Twin-screw multiphase pumps experience a severe decrease in efficiency, even the breakdown of pumping function, when operating under wet gas conditions. Additionally, field operations have revealed significant vibration and thermal issues which can lead to damage of the pump internals and expensive repairs and maintenance. There are limited models simulating the performance of twin-screw pump under these conditions. This project develops a pump-user oriented simulator to model the performance of twin-screw pumps under wet gas conditions. Experimental testing is conducted to verify the simulation results. Based on the simulations, an innovative solution is presented to improve the efficiency and prevent the breakdown of pumping function. A new model is developed based upon a previous Texas A&M twin-screw pump model. In this model, both the gas slip and liquid slip in the pump clearances are simulated. The mechanical model is coupled with a thermodynamic model to predict the pressure and temperature distribution along the screws. The comparison of experimental data and the predictions of both isothermal and non-isothermal models show a better match than previous models with Gas Volume Fraction (GVF) 95% and 98%. Compatible with the previous Texas A&M twin-screw pump model, this model can be used to simulate the twin-screw pump performance with GVF from 0% to 99%. Based on the effect of liquid viscosity, a novel solution is investigated with the newly developed model to improve the efficiency and reliability of twin-screw pump performance with GVF higher than 94%. The solution is to inject high viscosity liquid directly into the twin-screw pump. After the simulations of several different scenarios with various liquid injection rates and injection positions, we conclude that the volumetric efficiency increases with increasing liquid viscosity and injecting liquid in the suction is suggested.

The response of slotted plate, Venturi meter and standard orifice to the presence of two phase, three phase and low differential flows was investigated. Two mixtures (air-water and air-oil) were used in the two-phase analysis while a mixture of air, water and oil was employed in the three-phase case. Due to the high gas void fraction (α>0.9), the mixture was considered wet gas. A slotted plate was utilized in the low differential pressure analysis and the discharge coefficient behavior was analyzed. Assuming homogeneous flow, an equation with two unknowns was obtained for the multi-phase flow analysis. An empirical relation and the differential response of the meters were used to estimate the variables involved in the equation. Good performance in the gas mass flow rate estimation was exhibited by the slotted and standard plates for the air-water flow, while poor results were obtained for the air-oil and air-water oil flows. The performance of all the flow meter tested in the analysis improved for differential pressures greater than 24.9 kPa (100 in_H2O). Due to the tendency to a zero value for the liquid flow, the error of the estimation reached values of more than 500% at high qualities and low differential pressures. Air-oil and air-water-oil flows show that liquid viscosity influences the response of the differential pressure meters. The best results for high liquid viscosity were obtained in the Venturi meter using the recovery pressure for the gas flow estimation at differential pressures greater than 24.9 kPa (100 in_H2O). A constant coefficient Cd was used for the low differential pressure analysis and results did show that for differential pressure less than 1.24 kPa (5 inH2O) density changes are less than 1% making possible the incompressible flow assumption. The average of the computed coefficients is the value of Cd.

Understanding how swirl flows can be applied to processes in the oil and gas industry and how problems might hinder them, are the focus of this thesis. Three application areas were identified: wet gas metering, liquid loading in gas wells and erosion at pipe bends due to sand transport. For all three areas, Computational Fluid Dynamics (CFD) simulations were performed. Where available, experimental data were used to validate the CFD results. As a part of this project, a new test loop was conceived for the investigation of sand erosion in pipes. The results obtained from CFD simulations of two-phase (air-water) flow through a pipe with a swirl-inducing device show that generating swirl flow leads to separation of the phases and creates distinct flow patterns within the pipe. This effect can be used in each of the three application areas of interest. For the wet gas metering application, a chart was generated, which suggests the location of maximum liquid deposition downstream of the swirling device used in the ANUMET meter. This will allow taking pressure and phase fraction measurements (from which the liquid flow rate can be determined) where they are most representative of the flow pattern assumed for the ANUMET calculation algorithms. For the liquid loading application, which was taken as an upscaling of the dimensions investigated for the wet gas metering application, the main focus was on the liquid hold-up. This parameter is defined as the ratio of the flowing area occupied by liquid to the total area. Results obtained with CFD simulations showed that as the water rate increases, the liquid hold-up increases, implying a more effective liquid removal. Thus, it was concluded that the introduction of a swirler can help unload liquid from a gas well, although no investigation was carried out on the persistance of the swirl motion downstream of the device. For the third and final application, the erosion at pipe bends due to sand transport, the main focus was to check the erosion rate on the pipe wall with and without the introduction of a swirler. The erosion rate was predicted by CFD simulations. The flow that was investigated consisted of a liquid phase with solid particles suspended in it. The CFD results showed a significant reduction in erosion rate at the pipe walls when the swirler was introduced, which could translate into an extended working life for the pipe. An extensive literature review performed on this topic, complemented by the CFD simulations, showed the need for a dedicated multiphase test loop for the investigation of sand erosion in horizontal pipes and at bends. The design of a facility of this type is included in this thesis. The results obtained with this work are very encouraging and provide a broad perspective of applications of swirl flows and CFD for the oil and gas industry.

The response of slotted plate, Venturi meter and standard orifice to the presence of two phase, three phase and low differential flows was investigated. Two mixtures (air-water and air-oil) were used in the two-phase analysis while a mixture of air, water and oil was employed in the three-phase case. Due to the high gas void fraction (α>0.9), the mixture was considered wet gas. A slotted plate was utilized in the low differential pressure analysis and the discharge coefficient behavior was analyzed. Assuming homogeneous flow, an equation with two unknowns was obtained for the multi-phase flow analysis. An empirical relation and the differential response of the meters were used to estimate the variables involved in the equation. Good performance in the gas mass flow rate estimation was exhibited by the slotted and standard plates for the air-water flow, while poor results were obtained for the air-oil and air-water oil flows. The performance of all the flow meter tested in the analysis improved for differential pressures greater than 24.9 kPa (100 in_H2O). Due to the tendency to a zero value for the liquid flow, the error of the estimation reached values of more than 500% at high qualities and low differential pressures. Air-oil and air-water-oil flows show that liquid viscosity influences the response of the differential pressure meters. The best results for high liquid viscosity were obtained in the Venturi meter using the recovery pressure for the gas flow estimation at differential pressures greater than 24.9 kPa (100 in_H2O). A constant coefficient Cd was used for the low differential pressure analysis and results did show that for differential pressure less than 1.24 kPa (5 inH2O) density changes are less than 1% making possible the incompressible flow assumption. The average of the computed coefficients is the value of Cd.

No description available.

No description available.

O trabalho aborda a aplicação da técnica de reconciliação de dados para o balanço da movimentação de gás natural em uma malha de escoamento de gás não processado, elaborando também um método de cálculo rápido de inventário de um duto. Foram aplicadas, separadamente, a reconciliação volumétrica à condição padrão de medição e a reconciliação mássica, bem como realizadas comparações dos resultados em relação ao balanço original e verificação do balanço resultante de energia em termos de poder calorífico superior. Dois conjuntos de pesos foram aplicados, um arbitrado de acordo com o conhecimento prévio da qualidade do sistema de medição de cada um dos pontos, outro baseado no inverso da variância dos volumes diários apurados no período. Ambos apresentaram bons resultados e o segundo foi considerado o mais apropriado. Por meio de uma abordagem termodinâmica, foi avaliado o potencial impacto, ao balanço, da condensação de parte da fase gás ao longo do escoamento e a injeção de um condensado de gás natural não estabilizado por uma das fontes. Ambos tendem a impactar o balanço, sendo o resultado esperado um menor volume, massa e energia de fase gás na saída. Outros fatores de considerável impacto na qualidade dos dados e no resultado final da reconciliação são a qualidade da medição de saída do sistema e a representatividade da composição do gás neste ponto. O inventário é calculado a partir de uma regressão que se baseia em um regime permanente de escoamento, o que pode apresentar maior desvio quando fortes transientes estão ocorrendo no último dia do mês, porém a variação de inventário ao longo do mês possui baixo impacto no balanço. Concluiu-se que a reconciliação volumétrica é a mais apropriada para este sistema, pois os dados reconciliados levam os balanços mássicos e de energia em termos de poder calorífico, ambos na fase gás, para dentro do perfil esperado de comportamento. Embora um balanço volumétrico nulo apenas da fase gás não seja por si só o comportamento esperado quando se considera os efeitos descritos, para desenvolver um balanço mais robusto é necessário considerar as frações líquidas presentes no sistema, agregando maior dificuldade na aquisição e qualidade dos dados. / This purpose of this study is the application of data reconciliation to the balancing of a wet natural gas network and to develop a quick approach to calculate the gas linepack. Volumetric reconciliation, measured at standard conditions, and mass reconciliation were applied separately, the results were compared to the original balance and the energy balance in terms of gross calorific value was verified. Two sets of weights have been applied, one arbitrated according to the previous knowledge on the quality of the measurement system of each point, another based on the inverse of the variance of the daily volumes in the period. Both showed good results and the second was considered the most appropriate because of its adherence to the literature. Through a thermodynamic approach, the potential impact on the balance of the condensation of the gas phase along the flow and the injection of a not stabilized gas condensate by one of the sources have been evaluated. Both tend to impact the balance, resulting in smaller volume, mass and energy in the gas phase output. Others factors of significant impact in data quality and in the reconciliation results are the quality of the outlet flow measurement and the representativeness of the gas composition at this point. The linepack is calculated from a regression that relies on a steady flow approach, which can present a higher deviation when strong transients are taking place in that period, but the linepack variation over the month has showed low impact on the balance. The study concludes that the volumetric reconciliation is the most suitable for this system, as reconciled data lead the mass and energy balances, both in the gas phase, into the expected pattern of behavior, according to the thermodynamic evaluation. Although a volume balance reaching zero for the gas phase is not the expected behavior when taking into account the effects described, developing a more robust balance would demand to consider the liquid fractions present in the system, which may add more difficulty in the data acquisition and in guarantying its quality.

[pt] O objetivo deste trabalho é avaliar o desempenho metrológico e o potencial de aplicação do medidor tipo v-cone para medição de vazão de gás natural em condições de gás úmido. Observa-se que os medidores do tipo placa de orifício, geralmente utilizados na medição de vazão de gás no segmento de Exploração e Produção (E e P), podem não representar a tecnologia mais adequada. O medidor v-cone representa uma tecnologia relativamente recente, que vem demonstrando bom desempenho para a medição de vazão e vem ganhando aceitação de órgãos reguladores. O interesse e a motivação do pesquisador residem na busca de maior exatidão na medição de vazão em condições operacionais adversas (gás úmido não especificado), sem impacto significativo sobre o custo do sistema. O presente trabalho, por meio de uma pesquisa bibliográfica e documental, apresenta o estágio atual de desenvolvimento da tecnologia de medição por v-cone e detalha as características dos sistemas de medição de vazão de gás natural, além de abordar as normas e regulamentos relacionados ao tema em questão. A fase experimental busca avaliar o desempenho do medidor por meio de uma investigação empírica realizada em laboratório, simulando condições de gás úmido encontradas em campo. Essa análise envolve também a determinação de erros e incertezas de medição. A pesquisa realizada, em conjunto com a avaliação dos resultados dos testes e das correlações utilizadas, demonstra que o medidor v-cone apresenta boa confiabilidade na medição de vazão de gás natural em escoamento de gás úmido, podendo ser utilizado em aplicações encontradas no segmento de E e P. / [en] The aim of this study is to evaluate the metrological performance and potential of use of the v-cone type meter for measuring the natural gas flow rate under wet gas conditions. The orifice plate type meters, that are usually used to measure the gas flow rate in the Exploration and Production segment (E and P), may not represent the most appropriate technology. The v-cone meter represents a relatively recent technology, which has shown good performance for the flow rate measurement and is gaining acceptance from the regulators. The interest and motivation of the researcher are related to the quest for greater flow rate measurement accuracy in adverse operating conditions (unspecified wet gas), with no significant impact on the cost of the system. This work, through a literature and documentary search, presents the current stage of development of the v-cone flow rate measurement technology and details the characteristics of natural gas flow rate measurement systems, in addition to addressing the standards and regulations relating to the subject. The experimental phase aims to evaluate the meter performance through an empirical research conducted in laboratory, by simulating wet gas conditions found in the field. This analysis also involves the determination of measurement errors and uncertainties. The research and the evaluation of test results and correlations show that the v-cone meter has good reliability in natural gas flow rate measurement under wet gas conditions, allowing it to be used in applications found in E and P.

O trabalho aborda a aplicação da técnica de reconciliação de dados para o balanço da movimentação de gás natural em uma malha de escoamento de gás não processado, elaborando também um método de cálculo rápido de inventário de um duto. Foram aplicadas, separadamente, a reconciliação volumétrica à condição padrão de medição e a reconciliação mássica, bem como realizadas comparações dos resultados em relação ao balanço original e verificação do balanço resultante de energia em termos de poder calorífico superior. Dois conjuntos de pesos foram aplicados, um arbitrado de acordo com o conhecimento prévio da qualidade do sistema de medição de cada um dos pontos, outro baseado no inverso da variância dos volumes diários apurados no período. Ambos apresentaram bons resultados e o segundo foi considerado o mais apropriado. Por meio de uma abordagem termodinâmica, foi avaliado o potencial impacto, ao balanço, da condensação de parte da fase gás ao longo do escoamento e a injeção de um condensado de gás natural não estabilizado por uma das fontes. Ambos tendem a impactar o balanço, sendo o resultado esperado um menor volume, massa e energia de fase gás na saída. Outros fatores de considerável impacto na qualidade dos dados e no resultado final da reconciliação são a qualidade da medição de saída do sistema e a representatividade da composição do gás neste ponto. O inventário é calculado a partir de uma regressão que se baseia em um regime permanente de escoamento, o que pode apresentar maior desvio quando fortes transientes estão ocorrendo no último dia do mês, porém a variação de inventário ao longo do mês possui baixo impacto no balanço. Concluiu-se que a reconciliação volumétrica é a mais apropriada para este sistema, pois os dados reconciliados levam os balanços mássicos e de energia em termos de poder calorífico, ambos na fase gás, para dentro do perfil esperado de comportamento. Embora um balanço volumétrico nulo apenas da fase gás não seja por si só o comportamento esperado quando se considera os efeitos descritos, para desenvolver um balanço mais robusto é necessário considerar as frações líquidas presentes no sistema, agregando maior dificuldade na aquisição e qualidade dos dados. / This purpose of this study is the application of data reconciliation to the balancing of a wet natural gas network and to develop a quick approach to calculate the gas linepack. Volumetric reconciliation, measured at standard conditions, and mass reconciliation were applied separately, the results were compared to the original balance and the energy balance in terms of gross calorific value was verified. Two sets of weights have been applied, one arbitrated according to the previous knowledge on the quality of the measurement system of each point, another based on the inverse of the variance of the daily volumes in the period. Both showed good results and the second was considered the most appropriate because of its adherence to the literature. Through a thermodynamic approach, the potential impact on the balance of the condensation of the gas phase along the flow and the injection of a not stabilized gas condensate by one of the sources have been evaluated. Both tend to impact the balance, resulting in smaller volume, mass and energy in the gas phase output. Others factors of significant impact in data quality and in the reconciliation results are the quality of the outlet flow measurement and the representativeness of the gas composition at this point. The linepack is calculated from a regression that relies on a steady flow approach, which can present a higher deviation when strong transients are taking place in that period, but the linepack variation over the month has showed low impact on the balance. The study concludes that the volumetric reconciliation is the most suitable for this system, as reconciled data lead the mass and energy balances, both in the gas phase, into the expected pattern of behavior, according to the thermodynamic evaluation. Although a volume balance reaching zero for the gas phase is not the expected behavior when taking into account the effects described, developing a more robust balance would demand to consider the liquid fractions present in the system, which may add more difficulty in the data acquisition and in guarantying its quality.