Made available in DSpace on 2014-12-17T15:42:26Z (GMT). No. of bitstreams: 1 FranciscaSHTP_TESE.pdf: 2918129 bytes, checksum: e712b711537d456c1dd4eaa0f003f3af (MD5) Previous issue date: 2013-04-01 / The construction of wells is one of the most important activities of the oil industry. The drilling process is the set of activities and operations to design, program and perform the opening thereof. During this process, the cuttings are removed by the drilling fluid, or mud, and carted to the surface. This fluid is injected into the drill string and returns to the surface through the annular space between the well walls and the drill string. After the descent of the column casing, the annular space between the casing string and the walls of the borehole is filled with cement so as to secure the spine and prevent any migration of fluids between the various permeable zones traversed by the well behind of the coating. To ensure the good quality of the cementation scrubbers are used mattresses which are pumped ahead of the cement slurry so as to avoid contamination of the drilling fluid paste, or vice versa, and assist in the removal of plaster, formed by drilling fluid of the borehole walls, thus enabling a better cement bond to the well. Within this context, this work aims to evaluate the efficiency of mattresses scrubbers, the basis of ionic and nonionic surfactants, on the removal of nonaqueous drilling fluid, based on n-paraffin in oil wells, and the compatibility between the Mattress relations washer / drilling fluid bed scrubber / cement paste mattress washer / cement slurry / drilling fluid and the drilling fluid / cement slurry using laboratory tests rheology, thickening time and compressive strength. Also technique was performed X-ray diffraction (XRD) for a more detailed analysis of these mixtures with hydrated cement paste. In compatibility tests the conditions of temperature and pressure used in the same laboratory procedure simulating the conditions of oil wells, the well is considered the depth of 800 m. The results showed that the compositions of the mattress washer nonionic, KMS obtained a 100% efficient in removing the non-aqueous drilling fluid, and the best formulation showed good results with respect to compliance testing / A constru??o de po?os ? uma das atividades mais importantes da ind?stria do petr?leo. O processo de perfura??o de po?os ? o conjunto de atividades e opera??es destinadas a projetar, programar e realizar a abertura dos mesmos. Durante este processo, os cascalhos s?o removidos pelo fluido de perfura??o, ou lama, e carreados at? a superf?cie. Este fluido ? injetado no interior da coluna de perfura??o e retorna ? superf?cie atrav?s do espa?o anular entre as paredes do po?o e a coluna de perfura??o. Ap?s a descida da coluna de revestimento, o espa?o anular entre a coluna de revestimento e as paredes do po?o ? preenchido com cimento, de modo a fixar a coluna e evitar que haja migra??o de fluidos entre as diversas zonas perme?veis atravessadas pelo po?o, por tr?s do revestimento. Para garantir a boa qualidade da cimenta??o, s?o utilizados os colch?es lavadores, que s?o bombeados ? frente da pasta de cimento, de modo a evitar a contamina??o da pasta pelo fluido de perfura??o, ou vice-versa, al?m de auxiliar na remo??o do reboco, formado pelo fluido de perfura??o, das paredes do po?o, possibilitando assim uma melhor ader?ncia do cimento ao po?o. Dentro deste contexto, este trabalho tem como objetivo avaliar a efici?ncia de colch?es lavadores, a base de tensoativos i?nico e n?o i?nico, na remo??o do fluido de perfura??o n?o aquoso, ? base de n-parafina, em po?os de petr?leo, e a compatibilidade entre as rela??es colch?o lavador/fluido de perfura??o, colch?o lavador /pasta de cimento, colch?o lavador /pasta de cimento/fluido de perfura??o e fluido de perfura??o/pasta de cimento utilizando os ensaios laboratoriais de reologia, tempo de espessamento e resist?ncia ? compress?o. Tamb?m foi realizada a t?cnica difra??o de raios X (DRX) para uma an?lise mais detalhada dessas misturas com a pasta hidratada de cimento. Nos ensaios de compatibilidade as condi??es de temperatura e press?o utilizadas nos procedimentos laboratoriais simularam as mesmas condi??es dos po?os de petr?leo, sendo a profundidade do po?o considerada de 800 m. Os resultados mostraram que as composi??es do colch?o lavador n?o i?nico, o KMS, obtiveram uma efici?ncia de 100% na remo??o do fluido de perfura??o n?o aquoso e a sua melhor formula??o apresentou resultados satisfat?rios em rela??o aos testes de compatibilidade

Specially designed non-damaging lost circulation pills (LCP) are being effectively applied for drilling depleted zones worldwide. Optimizing the LCP compositions stop the lost circulation effectively and protect the production zone from liquid and solids invasion significantly. Shape, particle size distribution and concentration of the lost circulation materials (LCM) are key parameters determining the effectiveness of LCP. In this study, the Permeability Plugging Apparatus (PPA) is utilized to evaluate effectiveness of various LCM&rsquo / s in curing the lost circulation. Sized calcium carbonates are used as LCM in different concentrations and in different particle size distribution. Lost circulation zones are simulated using the ceramic disks and slotted disks. Ceramic disks with nominal pore sizes 20, 35, 60, 90, and 150 microns are characterized in terms of pore size distribution using the computerized image analysis technique. Filter cake quality, spurt loss and filtrate volume are basic parameters to be evaluated in this study. Tests are performed at 75 F and 300 psi of differential.

Gashydrate sind natürlich vorkommende feste Verbindungen aus Wasser und Gas, deren Erschließung als zukünftige Energiequelle von Interesse ist. Für die bohrtechnische Erschließung mariner Gashydratlagerstätten ist eine leistungsfähige Bohrspülung notwendig. Das vom Bohrmeißel gelockerte Sediment und darin enthaltenes Gashydrat werden durch die Bohrspülung nach übertage transportiert. Die Gashydratpartikel verlassen beim Aufsteigen im Ringraum in ca. 300 m Wassertiefe ihren Stabilitätsbereich und dissoziieren in Wasser und Gas. Um eine Verdünnung und eine Dichteerniedrigung der Bohrspülung zu verhindern, soll das Gashydratbohrklein stabilisiert werden. Gleichzeitig darf sich in der Bohrspülung bei Anwesenheit von freiem Gas in der Lagerstätte kein neues Gashydrat bilden. Die Arbeit beschäftigt sich mit der Suche nach Additiven, welche die Gashydratneubildung und -dissoziation gleichzeitig hemmen. Es wurde ein Schüttelautoklav genutzt, um die Dissoziationstemperatur von Methanhydrat bei ca. 85 bar zu ermitteln und die Verzögerung des Hydratzerfalls bei Anwesenheit verschiedener Additive zu vergleichen. Es konnte ein Additiv gefunden werden, das diese Anforderungen erfüllt. Des Weiteren wurden neue rheologische Untersuchungsprogramme für verschiedene Spülungstypen erarbeitet, die eine detaillierte Charakterisierung der Fließfähigkeit, Thixotropie und Geleigenschaften von Bohrspülungen erlauben.

Made available in DSpace on 2014-12-17T15:01:19Z (GMT). No. of bitstreams: 1 MiguelASN.pdf: 491289 bytes, checksum: be60500500779f6a3fd87b90108feb8c (MD5) Previous issue date: 2002-09-27 / The developments in formulating drilling fluids to apply in petroleum fields are based on new technologies and environmental challenges, where the technical performance of a developed drilling fluid is used to produce a minimum environmental impact, showing great economy in costs. It is well known that the potential use of oil-based drilling fluids is limited because these fluids when discharged in the sea do not disperse as much as water-based ones and may form waterproof films in the seabed, having a profound effect on plants and animals living in this environment. The current works have been made in investigating fluids called pseudofluids, which are synthetic ester-based, n-paraffin-based and other fluids formed from inverse emulsion. In this research the principal parameters involved in inverse emulsion process were studied, in laboratory scale, using esters as main component. Others commercial drilling fluids were used as comparative samples, as well as samples from laboratory and field where these drilling fluids are being applied. Concentrations of emulsifier and organophilic clay, which are viscosity donor, were varied to verify the influence of these parameters, in different oil/water ratios (55/45, 60/40, 65/35, 70/30, and 75/25). The salt concentration (NaCl) is an indicative parameter of stability and activity of an esterbased fluid. In this research the salt concentration was varied in 10,000, 20,000, and 50,000 ppm of NaCl. Some rheological properties of the produced fluids were studied, such as: initial gel, plastic viscosity, yield point, and apparent viscosity. Through the obtained rheological measures, the existence of two systems could be verified: fluid and flocculated. It could be noticed that the systems were influenced, directly, by the oil/water ratio and emulsifier, organophilic clay and NaCl concentrations. This study showed the viability to use an ester obtained from a regional vegetable product baba?u coconut oil to obtain an efficient and environmental safe drilling fluid / O desenvolvimento atual e futuro, em campos de petr?leo, baseia-se em novas tecnologias e desafios ao meio ambiente, onde se utiliza principalmente a performance t?cnica de um fluido de perfura??o que produza o m?nimo impacto ambiental, mostrando ainda, uma ?tima economia nos custos desses desenvolvimentos. Sabe-se que o potencial de continuidade de fluidos de perfura??o a base de ?leo est? limitado e, por conseguinte, o avan?o ambiental tem sido na investiga??o de fluidos chamados pseudo-fluidos, ou seja, fluidos sint?ticos base ?ster, ?ster, n-parafina e outros fluidos de emuls?o inversa, os quais est?o em estudo. Neste trabalho estudou-se em n?vel de laborat?rio as principais vari?veis envolvidas no processo de emuls?o inversa usando ?steres como componente principal, utilizando-se amostras comparativas de outros fabricantes, como tamb?m amostras provenientes de laborat?rio e de campo onde est?o sendo utilizados estes fluidos de perfura??o. As concentra??es de emulsificante ou argila organof?lica, que ? doadora de viscosidade, foram variadas para verificar a influ?ncia destes par?metros a diferentes raz?es ?leo/?gua (55/45, 60/40, 65/35, 70/30 e 75/25), mantendo-se constante os demais componentes do fluido. A concentra??o do sal, que ? um par?metro indicador de estabilidade e da atividade em fluido a base ?ster, foi variada em 10.000, 20.000 e 50.000 ppm de NaCl. Algumas propriedades reol?gicas dos fluidos assim produzidos foram estudadas, tais como: gel inicial, viscosidade pl?stica, limite de escoamento e viscosidade aparente. A partir das medidas reol?gicas obtidas, p?de-se verificar a exist?ncia de dois sistemas: fluido e floculado. P?de-se perceber que os resultados obtidos foram influenciados diretamente pela raz?o ?leo/?gua e pelas concentra??es do emulsificante, da argila organof?lica e do NaCl. Este estudo consolidou importantes conhecimentos que abrir?o portas para o sucesso de novas pesquisas, tornando-se fundamental a viabiliza??o de coloc?-lo posteriormente no mercado de trabalho do Brasil

Gashydrate sind natürlich vorkommende feste Verbindungen aus Wasser und Gas, deren Erschließung als zukünftige Energiequelle von Interesse ist. Für die bohrtechnische Erschließung mariner Gashydratlagerstätten ist eine leistungsfähige Bohrspülung notwendig. Das vom Bohrmeißel gelockerte Sediment und darin enthaltenes Gashydrat werden durch die Bohrspülung nach übertage transportiert. Die Gashydratpartikel verlassen beim Aufsteigen im Ringraum in ca. 300 m Wassertiefe ihren Stabilitätsbereich und dissoziieren in Wasser und Gas. Um eine Verdünnung und eine Dichteerniedrigung der Bohrspülung zu verhindern, soll das Gashydratbohrklein stabilisiert werden. Gleichzeitig darf sich in der Bohrspülung bei Anwesenheit von freiem Gas in der Lagerstätte kein neues Gashydrat bilden. Die Arbeit beschäftigt sich mit der Suche nach Additiven, welche die Gashydratneubildung und -dissoziation gleichzeitig hemmen. Es wurde ein Schüttelautoklav genutzt, um die Dissoziationstemperatur von Methanhydrat bei ca. 85 bar zu ermitteln und die Verzögerung des Hydratzerfalls bei Anwesenheit verschiedener Additive zu vergleichen. Es konnte ein Additiv gefunden werden, das diese Anforderungen erfüllt. Des Weiteren wurden neue rheologische Untersuchungsprogramme für verschiedene Spülungstypen erarbeitet, die eine detaillierte Charakterisierung der Fließfähigkeit, Thixotropie und Geleigenschaften von Bohrspülungen erlauben.

Submitted by Jorge Silva (jorgelmsilva@ufrrj.br) on 2017-10-31T17:20:21Z No. of bitstreams: 1 2016 - Elisa Vila Nova de Noronha.pdf: 4419781 bytes, checksum: 0804df588af66f56621082802458f769 (MD5) / Made available in DSpace on 2017-10-31T17:20:21Z (GMT). No. of bitstreams: 1 2016 - Elisa Vila Nova de Noronha.pdf: 4419781 bytes, checksum: 0804df588af66f56621082802458f769 (MD5) Previous issue date: 2016-12-21 / For the drilling process to succeed, it is necessary the use of a drilling fluid. The measurement of rheological properties from these fluids becomes important in order to allow good hydraulic gusher maintenance and management. If these measures are taken in an on- line order that will mean agility in decision-making about the maintenance of the properties of the fluid and it will result in savings of thousands of dollars during the drilling of a well. It is in this context that this current report, developed in the UFRRJ laboratory of fluid flow, aims to evaluate the performance of a modified and calibrated process viscometer, making it a unique equipment for conducting real-time measures of apparent viscosity and thixotropy curve. The process viscometer chosen has the geometry of coaxial cylinders being, thus similar to the current workbench equipment used in drilling rigs. The modified viscometer performance was confronted with the rheometer benchtop Haake Rheostress 1. Different compositions of fluids, containing assorted concentrations of viscosifier polymers and suspension solid have been tested. The results indicated that there was an agreement on the results towards a considered error permissible for a viscometer process. The online viscometer brings a pioneering real-time measuring capacity and plotting of rheological behavior curves towards the current technology used in drilling operation. / Para que o processo de perfura??o seja bem-sucedido, ? necess?rio o uso de um fluido de perfura??o. A medi??o das propriedades reol?gicas destes fluidos torna-se importante para permitir uma boa manuten??o e gest?o hidr?ulica do po?o. Se estas medidas forem realizadas de forma online isso significar? agilidade na tomada de decis?o sobre a manuten??o das propriedades do fluido e acarretar? na economia de milhares de d?lares durante a perfura??o de um po?o. ? neste contexto que o presente trabalho, desenvolvido no Laborat?rio de Escoamento de Fluidos da UFRRJ, tem como objetivo avaliar o desempenho de um viscos?metro de processo modificado e calibrado, tornando-o em um equipamento exclusivo, para realizar medidas em tempo real de curva de viscosidade aparente e tixotropia. O viscos?metro de processo escolhido tem a mesma geometria de cilindros coaxiais sendo desta forma semelhante ao atual equipamento de bancada utilizado nas sondas de perfura??o. O desempenho do viscos?metro modificado foi confrontado com o re?metro de bancada Haake Rheostress 1. Foram testadas diferentes composi??es de fluidos contendo concentra??es variadas de pol?meros viscosificantes e s?lidos em suspens?o. Os resultados obtidos indicaram que houve concord?ncia nos resultados diante de um erro considerado admiss?vel para um viscos?metro de processo. Acredita-se que o viscos?metro online avaliado traz uma capacidade pioneira de medi??o em tempo real e plotagem de curvas de comportamento reol?gico diante da atual tecnologia utilizada na ?rea petroqu?mica.

FAPEMIG - Fundação de Amparo a Pesquisa do Estado de Minas Gerais / Petrobrás - Petróleo Brasileiro S.A / Os fluidos de perfuração são substâncias injetadas no poço cuja principal função é trazer à superfície os cascalhos de rocha produzidos durante a perfuração. A separação e a reutilização do fluido de perfuração são de suma importância para que se atenda às exigências da legislação ambiental em relação ao descarte de resíduos. Além disso, é imprescindível a recuperação do fluido utilizado por questões de redução de custos da etapa de perfuração. O objetivo do presente estudo foi desenvolver um modelo matemático para a separação entre cascalho e fluido de perfuração por peneiras vibratórias com base nos princípios da dinâmica newtoniana e da lei de conservação de massa. Para tanto a tela da peneira foi considerada um leito empacotado de espessura muito fina e com inclinação ascendente. Correlações para a queda de pressão foram analisadas e uma nova correlação foi proposta com base em metodologias indicadas na literatura. O comportamento do fluido foi avaliado para a variação nos seguintes parâmetros: viscosidade plástica, tensão limite de escoamento, coeficiente de escoamento, inclinação da tela e força-g. O modelo não se mostrou sensível a variações na tensão limite de escoamento do fluido. Os demais parâmetros mostraram significativa influência sobre o comprimento de tela molhada. Os resultados obtidos estão de acordo com o relatado pela literatura e mostram que o modelo desenvolvido é adequado para a descrição do processo de peneiramento vibratório. / Drilling fluids are substances injected into the well whose main function is to suspend drilled solids, remove them from the well bore and release them at the surface. Separation and reuse of drilling fluids is of great importance to fulfill the requirements of environmental legislation regarding waste disposal. In addition, it is essential to recover the drilling fluid in order to reduce costs of the drilling process. The objective of the present study was to develop a mathematical model based on the principles of Newtonian dynamics and the law of mass conservation for the process of removal of drilled cuttings from drilling fluid using vibrating screens. For this purpose, the sieve screen was considered to be a very thin packed bed and tilted upward. Pressure drop correlations were analyzed and a new correlation was proposed based on methodologies indicated in the literature. The behavior of the fluid was evaluated for the variation in the following parameters: plastic viscosity, yield stress, flow coefficient, tilt of the screen and g factor. The model was not sensitive to variations in the yield stress of the fluid while other parameters showed a significant influence on wet screen length. Obtained results are in agreement with the reported ones in the literature and show that the developed model is suitable for the description of the process of vibrating screening. / Dissertação (Mestrado)

Drilling, one of the stages of oil and gas exploration, now has as targets regions of great complexity, with high depths. Coated or contaminated cuttings with drilling fluid are a result of drilling. The drilling fluids are water-based or non-aqueous based liquids. A more restrictive environmental legislation and the need to reduce the costs of drilling (exploration and production) lead to optimization of solid-liquid separation and recycling drilling fluids. Because oil industry has to submit itself to ever more stringent environmental laws it has applied a great deal of investments on sustainability research. In this context, this work provides a study of the characteristics of drilling cuttings and synthetic drilling muds at different steps of the solids control sistem, in order to know their behavior and its change over the process. The concentration of water, organic phase and solids in the mud were measured. The density and particle size of the cuttings were analyzed. The rheology and thixotropy of the mud were investigated. For this, samples of drilling mud were collected throughout the solids control system of five PETROBRAS onshore drilling rigs in Bahia (BA). The concentrations index are so important when investigating the efficiency of operation of the equipments in the solids control. The density of solids is very close to the density of clays. The results show that the rheology of drilling mud in the solids control process behaves as a non-Newtonian fluid, pseudoplastic, viscoplastic and thixotropic. The particle size of solids varies with operating conditions and always presents two average diameters by sample. The cutting dryer, a vertical centrifuge, plays a key role in the waste disposal due the stringent environmental laws, especially on offshore platforms. Thus, in order to research the optimization or restructuration of this step in the waste disposal, a study was carried on this equipment and the main points of its structure and operation were reported. / A perfuração, uma das etapas da exploração de petróleo e gás, hoje objetiva cenários geológicos de grande complexidade, com elevadas profundidades. Como efluente da atividade exploratória há a geração de cascalhos contaminados ou revestidos com fluido de perfuração. Uma legislação ambiental mais rigorosa e a necessidade de reduzir os custos de perfuração (prospecção e produção) apontam para a necessidade de otimização da separação e reciclagem do fluido de perfuração de poços de petróleo e gás. A atividade petrolífera é desenvolvida em condições cada vez mais restritivas do ponto de vista ambiental, sendo incessantes os estudos e investimentos em busca da sustentabilidade. Como exemplos de equipamentos para o processamento da lama de perfuração podem ser citados as peneiras vibratórias, os hidrociclones e as centrífugas. Neste contexto, o presente trabalho traz um estudo detalhado das características dos sólidos e da lama de perfuração base n-parafina em diferentes pontos do processo de controle de sólidos, com o objetivo de investigar o comportamento dos mesmos e sua alteração ao longo do processo. Foram realizadas análises de concentração de água, fase orgânica e sólidos na lama, densidade dos sólidos, reologia e tixotropia da lama e granulometria dos sólidos. Para isso, amostras de lama de perfuração foram coletadas ao longo do sistema de controle de sólidos em cinco sondas de perfuração terrestre da Petrobras no interior da Bahia (BA). As concentrações analisadas são de grande importância na investigação da eficiência de operação dos equipamentos do processo de controle de sólidos. A massa específica dos sólidos é bem próxima da massa específica de argilas. Os resultados de reologia mostram que a lama de perfuração em todo o processo de controle de sólidos se comporta como um fluido não-newtoniano, pseudoplástico, viscoplástico e tixotrópico. A granulometria dos sólidos varia com as condições de operação e apresenta, no geral, dois diâmetros médios em cada corrente amostrada. O secador de cascalho, um tipo de centrífuga vertical, desempenha papel fundamental na adequação dos resíduos às leis ambientais de descarte, principalmente em plataformas offshore. Assim, visando futuramente a otimização ou mesmo reestruturação desta etapa do processo de descarte de resíduos, foi realizado um estudo sobre esse equipamento e levantado os pontos principais de sua estrutura e operação. / Mestre em Engenharia Química

The need for energy and the associated economic benefits from the oil and gas deposits found mainly in the Niger Delta region of Nigeria necessitated the exploration and exploitation activities being carried out by the oil and gas Companies. However, these exploration and exploitation activities due to their unpredictable nature have a huge potential for environmental pollution as been experienced in the form of oil spills, gas flaring, irresponsible disposal of waste and several other activities that have resulted in the environmental degradation of the Niger Delta region. In the light of these, the Federal Government of Nigeria having experienced the consequences of pollution of the environment during the Koko Toxic Waste Dump incident in the then Bendel State in 1987 established a regulatory body tasked with the responsibility of harmonizing the economic interest from the oil and gas exploration and exploitation activities with the sustainability of the natural environment by developing well structured and articulated policies aimed at guiding the operations of the oil and gas operators, track their compliance and administer appropriate punitive measures for non compliance. However, this research work which is aimed at evaluating the impact of the environmental protection policies in upstream oil and gas activities in the Niger Delta region, involved the use of questionnaires and interviews. These questionnaires were completed by the management and staff of three major oil and gas companies operating within the area, the Department of Petroleum Resources and members of the Host communities. The interview was carried out to provide relevant feedback on their assessment of the impact made by the environmental protection policies on the upstream oil and gas activities in their operational areas/host communities. The study however concluded that “Although there is a regulatory body tasked with the responsibility to develop, implement and track compliance of the environmental protection policies in the upstream oil industry, the body is ineffective and as such the impact of the environmental protection policies is inadequate. Appropriate informed recommendations on the improvement strategies to the identified gaps that resulted in the unfavorable conditions were also provided. / Thesis (M.Ing. (Development and Management Engineering))--North-West University, Potchefstroom Campus, 2011

The need for energy and the associated economic benefits from the oil and gas deposits found mainly in the Niger Delta region of Nigeria necessitated the exploration and exploitation activities being carried out by the oil and gas Companies. However, these exploration and exploitation activities due to their unpredictable nature have a huge potential for environmental pollution as been experienced in the form of oil spills, gas flaring, irresponsible disposal of waste and several other activities that have resulted in the environmental degradation of the Niger Delta region. In the light of these, the Federal Government of Nigeria having experienced the consequences of pollution of the environment during the Koko Toxic Waste Dump incident in the then Bendel State in 1987 established a regulatory body tasked with the responsibility of harmonizing the economic interest from the oil and gas exploration and exploitation activities with the sustainability of the natural environment by developing well structured and articulated policies aimed at guiding the operations of the oil and gas operators, track their compliance and administer appropriate punitive measures for non compliance. However, this research work which is aimed at evaluating the impact of the environmental protection policies in upstream oil and gas activities in the Niger Delta region, involved the use of questionnaires and interviews. These questionnaires were completed by the management and staff of three major oil and gas companies operating within the area, the Department of Petroleum Resources and members of the Host communities. The interview was carried out to provide relevant feedback on their assessment of the impact made by the environmental protection policies on the upstream oil and gas activities in their operational areas/host communities. The study however concluded that “Although there is a regulatory body tasked with the responsibility to develop, implement and track compliance of the environmental protection policies in the upstream oil industry, the body is ineffective and as such the impact of the environmental protection policies is inadequate. Appropriate informed recommendations on the improvement strategies to the identified gaps that resulted in the unfavorable conditions were also provided. / Thesis (M.Ing. (Development and Management Engineering))--North-West University, Potchefstroom Campus, 2011