optical and thermal remote sensing instruments. Oil emulsions form after crude oil is discharged in the ocean and is subjected to weathering and coagulation processes that increase thicknesses of floating oil layers. The method of detection identifies regions of increased radar backscattering within larger regions of oil-covered water. Detection is dependent on SAR incident angles and the type of SAR beam mode configuration. L-band SAR was found to have the largest window of incidence angles (16 – 38o off-nadir) that could be used to detect oil emulsions. C-band SAR showed a narrower window (18 – 32o off-nadir) than L-band, while X-band SAR had the narrowest window (20 – 31o off-nadir). The results suggest that in case of future spills in the ocean, SAR data may be used to find locations of thick oil to help make management decisions.