Orientador: Denis José Schiozer / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica e Instituto de Geociências / Made available in DSpace on 2018-08-16T03:09:54Z (GMT). No. of bitstreams: 1 Bento_DeboraFerreira_M.pdf: 5080634 bytes, checksum: fb4f6d1d73f4079215e05919e962ccb6 (MD5) Previous issue date: 2010 / Resumo: O sucesso de um projeto de desenvolvimento de um campo de petróleo depende de uma estratégia de produção adequada. A seleção da estratégia através de um processo de otimização busca menores investimentos e custos operacionais e maiores produções de óleo e gás, melhorando o lucro medido através do valor presente líquido do projeto (VPL). Existem inúmeras metodologias para otimização da estratégia de produção que, em geral, são trabalhosas e demandam grande esforço computacional. Como o tempo é uma variável impactante no retorno econômico de projetos, a indústria tende a simplificar as simulações numéricas, principalmente separando as modelagens dos reservatórios e dos sistemas operacionais. Este trabalho tem como objetivo verificar se estas simplificações influenciam no resultado final do processo de seleção de estratégias de produção. Complementando trabalhos anteriores, foram selecionadas e estudadas duas restrições operacionais: perda de carga nas linhas de produção e o limite de escoamento do gás. Foi proposta ainda uma metodologia de otimização de estratégia de produção e de análise da influência da restrição operacional, com foco nos casos estudados. Os resultados mostram a influência das restrições no processo, possibilitando ainda identificar as características dos reservatórios, fluídos e cenário econômico onde essa influência é mais significativa / Abstract: The success of a development project of a petroleum field depends on adequate production strategy. The selection of the strategy through an optimization process searches for minors investments and operational costs and greater oil and gas productions, improving the profit measured through the liquid present value of the project (LPV). There are innumerable methodologies for production strategy optimization and, in general, they are laborious and demand a great computational effort. Considering that time is an important variable in the project economic return, the industry tends to simplify the numerical simulations, mainly separating the reservoir and operational systems. The objective of this work is to verify if these simplifications have significant influence on the final result of the production strategy selection process. Complementing previous works, two operational constraints were selected and studied: pressure drop in the production lines and the gas flow limit. Two methodologies were proposed, with focus in the studied cases: a production strategy optimization process and an operational constraints influence analysis. The results demonstrate the influence of the operational constraints restrictions in the process, making it possible to identify the characteristics of the reservoirs, fluids and economic scenario where this influence is more significant / Mestrado / Reservatórios e Gestão / Mestre em Ciências e Engenharia de Petróleo

No description available.

The BETTER water quality model, created by TVA, was used to model the temperature and dissolved oxygen (DO) in Spring Hollow Reservoir. The water balance consisted of pump discharge from the Roanoke River, runoff, releases at the dam, leakage, and storage. The geometry of the reservoir was represented by four columns and a variable number of five-foot layers. Through a sensitivity analysis, the parameters that influenced temperature and DO the most were determined. Temperature was then calibrated to a subset of the 19-month simulation period by systematically varying the most sensitive parameters. DO was calibrated to the entire simulation period due to the young age of the reservoir and the inconsistent inflow rates and timing. The verification process showed that the model reasonably reproduced the seasonal temperature patterns. By varying the sediment oxygen demand temporally and spatially, the model depicted the gradual hypolimnetic oxygen depletion in the reservoir. The model results suggest that the inflow organics and subsequent settling and accumulation are key factors in the DO depletion rate. Therefore, to enhance water quality conditions in the reservoir, a monitoring system in the Roanoke River should be installed with filling carried out when water quality in the river is optimal. For future modeling purposes, this research indicated that the model was very sensitivity to meteorological data, especially in determining temperature. Thus, a weather station located at the reservoir would permit collection of more accurate meteorological data, leading to greater confidence in the interpretation of the model predictions. / Master of Science

The preliminary assessment for reservoir sites in George County targeted three basins within the county as the initial focus of the research study: Big Creek, Big Cedar Creek, and Escatawpa River basins. As a portion of the reservoir study, this study was a basin-specific geological assessment of the three basins within George County through literature review, well log correlation, and a county wide spring inventory. The goal of this study was to obtain and interpret subsurface data in order to develop detailed geologic maps and stratigraphic cross sections which aided in the site assessment and characterization of the geologic and hydro-geologic suitability of potential reservoir sites. This study concluded that the hypothesis was proved and all three selected drainage basins were potentially geologically suitable to sustain a large reservoir, therefor other factors should be taken into account to determine specific reservoir location such as stream discharge and water quality.

Lake Manassas, located in the Occoquan Watershed in Virginia is a man-made impoundment of the Broad Run river. This lake surface area is approximately 697 acres, and it drains approximately 46,500 acres. Currently, the reservoir supplies drinking water to the City of Manassas and some areas of Western Prince William County, but if necessary, can help supply drinking water to 750,000 people in the Northern Virginia area. Since 1984, the Occoquan Watershed Monitoring Laboratory has been sampling seven streams and eight lake stations as part of a program funded by of the City of Manassas. Lake Manassas is an important drinking water resource for the City and the surrounding areas and is used for recreational purposes as well. It is extremely important to continuously monitor the lake closely so that any6 undesirable trends in water quality may be detected and addressed. Currently surrounding the lake are two golf courses, with two more golf courses planned for the future, as well as homes, and recreational areas. Overall, Lake Manassas is still considered to be eutrophic, which is the same conclusion reached in previous reports. The main nutrient source is Broad Run, but there are other smaller sources as well that are of concern. South Run has decreased nutrient loadings since the last report in 1996. Another conclusion is that the lake is Phosphorus-limited, but at times, the lake comes close to being nitrogen-limited. / Master of Science

Seismic time-lapse monitoring of production is an important tool used to efficiently drain a hydrocarbon reservoir. Repeat seismic surveys may be used, because the seismic method is sensitive to the reservoir fluid. A prominent seismic attribute is the reflectivity (or amplitude) as a function of offset (AVO) which strongly depends on material properties, and hence, on the pore fluid. Repeat surveys, however, are very costly. To reduce the risks, the repeat survey is simulated on a computer for a number of different scenarios. Hence, the objectives of this study are to predict the seismic responses after five years of production of the reservoirs at the well locations, correlate the seismic attributes to fluid conditions in the reservoirs, assess the detectability of changes in AVO attributes due to changes in fluid conditions, and determine which attribute is more diagnostic of fluid changes. Petrophysical models were generated for different pore fluids using well logs from a field in the Gulf of Mexico. Synthetic seismograms were then calculated using a layerstack scheme to study the effects of the reservoir fluids on AVO. Compared to idealized half-space models, it was found that the AVO responses are contaminated by the overburden and the thinness of the reservoir. In order to remove transmission loss due to overburden effects, the synthetic AVO curves were scaled by normalizing an overburden-over-half-space model to an idealized analytical Zoeppritz model. In a second step, an offset-dependent overburden correction was applied using a low order polynomial, which was fitted to the amplitude ratios between the overburden/half-space model and the idealized model. Finally, a zero-offset tuning correction was applied. The results of the AVO analyses showed that some errors were unresolved using the applied overburden and tuning corrections, and amplitudes at large offsets were possibly contaminated by multiples and converted waves. Since there is no shallower production or steam injection for this particular field, the repeat surveys should have the same overburden, tuning, multiple-related and converted wave contamination. It appears reasonable to assume that any changes in amplitude between the repeat surveys would be due to fluid saturation changes. Therefore, it was concluded that it is not necessary to attempt to remove the overburden and tuning effects. Results from the AVO analyses of the uncorrected models showed that AVO attributes should be a useful tool to detect reservoir conditions during the production of the field. Generally, the water-flood changes the AVO by decreasing the intercept and increasing the gradient from the in-situ oil/gas cases. The relative changes in both intercept and gradient due to the water-flood are detectable assuming a 20% relative-change detection threshold, and gradient is more diagnostic because the relative change in gradient is very large compared to that for intercept. / Master of Science

An 18-month study (July 2009 – December 2010) was conducted to determine the influence of four dams located in series along the Perak River, in Malaysia: Temengor, Bersia, Kenering and Chenderoh dams. The framework for investigation centered around the Serial Discontinuity Concept (SDC) and the Cascading Reservoir Continuum Concept (CRCC). In addition to reservoir, tailwater and riverine reach characteristics, the interacting influences of tributary streams and watersheds were addressed. Variables included in-situ environmental physical parameters, nutrients, seston concentration and transport, and fish assemblage characteristics. In-situ variables, water and seston samples, were recorded/collected monthly from all four reservoirs, their associated riverine sections, and their primary tributaries. Fish samples were collected by using experimental gill nets in reservoirs. Fish were enumerated taxonomically and total length and weight were measured for the bony-lipped barb, Osteochilus hasselti (Valenciennes, 1842). Hypotheses were tested using analyses of variance with permutations. Relationships were determined using correlation, and multivariate and regression analyses. The integrated influences of discontinuity and cascading on nutrient and seston transport dynamics and fish assemblages (except for relative condition and biomass of O. hasselti) were operative in dynamic juxtaposition along the river’s continuum, and depended on distance between dams and presence and size of tributary streams. However, principal tributaries along the four serial dams in the Perak River appeared to have little spatial influence on their respective system’s nutrient and seston dynamics due to dilution effects of mainstem discharges. Among all tributaries, only the Rui River depicted reversal of the serial discontinuity trend in its system. Even so, its influence on its system was limited. Effects of ecosystem fragmentation along the river’s continuum on in-situ, nutrients and seston transport dynamics, and fish assemblages existed, but not necessarily in line with the SDC nor in line with the CRCC. The dynamics of in-situ, nutrient, seston and fish assemblage parameters were more associated with land use, reservoir surface area and dam discharge. Results from this study generated a hypothesis that submerged woody vegetation in the reservoirs may augment and compensate lost nutrients, thereby minimizing functional impacts of serially-arranged dams.

This thesis integrated geology, geophysics, and petroleum engineering data to build a detailed reservoir characterization models for three gas pay sands in the Grand Isle 33 & 43 fields, offshore Louisiana. The reservoirs are Late Miocene in age and include the upper (PM), middle (QH), and lower (RD) sands. The reservoir models address the stratigraphy of the upper (PM) sand and help delineate the lower (RD) reservoir. In addition, this research addresses the partially depleted QH-2 reservoir compartment. The detailed models were constructed by integrating seismic, well log, and production data. These detailed models can help locate recoverable oil and gas that has been left behind. The upper PM model further delineated that the PM sand has several areas that are shaled-out effectively creating a flow barrier within reservoir compartments. Due to the barrier in the PM-1 reservoir compartment, an area of potentially recoverable hydrocarbons remains. In Grand Isle 33, the middle QH sand was partially depleted in the QH-2 reservoir compartment by a series of development wells. Bottom hole pressure data from wells in Grand Isle 32 & 33 reveal that the two QH fault compartments are in communication across a leaking fault. Production wells in the QH-1 compartment produced reserves from the QH-2 compartment. The lower RD sand model helped further delineate the reservoir in the RD-2 compartment and show that this compartment has been depleted. The RD model also shows the possible presence of remaining recoverable hydrocarbons in the RD-1 compartment. It is estimated that about 6.7 billion cubic feet of gas might remain within this reservoir waiting to be recovered. A seismic amplitude anomaly response from the QH and RD sands is interpreted to be a lithologic indicator rather than the presence of hydrocarbons. Amplitude response from the PM level appears to be below the resolution of the seismic data. A synthetic seismogram model was generated to represent the PM and surrounding sands. This model shows that by increasing the frequency of the seismic data from 20 Hz to a dominant frequency of 30 Hz that the PM and surrounding sands could be seismically resolvable. Also the PM-1 compartment has possible recoverable hydrocarbons of 1.5 billion cubic feet of gas remaining.

Numerical reservoir simulation has been used to describe mechanism of methane gas desorption process, diffusion process, and fluid flow in a coalbed methane reservoir. The reservoir simulation model reflects the response of a reservoir system and the relationship among coalbed methane reservoir properties, operation procedures, and gas production. This work presents a procedure to select the optimum well spacing scenario by using a reservoir simulation. This work uses a two-phase compositional simulator with a dual porosity model to investigate well-spacing effects on coalbed methane production performance and methane recovery. Because of reservoir parameters uncertainty, a sensitivity and parametric study are required to investigate the effects of parameter variability on coalbed methane reservoir production performance and methane recovery. This thesis includes a reservoir parameter screening procedures based on a sensitivity and parametric study. Considering the tremendous amounts of simulation runs required, this work uses a regression analysis to replace the numerical simulation model for each wellspacing scenario. A Monte Carlo simulation has been applied to present the probability function. Incorporated with the Monte Carlo simulation approach, this thesis proposes a well-spacing study procedure to determine the optimum coalbed methane development scenario. The study workflow is applied in a North America basin resulting in distinct Net Present Value predictions between each well-spacing design and an optimum range of well-spacing for a particular basin area.

Optimizing well spacing in unconventional gas reservoirs is difficult due to complex heterogeneity, large variability and uncertainty in reservoir properties, and lack of data that increase the production uncertainty. Previous methods are either suboptimal because they do not consider subsurface uncertainty (e.g., statistical moving-window methods) or they are too time-consuming and expensive for many operators (e.g., integrated reservoir characterization and simulation studies). This research has focused on developing and extending a new technology for determining optimal well spacing in tight gas reservoirs that maximize profitability. To achieve the research objectives, an integrated multi-well reservoir and decision model that fully incorporates uncertainty was developed. The reservoir model is based on reservoir simulation technology coupled with geostatistical and Monte Carlo methods to predict production performance in unconventional gas reservoirs as a function of well spacing and different development scenarios. The variability in discounted cumulative production was used for direct integration of the reservoir model with a Bayesian decision model (developed by other members of the research team) that determines the optimal well spacing and hence the optimal development strategy. The integrated model includes two development stages with a varying Stage-1 time span. The integrated tools were applied to an illustrative example in Deep Basin (Gething D) tight gas sands in Alberta, Canada, to determine optimal development strategies. The results showed that a Stage-1 length of 1 year starting at 160-acre spacing with no further downspacing is the optimal development policy. It also showed that extending the duration of Stage 1 beyond one year does not represent an economic benefit. These results are specific to the Berland River (Gething) area and should not be generalized to other unconventional gas reservoirs. However, the proposed technology provides insight into both the value of information and the ability to incorporate learning in a dynamic development strategy. The new technology is expected to help operators determine the combination of primary and secondary development policies early in the reservoir life that profitably maximize production and minimize the number of uneconomical wells. I anticipate that this methodology will be applicable to other tight and shale gas reservoirs.