Tim Nedwed's research while affiliated with ExxonMobil and other places

Publications (63)

Article
Photooxidation can alter the environmental fate and effects of spilled oil. To better understand this process, oil slicks were generated on seawater mesocosms and exposed to sunlight for 8 days. The molecular composition of seawater under irradiated and non-irradiated oil slicks was characterized using ion mobility spectrometry-mass spectrometry an...
Article
Properties and stability of water-in-oil emulsions influence oil behavior and response decisions. Closed-system lab protocols that assess emulsion stability cannot fully represent oil behavior in the open sea. We developed a novel test system that allows emulsions to spread over a laboratory flat pan. Nine highly weathered oils were studied and sev...
Article
In situ burning (ISB) hasn’t been widely used for offshore oil spill response for various reasons. We present a feasibility study for a new ISB method – the Burning Tongue (BT) concept. We conducted scaled experiments in the Ohmsett wave tank to demonstrate its feasibility. We produced a 35-m long “tongue” of burnable oil (average oil thickness 4.2...
Article
While chemical dispersants are a powerful tool for treating spilled oil, their effectiveness can be limited by oil weathering processes such as evaporation and emulsification. It has been suggested that oil photo-oxidation could exacerbate these challenges. To address the role of oil photo-oxidation in dispersant effectiveness, outdoor mesocosm exp...
Article
Controversy remains on the use of Sub-Sea Dispersant Injection (SSDI) during the Deepwater Horizon (DWH) spill to minimize the exposure of responders on surface vessels to volatile organic compounds (VOC). Here, we use extensive evidence (>90,000 VOC measurements) collected near the oil well MC252 site during the DWH spill and demonstrate at a high...
Article
The timely deployment of oil spill response resources is a key factor that influences response success. This is particularly true in river environments where high flow rates can quickly move oil long distances. A key success factor for a river spill is safe and rapid deployment of diversion boom. Current practice for deploying diversion boom in a r...
Article
There are still concerns about well control especially for operations in sensitive environments. Currently the final barrier while drilling oil and gas wells is a valve system (blowout preventer or BOP) located on top of wells. These valves can isolate wells by sealing around or shearing through obstructions in the well (e.g. drilling pipe and casi...
Article
Tier II/III SMART protocol for dispersant use requires placing fluorometers in the water and towing them under a slick by boat. To protect the health of SMART teams, boats typically remain at least 2 miles away from slicks during aerial dispersant treatment. After the spray completes, the SMART boats transit into oil slicks. The time between comple...
Article
Mechanical recovery for large offshore oil spills (defined as the marine environment over 10 km from shore outside of bays, lagoons, and marinas) depends on oil behavior, environmental conditions, equipment specifications, and operational issues. These factors limit oil recovery with booms and skimmers. The “rule of thumb” has been that 10–30% of t...
Article
The preparation of the water-accommodated fraction (WAF) is important for evaluating the toxicity of oil. The Chemical Response to Oil Spills: Ecological Research Forum method, which uses a magnetic stirrer in aspirator bottles, is commonly used. Thus, it is investigated herein focusing on the hydrodynamics. The particle image velocimetry technique...
Article
The industry maintains well control through proper well design and appropriate controls and barriers. This has made a hydrocarbon release from loss of well control a very–low–probability event. The current final barrier to maintain control is a valve system [blowout preventer (BOP)] located on top of wells, capable of isolating them by sealing arou...
Article
Oil spill model simulations of a deepwater blowout in the Gulf of Mexico De Soto Canyon, assuming no intervention and various response options (i.e., subsea dispersant injection SSDI, in addition to mechanical recovery, in-situ burning, and surface dispersant application) were compared. Predicted oil fate, amount and area of surfaced oil, and expos...
Article
A test program was conducted at laboratory and pilot scale to assess the ability of clays used in drilling mud (calcite, bentonite and barite) to create oil-mineral aggregates and disperse crude oil under arctic conditions. Laboratory tests were performed in order to determine the most efficient conditions (type of clay, MOR (Mineral/Oil Ratio), mi...
Conference Paper
Industry maintains well control through proper well design and appropriate controls and barriers. This has made loss of well control a very low probability event. Currently the final barrier to maintain control is a valve system (blowout preventer or BOP) located on top of wells capable of sealing around or shearing through obstructions that might...
Conference Paper
Oil spill response in ice-prone regions requires access to all response tools because of the multiple challenges that ice produces. Oil spilled in ice can become rapidly encapsulated into the ice during the ice-growth season. This encapsulation minimizes marine organisms contactwith oil, but also restricts / eliminates access to the oil for respons...
Article
Boom is used to contain oil for burning or skimming, deflect oil from sensitive areas, or protecting shorelines. For a large spill, hundreds of kilometers of boom could be deployed in efforts to protect shorelines. Currently, aerial or vessel-based observers are sent to determine if a boom is contacting oil or to monitor its integrity. The level of...
Article
(2017-387) The application of existing remote sensing sensors and technologies for the detection of oil in and under ice is an ongoing and active research area. Currently, the suite of sensors that have and are being tested include acoustic, radar, optical and fluorosensors. Another technology being tested is Nuclear Magnetic Resonance (NMR) in the...
Article
New and novel results regarding effectiveness and use of subsea dispersant injection (SSDI) are presented in this paper. These findings are relevant for operational guidance, decision making and improvement of models of subsea releases of oil and gas. More specifically, the paper presents data from a comprehensive set of laboratory experiments to m...
Article
Knowledge of the spatial distribution of oil thickness patterns within an on-water spill is of obvious importance for immediate spill response activities as well as for subsequent evaluation of the spill impacts. For long-lasting continuous spills like the 2010 3-month Deepwater Horizon (DWH) event in the Gulf of Mexico, it is also important to ide...
Conference Paper
Oil spill response strategies for offshore spills can include well control, natural attenuation, remote sensing, mechanical on-water recovery, dispersants used at the surface or subsea, in-situ burning, as well as shoreline protection and recovery. For offshore subsea releases, injection of dispersants subsea at a wellhead offers some significant b...
Article
Full-text available
To meet the world's growing energy needs, the oil industry is pursuing oil resources in ice-prone regions. These activities will require robust oil spill contingency plans. One area of need is a method to remotely detect oil that is trapped beneath or within ice. The current operational method for oil detection within or under ice requires placing...
Article
The application of existing remote sensing sensors and technologies for the detection of oil in and under ice is an ongoing and active research area. Currently, the suite of sensors that have and are being tested include acoustic, radar, optical and fluorosensors. Another technology being tested is Nuclear Magnetic Resonance (NMR) in the earth's ma...
Article
American Petroleum Institute (API) and its member companies have initiated a multi-year research program to generate information that can be used in subsea dispersant application decision-making. An important part of this program is the evaluation of biodegradation and toxicity of oil, dispersants and dispersed oil in a deepwater environment. The a...
Article
Since the 2011 Conference (Buist et al. 2011 and Buist and Nedwed 2011), work on advancing oil herding agents for in-situ burning (ISB) has focused on three areas: • Obtaining regulatory approvals for their use in North America; • Developing an application system for use in a helicopter; and, • Researching the effectiveness of herders for rapid-re...
Article
Vessels of opportunity (VoOs), such as fish and shrimp boats, can be employed to aide offshore oil spill response operations. During the 2010 Macondo response, VoOs were utilized to collect surface slicks in booms, however, VoOs were not equipped to skim and recover the collected oil. Because of this, dedicated skimming vessels were directed to VoO...
Article
This study evaluated the effectiveness of three dispersants in simulated seawater on five different fuel oils (both intermediate fuel oils (IFOs) and heavy fuel oils (HFOs)) with viscosities ranging from 1,079 to 6,615 cSt and densities ranging from 0.995 to 0.998 g/cc. The three dispersants were COREXIT® 9500 dispersant, a dispersant under develop...
Article
The use of unmanned aerial systems (UAS) has significantly increased for a variety of tasks over the past decade. ExxonMobil is currently evaluating two applications of these technologies to enhance industry’s oil spill response capabilities. One of these application is to adapt UAS for offshore spill detection. It is well known that oil slicks are...
Article
This study used the ExxonMobil Dispersant Effectiveness Test (ExDET) to evaluate the dispersant effectiveness (DE) of COREXIT® 9500 dispersant at salinities ranging from seawater (35 parts per thousand (ppt)) to near freshwater (1.75 ppt) with dispersant to oil ratios (DOR) of 1:20 and 1:10. Five crudes and one intermediate fuel oil (IFO) were test...
Article
A method and system are described for enhanced oil release management system by using one or more booms, one or more skimmers and one or more floating burners. The method and system may include skimmers to capture a fluid that is supplied to the floating burner.
Article
Application of chemical dispersants to marine oil spills is an important response option that yields net environmental benefits in many instances—particularly for large offshore spills. When properly applied, the dispersion process quickly dilutes the dispersed oil droplets to concentrations below toxicity thresholds and allows naturally occurring...
Article
As oil exploration moves into ice-prone regions, oil spill contingency planning will require a method to quickly and accurately detect oil under ice. Currently, the expected operational detection method is to deploy personnel on the ice with an ice auger to drill through the ice. There are several promising methods currently in the research phase....
Article
Oil spill response strategies are designed to minimize environmental impacts to the extent possible. Each response option must be evaluated for operational limitations (e.g., sea state), potential effectiveness, environmental impacts, and applicability given the size, type, and location of the spill, in addition to considering the health and safety...
Article
Oil spill response strategies are designed to minimize environmental impacts tothe extent possible. Each response option must be evaluated for operationallimitations (e.g., sea state), potential effectiveness, environmental impactsof the response option itself, and applicability under various oil spillscenarios (e.g., size and location of the spill...
Article
Oil herders have been available to the spill response industry for many years. As long ago as 1975, Shell Oil Company developed, and for a while, sold a product called "Shell Oil Herder". Exxon Corporation also produced and marketed a product called OC-5. Neither was commercially successful. Others have developed materials for similar functions, bu...
Article
Oil spill response strategies are designed to minimize environmental impacts to the extent possible. Each response option must be evaluated for operational limitations (e.g., sea state), potential effectiveness, environmental impacts of the response option itself, and applicability under various oil spill scenarios (e.g., size and location of the s...
Article
In situ burning is an oil spill response option particularly suited to remote, ice-covered waters. The key to effective in situ burning is thick oil slicks. If ice concentrations are high, the ice can limit oil spreading and keep slicks thick enough to burn. In drift ice conditions and open water, oil spills can rapidly spread to become too thin to...
Conference Paper
Full-text available
Many light-to-medium crude and fuel oils will spread rapidly on open water to an average thickness < 1 mm and perhaps < 0.1 mm. Effective application of dispersants results in the rapid transport of oil as small droplets into the water column. Simple calculations predict that the turbulence of 1 m waves will rapidly entrain dispersed oil into the t...
Article
In situ burning is an oil spill response option particularly suited to remote ice-covered waters. The key to effective in situ burning is thick oil slicks. In drift ice conditions (< 7/10ths) oil spills can spread to become too thin to ignite. Fire booms can be used to maintain adequate slick thickness in open water; however, even light ice conditi...
Article
Since 2004, the main goal of R&D on herding agents (also called oil collecting agents) has been to determine their ability to enhance in situ burning of oil in ice concentrations too low for natural containment of the oil slick by the ice itself (i.e., ice concentrations between <10 and 60%). Unexpectedly, the results also indicate that the concept...
Article
This paper describes research on a new approach to oil spill response that utilizes a silicone-based spreading agent to cause thick oil slicks to spread to extremely thin sheens. The increased surface area of the thin sheens will enhance the evaporation of the oil. Although this requires additional study, we expect that any residual oil that remain...
Article
Buist et al. (2007) found that herding agents will allow thickening of oil slicks and in situ burning in drift ice and close a gap for this response option in ice. The herding agents studied were developed in the 1970's and used hydrocarbon-based surfactants as the active ingredient. The best herding agent found was a formula developed by the US Na...
Article
The United States Department of Agriculture's high-speed wind tunnel facility in College Station, Texas, USA was used to determine droplet size distributions generated by dispersant delivery nozzles at wind speeds comparable to those used in aerial dispersant application. A laser particle size analyzer (LaVision SprayMaster) was used to quantify dr...
Article
Recent research has led to a next-generation dispersant that potentially provides significant improvements for all spill scenarios where dispersants are an option in addition to extending dispersant use to oils previously considered too viscous. The new dispersant is formulated as a positively buoyant viscous gel with the consistency of honey. This...
Article
Beaker and basin dispersant-effectiveness tests are used to help determine if application of dispersants in a real oil-spill incident is worthwhile. This paper provides evidence indicating that these tests negatively bias expected dispersion at sea because beakers and basins do not allow the spreading of oil slicks that occurs after application of...
Article
Concentrated ice cover in a marine environment reduces the wave energy needed to disperse chemically-treated oil slicks. ExxonMobil is currently evaluating a concept to utilize the propeller wash from vessels to enhance chemical dispersion. Tests in an arctic basin utilizing a 1:25 scale model of an azimuthal-stern-drive platform-standby icebreaker...
Article
The concept of using herding agents, also known as oil collecting agents, to thicken oil slicks among loose pack ice for the purpose of in situ burning has undergone testing at successively larger scales over the last three years. These tests included: 1. Preliminary and small-scale laboratory testing at the scale of 1 m2 and 10 m2 in 2004; 2. A te...
Article
Spring, et al. (2006) describes lab-scale and arctic-basin testing of a concept to utilize azimuthal-stern-drive (ASD) icebreakers to provide the mixing energy required to promote chemical dispersion of oil spilled in a sea ice environment. The combined findings from the lab-scale and arctic-basin tests indicate that an ASD icebreaker is potentiall...
Article
This paper describes lab-scale and model-basin testing of a concept to utilize azimuthal-stern-drive (ASD) icebreakers to provide the mixing energy required to promote chemical dispersion of oil spilled in a sea ice environment. Lab-scale tests that used near 0°C seawater with ice and simulated an ASD icebreaker using a 1:12 scale motorized propell...

Citations

... Oil slicks resulting from spills from ships, offshore oil platforms, as well as seafloor hydrocarbon reservoirs cause marine pollution [5,7]. Dong et al. [5] revealed that ocean oil slicks were dominantly contributed by anthropogenic discharges (94%) rather than natural seepages (6%). ...
... If viscosity was simply a function of API gravity, evaporation alone would be unlikely to lead to inhibitory viscosityfor example the API gravity of a Light Nigerian crude changed from 35 to 26 on evaporation, while a Medium Venezuelan oil changed from 27 to 19 (Yang and Wang, 1977). Photooxidation likely increases density as oxygens are incorporated into hydrocarbons (Aeppli et al., 2012(Aeppli et al., , 2022, but the major impediment seems to be the generation of water-in-oil emulsions that assume the consistency of chocolate mousse (Bridié et al., 1980), and see videos listed in Table 1. True chocolate mousse (mousse au chocolat) seems to have originated in France in the 19th century. ...
... In practice, the rate can be lowered or raised at any time during the displacement procedure. Simply read and record the circulating casing pressure and keep it constant while adjusting the pumping rate and establishing a new drill pipe pressure (Nedwed & Mitchell, 2021). Because the expansion near the surface is quite rapid, changing the rate should take no more than one to two minutes (Muneer et al., 2021). ...
... Of course coverage was not homogeneous, as indicated by the standard deviations (S.D.) cited, and windrows typically appear (Simecek-Beatty and Lehr, 2017), but such vast areas are impossible to cover with response vessels that can travel at only a few knots. Dispersant application from vessels is very useful in specific areas, such as around the vessels attempting to stem the flow from a damaged well head (Zhao et al., 2021), but otherwise vessels cannot treat a significant portion of a large spill. In contrast, planes can cover much larger areas in a much broader range of weather, especially now that dispersants can be applied by Boeing 727 aircraft flying 150 knots at 150 feet (Caetano and White, 2017). ...
... With the fast growth of industry and transportation, the enormous need for oil has expedited the exploitation of offshore crude oil, leading to a series of oil spill accidents and inflicting significant harm to the marine ecosystem and human health [1][2][3][4][5][6]. Various traditional oil remediation strategies, such as controlled burning and skimming [7][8][9][10][11], are inefficient and may cause secondary contamination. Recently, porous absorption materials with hydrophobicity/oleophilicity, including sponges [12][13][14][15][16], aerogels [17][18][19][20], and membranes [21][22][23][24], have been considered the most appropriate candidates for oil absorption because of their high selectivity and efficiency. ...
... This strengthened the findings for the 1 g/L WAF that the dissolved PAHs were more dependent on their solubility instead of mixing durations, as the WAF concentrations measured by GC-MS were at the same order for both alkanes and aromatics regardless of the oil loading. Based on these findings, the preparation of WAFs needs about 18 h mixing and 6 resting to provide sufficient energy for both droplets and dissolved components to reach equilibrium, when using a mixing energy of 0.04 W/kg (the mixing condition applied in the 4 L aspirator bottle, obtained from Daskiran et al. (2020)) and at an oil loading of 1 g/L or 10 g/L. ...
... These reactions are exothermic and highly adjustable depending on functionalization of both the monomers and the catalysts (Bielawski & Grubbs, 2007) allowing cure times that range from seconds to hours (Griffiths and Diver, 2015). The monomer formulations and the catalyst suspensions have rheological properties that allow them to easily flow under the conditions needed to rapidly fill a damaged blowout preventor (BOP) and form a polymer seal that stops additional hydrocarbon flow (Nedwed et al., 2019). Further, the resulting polymer is high strength with considerable toughness and good elongation properties (Woodson and Grubbs, 2000). ...
... In a study of oil spilled under broken ice, Yapa and Weerasriya (1997) expanded the relationship between axis-symmetrical oil spread and unidirectional oil spread under broken ice. Boufadel et al. (2018) conducted a numerical investigation to explore the behavior of oil droplets under ice. Li et al. (2013) explored the movement of oil that spilled in ice-covered waters through computational fluid dynamics (CFD) method. ...
... Wenning et al., 2018;Bock et al., 2018) and on the sensitivity of modeled oil fate and exposure due to dispersant use (e.g. Bejarano et al., 2014;French-McCay et al., 2018;French-McCay et al., 2019). Therefore, the new guidelines published on SIMA became a resource for researchers, and studies in different research areas have increased the number of articles after 2016. ...
... Nanoparticles exhibit higher adsorption affinity and capacity for asphaltenes than microparticles, which in turn impairs the interfacial tension between oil and seawater (Mazloom et al., 2020). These mechanisms cause montmorillonite has more effective property than kaolinite, quartz, illite to promote the dispersion and sinking process of spilled oil, which provides a practical guide for hydrocarbon removal during the washing of petroleum-contaminated soil and the application of clay mineral particles to an oil slick in ice-packed waters (Li et al., 2016;Jézéquel et al., 2018). Continuous adhesion of free particles on the formed OMAs is the main reason for the gradual increase of their density over time. ...