Materials for Well Integrity: Performance of Setting Materials for Well Cementing Operation

Primary cementing operation is the process of pumping and placing a cementitious slurry in a well. After setting, the so-called barrier material has to provide zonal isolation in the annular gap behind casing string. After a hundred years of using hydraulic Portland cement as prime material for cementing operation, although the chemistry of the material is well-developed, still shortcomings are reported in short- and long-term properties. Safe and cost-efficient operations have been the motivation for improving the performance of barrier material. Additionally, annual increase of the carbon tax is a driving force for switching to green alternatives to Portland cement. The present study includes scientific examination of candidate barrier materials for cementing operation. These materials are an industrial class of expansive cement, a non-cement-based pozzolanic material, an inorganic polymer known as geopolymer, and organic thermosetting resin. The materials were assessed aiming to evaluate their performance at equal conditions. The thesis is divided into two main sections comprising a core that describe the research project and appended papers discussing scientific achievements. The outcome of this study includes strengths and weaknesses of each material, which are published in seven scientific papers: three journals, two peer-reviewed conferences, and two SPE conferences. The papers are included as Appendix and labeled using Roman numerals. In the present review, same numerals are used when referring to the papers. Paper I includes fluid-state properties of the candidate barrier material. Density, viscosity profile, static fluid-loss, and the pumpability of the materials are tested at bottom-hole circulating temperature. Paper II presents short-term mechanical properties of Portland cement-based systems and highlights the effect of chemical additives on the mix design. In this study, the mechanical properties of expansive cement and API neat class G cement are included. The samples were cured from one day to fourteen days at bottom-hole static temperature and under elevated pressure. Paper III includes the mechanical properties of candidate barrier materials. The short-term mechanical properties were tested up to seven days. Paper IV shows mechanical properties of the materials up to one month. In this paper, uniaxial compressive strength, tensile strength, and Young’s modulus are measured and possible correlations between these parameters are investigated. Moreover, sonic strength development rate of the materials is tested by using ultrasonic cement analyzer. Paper V includes shear bond and hydraulic sealability of cement-based systems and geopolymer. Shear bond strength of these materials is examined at two circumferential surfaces by placing the cementitious material between a pipe and bar. For both shear bond and hydraulic sealability, both clean and rusty steel are considered as casing string representatives. Paper VI has bond strength and hydraulic sealability of the setting materials. The interface of materials with steel is studied by scanning electron microspore. Morphology and mineralogy of materials at their interface satisfy the behavior of materials in shear bond and hydraulic sealability tests. Paper VII includes mechanical properties of the materials up to nine months of curing at bottom-hole static temperature and elevated pressure. Additionally, morphology and mineralogy of the materials are tested to support the mechanical behavior of materials

Tratamento de águas residuais industriais com nanomateriais sintetizados para um ambiente sustentável

Quality of the final discharged effluents from industrial activities has been the subject of significant efforts over several decades to improve the performance of the methods applied for their treatment, either by physico-chemical, biological, or a combination of these processes. Among the emerging technologies, the application of various types of engineered nanomaterials (ENMs) has gained a particular attention in recent years. The present thesis aimed to carry out either experimental studies, surveys and critical reviews in order to synthesize the most sustainable nanomaterials for the treatment of recalcitrant pollutants from the content of industrial effluents. In parallel, the sustainability of other biological and physicochemical methods has been critically assessed and the most sustainable treatment methods have been suggested to be adopted by the industries. It was demonstrated in this thesis that the application of Tagguchi approach can considerably aid to control the properties of iron-based nanoscale particles synthesized by a liquidphase reduction process. Working with this system revealed that both the (reductant/Fe3+) ratio, (R), and the Fe3+concentration, [Fe3+], are the parameters that determine critical characteristics including particle crystalline phase composition, crystallinity and surface area although R has been revealed as the most important one. Nano zero valent iron particles with enhanced properties, synthesized by utilization of ultrasonic irradiation, was successfully tested to degrade organic dyes (methylene blue, as a case study) which are dominant in the wastewater from some industries such as textile factories. Recovery of the nanomaterials after being applied for the treatment purposes is also among the most important parameters for the selection and synthesis of the most sustainable nanomaterials for environmental applications. A novel ZnO/Fe3O4 on Bentonite nanocomposite prepared in this thesis showed acceptable photocatalytic decomposition of 2,4 dichlorophenol besides the ability to be recovered after being used. Magnetic nanocomposites were also tested for the degradation of AOXs from pulp and paper mill effluents and showed acceptable performance in such applications. A framework was also developed in this thesis for the sustainability assessment of the best available technologies to deal with industrial effluents, showing the efficiency of biological treatment methods to deal with industrial effluents although having some limitation to deal with phenolic industrial effluents. With a precise acclimatization process, very high efficiency for the biodegradation of phenol with a high degree of resistance to the shock of initial phenol concentration was achieved using activated sludge process. The results of a critical review, as the future outlook of this thesis, indicated the possibility of integration of engineered nanomaterials and also biological treatment with the membrane technologies in order to overcome the existing barriers for the rapid development of membrane technologies for the treatment of industrial effluents.A qualidade dos efluentes finais de atividades industriais tem sido, ao longo de várias décadas, objeto de esforços significativos para melhorar o desempenho dos seus métodos de tratamento, seja por via físico-química, biológica ou uma combinação destes. Entre as tecnologias emergentes, o recurso a nanomateriais sintetizados (ENMs) tem sido alvo de especial atenção nos últimos anos. A presente tese teve como objetivo realizar estudos experimentais, levantamentos de informação e revisões críticas, a fim de sintetizar nanomateriais sustentáveis para o tratamento de poluentes recalcitrantes existentes em efluentes industriais. Paralelamente, a sustentabilidade de outros métodos biológicos e físico-químicos foi avaliada criticamente, tendo-se sugerido os métodos de tratamento mais sustentáveis para serem adotados pelas indústrias. Foi demonstrado nesta tese que o recurso à abordagem de Tagguchi pode auxiliar consideravelmente no controlo das propriedades de partículas nanométricas à base de ferro, sintetizadas por um processo de redução em fase líquida. O estudo deste sistema revelou que tanto a razão (agente redutor/ Fe3+) como a concentração de Fe3+ são os parâmetros que determinam características críticas dos precipitados, incluindo a sua composição de fases cristalinas, grau de cristalinidade e área superficial específica. As nanopartículas de ferro de valência zero com propriedades melhoradas, sintetizadas pela utilização de irradiação por ultrasons, foram testadas com sucesso para degradar corantes orgânicos (azul de metileno como corante modelo) que são compostos dominantes nas águas residuais de algumas indústrias, designadamente de fábricas de têxteis. A recuperação dos nanomateriais após a sua aplicação em tratamentos de efluentes também é um dos aspectos mais importantes a ter em consideração na seleção e síntese de nanomateriais sustentáveis para aplicações ambientais. Um novo nanocompósito de ZnO/Fe3O4 sobre Bentonite, produzido neste trabalho, revelou uma capacidade aceitável para decomposição fotocatalítica do 2,4 diclorofenol, além da capacidade de ser recuperado após utilização. Testaram-se também nanocompósitos magnéticos na degradação de AOXs de efluentes da indústria do papel e celulose que evidenciaram um desempenho aceitável nessas aplicações. Definiu-se também nesta tese um contexto para a avaliação da sustentabilidade das melhores tecnologias disponíveis para lidar com efluentes industriais, tendo-se revelado a eficiência dos métodos de tratamento biológico para lidar com efluentes industriais, embora com alguma limitação para lidar com efluentes industriais fenólicos. Com um processo de aclimatação preciso, conseguiu-se uma eficiência muito elevada para a biodegradação do fenol, com alto grau de resistência ao choque da concentração inicial de fenol, utilizando-se o processo de lamas ativadas. Mediante uma revisão crítica da literatura, e como perspectivas de futuro a extrair do presente trabalho, aponta-se a possibilidade de integrar nanomateriais sintetizados e tratamento biológico nas tecnologias de membrana, para superar as barreiras actualmente existentes ao rápido desenvolvimento das tecnologias de membrana para o tratamento industrial efluentes.Programa Doutoral em Ciências e Engenharia do Ambient

Green synthesis of nanomaterials - a scientometric assessment

The green synthesis of engineered nanomaterials (NMs) has deserved an enormous academic interest and huge financial investments during the last decades. However, this prominent position has not been followed by the rapid commercialization of NMs for real applications thus rendering their practical usefulness very doubtful and the appropriateness of novel investments in the field highly questionable. The present manuscript presents the first scientometric study on the green synthesis of NMs aiming to survey the scientific progress in this particular field and identify its main gaps while providing applicable suggestions to facilitate the knowledge transfer from laboratories to real full scale production and applications. The research on green synthesis of nanomaterials published in Web of Science during the period 1991–2019 is here carefully analyzed. Overall, 9 scientometric indicators are employed to interpret the results retrieved from the 8761 documents collected. It is found that 107 countries and nearly 22,400 authors have contributed to this subject, hence highlighting the relevance of this topic. The keywords spectrum is dominated by the term “nanoparticle” which full adoption takes place at the beginning of the 21st century. Some few years later, a batch of words like “silver nanoparticle”, “gold nanoparticle” and “nanocomposite” reaches a significant impact reflecting the emergence of commercial applications for these nanomaterials. It is only in 2009 that the keyword “green synthesis” gains strength, followed then by “biosynthesis” in 2010, making it evident a trend towards environmentally friendly reagents. The number of publications on green synthesis of nanomaterials displays up to now a sigmoidal like growth pattern, which points actually to a decrease on new arrivals, thus suggesting a possible forthcoming decline in this field. However, the analysis carried out in the present work allows identifying various gaps related to sustainability, which, if appropriately addressed, may contribute to a resurgence of the research on nanomaterials synthesis while fostering more frugal approaches on material synthesis tendencies.publishe

Bonding Mechanism of Zonal Isolation Materials to Clean and Rusted Casing

In oil and gas and geothermal well construction, a cementitious material is pumped in the wellbore to provide zonal isolation and support the casing during the life cycle of the well. Thus, the cementitious barrier materials must be durable in terms of chemical and mechanical properties and have chemical compatibility with casing pipe. The complex region of casing-cement interface is considered a key parameter to fulfill long-term zonal isolation. This interface must be chemically stable and impermeable to block unwanted formation fluid communication. Shortcomings of conventional Portland cement under operational conditions and increasing sensitivity to its carbon footprint are motivations for a green alternative. Bond strength and sealability of cement with steel surface have been measured previously. But few research works cover surface characterization and morphological analysis of barrier materials and the connected steel surface. This study provides a full picture of selected alternative materials in terms of shear bond strength, hydraulic sealability, and interface morphology analysis of the materials. Materials include API Class G cement, an industrial expansive cement, noncement-based pozzolanic material, geopolymer, and thermosetting resin. Also, clean and rusted steels were considered as a representative for the casing pipe in the field. The samples were prepared under elevated pressure and temperature. The results proved that higher shear bond strength is not an indication of good sealability, and the ingredients used to mix slurries have a critical role in the structure of the interfacial zone between casing and barrier material.publishedVersio

Single precursor sonochemical synthesis of mesoporous hexagonal-shape zero-valent copper for effective nitrate reduction

This short communication reports an efficient protocol for green synthesis of three-dimensional hexagonal-like zero-valent Cu following a facile sonochemical route. The method involved the use of copper(II) acetate [Cu(CH3COO)2] as a precursor, and a mixture of ethylene glycol (C2H4(OH)2) and ethanol (1:1) as the solvent. The final products obtained were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) surface area, porosity analysis and UV–visible spectroscopy to investigate the reduction of nitrate from polluted waters. Surface activity of the prepared materials for the removal of nitrate was examined by ion chromatography. The results indicated that the prepared zero-valent copper has a hexagonal shape and is well crystallized with a specific surface area of 23 m2/g. High reactivity of products towards nitrate (>90% after 30 min) clearly demonstrated the efficiency of this novel, fast, facile, and green method for the synthesis of pure-phase copper zero-valent materials for environmental remediation.publishe

Hydrocarbon source rocks in Kazhdumi and Pabdeh formations—a quick outlook in Gachsaran oilfield, SW Iran

Geochemical study of Kazhdumi and Pabdeh Formations as potential source rocks in Gachsaran Oilfield demonstrates that the Kazhdumi Formation has a fair to good capability of hydrocarbon generation and predominately contains type II-III kerogen. On the other hand, the Pabdeh Formation has a poor to good petroleum potential and contains different kerogen types, including type II, type II-III, type III and even for one sample, type IV, indicating different depositional conditions for this formation. The geochemical log of the Kazhdumi Formation shows that there is a close correlation between different geological parameters as noticed prominently in well number 55, which suggests the more extensive the anoxic condition, the higher the petroleum potential is for Kazhdumi Formation. By contrast, a poor correlation between TOC and other Rock–Eval-derived parameters for the Pabdeh Formation at a depth of more than 2100 m may demonstrate the inert organic matter and mineral matrix effects at this depth interval. However, biomarkers show differences in lithology and depositional environment for the Kazhdumi Formation in well numbers 55 and 83. On the other hand, the Pabdeh Formation has a mixed lithology (carbonate-shale) deposited in a marine setting under suboxic–anoxic condition. Moreover, thermal maturity indicators suggest that Pabdeh and Kazhdumi Formations are immature and early mature, respectively

Sustainability of treatment technologies for industrial biowastes effluents

Despite the huge efforts to develop efficient technologies for the treatment of recalcitrant biowastes and other emerging pollutants, selecting the most sustainable method among the possible alternatives is still a formidable task. This is mainly because of the integration of technical, economic, environmental, and social criteria in decision-making process. Traditionally, various multi-criteria decision-making approaches have been adopted to integrate innumerable criteria for environmental applications. In this study, we have examined the fuzzy-Delphi approach to evaluate seventeen parameters for integrating technical, economic, environmental and social criteria in order to rank the nine treatment technologies divided in two categories (physico-chemical and biological processes). The results of this study indicated that although efficiency of treatment methods is the most important criterion, but contribution of other sustainability criteria should also be considered because they are of high importance for the selection of sustainable wastewater treatment methods. As per our proposed framework on membrane technologies (among the many other physico-chemical methods) and anaerobic sludge blanket technology (among the biological treatment methods) are the most promising approaches for the treatment of highly polluted emerging industrial pollutants. The findings of this study are fully supported by the consensus achieved by a group of fifty experts from nineteen different countries. Opportunities for the improvement of the methods as per data generated are discussed.publishe

Alternative setting materials for primary cementing and zonal isolation – Laboratory evaluation of rheological and mechanical properties

Portland cement is the prime zonal isolation material used in hydrocarbon wells and its utilization has been extended to geothermal, carbon sequestration and gas storage wells. Despite the vast quantity of research activities and publications, well integrity reports show shortcomings associated with Portland cement at specific conditions of pressure, temperature, chemical environment and geographical locations. In this experimental study, four alternative barrier materials have been selected for further experiments at laboratory scale: an industrial class of expansive cement, a non-cement pozzolanic slurry, a rock-based geopolymer and an organic thermosetting resin. Neat class G cement was used as reference material for comparing the results. The study includes the rheological behavior of the candidate materials, static fluid-loss and pumpability at both atmospheric and elevated pressures. All of the materials at the liquid phase showed an acceptable viscosity profile at the operational shear rates. The consistency curve of the slurries showed that the barrier materials are pumpable for the desired period with the right-angle set (RAS), except for the pozzolanic slurry, which was not able to make gel up to 24 h at dynamic conditions. Mechanical properties of the candidate barrier materials including uniaxial compressive strength (UCS), modulus of flexibility, sonic strength development and tensile strength of the samples were characterized up to 28 days of curing. The UCS test results showed that the thermosetting resin has an extremely high compressive strength compared to the other materials, while the geopolymer and the pozzolanic slurry are more ductile. The tensile strength of the materials experienced no significant change over time; however, for the neat class G cement, it is reduced after 28 days.publishedVersio

Enhanced biodegradation of phenolic wastewaters with acclimatized activated sludge – a kinetic study

This work reports the biodegradation of phenol with enhanced efficiency in a sequencing batch reactor (SBR) after an acclimatization procedure with mixed culture activated sludge. The effects of temperature, initial phenol concentration and acclimatization procedure on phenol biodegradation were investigated. Acclimatization greatly favoured biodegradation rate of the phenol, while temperature showed no significant effect. After 60 days of acclimatization, the Haldane kinetic inhibition model indicated that activated sludge could degrade phenol at the maximum rate of 0.117 (g phenol/g VSS/h) at pH ~6 and phenol concentration of 400 mg/L at room temperature (T = 15–18 °C). Kinetic parameters including maximum phenol degradation rate (qmáx) of 0.521 (g phenol/g VSS/h), half-saturation constant (KS) of 692 mg/L and an inhibition constant KI of 231 mg/L were computed. The results of this study represent the highest phenol biodegradation efficiency in terms of the parameters such as time and phenol concentration, suggesting that acclimatized activated sludge exhibited a high resistant ability to phenol. In addition, inhibitory effects were identified at phenol concentrations higher than 400 mg/L. The system also showed high degree of stability and resistance to a load shock by increasing the initial concentration of phenol from 500 to 1000 mg/L.publishe