Volumetric And Phase Behavior Of Oil Field Hydrocarbon Systems

Within the past few decades, the production of high-wax oils at offshore fields in Vietnam has been fraught with severe problems due to the intense formation of asphalt-resin-paraffin deposits (ARPD) in the downhole oil and gas equipment. The formation of organic wax deposits in the tubing string led to a significant decrease in gas-lift wells production, efficiency of compressor units, transport capacity of the piping systems, along with an increase in equipment failure. Subsequently, the efficiency of gas-lift wells dramatically decreased to less than 40% as a whole. The existing methods and technologies for combating organic wax deposit formation in downhole equipment have many advantages. However, their use in producing high-wax anomalous oil does not entirely prevent the wax formation in the tubing string and leads to a significant reduction in oil production, transport capacity, and treatment intervals. The results of theoretical and experimental studies presented in this article demonstrate that a promising approach to improve the efficiency of gas-lift wells during the production of high-wax oil is to use the technology of periodic injection of hot associated petroleum gas (APG) into the annulus of an oil-producing well. The effectiveness of the proposed method of combating wax formation in gas-lift wells highly depends on the combination of a few factors: the determination of wax deposit formation intensity in the well and the implementation of a set of preparatory measures to determine the optimal injection mode of hot APG (flow rate and injection depth) into the annulus between tubing strings and technological pipes. The injection depth of the hot APG should not be less than the depth of wax formation in the tubing string. The optimal injection rate of hot APG is determined by analyzing and mathematically modeling the APG injection system based on well-known thermodynamic laws.

Technology for Preventing the Wax Deposit Formation in Gas-Lift Wells at Offshore Oil and Gas Fields in Vietnam

In recent years, an insurmountable problem in high-wax oil production has been the intensive formation of organic deposits in the bottom-hole zone of the formation, downhole and surface equipment, leading to a dramatic loss in wells production, transportation capability, and subsequently has a detrimental effect on efficiency. Gas-lift is a widely used method, where compressed high-pressure gas is injected through the tubing annulus. Consequently, the current fluid level in the annulus decreases and increases in the tubing string. The compressed gas enters the tubing through gas-lift valves, mixing with the liquid. During production, changes in pressure, temperature, and fluid composition along the well bore highly depend upon the compressed gas injected into the well.  At temperatures below the wax appearance temperature, organic wax crystals will form either in bulk volumes of fluid or on cold surfaces of equipment, consequently, covering the surface. Wax formation is a hazardous and costly task in the oil and gas industry, especially when operating gas-lift wells. Hence, the prevention of wax formation in gas-lift wells is of utmost importance. Although, numerous methods have been implemented to handle the wax formation problem in recent decades, questions concerning their economic viability as well as their effectiveness remain relevant. 
 In this paper, a complete algorithm for determining changes in the oil component composition in a gas-lift well during the injection of associated petroleum gas is detailed. The obtained results play a pivotal role in the study of wax deposition. A technological scheme has been developed to prevent wax deposit formation in the tubing strings during gas-lift well operation. A simulation using the introduced process and technology has been run, and an observed result obtained. After running the simulation, we determined the optimal composition of the associated petroleum injection gas based on the required flow rate of the working agent and the lowest value of the wax appearance temperature. This method offers potential solutions to increasing gas-lift well production efficiency under complex wax formation conditions. 

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An extensive solution to prevent wax deposition formation in gas-lift wells

A producao em campos offshore, em especial de aguas profundas e ultra profundas de campos do pre-sal, possui desafios caracteristicos a garantia de escoamento. Entre eles, pode-se destacar a deposicao de parafina ao longo das extensas tubulacoes de producao, em funcao das profundas lâminas d’agua e do consequente perfil de temperatura ao longo do escoamento. As parafinas sao componentes de alto peso molecular do petroleo e tendem a se precipitar e se depositar nas superficies solidas das paredes das tubulacoes, quando a temperatura do oleo e reduzida a temperatura inicial de aparecimento de cristais. Ao se acumularem, os depositos de parafina levam a reducao da area aberta ao fluxo nas linhas de escoamento, prejudicam a vazao de producao, e podem bloquear as tubulacoes. Este trabalho apresenta uma analise quanto a garantia de escoamento de oleo em aguas profundas, em que se pode verificar, por meio de simulacao computacional, o perfil de temperatura e as condicoes favoraveis a cristalizacao e deposicao de parafina ao longo das linhas de producao. A simulacao foi feita considerando dados de producao do poco Lula Oeste, do Campo de Lula, presente na Bacia de Santos. Por meio do estudo realizado foi possivel concluir que a producao de petroleo nas condicoes de aguas profundas e ultra profundas se mostra complexa e desafiadora, o que torna fundamental para a operacao a gestao de metodos e estrategias de prevencao e remocao de depositos de parafina, de forma a garantir o escoamento de oleo nas tubulacoes.

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Análise da garantia de escoamento de petróleo em águas profundas em relação à deposição de parafina

The use of natural resources and their derivatives is gaining massive courtesy because of the growing demand for green chemistry. The present perspective features the challenges and opportunities of using carbohydrate polymer-modified carbon allotropes (CPMCAs) as nanofillers in reinforced polymer-composite coatings. CPMCAs can be regarded as an eco-friendly as well as a cost-effective approach and they are flattering ideal substitutes for traditional toxic nanofibers. They are associated with many essential features such as high surface area, uniform distribution, self-healing properties, high durability, long-term protection, optimized hydrophilicity, etc. that make them ideal substitutes. The anticorrosive potential gets magnified in CPMCAs as carbon allotropes prevent the diffusion of corrosive species and carbohydrate polymers prevent their galvanic coupling with the metal/alloy surfaces. CPMCAs successfully fulfil the requirements of self-healing or self-repairing coatings and provide long-term protection and self-healing properties for long exposure. The inhibition action of CPMCAs and self-healing have also been described. 

Carbohydrate Polymers-Modified Carbon Allotropes for Enhanced Anticorrosive Activity: State-of-Arts and Perspective

Simultaneous Flow Assurance and Production Optimization Using Chemical Paraffin Inhibition Method

Accurate determination of molecular weight of heptane plus( ) fractions is essential in reliable phase behavior calculations and compositional EOS modeling studies Empirical correlations provide cheaper alternatives in time and cost, to obtaining reliable molecular weight data than by experiments, though with compromised accuracies
Several empirical correlations developed to predict molecular weight of  fractionsof petroleum were reviewed A new correlation for calculating molecular weight of heptane plus fractions of light crudes was developed from a database compiled from Niger Delta fields for over 1,200 light crude oil assays, conventional PVT reports, and literature data The correlation was developed using rational multiple regression analysis method
The new correlation’s performance was compared with five others which do not depend on boiling point temperatures Results showed that the new correlation has superior performance with the lowest absolute average and relative mean square errors The new correlation had an average relative error of 815%, root mean square error of 009% and correlation coefficient of 0955

Improved Characterization of Heptane Plus Fraction of Niger Delta Light Crudes


 Oilfield scales are crystalline minerals made up of Na, K, Mg, Ca, Ba, Sr, Fe, Cl from produced water that can precipitate out in the reservoir, well, pipelines and process during the production and transportation of oil and gas. These precipitates can deposit as a result of thermodynamic and/or chemical changes and pose costly flow assurance issues to the oil industry. Several factors have been identified to be responsible including temperature, pressure, ionic strength, pH, evaporation, bicarbonate anion, super-saturation and contact time and water chemistry. Attempts to solve this problem in the past have focused mainly on the use of chemical inhibitors and the most accepted mechanism of scale inhibition is squeeze injection method. While adsorption and retention of scale inhibitors on rock formations needs more research, there had been improvement to better ways of ensuring adsorption and precipitation through nanotechnology including the use of nano-carbon enhanced squeeze treatment (NCEST). The uses of these conventional inhibitors have been found to be toxic to the flora and fauna in biotic communities during water disposal. In order to reduce the environmental burden caused by these conventional solutions and still manage the problem effectively, greener solutions have been proposed. This review x-rays the mechanisms of scale precipitation and deposition, evaluate the solutions that have been provided in literature based on efficiency, economics and environmental impact and propose guidelines to field operators in selecting optimum solutions.

Understanding Oilfield Scale Deposition and Inhibition Mechanisms for Optimum Management: A Review


 Preventing and mitigating corrosion problems can be very challenging due to technical considerations and prohibitive economic implications. It is thus imperative to arrest the escalating corrosion rates and impede the deterioration effects of corrosion with versatile remedies. In this review, previous research efforts on the application of plant-derived polysaccharides as potential inhibitors of metal corrosion in various aggressive media are studied. The deployment of corrosion inhibitors has proven to be an outstanding solution to prolonging the lifespan of metals. However, the most applied inhibitors such as the inorganic and some organic compounds are prohibitively expensive, hazardous, and toxic. These limiting factors have stimulated interest in more research into greener and less toxic natural alternatives. Considering the success of synthetic polymers for corrosion inhibition, a wide range of plants with high natural polysaccharide content have been evaluated to determine their effectiveness as biodegradable, renewable, and more economical corrosion inhibitors. Studies generally show that natural polysaccharides exhibit over 90% efficiency for corrosion inhibition with appreciable adsorption on the metal surface. Modification and grafting of the plant polysaccharides to enhance their inhibition efficiencies and to make them more desirable are currently being investigated. Such bio-inspired polymeric molecules thus have invaluable significance as potential alternatives for the problematic corrosion inhibitors.

A Review of Natural Polysaccharides as Corrosion Inhibitors: Recent Progress and Future Opportunities

Introduction: Natural plant polymers demonstrate effective corrosion inhibition abilities, because of their numerous binding sites and excellent adsorption abilities. Methodology: In this study, the Box-Behnken method, gravimetric and electrochemical analyses were used to design and investigate the corrosion inhibition potential of a modified graft polymer of okra for mild steel in a 1M HCl medium. The influence of inhibitor concentration, temperature, and time were also investigated. Qualitatively, the Fourier Transform Infrared (FTIR) spectroscopy, Thermogravimetric Analysis (TGA), and Field emission scanning electron microscopy (FESEM) were used to characterize the extracts and evaluate the metal’s surface morphology. Results and discussion: The quantitative analyses showed that the modified natural polymer’s inhibition efficiency (IE) increased with concentration and reached 73.5% at 800 ppm, with a mixed-type mode of inhibition. From the response surface methodology, it was revealed that temperature influences the IE more than concentration and immersion time. The optimized IE using the desirability function showed the possibility of attaining 88.2% inhibition with inhibitor concentration at 142.3 ppm, temperature at 60.4°C, and an immersion time of 22.4 h. The new functional groups in the hybrid polymer revealed by FTIR analysis shows that grafting improved the inhibitor’s adsorption abilities. TGA analysis confirmed the extract’s high thermal stability, which highlights the inhibitor’s strong adsorption and efficiency for high temperatures. FESEM analysis indicated evidence of inhibitor adsorption onto the metal surface. Conclusion: These findings suggest that the grafting of okra with acrylamide enhances its inhibition properties and contributes to its functionality as a cost-effective plant-based alternative inhibitor against corrosion for mild steel facilities.

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Princess Christiana Nwankwo

Papers

Simultaneous Flow Assurance and Production Optimization Using Chemical Paraffin Inhibition Method

Improved Characterization of Heptane Plus Fraction of Niger Delta Light Crudes

Understanding Oilfield Scale Deposition and Inhibition Mechanisms for Optimum Management: A Review

A Review of Natural Polysaccharides as Corrosion Inhibitors: Recent Progress and Future Opportunities

Quantitative and qualitative analyses of grafted okra for corrosion inhibition of mild steel in acidic medium