Properly preparing the drilling fluid is an essential part of any successful drilling operation, especially in complex operations like deviated and horizontal drilling. Understanding the flow behavior of the polymers used in the drilling fluids under different conditions takes a key part in this preparation. In this study, shear rheology of some traditionally used water soluble polymers in drilling and completion fluids / namely PAC (polyanionic cellulose) and xanthan gum, were investigated experimentally. Instead of an oilfield standard Fann Model 35 Viscometer, an Ofite Model 900 Viscometer was used because of its capability to measure at ultra-low shear rates. Effects of the concentration of the polymer, time of shear applied, test temperature and effects of aging were examined. Rheological measurements were conducted between the shear rate ranges of 0.01 to 1000s-1 with concentrations changing from 0.25 to 1.5 grams of polymer per 350 milliliters of water (equivalent to 0.25 to 1.5 lb/bbl). Rheograms were constructed to identify the effect the polymers in question have on the flow characteristics of the drilling fluid. An appropriate constitutive model was used to define the flow behavior of the polymer in question mathematically. It was observed from the constructed rheograms that increase in polymer concentration results in consistent increase of apparent viscosity. Amount of time of shear does not affect the selected polymers if they are dynamically aged at least for two hours. Also as expected increasing temperature of the sample lowers the apparent viscosity considerably.

Drilled shaft construction often requires the use of drill slurry to maintain borehole stability during excavation and concreting. While drill slurry may be composed of fluids ranging from air to petroleum, drilled shaft construction typically makes use of water based drilling fluids. Although clean water may be utilized as a drilling fluid, a premixed slurry consisting of water, minerals, and/or polymers is more commonly used. Florida Department of Transportation (FDOT) specifications require the use of mineral slurry for all primary structures. The slurry resists the intrusion of groundwater, slows the outward migration of drilling fluid from the excavation, and aids in the removal of suspended soil cuttings. The mechanisms by which mineral slurries work are quite different from those of polymer slurries. Due to these differences, it is unclear whether a mineral based slurry, which has been fortified with polymers by manufacturers or enhanced through the addition of polymers in the field, behaves more like a mineral slurry rather than polymer slurry. This thesis provides an overview of the methods used to measure physical slurry parameters of interest. These parameters include density, viscosity, pH, sand content, and filtration control. Methods employed to describe the slurry parameters include tools and instrumentation commonly used in both field and laboratory settings.

Differential scanning calorimetry has been used to study the kinetics of formation of clathrate hydrates in the systems water-CCl3F and water-CH4, in which the water phase was dispersed in an oil phase in the form of an emulsion. CCl3F hydrates were formed at ambient pressure and constant temperatures of -10, -15 and -20 °C. The results showed that the crystallization of both ice and hydrate are in competition at the lowest temperature, whereas only hydrate is formed at -10 or -15 °C. CH4 hydrates were studied using a high-pressure DSC in the range 10 to 40 MPa, at various temperatures. At high driving force, the heat peak related to the formation of hydrates has a regular and symmetric shape, and its height and width depend on the gas pressure and sub cooling degree. At near equilibrium conditions, hydrate formation can be delayed by several hours, but is still clearly observable. A model based on crystal growth theory coupled with a statistical law to take into account the germination in micro sized droplets is proposed.

Filter cake characterization is very important in drilling and completion operations. Heterogeneity of the filter cake plays a key role in the design of chemical treatments needed to remove the filter cake. The objectives of this study are to characterize the filter cake under static and dynamic conditions, evaluate the using of polylactic acid and chelating agents to remove calcium carbonate-based filter cake, assess glycolic acid to remove Mn3O4-based filter cake, and evaluate ilmenite as a weighting material for water-based drilling fluid. In order to characterize the filter cake, computer tomography (CT) was used in combination with the scanning electronic microscopy (SEM) to analyze the filter cake. A modified HPHT filter cell was developed to perform the filtration tests. A see-through-cell was used to check the compatibility of different chemicals that were used to remove the filter cake. The results obtained from the CT scan showed that the filter cake was heterogeneous and contained two layers with different properties under static and dynamic conditions. Under static conditions, the formation of filter cake changed from compression to buildup; while under dynamic conditions, the filter cake was formed under continuous buildup. Polylactic acid was used as a component of the drilling fluid components and the results obtained showed that the drill-in fluid had stable rheological properties up to 250˚F over 24 hrs. The removal efficiency of the filter cake was nearly 100% and the return permeability was about 100% for Indiana limestone and Berea sandstone cores, when using a weight ratio of polylactic acid to calcium carbonate 3 to 1. GLDA (pH 3.3) and HEDTA (pH 4) can be used to remove the filter cake in one step without using α-amylase enzyme solutions. GLDA (20 wt% in a 200 g solution and pH of 3.3) and HEDTA (20 wt% in a 200 g solution and pH 4) had 100% removal efficiency of the filter cake using Indiana limestone and Berea sandstone cores. Chelate solutions, GLDA (pH of 3.3 - 13) and HEDTA (pH of 4 and 7) were incompatible with α-amylase enzyme solutions over a wide range of temperatures. CT results showed that no formation damage was observed when using chelating agents as a breaker to remove the calcium carbonate filter cake. Manganese tetraoxide-based filter cake had a removal efficiency of 85% after 20 hrs soaking with glycolic acid (5 wt%) after soaking with α-amylase for 24 hrs, and 89% after reaction with acid mixture (1 wt% HCl and 7 wt% glycolic acid) for 16 hrs. for both methods, the retained permeability was 100% for Indiana limestone cores and 120% for Berea sandstone cores, which indication maximum productivity of these formations. Ilmenite-based filter cake was ideal for HPHT applications, 0.2 in. thickness and 12 cm3 filtrate under dynamic conditions. The filtrate volume was reduced by adding a minor amount of CaCO3 solids that improved the particles packing. No sag problem was observed when using the micronized ilmenite in water-based drilling fluids. Ilmenite has a negative zeta potential in alkaline media and had a stable dispersion in water at pH > 7.

Na perfuração de poços para extração de petróleo são utilizados fluidos de perfuração compostos por diversos produtos químicos com finalidades específicas em função das características de cada poço. Durante vários anos utilizou-se fluido a base de óleo diesel, devido à excelente performance proporcionada à perfuração. O aumento da preocupação ambiental levou a indústria do petróleo a elaborar composições de fluidos que fossem menos agressivas ao ambiente e, ao mesmo tempo, apresentassem performances semelhantes à do fluido base óleo diesel, destacando-se na atividade de perfuração na bacia do Recôncavo, Bahia, o fluido n-Parafina. Entre os compostos de interesse ambiental presente neste tipo de fluido, destacam-se a n-Parafina e cloretos, algumas vezes com traços de BTEX (benzeno, tolueno, etilbenzeno e xilenos). Como durante a perfuração podem ser atravessados aqüíferos portadores de água doce, resta a preocupação de que o contato desses fluidos com estes aqüíferos possa gerar problemas de contaminação ambiental. Este trabalho apresenta uma avaliação de situações de poços, onde o aqüífero São Sebastião, principal da bacia do Recôncavo, foi atravessado utilizando-se fluido n-Parafina. A avaliação foi baseada em simulações matemáticas do transporte dos compostos encontrados no fluido n-Parafina e em amostras coletadas a partir de testes de formação a cabo durante a perfuração dos poços. A partir da simulação destes valores reais, pôde-se concluir que, a menos de 0,5 m da parede dos poços, as concentrações encontram-se perfeitamente dentro dos padrões de potabilidade para todos os compostos analisados. De acordo com a metodologia utilizada, as utilizações do fluido n-Parafina são ambientalmente inofensivas como fluido de perfuração a ser utilizado neste tipo de cenário hidrogeológico. / The use of drilling fluids or muds is standard practice in oil industry. The composition of these fluids is designed according to the formation and the well properties. For many years oil- based muds (OBM) had a worldwide use because they offered advantages over water-based muds (WBM). Increasing environmental concern led the oil industry into the formulation of a variety of syntetic organic based mud (SBM) or low-tox mineral oil- based mud, like the n-parafin based mud, with a large use at the Reconcavo Basin, Bahia, Brazil. Some of the compounds that are common to most fluid formulas are considered potential environmental contaminants, among them n-parafin and chloride, sometimes with trace BTEX (benzene, toluene, ethylbenzene and xylenes). The drilling of the well might cross aquifers that are used for drinking purposes before reaching the oil reservoir and the contact of the water with the drilling fluid might pose some concern about the aquifer contamination. This paper presents case studies where a well penetrated São Sebastião Aquifer, in Reconcavo Basin, using n-Parafin based mud and a mathematical model was applied to simulate the fate and transport of the compounds found in fluid and samples collected during the drilling. The results indicated that all concentration values of the detected compounds were well below water drinking standards within 0,5 m from the well. According to this conclusion, the use of the n-parafin fluid is considered harmless to the environment and is recommended for similar geological scenarios.

ABSTRACT HYDRAULICS OPTIMIZATION OF FOAM DRILLING IN DRILLING OPERATIONS &Ouml / zer, Ceren M. Sc., Department of Petroleum and Natural Gas Engineering Supervisor: Assoc. Prof. Dr. Evren &Ouml / zbayoglu September 2009, 72 pages In drilling, drilling fluid affects every single step of operation. If rig system is thought as the human body, drilling mud can be defined as the blood system of it. Drilling fluid carries the cuttings, cools the bit, it conditions the hole and so on. Some special kinds of drilling fluids are used for special purposes such as underbalanced drilling. Underbalanced drilling is generally used to prevent formation damage, lost circulation and to increase the penetration rate.Since 1980&rsquo / s foam is used as drilling fluid for underbalanced drilling purposes and there are some models for bit hydraulic optimizations. In this study, mathematical model has been derived considering not the volumetric flow rate but the mass flow rate of the foams. Maximum hydraulic horse power at the bit is determined as a function of mass flow rate. Using this concept, optimum volumetric flow rates for liquid and gas phases as well as optimum nozzle size are determined.Using this mathematical model, a computer program is developed for comparing the results with the existing data available in the literature. It accounts for the compressibility of foam and pressure losses inside the drill string, bit and annulus.Hole size, drill-string properties, formation temperature and pressure, maximum inlet pressure are used as input parameters. Program calculates static back pressure,pressure losses in the whole system, bottom hole foam properties such as quality and velocity and optimum liquid and gas flow rates which are the key parameters of foamdrilling optimization. Results show that liquid and gas rates should be increased with increasing hole sizeand formation pressure. Increasing temperature gradient causes a minimal decrease on foam rate properties. In addition, pressure losses due to friction increases with increasing hole size and formation pressure. Decrease in formation temperature also decreases the foam quality. Changes in temperature gradient causes minimal changes on foam rate properties. Comparisons of the proposed model with other models from the literature also gave good match. The optimization criteria and assumptions are differing from the existing models. As a result the comparison does not have to one to one match with the others. The results from this study may be used for optimization of flow rate of foam as drilling fluid based on mass flow.

Gas hydrate formation generally involves gas dissolution, formation of nuclei and growth of new nucleus. On condition of synthesizing experiments without agitation, the formation of hydrate nuclei is comparatively difficult and needs an induction period which is considerably uncertain and random. Some additives such as surfactant sodium dodecyl sulfate (SDS) can increase the formation rate and reduce the induction time. A hydrate formation and mini drilling experimental system was used to carry on methane hydrate formation experiments with small quantity of SDS and SDS- tetrahydrofuran(THF) in deionized water. The reactor is a high pressure cell (40Mpa) made of titanium alloy with 4 transparent windows and an inner volume of about 2.8 liters. The effect of SDS and THF hydrate on the formation rate and amount of methane hydrate was studied by comparative testing and analyzing the collected data of temperature and pressure. According to the results of the tests, the formation rate of methane hydrate in the SDS-THF solution was faster than that in the SDS solution. As a water-soluble hydrate former, THF hydrate nucleation may be benefit of methane hydrate nucleation. A small amount of SDS and THF could dramatically promote the formation of methane hydrate in the pure water, and rapidly increase the amount of methane hydrate too. Therefore, a great deal of time for experiment was saved, which established a good basis for the coming mini drilling and drilling fluid experiments.

In efforts to render the safest, fastest, and most cost efficient drilling program for a high temperature and high pressure (HT/HP) well the maximization of drilling operational efficiencies is key. Designing an adequate, HT/HP well specific, drilling fluid is of most importance and a technological challenge that can greatly affect the outcome of the overall operational efficiency. It is necessary to have a sound fundamental understanding of the behavior that water-based muds (WBM) exhibit when exposed to HT/HP conditions. Therefore, in order to adequately design and treat a WBM for a HT/HP well specific drilling program, it is essential that the mud be evaluated at HT/HP conditions. Currently, industry standard techniques used to evaluate WBM characteristics involve aging the fluid sample to a predetermined temperature, based on the anticipated bottom hole temperature (BHT), either statically or dynamically, for a predetermined length, then cooling and mixing the fluid and measuring its rheological properties at a significantly lower temperature. This, along with the fact that the fluid is not subjected to the anticipated bottom hole pressure (BHP) during or after the aging process, brings to question if the properties recorded are those that are truly experienced down-hole. Furthermore, these testing methods do not allow the user to effectively monitor the changes during the aging process. The research in this thesis is focused on evaluating a high performance WBM and the current test procedures used to evaluate their validity. Experimental static and dynamic aging tests were developed for comparative analysis as well to offer a more accurate and precise method to evaluate the effects experienced by WBM when subjected to HT/HP conditions. The experimental tests developed enable the user to monitor and evaluate, in real-time, the rheological changes that occur during the aging of a WBM while being subjected to true BHT and BHP. Detailed standard and experimental aging tests were conducted and suggest that the standard industry tests offer false rheological results with respect to true BHT and BHP. Furthermore, the experimental aging tests show that high pressure has a significant effect on the rheological properties of the WBM at elevated temperatures.

In the process of drilling, the rock fragments generated by the drill are taken from the well to the surface by the drilling fluid. The drilling fluid used in Brazil is made by synthetic oil, it presents several advantages over other types of drilling fluid. However, it has the disadvantage of having high toxicity and low biodegradability, requiring a separation system of drilled cuttings contaminated with this drilling fluid. Currently, the responsible equipment for reducing these levels to the permitted by law is working under extreme conditions and residual levels generated are very close to permitted by environmental legislation. For this reason, the technique of microwave drying has been studied for use in remediation of drilled cuttings and has shown very promising because it presents high efficiency and low operational problems when it is compared to conventional equipment. Therefore, the aim of this work are to investigate the influence of various operating parameters of a microwave dryer, analyze the efficiency of the dryer microwave suited for this job and to obtain operational conditions and information for operating a industrial microwave operating in continuous flow. So were tested influence of temperature, flow rate of inert, initial fluid content, reuse of drilled cuttings, rock type, fluid type and mechanical agitation in microwave drying; tests of drying kinetics and the mapping drying inside the microwave were made. The results showed no difference in drying with the influence of inert flow and the type of fluid, but there was influence of drying temperature, the initial salt content, initial fluid content and rock type. Drying with agitation can increased the removal efficiency in 17 % with 27 mm of bed thickness, rocks with slow heating improve the removal efficiency, drilled cuttings with similar physical aspects have similar removal efficiency. The heating of rocks in the microwave depends strongly of the oxides content in its composition. The temperature control of the bed should be the upper limit of the boiling range of the hydrocarbons present in the drilling fluid. The mapping study showed that there are drying gradients inside the microwave, besides showing the intrusive effect of metals in the material, effect of the edges of the recipes and the position of exhaust fan. The equipment showed to be as efficient as others listed in the literature, which can reduce the levels of n-paraffin to below 1 % by mass. / No processo de perfuração de poços de petróleo, os fragmentos de rocha gerados pela broca, são transportados do fundo do poço até a superfície pelo fluido de perfuração. O fluido de perfuração mais utilizado no cenário brasileiro é o de base sintética, pois apresenta diversas vantagens com relação a outros tipos de fluido. Porém, apresenta a desvantagem de possuir alta toxicidade e baixa biodegrabilidade, necessitando de um sistema de separação para que o cascalho contaminado com esse fluido possa ser descartado no meio ambiente. Atualmente, o equipamento responsável pela redução destes teores até os limites permitidos por lei, opera de maneira sobrecarregada e os teores residuais alcançados estão muito próximos do permitido pela legislação ambiental. Por essa razão, a técnica de secagem por micro-ondas vem sendo estudada para ser utilizada na descontaminação de cascalhos contaminados com fluido de perfuração. Essa tecnologia mostra-se ser muito promissora, pois apresenta altas eficiências de remoção e menores problemas operacionais quando comparados aos equipamentos convencionais. Por isso, o objetivo deste trabalho é verificar a influência de algumas variáveis de operação de um secador micro-ondas de bancada adaptado para a descontaminação de cascalhos de perfuração. Além de verificar a eficiência desse equipamento e obter condições operacionais e informações suficientes para o projeto de um micro-ondas semi-industrial contínuo. Para isso, foram testadas as influências da temperatura, vazão de inerte, teor inicial de fluido, reutilização do cascalho, tipo de rocha, tipo de fluido e a presença da agitação mecânica na secagem por micro-ondas; foram feitos testes de cinética de secagem por micro-ondas e feito o mapeamento da secagem no interior do equipamento. Os resultados mostraram que não houve diferença na secagem por micro-ondas para diferentes vazões de inerte e tipo de fluido, porém houve influência da temperatura da secagem, do teor inicial de sal, do teor inicial de fluido e do tipo de rocha. A agitação mecânica aumentou a eficiência de remoção em 17% para um leito de 27 mm de espessura; o aquecimento lento de cascalhos melhoram a eficiência de remoção; cascalhos contaminados que apresentam aspectos físicos iguais apresentam eficiência de remoção semelhantes. O aquecimento de rochas no micro-ondas depende, fortemente, dos teores de óxidos em sua composição. A temperatura de controle do leito deve ser acima do limite superior da faixa de ebulição dos hidrocarbonetos presentes na base do fluido de perfuração. O estudo de mapeamento mostrou que há gradientes de secagem no interior do micro-ondas, além de mostrar o efeito intrusivo de metais no material e efeito das bordas do recipiente. O equipamento apresentou ser tão eficiente quanto outros reportados na literatura, podendo reduzir os teores de n-parafina até abaixo de 1%, em massa. / Mestre em Engenharia Química

Made available in DSpace on 2014-12-17T15:41:44Z (GMT). No. of bitstreams: 1 EmanuellaLFV.pdf: 2331935 bytes, checksum: 3f4df9b602349e41bf8ab4d2c561b59d (MD5) Previous issue date: 2009-01-14 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The clay swelling is today one of the major problems during the well drilling. Nearly 50% of clays that constitute shale expand easily in the presence of water molecules. During the drilling of a geological formation containing swelling clays, when is feasible the use of water base fluids, it is necessary to apply clay inhibitors. This avoids the incorporation of the cutting to the drilling fluid which is responsible for the wall swelling and crumbling. The aim of this work was to evaluate the synergistic behavior that occurs when swelling clay inhibitors are associated to NaCl and KCl salts. Three swelling clay inhibitors samples, INIB A, INIB B and INIB C, were analyzed. Each inhibitor was characterized by the amount of chlorides and active matter content. For the water-clay interaction evaluation in the presence of various fluids, it was used the Capillary Suction Timer (CST, Fann) and Linear Swell Meter (LSM 2000, Fann). For better interpretation of results, a Design of Experiments (DOE, Umetrics MODDE 7.0 TM) through Result Surface Methodology (RSM) was employed, taking into account the type, the swelling inhibitors concentration and the contact time with the clay. The results showed different efficiencies among the inhibitors employed, and the salt-inhibitors mixtures were more efficient than those products alone. However, for field operation, other parameters should be taking into account, as operational cost, environmental requests and time of application for each product / O inchamento das argilas, quando em contato com o fluido de perfura??o, tem sido um dos maiores vil?es na perfura??o de po?os de petr?leo. Aproximadamente 50 % das argilas que constituem um folhelho se expandem facilmente na presen?a de mol?culas de ?gua. Na perfura??o de camadas geol?gicas contendo folhelhos hidrat?veis, quando ? vi?vel a utiliza??o de fluidos ? base de ?gua, h? a necessidade de utiliza??o de inibidores de inchamento de argilas. Estes inibidores evitam que os s?lidos perfurados incorporem-se ao fluido, e impedem o inchamento e o desmoronamento das paredes dos po?os. Esta disserta??o teve como objetivo realizar um estudo sobre o comportamento sinerg?tico de inibidores de hidrata??o de argila quando associados aos sais de NaCl e KCl. Foram analisadas tr?s amostras de inibidores de inchamento de argila comerciais, INIB A, INIB B e INIB C. Cada inibidor foi caracterizado quanto ao teor de cloreto e de mat?ria ativa. Para avalia??o da intera??o ?gua-argila na presen?a dos diversos fluidos, amostras de argila ativada foram submetidas a testes de capilaridade no CST (Capilary Succion Timer) e de inchamento no LSM (Linear Swell Meter). Para melhor interpreta??o dos resultados, foi empregada an?lise estat?stica experimental (DOE), por metodologia de resposta de superf?cie (RSM), atrav?s do programa MODDE 7.0TM da Umetrics, em que se levou em considera??o o tipo, a concentra??o dos inibidores de inchamento e o tempo de contato com a argila. A an?lise dos resultados comprovou as diferen?as de efici?ncia entre os inibidores empregados e que misturas dos inibidores com sais s?o mais eficientes que os produtos individualmente. Entretanto, para opera??es de campo, outros par?metros devem ser levados em considera??o, tais como custo, exig?ncias dos ?rg?os ambientais e tempo de atua??o do produto