Incorporação de resíduo cerâmico para prevenção da retrogressão da resistência de cimentos de poços de petróleo submetidos à injeção de vapor

Steam injection is the most used thermal recovery method of oil nowadays because of the high degree of development of the technique that allows high recovery factors. However, injection of superheated steam into the reservoir affects the entire structure of the well, including the cemented layer that presents a retrogression of compressive strength and increases the permeability due to formation of more crystalline and denser phases at temperatures above 110 °C. These changes result in failures in the cement that favor the entrance of formation fluids into the annulus space resulting in unsafe operations and restrictions in the economic life of the well. But the strength retrogression can be prevented by partial replacement of cement by silica-based materials that reduce the CaO/SiO2 ratio of cement slurries changing the trajectory of the reactions, converting those deleterious phases in phases with satisfactory mechanical strength and permeability. The aim of this study was to evaluate the behavior of a ceramic waste material rich in silica in partial and total substitution of a mineral additive used to fight the strength retrogression of cement slurries subjected to high temperatures. The evaluation was made by compression, X-ray diffraction (XRD) and thermogravimetry (TG/DTG). The samples were submitted to a cycle of low temperature (38 °C) for 28 days and a cycle of low temperature followed by exposure to 280 ºC and 1000 psi by 3 days. The results showed that slurries with additions of up to 30% of the waste material are not enough to prevent the strength retrogression, while slurries with additions of the waste material combined with silica flour in various proportions produced hydrated products of low Ca/Si ratios that maintained the compressive strength at satisfactory levels

Formulação e caracterização de pastas espumadas por incorporação de ar e estabilizantes minerais

Cementing operations may occur at various stages of the life cycle of an oil well since its construction until its definitive abandonment. There are some situations in which the interest zones are depleted or have low fracture pressure. In such cases, the adoption of lowdensity cement slurries is an efficient solution. To this end, there are basically three ways to reduce the density of cement slurries: using microspheres, water extending additives or foamed cement. The objective of this study is to formulate, to study and to characterize lowdensity foamed cement, using an air entrainment surfactant with vermiculite or diatomite as water extenders and stabilizers. The methodology consists on preparation and evaluation of the slurries under the American Petroleum Institute (API) and the Brazilian Association of Technical Standards (ABNT) guidelines. Based on calculated densities between 13 and 15 ppg (1.559 and 1.799 g/cm3), the slurries were prepared with fixed surfactant concentration, varying the concentrations of vermiculite and diatomite and were compared with the base slurries. The results of plastic viscosity, yield point and gel strength and the compressive strength for 24 h showed that the slurries presented suitable rheology and mechanical strength for cementing operations in oil wells, and had their densities reduced between 8.40 and 11.89 ppg (1.007 and 1.426 g/cm3). The conclusion is that is possible, under atmospheric conditions, to obtain light weighted foamed cement slurries with satisfactory rheological and mechanical properties by means of air entrainment and mineral additions with extenders and stabilizers effects. The slurries have great potential for cementing operations; applicability in deep wells, in low fracture gradient formations and in depleted zones and bring cost savings by reducing the cementing consumption

Efeito da adição de microfibras de lã de vidro na tenacidade à ruptura de pastas de cimento para poços de petróleo

Although there are a wide variety of additives that act in fresh state, to adjust the properties of cement, there is also a search by additions that improve the tenacity of the cement in the hardened state. This, in turn, can often be increased by inserting fibers, which act on the deflection of microcracks. This study aimed to use a microfiber glass wool (silica-based) as an additive reinforcing the cement matrix, improving the rupture tenacity, in order to prevent the propagation of microcracks in the cement sheath commonly found in oil wells submitted to high temperatures. The fibers were added at different concentrations, 2 to 5% (BWOC) and varied average sizes, grinding for 90 s, 180 s, 300 s, 600 s. The cement slurries were made with a density of 1,90 g/ cm3 (15,6 lb/gal), using Portland cement CPP- Special Class as the hydraulic binder and 40% silica flour. The characterization of the fiber was made by scanning electron microscopy (SEM), particle size by sieving, X-ray fluorescence (XRF), X-ray diffraction (XRD) and thermogravimetry (TG / DTG). Were performed technological tests set by the API (American Petroleum Institute) by rheology, stability, free water, compressive strength, as well as testing rupture energy, elastic modulus and permeability. The characterization results showed good thermal stability of the microfiber glass wool for application in oil wells submitted to steam injection and, also, that from the particle size data, it was possible to suggest that microfibers milled up to 300 s, are ideal to act as reinforcement to the cement slurries. The rheological parameters, there was committal of plastic viscosity when larger lengths were inserted of microfiber (F90). The values obtained by free water and stability were presented according to API. The mechanical properties, the incorporation of microfiber to the cement slurries gave better rupture tenacity, as compared to reference cement slurries. The values of compressive strength, elastic modulus and permeability have been maintained with respect to the reference cement slurries. Thus, cement slurries reinforced with microfiber glass wool can ensure good application for cementing oil wells submitted to steam injection, which requires control of microcracks, due to the thermal gradients

Influência da adição de cinza do bagaço de cana calcinada em sistemas de pastas para cimentação de poços petrolíferos

Cementing operation is one of the most important stages in the oil well drilling processes and has main function to form hydraulic seal between the various permeable zones traversed by the well. However, several problems may occur with the cement sheath, either during primary cementing or during the well production period. Cements low resistance can cause fissures in the cement sheath and compromise the mechanical integrity of the annular, resulting in contamination of groundwater and producing zones. Several researches show that biomass ash, in particular, those generated by the sugarcane industry have pozzolanic activity and can be added in the composition of the cementing slurries in diverse applications, providing improvements in mechanical properties, revenue and cement durability. Due to the importance of a low cost additive that increases the mechanical properties in a well cementing operations, this study aimed to potentiate the use of sugarcane bagasse ash as pozzolanic material, evaluate the mechanisms of action of this one on cement pastes properties and apply this material in systems slurries aimed to cementing a well with 800 m depth and geothermal gradient of 1.7 °F/100 ft, as much primary cementing operations as squeeze. To do this, the ash beneficiation methods were realized through the processes of grinding, sifting and reburning (calcination) and then characterization by X-ray fluorescence, XRD, TG / DTG, specific surface area, particle size distribution by laser diffraction and mass specific. Moreover, the ash pozzolanic activity added to the cement at concentrations of 0%, 20% and 40% BWOC was evaluated by pozzolanic activity index with lime and with Portland cement. The evaluation of the pozzolanic activity by XRD, TG / DTG and compressive strength confirmed the ash reactivity and indicated that the addition of 20% in the composition of cement slurries produces improvement 34% in the mechanical properties of the slurry cured. Cement slurries properties evaluated by rheological measurements, fluid loss, free fluid, slurry sedimentation, thickening time and sonic strength (UCA) were satisfactory and showed the viability of using the sugarcane ash in cement slurries composition for well cementing

Efeito da adição de cargas minerais leves na resistência mecânica de grautes para cimentação de poços offshore

The preparation of cement slurries for offshore well cementing involves mixing all solid components to be added to the mixing water on the platform. The aim of this work was to study the formulation of pre-prepared dry mixtures, or grouts, for offshore oilwell cementing. The addition of mineral fillers in the strength of lightweight grouts applied for depths down to 400 m under water depths of 500 m was investigated. Lightweight materials and fine aggregates were selected. For the choice of starting materials, a study of the pozzolanic activity of low-cost fillers such as porcelain tile residue, microsilica and diatomaceous earth was carried out by X-ray diffraction and mechanical strength tests. Hardened grouts containing porcelain tile residue and microsilica depicted high strength at early ages. Based on such preliminary investigation, a study of the mechanical strength of grouts with density 1.74 g/cm3 (14.5 lb/gal) cured initially at 27 °C was performed using cement, microsilica, porcelain tile residue and an anti-foaming agent. The results showed that the mixture containing 7% of porcelain tile residue and 7% of microsilica was the one with the highest compressive strength after curing for 24 hours. This composition was chosen to be studied and adapted for offshore conditions based on testes performed at 4 °C. The grout containing cement, 7% of porcelain tile residue, 7% of active silica and admixtures (CaCl2), anti-foaming and dispersant resulted satisfactory rheology and mechanical strength after curing for 24 hours of curing

Avaliação da qualidade da assistência aos portadores de úlceras venosas atendidos no ambulatório de um hospital universitário em Natal/RN

Study descriptive that was designed to assess the quality of care for people with venous ulcers (VUs) tended at the ambulatory of a university hospital in Natal / RN. The target population of the study was composed by 40 users bearers of venous ulcers served in the ambulatory of angiology of a university hospital in the level of tertiary education. The study received assent of the Ethics Committee of the Federal University of Rio Grande do Norte (Protocol No. 169/06). The collect of data was performed using a form of interview and tour with collection of measures biophysiologic, for a team comprised by the researchers and an academic of nursing, in the period of three months. The data were analyzed in SPSS 14.0, using descriptive statistics and presented in the form of charts, tables and graphs. Identified a clientele of holders of VUs predominantly female, married, aged up to 59 years, low level of education and household income, from Natal, retirees or those exercising professions and occupations that require long periods standing or sitting. In relation to the characteristics of health, those surveyed had risk factors for venous disease and had UVs chronic, located in Zone 2, lost tissue in grade II and serous exudates on average quantity. The assistance to holders of UVs has been characterized by a lack of professional nurses and unavailability of products for the realization of the right curative in ambulatory and outside it; by the inadequacy of products used in VUs, for long periods of treatment without resolution, where the compressive therapy is not priority, by the lack of completeness in the levels of assistance; by monitoring the bearer of UVs only by doctors and the nurses, even with the other team of professionals in the health service; by the completion of guidelines by health professionals and the lack the standardization of conducting laboratory and specifics tests. The assistance was assessed as inadequate in aspects: reference and counter-reference (75.0%), number of consultations with angiologists last year (87.5%), documentation of the clinical findings (85.0%), use of compressive therapy in the past 30 days (77.5%), part of the team interdisciplinary (97.5%), completion of laboratory and specifics tests in the last year (100%), availability of products used in achieving the curative in ambulatory (80, 0%), and indication of products used in the conduct of dressing outside the clinic (70.0%) and appropriate in the guidelines made on the use of socks, lifting of the members and prescription of exercises regular (82.5%) and indication products used in achieving the curative in ambulatory (97.5%). We conclude that the assistance provided to holders of UV was inadequate in 80% of cases interviewed, becoming non-resolutive and assistematic

Avaliação da assistência à saúde dos portadores de úlceras venosas atendidos no programa saúde da família do município de Natal/RN

Descriptive research aimed at evaluating the assistance offered to patients with venous ulcers, on lower limbs, attended by the Family Health Program (FHP) team, from the municipality of Natal/RN. The target population was composed of 74 patients with venous ulcers (VU), attended by the FHP teams in the 31 FHUs. The study was approved by the Ethics Committee of the Federal University of Rio Grande do Norte (protocol n.55/05). The data collection was performed in patients homes and in the FHUs, through structured interviews and physical examinations of patients with VU and non-participant observation during the changing of wound dressings in these Units and in users homes. The data was organized into an Excel electronic table and transported into the SPSS 14.0 program, for descriptive analysis on 2x2 contingency tables and inferential (Qui-Square χ2, Spearman Correlation, Binomial Proportion Test and p-value <0.05). The prevalence of VU (0.36/1000) in the target population (over 20 years of age) was greater than in the population registered in FHP (0.25/1000). We detected a greater prevalence in the age area of over 60 years (2.22/1000), with 2.98/1000 for females and 1.3/1000 for males (p-value=0.008). The sociodemographical and health characteristics of patients with VU revealed predominance of females (74.5%), elders over 60 years of age (67.6%), with fundamental education (74.3%), family earnings of up to 2 minimum wages (68.9%), retired (90.5%), ortostatic position (23.0%), inadequate sleep (59,9%), presence of CVI (100.0%), hypertension (44.6%) and diabetes (25.7%). As for the time of existence of the VU, 64.9% had over 1 year, and 35.1% less than 1 year), with predominance of one wound (67.6%). The changing of wound dressings is performed mostly at home, in and inadequate way, especially with incorrect cleaning techniques, likewise incorrect use of products and substances, and reduced participation of the FHP team on the evaluation and application of the dressing and choosing of products and substances. The compressive therapy is not part of therapeutic conducts for treatment in the FHUs. As for the evaluation of assistance to patients with VU, 90.5% were inadequate and only 9.5% adequate. The main inadequacy factors were the absence of: diagnosis (47.3%), consultation with and angiologist (63.5%), compressive treatment (100.0%), adequate optical therapy (98.62%), adequate dressing kit (70.3%), training for the changing of dressings (67.6%), following by the FHP team (51.4%) and performed exams (55.4%). We ve concluded that patients with VU mostly present now socioeconomical level and associated chronic diseases. Considering that assistance offered by FHP is non-systematic, fragmented, with no diagnosis planning, continual evaluation and evolution, we qualify the assistance as inadequate and with low level of solution, directly interfering on the maintenance of the VUs chronic state

Análise da adesão ao tratamento e da qualidade de vida de pessoas com úlcera venosa

The therapeutic adherence is still a big problem among people with venous ulcers (VU) because the treatment is long, expensive and demand changes in lifestyle. In this context, this study aims to examine treatment adherence and quality of life (QOL) of people with VU assisted at primary health care. This is an analytical, cross-sectional study with a quantitative approach to treatment and data analysis. The study had the scenario 13 Family Health Units and 02 Units Mixed of Natal. The target population consisted of 44 persons with UV indicated by the teams of the Family Health Strategy between February and April 2014. Three instruments were used: an instrument to characterize the sociodemographic, health and care aspects, the Multidimensional Scale of Adherence Therapy composed of the dimensions: healthy lifestyle, compressive therapy and neurovascular monitoring and the Charing Cross Venous Ulcer Questionnaire (CCVUQ) that evaluates QOL in persons with VU composed by the domains: Total Score, Social Interaction, Domestic Activities, Aesthetics and Emotional State. The study was approved by the Ethics Committee in Research of the Federal University of Rio Grande do Norte, CAAE: 07556312.0.0000.5537. The data concerning the sociodemographic characteristics showed that there was a predominance of females (65.9%), age range as of 60 years (59.1%) and income of up to 1 minimum wage (81.8%). With the characterization of health, it was evident that most people reported chronic diseases (63.6%), sleep more than 6 hours (81.8%), present pain (81.8%), denying alcoholism (86 4%) and smoking (77.3%) and showed a number greater than or equal to 1 (77.3%) recurrences. Concerning the therapeutic adherence was found that in the dimension compressive therapy there poor adherence. No associations between the domains of adherence and sociodemographic and health variables were found. Was observed, however, better adherence among individuals without pain and with higher schooling. When analyzed the averages of the dimensions of therapeutic adherence with the care characteristics there was statistical significance between: adherence to compression therapy and guidance for use of compressive therapy (p = 0.002) and guidance for regular exercise (p = 0.026). Considering the mean of total score of CCVUQ (mean 51.47, SD 18.33) it is observed that the overall QOL of respondents has approximate value of the median of the scale (50). The mean of the domain Social Interaction (mean 44.23, SD 21.38) and Domestic Activities (mean 45.70, SD 23.21) were those who reported better QOL. There were weak correlations but significant between adherence to healthy lifestyle and Domains Total Score (p = 0.012), social interaction (p-value = 0.048), Aesthetics (p-value = 0.025) and Emotional State (0.017) of CCVUQ. From the data analysis it is concluded that among people with UV, there poor adherence to compressive therapy. Furthermore, we found no statistically significant association between treatment adherence and sociodemographic and health characteristics. It is added that there was a correlation between the healthy lifestyle dimension and domains CCVUQ

Estudo do comportamento mecânico de areias artificialmente cimentadas

Soil improved with the addition of cement have been utilized as an alternative to the construction of various types of geotechnical works, almost always present economic and environmental advantages. This paper presents a study on the usage of cement in the improvement of mechanical properties of sandy soils, characteristic of the region of Natal, collected from its dunes. This research was made in order to analyze the influence of cement content, voids, and also including water immersion and confining pressure. Samples molded from cement-soil mixtures were tested for unconfined compression tests and triaxial tests. The samples had the percentage of cement mixed in 2.5%, 5% and 10% by weight. The cement agent used was the Portland Cement of High Early strength(CPV-ARI), which promoted agility to the experimental procedure for presenting a rapid gain in strenght. The void ratio used ranged from 0.7 (more compact), 0,9 and 1,1(softer). The soil under study can be considered as pure sand. In general, it can be stated that the larger the amount of cement added to the sand studied is, the greater ultimate strength will be. Likewise, as more compact the soil is, the less void ratio and more resistant it will be present. The confining pressure tends to increase the resistance of the specimens. The cementing adopted grades showed that the use of different criteria for failure did not significantly alter the stress-strain parameters for the sand studied. The angle of friction values were found within the typical range of medium and compact sands. Cementing acted in the sand providing an intercepted cohesion which increased enhancing the potential cementation. In triaxial compression tests, the sand with void ratio is equal to 0.7 and showed the expected behavior for a compact sand while the stress-strain behavior of the same sand with the void ratio of 0.9 tended to be expected for the soft sand as well

Análise de Argamassas Com Substituição Parcial do Cimento Portland Por Cinza Residual de Lenha de Algaroba

With the increase in cement consumption, it has quickly become one of the inputs most consumed by mankind over the last century. This has caused an increase in CO2 emissions, as cement production releases large quantities of this gas into the atmosphere. Adding this fact to the growing consciousness of environmental preservation, it has led to a search for alternatives to cement to complement its derivatives, in the form of waste materials like the ashes. This research aimed to analyze the properties of mortars in fresh and hardened state with partial replacement of Portland cement by residual algaroba wood ash (CRLA) potteries produced by the state of Rio Grande do Norte. The CRLA was collected and sieved, where part of it was ground and characterized in comparison with that just sifted, being characterized according to its chemical composition, grain size, fineness, density, bulk density and index of pozzolanic activity. It was found that the wood ash does not act as pozzolan, and grinding it has not changed its characteristics compared to those just sifted, not justifying its use. Two traces were adopted for this research: 1:3 (cement: fine sand) and 1:2:8 (cement: hydrated lime: medium sand); both in volume, using as materials the CRLA just sifted, CP II F-32 Portland cement, CH-I hydrated lime, river sand and water from the local utility. For each trace were adopted six percentages of partial replacement of cement for wood ash: 0% (control) 5%, 7%, 10%, 12% and 15%. In the fresh state, the mortars were tested towards their consistency index and mass density. In the hardened state, they were tested towards their tensile strength in bending, compressive strength and tensile adhesion strength, and its mass density in the hardened state. The mortar was also analyzed by scanning electron microscopy and X-ray diffraction. Furthermore, it was classified according to NBR 13281 (2005). The results showed that up to a content of 5% substitution and for both traces, the residual algaroba wood ash can replace Portland cement without compromising the mortars microstructure and its fresh and hardened state

Análise do Comportamento Mecânico de Concretos Produzidos com Incorporação de Cinza do Bagaço da Cana-de-Açúcar de Variedades SP911049, RB92579 E SP816949

Concrete is the second most consumed product in the world and the incorporation of the Sugar Bagasse Ash (SBA) into this material can provide solutions for the utilization of by-products from other industries, thus reducing the environmental impact. The general aim of this dissertation focuses on analyzing the mechanical behavior of concrete with addition of SBA from three different species of sugar cane, through tests of consistency, compressive strength, porosity, absorption, voids and Scanning Electron Microscopy (SEM). Were prepared 13 specimens for each specific pattern and level of incorporation of SBA (10%, 20% and 30%) of the three varieties collected, totaling 130 samples of concrete. The trait was employed 1:2:3 (cement: sand: aggregates) in relation to the cement mass with a water / cement ratio of 0.532 and 1% additive Tec 400 Mult also based on the weight of cement. According to the results obtained in this study, it was concluded that the variety of cane sugar, used in the production of the CBC, influenced the mechanical behavior of the resulting concrete. All concrete with addition of SBA, reported a reduction of at least 10% in the properties related to permeability and an increase in the compressive strength of at least 16% compared to standard concrete at 28 days

Estudo de concretos de diferentes resistências à compressão submetidos a altas temperaturas sem e com incorporação de fibras de politereftalato de etileno (PET)

The reinforced concrete structures are largely used in buildings worldwide. Upon the occurrence of fire in buildings, there is a consensus among researchers that the concrete has a high resistance to fire, due mainly to its low thermal conductivity. However, this does not mean that this material is not affected by exposure to high temperatures. Reduction of the compressive strength, modulus of elasticity, discoloration and cracking, are some of the effects caused by thermal exposure. In the case of concretes with higher resistance occurs even desplacamentos explosives, exposing the reinforcement to fire and contributing to reducing the support capacity of the structural element. Considering the above, this study aims to examine how the compressive strength and porosity of concrete are affected when subjected to high temperatures. Were evaluated concrete of different resistances, and even was the verified if addition fibers of polyethylene terephthalate (PET) in concrete can be used as an alternative to preventing spalling. The results indicated that explosive spalling affect not only high strength concrete whose values of this study ranged from 70 to 88 MPa, as well as conventional concrete of medium strength (52 MPa) and the temperature range to which the concrete begins to suffer significant changes in their resistance is between 400 º C and 600 º C, showing to 600 º C a porosity up to 188% greater than the room temperature

Avaliação do concreto de cimento portland com resíduo da produção de scheelita em substituição ao agregado miúdo

From the 70`s, with the publication of the Manifesto for Environment UN Conference, held in Stockholm, in Sweden (1972), defend and improve the environment became part of our daily lives. Thus, several studies have emerged in several segments in order to reuse the waste. Some examples of waste incorporated in portland cement concrete are: rice husk ash, bagasse ash of cane sugar, powder-stone, microsilica, tire rubber, among others. This research used the residue of the mining industry Scheelite, to evaluate the incorporation of the residue composition of Portland cement concrete, replacing the natural sand. The percentage of residue were incorporated from 0% to 100%, with a variation of 10%, 11 being produced concrete mix in the ratio 1:2:3:0.60, by mass. We evaluated the following characteristics of concrete: slump test, compressive strength, tensile strength by diametral compression, water absorption, porosity and density, based on the ABNT, through tests performed in the Laboratory of Civil Construction, UFRN. The trace with the addition of 60% scheelite residue was obtained which better performance. Therefore, the use of the waste from the production of Scheelite is feasible due to the durability parameters (water absorption and porosity), sustainability, and the good results of the resistance of the concrete

Estudo da viabilidade da utilização de cinza de lodo de esgoto como adição em argamassa de cimento Portland

The use of sewage sludge as a raw material falls within the waste recycling key in the current process model environmental sustainability .Waste recycling has been consolidated as a sustainable environmentally sound technical solution, and. Despite showing very variable composition and characteristics, sewage sludge, can be considered as a residue with a high recycling potential in the building sector. In this paper the feasibility of using sewage sludge ash was studied in addition to Portland cement mortar in 1:3 mass considered the standard dash. This gray additions were studied in proportions of 5%, 10 %, 15 %, 20 %, 25% and 30% by mass of cement. The methodology was focused on the characterization of materials by physical, chemical , mechanical , environmental and morphological followed by the production of mortar tests ,and finalized by the characterization tests of mortar in the fresh state, through the consistency index, content of entrained air, bulk density and water retention, and in the hardened state by bulk density, water absorption by capillarity capillarity coefficient, compressive strength, tensile strength in bending ,tensile bond strength and microstructural analysis for percentages of 0 to 20%. After comparing with the standard mortar mortars with addition of ash, it is concluded that the ash of sewage sludge did not impair the integrity and properties of mortars with addition, including increasing resistance to compression and tension, being 20% more indicated percentage. Thus, it becomes feasible the addition of sewage sludge ash in Portland cement mortar for the trait studied