Advanced Aerogel Composites for Oil Remediation and Recovery

Oil spills in marine environments often damage marine and coastal life if not remediated rapidly and efficiently. In spite of the strict enforcement of environmental legislations (i.e., Oil Pollution Act 1990) following the Exxon Valdez oil spill (June 1989; the second biggest oil spill in U.S. history), the Macondo well blowout disaster (April 2010) released 18 times more oil. Strikingly, the response methods used to contain and capture spilled oil after both accidents were nearly identical, note that more than two decades separate Exxon Valdez (1989) and Macondo well (2010) accidents.

The goal of this dissertation was to investigate new advanced materials (mechanically strong aerogel composite blankets-Cabot® Thermal Wrap™ (TW) and Aspen Aerogels® Spaceloft® (SL)), and their applications for oil capture and recovery to overcome the current material limitations in oil spill response methods. First, uptake of different solvents and oils were studied to answer the following question: do these blanket aerogel composites have competitive oil uptake compared to state-of-the-art oil sorbents (i.e., polyurethane foam-PUF)? In addition to their competitive mechanical strength (766, 380, 92 kPa for Spaceloft, Thermal Wrap, and PUF, respectively), our results showed that aerogel composites have three critical advantages over PUF: rapid (3-5 min.) and high (more than two times of PUF’s uptake) oil uptake, reusability (over 10 cycles), and oil recoverability (up to 60%) via mechanical extraction. Chemical-specific sorption experiments showed that the dominant uptake mechanism of aerogels is adsorption to the internal surface, with some contribution of absorption into the pore space.

Second, we investigated the potential environmental impacts (energy and chemical burdens) associated with manufacturing, use, and disposal of SL aerogel and PUF to remove the oil (i.e., 1 m3 oil) from a location (i.e., Macondo well). Different use (single and multiple use) and end of life (landfill, incinerator, and waste-to-energy) scenarios were assessed, and our results demonstrated that multiple use, and waste-to-energy choices minimize the energy and material use of SL aerogel. Nevertheless, using SL once and disposing via landfill still offers environmental and cost savings benefits relative to PUF, and so these benefits are preserved irrespective of the oil-spill-response operator choices.

To inform future aerogel manufacture, we investigated the different laboratory-scale aerogel fabrication technologies (rapid supercritical extraction (RSCE), CO2 supercritical extraction (CSCE), alcohol supercritical extraction (ASCE)). Our results from anticipatory LCA for laboratory-scaled aerogel fabrication demonstrated that RSCE method offers lower cumulative energy and ecotoxicity impacts compared to conventional aerogel fabrication methods (CSCE and ASCE).

The final objective of this study was to investigate different surface coating techniques to enhance oil recovery by modifying the existing aerogel surface chemistries to develop chemically responsive materials (switchable hydrophobicity in response to a CO2 stimulus). Our results showed that studied surface coating methods (drop casting, dip coating, and physical vapor deposition) were partially successful to modify surface with CO2 switchable chemical (tributylpentanamidine), likely because of the heterogeneous fiber structure of the aerogel blankets. A possible solution to these non-uniform coatings would be to include switchable chemical as a precursor during the gel preparation to chemically attach the switchable chemical to the pores of the aerogel.

Taken as a whole, the implications of this work are that mechanical deployment and recovery of aerogel composite blankets is a viable oil spill response strategy that can be deployed today. This will ultimately enable better oil uptake without the uptake of water, potential reuse of the collected oil, reduced material and energy burdens compared to competitive sorbents (e.g., PUF), and reduced occupational exposure to oiled sorbents. In addition, sorbent blankets and booms could be deployed in coastal and open-ocean settings, respectively, which was previously impossible.

Tab. 1+2+3: Selected principal soil properties in the oil exploitation region of KomiArcticOil (Usinsk) in the Russian tundra

Oil polluted and not oil polluted soils (crude oil hydrocarbons contents: 20-92500 mg/kg dry soil mass) under natural grass and forest vegetation and in a bog in the Russian tundra were compared in their principal soil ecological parameters, the oil content and the microbial indicators. CFE biomass-C, dehydrogenase and arylsulfatase activity were enhanced with the occurrence of crude oil. Using these parameters for purposes of controlling remediation and recultivation success it is not possible to distinguish bctween promotion of microbial activity by oil carbon or soil organic carbon (SOC). For this reason we think that these parameters are not appropriate to indicate a soil damage by an oil impact. In contrast the metabolie quotient (qC02), calculated as the ratio between soil basal respiration and the SIR biomass-C was adequate to indicate a high crude oil contamination in soil. Also, the ß-glucosidase activity (parameter ß-GL/SOC) was correlated negatively with oil in soil. The indication of a soil damage by using the stress parameter qCO, or the specific enzyme activities (activity/SOC) minimizes the promotion effect of the recent SOC content on microbial parameters. Both biomass methods (SIR, CFE) have technical problems in application for crude oil-contaminated and subarctic soils. CFE does not reflect the low C_mic level of the cold tundra soils. We recommend to test every method for its suitability before any data collection in series as well as application for cold soils and the application of ecophysiological ratios as R_mic/C_mic, C_mic/SOC or enzymatic activity/SOC instead of absolute data.

Oil Market Modelling: A Comparative Analysis of Fundamental and Latent Factor Approaches

We formally compare fundamental factor and latent factor approaches to oil price modelling. Fundamental modelling has a long history in seeking to understand oil price movements, while latent factor modelling has a more recent and limited history, but has gained popularity in other financial markets. The two approaches, though competing, have not formally been compared as to effectiveness. For a range of short- medium- and long-dated WTI oil futures we test a recently proposed five-factor fundamental model and a Principal Component Analysis latent factor model. Our findings demonstrate that there is no discernible difference between the two techniques in a dynamic setting. We conclude that this infers some advantages in adopting the latent factor approach due to the difficulty in determining a well specified fundamental model.

Oil Flow Rate Measurements Using 198au And Total Count Technique

In industrial plants, oil and oil compounds are usually transported by closed pipelines with circular cross-section. The use of radiotracers in oil transport and processing industrial facilities allows calibrating flowmeters, measuring mean residence time in cracking columns, locate points of obstruction or leak in underground ducts, as well as investigating flow behavior or industrial processes such as in distillation towers. Inspection techniques using radiotracers are non-destructive, simple, economic and highly accurate. Among them, Total Count, which uses a small amount of radiotracer with known activity, is acknowledged as an absolute technique for flow rate measurement. A viscous fluid transport system, composed by four PVC pipelines with 13m length (12m horizontal and 1m vertical) and ½, ¾, 1 and 2-inch gauges, respectively, interconnected by maneuvering valves was designed and assembled in order to conduct the research. This system was used to simulate different flow conditions of petroleum compounds and for experimental studies of flow profile in the horizontal and upward directions. As 198Au presents a single photopeak (411,8 keV), it was the radioisotope chosen for oil labeling, in small amounts (6 ml) or around 200 kBq activity, and it was injected in the oil transport lines. A NaI scintillation detector 2”x 2”, with well-defined geometry, was used to measure total activity, determine the calibration factor F and, positioned after a homogenization distance and interconnected to a standardized electronic set of nuclear instrumentation modules (NIM), to detect the radioactive cloud.

Physical and chemical kinetics of structural build-up of cement suspensions

Abstract : The structural build-up of fresh cement-based materials has a great impact on their structural performance after casting. Accordingly, the mixture design should be tailored to adapt the kinetics of build-up given the application on hand. The rate of structural build-up of cement-based suspensions at rest is a complex phenomenon affected by both physical and chemical structuration processes. The structuration kinetics are strongly dependent on the mixture’s composition, testing parameters, as well as the shear history. Accurate measurements of build-up rely on the efficiency of the applied pre-shear regime to achieve an initial well-dispersed state as well as the applied stress during the liquid-solid transition. Studying the physical and chemical mechanisms of build-up of cement suspensions at rest can enhance the fundamental understanding of this phenomenon. This can, therefore, allow a better control of the rheological and time-dependent properties of cement-based materials. The research focused on the use of dynamic rheology in investigating the kinetics of structural build-up of fresh cement pastes. The research program was conducted in three different phases. The first phase was devoted to evaluating the dispersing efficiency of various disruptive shear techniques. The investigated shearing profiles included rotational, oscillatory, and combination of both. The initial and final states of suspension’s structure, before and after disruption, were determined by applying a small-amplitude oscillatory shear (SAOS). The difference between the viscoelastic values before and after disruption was used to express the degree of dispersion. An efficient technique to disperse concentrated cement suspensions was developed. The second phase aimed to establish a rheometric approach to dissociate and monitor the individual physical and chemical mechanisms of build-up of cement paste. In this regard, the non-destructive dynamic rheometry was used to investigate the evolutions of both storage modulus and phase angle of inert calcium carbonate and cement suspensions. Two independent build-up indices were proposed. The structural build-up of various cement suspensions made with different cement contents, silica fume replacement percentages, and high-range water reducer dosages was evaluated using the proposed indices. These indices were then compared to the well-known thixotropic index (Athix.). Furthermore, the proposed indices were correlated to the decay in lateral pressure determined for various cement pastes cast in a pressure column. The proposed pre-shearing protocol and build-up indices (phases 1 and 2) were then used to investigate the effect of mixture’s parameters on the kinetics of structural build-up in phase 3. The investigated mixture’s parameters included cement content and fineness, alkali sulfate content, and temperature of cement suspension. Zeta potential, calorimetric, spectrometric measurements were performed to explore the corresponding microstructural changes in cement suspensions, such as inter-particle cohesion, rate of Brownian flocculation, and nucleation rate. A model linking the build-up indices and the microstructural characteristics was developed to predict the build-up behaviour of cement-based suspensions The obtained results showed that oscillatory shear may have a greater effect on dispersing concentrated cement suspension than the rotational shear. Furthermore, the increase in induced shear strain was found to enhance the breakdown of suspension’s structure until a critical point, after which thickening effects dominate. An effective dispersing method is then proposed. This consists of applying a rotational shear around the transitional value between the linear and non-linear variations of the apparent viscosity with shear rate, followed by an oscillatory shear at the crossover shear strain and high angular frequency of 100 rad/s. Investigating the evolutions of viscoelastic properties of inert calcite-based and cement suspensions and allowed establishing two independent build-up indices. The first one (the percolation time) can represent the rest time needed to form the elastic network. On the other hand, the second one (rigidification rate) can describe the increase in stress-bearing capacity of formed network due to cement hydration. In addition, results showed that combining the percolation time and the rigidification rate can provide deeper insight into the structuration process of cement suspensions. Furthermore, these indices were found to be well-correlated to the decay in the lateral pressure of cement suspensions. The variations of proposed build-up indices with mixture’s parameters showed that the percolation time is most likely controlled by the frequency of Brownian collisions, distance between dispersed particles, and intensity of cohesion between cement particles. On the other hand, a higher rigidification rate can be secured by increasing the number of contact points per unit volume of paste, nucleation rate of cement hydrates, and intensity of inter-particle cohesion.

Development of variable displacement oil pump for internal combustion engines

In the last years the need to develop more environmentally friendly and efficient cars as led to the development of several technologies to improve the performance of internal combustion engines, a large part of the innovations are focused in the auxiliary systems of the engine, including, the oil pump, this is an element of great importance in the dynamics of the engine as well a considerable energy consumer. Most solutions for oil pumps to this day are fixed displacement, for medium and high speeds, the pump flow rate is higher than the needs of the engine, this excess flow leads to the need for recirculation of the fluid which represents a waste of energy. Recently, technological advances in this area have led to the creation of variable displacement oil pumps, these have become a 'must have' due to the numerous advantages they bring, although the working principle of vane or piston pumps is relatively well known, the application of this technology for the automotive industry is new and brings new challenges. The focus of this dissertation is to develop a new concept of variable displacement system for automotive oil pumps. The main objective is to obtain a concept that is totally adaptable to existing solutions on the market (engines), both dimensionally as in performance specifications, having at the same time an innovative mechanical system for obtaining variable displacement. The developed design is a vane pump with variable displacement going in line with existing commercial solutions, however, the variation of the eccentricity commonly used to provide an variable displacement delivery is not used, the variable displacement is achieved without varying the eccentricity of the system but with a variation of the length of the pumping chamber. The principle of operation of the pump is different to existing solutions while maintaining the ability to integrate standard parts such as control valves and mechanical safety valves, the pump is compatible with commercial solutions in terms of interfaces for connection between engine systems and pump. A concept prototype of the product was obtained in order to better evaluate the validity of the concept. The developed concept represents an innovation in oil pumps design, being unique in its mechanical system for variable displacement delivery.

Impacts of oil exploration and exploitation activities on marine environment

Iran possess huge oil reservoir and occupies second place in OPEC. Recent investigation has revealed that reservoir capacity in the country amount to 60 billion barrel of oil. Many measures has been carried out to increase production capacity of oil fields to 4.2 million barrel per day. Thus any distribution in oil exploration may leave adverse effects on social and economic activities. Unfortunately due to absence of a comprehensive CPM on environmental impact assessment, lots of environmental distribution has been occurred in land and off-shore. It is well known that implementation of EIA can reduce environmental hazards. In the present investigation, all major and minor activities associated with oil exploration is identified and subsequently their effects on physical, chemical and biological environment (aquatic) has been brought out. In this context, economical, social and cultural effects of marine oil exploration is also discussed. Subsequently, all methods of EIA were studied and best mitigation plans were drawn up both for exploitation and exploration phases.

Dual layer solid phase extraction based on molecular imprinting technology: Seeking a route to enhance selectivity for trace analysis of pesticide residues in olive oil.

Aiming to introduce a multiresidue analysis for the trace detection of pesticide residues belonging to organophosphorus and triazine classes from olive oil samples, a new sample preparation methodology comprising the use of a dual layer of “tailor-made” molecularly imprinted polymers (MIPs) SPE for the simultaneous extraction of both pesticides in a single procedure has been attempted. This work has focused on the implementation of a dual MIP-layer SPE procedure (DL-MISPE) encompassing the use of two MIP layers as specific sorbents. In order to achieve higher recovery rates, the amount of MIP layers has been optimized as well as the influence of MIP packaging order. The optimized DL-MISPE approach has been used in the preconcentration of spiked organic olive oil samples with concentrations of dimethoate and terbuthylazine similar to the maximum residue limits and further quantification by HPLC. High recovery rates for dimethoate (95%) and terbuthylazine (94%) have been achieved with good accuracy and precision. Overall, this work constitutes the first attempt on the development of a dual pesticide residue methodology for the trace analysis of pesticide residues based on molecular imprinting technology. Thus, DL-MISPE constitutes a reliable, robust, and sensitive sample preparation methodology that enables preconcentration of the target pesticides in complex olive oil samples, even at levels similar to the maximum residue limits enforced by the legislation.

Estudos de Durabilidade Frente ao Ataque Ácido de Compósitos Portland-Polímero para Cimentação de Poços de Petróleo

Portland-polymers composites are promising candidates to be used as cementing material in Northeastern oil wells of Brazil containing heavy oils submitted to steam injection. In this way, it is necessary to evaluate its degradation in the commonly acidizind agents. In addition, to identify how aggressive are the different hostile environments it is an important contribution on the decision of the acidic systems to be used in. It was investigated the performance of the Portland-polymer composites using powdered polyurethane, aqueous polyurethane, rubber tire residues and a biopolymer, those were reinforced with polished carbon steel SAE 1045 to make the electrochemical measurements. HCl 15,0 %, HCl 6,0 % + HF 1,5 % (soft mud acid), HCl 12,0 % + HF 3,0 % (regular mud acid) and HAc 10 % + HF 1,5 % were used as degrading environment and electrolytes. The more aggressive acid solution to the plain Portland hardened cement paste was the regular mud acid, that showed loss of weight around 23.0 %, followed by the soft mud acid, the showed 11.0 %, 15.0 % HCl with 7,0 % and, at last the 10.0 % HAc plus HF 1.5 % with just 1.0 %. The powdered polyurethane-composite and the aqueous polyurethane one showed larger durability, with reduction around 87.0 % on the loss of weight in regular mud acid. The acid attack is superficial and it occurs as an action layer, where the degraded layer is responsible for the decrease on the kinetic of the degrading process. This behavior can be seen mainly on the Portland- aqueous polyurethane composite, because the degraded layer is impregnated with chemically modified polymer. The fact of the acid attack does not have influence on the compressive strength or fratography of the samples, in a general way, confirms that theory. The mechanism of the efficiency of the Portland-polymers composites subjected to acid attack is due to decreased porosity and permeability related with the plain Portland paste, minor quantity of Ca+2, element preferentially leached to the acidic solution, wave effect and to substitute part of the degrading bulk for the polymeric one. The electrolyte HAc 10 % + HF 1,5 % was the least aggressive one to the external corrosion of the casing, showing open circuit potentials around +250 mV compared to -130 mV to the simulated pore solution to the first 24 hours immersion. This behavior has been performed for two months at least. Similar corrosion rates were showed between both of the electrolytes, around 0.01 μA.cm-2. Total impedance values, insipient arcs and big polarization resistance capacitive arcs on the Nyquist plots, indicating passivity process, confirm its efficiency. In this way, Portlandpolymers composites are possible solutions to be succeed applied to oilwell cementing concomitant submitted to steam injection and acidizing operation and the HAc 10,0 % + HF 1,5 % is the less aggressive solution to the external corrosion of the casing

Adição do resíduo de biomassa da cana-de-açúcar em pastas para cimentação de poços petrolíferos produtores de óleos pesados

The Potiguar basin has large fields of viscous oil where the used method for recovering is based on vapor injection; this operation is carried out by injecting vapor in the oilwell directly, without the protection of a revetment through thermal insulation, what causes its dilation and, consequently, cracks in the cement placed on the annular, and lost of hydraulic insulation; this crack is occasioned by the phenomenon of retrogression of the compressive resistance due to the conversion of the hydrated calcium silicate in phases calcium-rich, caused by the high temperatures in the wells, subjected to thermal recuperation. This work has evaluated the application of composite pastes with addition of residue of biomass of ground sugar-cane bagasse as anti-retrogression mineral admixture for cementation of oil-wells subjected to thermal recuperation. The addition of the mineral residue was carried out considering a relative amount of 10, 20, 30, 40 and 59% in relation to cement mass, trying to improve the microstructure of the paste, still being developed a reference paste only with cement and a paste with addition of 40% of silica flour - renowned material in the oil industry as anti-retrogression additive. Pozzolanic activity of the ash was evaluated through XRD, TG/DTG, as the resistance to compression, and it was also determined the physical and mechanical behavior of the pastes when submitted to cure at low temperatures (22 and 38º C); besides it was evaluated the behavior of the pastes when submitted to two cycles of cure at high temperature (280ºC) and pressure (7 MPa). It was verified that the ash of the sugar-cane biomass presents pozzolanic reaction and has great efficiency in decrease the permeability of the paste by filler effect, as well as that addition of ash in a relative amount of 10, 20 e 30% increases cured compressive resistance at low temperatures. It was also showed that the ash in a relative amount of 40% and 59% has very significant efficiency as anti-retrogression additive, since it prevents the decrease of compressive resistance and forms hydrated calcium silicate type xenotlita and tobermorita which have more resistance and stability in high temperatures

Utilização de nanosílica como aditivo estendedor para pastas cimentantes de baixa densidade destinadas à cimentação de poços petrolíferos

Cementing operations are conducted at different times of the well s life and they have high importance, because the functions are fundamental to keep good properties during a long life of the well, such as, maintain the mechanical stability of the well, to promote the isolation hydraulic and support the tubing. In some situations, the rocky zones have low fractures pressures and require the use of lightweight slurries to prevent the hydrostatic pressure in the formation is greater than the pressure of fracture. There are three ways to reduce the density of cement slurries: exterders water additives, microspheres and foamed slurries. The most used extender water additive is sodium bentonite, which is a clay with a good capacity of water absorption and expansion of its volume, the main disadvantage of this additive is the reduction of the strength. Currently, the use of nanoscale particles has received special attention, mainly because they get new functionalities. Following this trend, this paper aims to use a colloidal solution of nano-silica as an exterders water additives for use in oil wells. Slurries were designed with fixed 13lb/gal density and concentration of nano silica 0.1 gpc; 0.4 gpc; 0.7 and 1gpc, the influence of nano-silica was studied at these levels in isolation and combined varying concentrations of CaCl2,. Tests including rheology, stability, strength, thickening time, porosity and permeability. Besides the API tests, microstructural characterizations were performed after 28 days of the slurries, X-ray diffraction (XRD) and scanning electron microscopy (SEM)

Applications of synchrotron x-ray powder diffraction in hydrated cements: high-resolution and high-pressure studies

The main aim of this study is to apply synchrotron radiation techniques for the study of hydrated cement pastes. In particular, the tetracalcium aluminoferrite phase, C4AF in cement nomenclature, is the major iron-containing phase in Ordinary Portland Cement (OPC) and in iron rich belite calcium sulfoaluminate cements. In a first study, the hydration mechanism of pure tetracalcium aluminoferrite phase with water-to-solid ratio of 1.0 has been investigated by HR-SXRPD (high resolution synchrotron X-ray powder diffraction). C4AF in the presence of water hydrates to form mainly an iron-containing hydrogarnet-type (katoite) phase, C3A0.84F0.16H6, as single crystalline phase. Its crystal structure and stoichiometry were determined by the Rietveld method and the final disagreement factors were RWP=8.1% and RF=4.8% [1]. As the iron content in the product is lower than that in C4AF, it is assumed that part of the iron also goes to an amorphous iron rich gel, like the hydrated alumina-type gel, as hydration proceeds. Further results from the high-resolution study will be discussed. In a second study, the behavior of pure and iron-containing katoites (C3AH6 and C3A0.84F0.16H6) under pressure have been analyzed by SXRPD using a diamond anvil cell (DAC) and then their bulk moduli were determined. The role of the pressure transmitting medium (PTM) has also been studied. In this case, silicone oil as well as methanol/ethanol mixtures have been used as PTM. Some “new peaks” were detected in the pattern for C3A0.84F0.16H6 as pressure increases, when using ethanol/methanol as PTM. These new peaks were still present at ambient pressure after releasing the applied pressure. They may correspond to crystalline nordstrandite or doyleite from the crystallization of amorphous aluminium hydroxide. The results from the high-pressure study will also be discussed.

Influência da adição do NaCl e KCl em sistemas de pastas contendo sílica para poços de petróleo em zonas evaporíticas e carbonáticas

One of the major challenges faced nowadays by oil companies is the exploration of pre-salt basins. Thick salt layers were formed in remote ages as a consequence of the evaporation of sea water containing high concentrations of NaCl and KCl. Deep reservoirs can be found below salt formations that prevent the outflow of oil, thus improving the success in oil prospection. The slurries used in the cement operations of salt layers must be adequate to the properties of those specific formations. At the same time, their resulting properties are highly affected by the contamination of salt in the fresh state. It is t herefore important to address the effects of the presence of salt in the cement slurries in order to assure that the well sheath is able to fulfill its main role to provide zonal isolation and mechanical stability. In this scenario, the objective of the present thesis work was to evaluate the effect of the presence of NaCl and KCl premixed with cement and 40% silica flour on the behavior of cement slurries. Their effect in the presence of CO2 was also investigated. The rheological behavior of slurries containing NaCl and KCl was evaluated along with their mechanical strength. Thermal and microstructural tests were also carried out. The results revealed that the presence of NaCl and KCl affected the pozzolanic activity of silica flour, reducing the strength of the hardened slurries containing salt. Friedel´s salt was formed as a result of the bonding between free Cl- and tricalcium aluminate. The presence of CO2 also contributed to the degradation of the slurries as a result of a process of carbonation/bicarbonataion

Biodiesel production from Jathropha curcas l. oil using chemical or enzymatic catalysts

Doutoramento em Engenharia dos Biossistemas - Instituto Superior de Agronomia - UL