This research covers simulation of Cyclic Steam Stimulation (CSS) Thermal Enhanced Oil Recovery (TEOR) and potential benefits for use of produced water in agriculture and food security, using a case study of oil fields in South Sudan. Oil production in many oil fields in South Sudan is declining, has high water cut, and low recovery factor. It is costly to manage the produced water. At the same time, agriculture in South Sudan is almost entirely rainfed, and this affects food security. Produced water can be managed by using it for TEOR and agriculture to solve water management issues, enhance oil production, reduces competition over water resources, and improve food security. Field A is a deep reservoir in South Sudan with oil gravity between 25 and 31 API. There are limited and mixed results from applications of TEOR methods in deep reservoirs. As such history matching and sensitivity analysis, and CSSS TEOR simulations were performed to examine most uncertain reservoir properties and the compatibility of Field A properties with CSS TEOR method. The results of simulation show that aquifer volume (AQV) and productivity index (PI) are the most uncertain property that affect reservoir pressure; cumulative oil, gas, and water production; water cut; and gas oil ratio. CSS TEOR simulation was not successfully due to the high API gravity suggesting that Field A is not a good candidate for CSS TEOR. The produced water is sufficient to irrigate large areas of farms and watering thousands of livestock. However, analysis results from untreated water; water treated by demulsifer-defoamer and bioremediation shows high total dissolved solids (TDS) and sodium absorption ratio (SAR) values. Therefore, reverse osmosis (RO) membrane technology was applied to treat the produced water. RO rejected more than 90% of elements in the produced water with exception of elements B, Cu, Pb, and Ca. Consequently, water from RO does not meet food and agriculture organization (FAO) standards for all uses in agriculture. ANOVA showed that there was no significant difference in TDS reductions between the different applied treatment technologies. Therefore, caution is needed when using statistical analysis to verify operationalization of RO technology which rejected more than 90% of the elements in the produced water. / Doctor of Philosophy / This research discusses how to increase oil production by injecting steam in the reservoir and leaving it to soak before the next injection and start of oil production, along with potential benefits for use of produced water in agriculture and food security, all using a case study of oil fields in South Sudan. In many oil fields in South Sudan the volume of oil produced is decreasing while that of water is increasing rapidly, so that now nearly 90% of the total fluids produced is water. Management of produced water can be very costly. Despite the large quantities of produced water, agriculture in South Sudan still depends on rain water, and this dependency on rain water can affect crop production and food security, and also cause conflict amongst nomads and farmers over water resources during the dry season. These problems can be mitigated by using produced water to increase oil production and then be applied for agricultural uses. The first study simulated steam injection in the reservoir in Oil Field A. The results showed that process of injection did not work well due to the properties of the oil in that formation, and therefore other methods may be needed to increase oil production in Field A. In the second study, water which is produced together with oil (produced water) was analyzed to check its quality. This analysis determined that the water has very high concentration of total dissolved solids. Treatment methods that have been applied in the oil fields for treating produced water do not currently make the water clean enough to be use for agriculture use. Therefore, reverse osmosis membrane technology was applied to reduce the concentration of the elements in the water. Reverse osmosis treatment technology is capable of removing 90 % concentration of most elements in the produced water, but some potentially harmful elements, such as boron, remained. As a result, the water treated by reverse osmosis can only be used for livestock watering unless additional treatment methods are adopted to reduce boron concentrations to acceptable level.

Made available in DSpace on 2014-12-17T14:08:43Z (GMT). No. of bitstreams: 1 TiagoPC_DISSERT.pdf: 1471839 bytes, checksum: 916c40a19572e874803d077f6852a370 (MD5) Previous issue date: 2010-09-18 / In Brazilian Northeast there are reservoirs with heavy oil, which use steam flooding as a recovery method. This process allows to reduce oil viscosity, increasing its mobility and consequently its oil recovery. Steam injection is a thermal method and can occurs in continues or cyclic form. Cyclic steam stimulation (CSS) can be repeated several times. Each cycle consisting of three stages: steam injection, soaking time and production phase. CSS becomes less efficient with an increase of number of cycles. Thus, this work aims to study the influence of compositional models in cyclic steam injection and the effects of some parameters, such like: flow injection, steam quality and temperature of steam injected, analyzing the influence of pseudocomponents numbers on oil rate, cumulative oil, oil recovery and simulation time. In the situations analyzed was compared the model of fluid of three phases and three components known as Blackoil . Simulations were done using commercial software (CMG), it was analyzed a homogeneous reservoir with characteristics similar to those found in Brazilian Northeast. It was observed that an increase of components number, increase the time spent in simulation. As for analyzed parameters, it appears that the steam rate, and steam quality has influence on cumulative oil and oil recovery. The number of components did not a lot influenced on oil recovery, however it has influenced on gas production / No Nordeste brasileiro existem reservat?rios de ?leos pesados, nos quais se utiliza a inje??o de vapor como m?todo de recupera??o. Este processo permite diminuir a viscosidade do ?leo, aumentando a sua mobilidade e melhorando o volume de ?leo a ser recuperado. A inje??o de vapor ? um m?todo t?rmico e ocorre na forma cont?nua ou c?clica. A inje??o c?clica de vapor pode ser repetida diversas vezes. Cada ciclo consiste de tr?s etapas distintas: a fase de inje??o, fase de fechamento (soaking) e fase de produ??o. A inje??o c?clica se torna menos eficiente ? medida que o n?mero de ciclos aumenta. Neste sentido, este trabalho visa estudar a influ?ncia de modelos composicionais na inje??o c?clica de vapor e os efeitos de alguns par?metros, tais como: vaz?o de inje??o, qualidade do vapor e temperatura do vapor injetado; analisando a influ?ncia do n?mero de pseudocomponentes, no que diz respeito ? vaz?o de ?leo, produ??o acumulada de ?leo, fator de recupera??o e tempo de simula??o. Nas situa??es analisadas foi comparado o modelo de fluido de tr?s fases e tr?s componentes conhecido como Black-oil . Foram realizadas simula??es, utilizando um simulador comercial a partir de um modelo de reservat?rio homog?neo com caracter?sticas similares ?s encontradas no Nordeste brasileiro. Observou-se que quanto maior o n?mero de componentes, maior ? o tempo gasto na simula??o. J? para os par?metros analisados, verifica-se que a vaz?o de inje??o de vapor e a qualidade do vapor influenciam na produ??o acumulada de ?leo e no fator de recupera??o. O n?mero de componentes n?o exerceu muita influ?ncia na produ??o acumulada, nem no fator de recupera??o de ?leo, por?m foi significativa na produ??o de g?s do sistema

The Nigeria economy is wholly dependent on revenue from oil. However, bitumen has been discovered in the country since 1903 and has remained untapped over the years. The need for the country to complement oil exploration with the huge bitumen deposit cannot be overemphasized. This will help to improve the country's gross domestic product (GDP) and revenue available to government. Bitumen is classifled as heavy crude with API (American petroleum Institute) number ranging between 50 and 110 and occurs in Nigeria, Canada, Saudi Arabia, Venezuela etc from which petroleum products could be derived. This dissertation looked at the Canadian experience by comparing the oil and tar sand deposit found in Canada with particular reference to Athabasca (Grosmont, Wabiskaw McMurray and Nsiku) with that in Nigeria with a view of transferring process technology from Canada to Nigeria. The Nigeria and Athabasca tar sands occur in the same type of environment. These are the deltaic, fluvial marine deposit in an incised valley with similar reservoir, chemical and physical properties. However, the Nigeria tar sand is more asphaltenic and also contains more resin and as such will yield more product volume during hydro cracking albeit more acidic. The differences in the components (viscosity, resin and asphaltenes contents, sulphur and heavy metal contents) of the tar sands is within the limit of technology adaptation. Any of the technologies used in Athabasca, Canada is adaptable to Nigeria according to the findings of this research. The techno-economics of some of the process technologies are. x-rayed using the PTAC (petroleum technology alliance Canada) technology recovery model in order to obtain their unit cost for Nigeria bitumen. The unit cost of processed bitumen adopting steam assisted gravity drainage (SAGD), in situ combustion (ISC) and cyclic steam stimulation (CSS) process technology is 40.59, 25.00 and 44.14 Canadian dollars respectively. The unit cost in Canada using the same process technology is 57.27, 25.00 and 61.33 Canadian dollars respectively. The unit cost in Nigeria is substantively lesser than in Canada. A trade off is thereafter done using life cycle costing so as to select the best process technology for the Nigeria oil/tar sands. The net present value/internal rate of return is found to be B$3,062/36.35% for steam assisted gravity drainage, B$I,570124.51 % for cyclic steam stimulation and B$3,503/39.64% for in situ combustion. Though in situ combustion returned the highest net present value and internal rate of return, it proved not to be the best option for Nigeria due to environmental concern and response time to production. The best viable option for the Nigeria tar sand was then deemed to be steam assisted gravity drainage. An integrated oil strategy coupled with cogeneration using MSAR was also seen to considerably amplify the benefits accruable from bitumen exploration; therefore, an investment in bitumen exploration in Nigeria is a wise economic decision. / Thesis (M.Ing. (Development and Management))--North-West University, Potchefstroom Campus, 2010.

The Nigeria economy is wholly dependent on revenue from oil. However, bitumen has been discovered in the country since 1903 and has remained untapped over the years. The need for the country to complement oil exploration with the huge bitumen deposit cannot be overemphasized. This will help to improve the country's gross domestic product (GDP) and revenue available to government. Bitumen is classifled as heavy crude with API (American petroleum Institute) number ranging between 50 and 110 and occurs in Nigeria, Canada, Saudi Arabia, Venezuela etc from which petroleum products could be derived. This dissertation looked at the Canadian experience by comparing the oil and tar sand deposit found in Canada with particular reference to Athabasca (Grosmont, Wabiskaw McMurray and Nsiku) with that in Nigeria with a view of transferring process technology from Canada to Nigeria. The Nigeria and Athabasca tar sands occur in the same type of environment. These are the deltaic, fluvial marine deposit in an incised valley with similar reservoir, chemical and physical properties. However, the Nigeria tar sand is more asphaltenic and also contains more resin and as such will yield more product volume during hydro cracking albeit more acidic. The differences in the components (viscosity, resin and asphaltenes contents, sulphur and heavy metal contents) of the tar sands is within the limit of technology adaptation. Any of the technologies used in Athabasca, Canada is adaptable to Nigeria according to the findings of this research. The techno-economics of some of the process technologies are. x-rayed using the PTAC (petroleum technology alliance Canada) technology recovery model in order to obtain their unit cost for Nigeria bitumen. The unit cost of processed bitumen adopting steam assisted gravity drainage (SAGD), in situ combustion (ISC) and cyclic steam stimulation (CSS) process technology is 40.59, 25.00 and 44.14 Canadian dollars respectively. The unit cost in Canada using the same process technology is 57.27, 25.00 and 61.33 Canadian dollars respectively. The unit cost in Nigeria is substantively lesser than in Canada. A trade off is thereafter done using life cycle costing so as to select the best process technology for the Nigeria oil/tar sands. The net present value/internal rate of return is found to be B$3,062/36.35% for steam assisted gravity drainage, B$I,570124.51 % for cyclic steam stimulation and B$3,503/39.64% for in situ combustion. Though in situ combustion returned the highest net present value and internal rate of return, it proved not to be the best option for Nigeria due to environmental concern and response time to production. The best viable option for the Nigeria tar sand was then deemed to be steam assisted gravity drainage. An integrated oil strategy coupled with cogeneration using MSAR was also seen to considerably amplify the benefits accruable from bitumen exploration; therefore, an investment in bitumen exploration in Nigeria is a wise economic decision. / Thesis (M.Ing. (Development and Management))--North-West University, Potchefstroom Campus, 2010.