Estimation of the Substrate Concentration Profiles in Petroleum Pipelines Containing Biofilms

Abstract

In industrial systems, the formation of biofilms can cause many problems, such as an increase in the flow resistance of pipelines, energy losses in fluid transport and heat exchangers, product contamination, materials deterioration, and biocorrosion. As a result, biofilms contribute substantially to economic losses in the industry. Corrosion is particularly an issue in the petroleum industry and its implications range from down-hole completion through petroleum processing units. Much of this corrosion is attributed to microbial activities. This paper proposes a mathematical model for predicting substrate concentration for such microbial growth. Substrate concentrations in the system and near the biofilm surface are one of the parameters that has a great effect in determining the extent of the problems associated with biofilms. In this study, a convective-diffusion model under various flow conditions (stagnant, laminar, and turbulent) has been solved using the finite difference technique, employing the alternating direction implicit (ADI) method. The model assumes that a liquid containing substrate and bacteria is flowing in a pipeline with known concentrations at the inlet and then predicts the variation of the transient (as a function of time) substrate concentration along the pipeline and as a function of the pipe radius. The model is then used to predict and estimate the substrate concentration profiles on the biofilm surface under different environmental conditions. A parametric study was also conducted to study the effect of the different parameters influencing the substrate concentration profiles in the system and on the biofilm surface.     

触变性流体的泊肖叶流动和渗流

由于我国原油含蜡量较高,表现出显着的触变特性,因此,关于触变性流体流动行为的研究,对于我国的石油工业具有重要的实际意义。笔者采用Moore型触变性流体本构方程(一种无弹性流体模型),对石油工业中两种典型的流动形式进行了研究。其一是圆管层流(又称泊肖叶流动),得到其流量和沿管方向压力梯度之间的解析关系式。该关系式为很复杂的非线性形式。为了便于分析原油输送中的某些问题,还给出了该解析解的一种近似形式。另一典型流动是渗流,它是分析地层中原油流动行为的理论基础。给出了Moore型触变性流体的渗流方程并求得平面径向渗流问题的解析解,研究结果为正确估计原油生产中的压力分布提供了重要的理论依据。     

Rutin inhibits mono and multi-species biofilm formation by foodborne drug resistant Escherichia coli and Staphylococcus aureus

Considering the role of biofilm in food spoilage and the food industry, inhibition of biofilm formation by natural agents is expected to be safe and could also enhance the efficacy of other antimicrobial strategies for controlling microbial food spoilage. Plant flavonoids are known for their diverse biological activity including antimicrobial. Therefore, rutin was investigated for its biofilm inhibitory activity at sub-minimum inhibitory concentrations (sub-MICs) values against common foodborne pathogens (Escherichia coli and Staphylococcus aureus). Minimum inhibitory concentrations (MIC) ranged from 400 to 1600 μg/ml against the selected strains. Sub-MICs (1/16 × MIC to 1/2 × MIC) were used to assess the inhibition of biofilm formed by E. coli and S. aureus in microtitre plate assay. Mono strain biofilm formation by Escherichia coli and Staphylococcus aureus was greatly reduced by rutin at their respective 1/2 × MIC. For multi-species (E. coli: and S. aureus) biofilm formation, the reduction in biofilm production was concentration dependent. No significant bacteria mass reduction was recorded for any sub-MIC. SEM images of biofilm inhibition on steel chips confirmed the reduction in number of microcolonies. Exopolysaccharide production responsible for adherence and maturation of biofilms was also significantly (p ≤ 0.05) reduced at respective concentrations of rutin in tested strains. To the best of our knowledge, this is the first study describing the effect of flavonoid, rutin on multi-species biofilms consisting of S. aureus and E. coli. Findings of the study indicate a potential application of rutin in the prevention of biofilm on industrial equipment and food contact surfaces and prevent food contamination and spoilage.     

Evaluation of rhamnolipid and surfactin to reduce the adhesion and remove biofilms of individual and mixed cultures of food pathogenic bacteria

Biofilms represent a great concern for food industry, since they can be a source of persistent contamination leading to food spoilage and to the transmission of diseases. To avoid the adhesion of bacteria and the formation of biofilms, an alternative is the pre-conditioning of surfaces using biosurfactants, microbial compounds that can modify the physicochemical properties of surfaces changing bacterial interactions and consequently adhesion. Different concentrations of the biosurfactants, surfactin from Bacillus subtilis and rhamnolipids from Pseudomonas aeruginosa, were evaluated to reduce the adhesion and to disrupt biofilms of food-borne pathogenic bacteria. Individual cultures and mixed cultures of Staphylococcus aureus, Listeria monocytogenes and Salmonella Enteritidis were studied using polystyrene as the model surface. The pre-conditioning with surfactin 0.25% reduced by 42.0% the adhesion of L. monocytogenes and S. Enteritidis, whereas the treatment using rhamnolipids 1.0% reduced by 57.8% adhesion of L. monocytogenes and by 67.8% adhesion of S. aureus to polystyrene.Biosurfactants were less effective to avoid adhesion of mixed cultures of the bacteria when compared with individual cultures. After 2 h contact with surfactin at 0.1% concentration, the pre-formed biofilms of S. aureus were reduced by 63.7%, L. monocytogenesby 95.9%, S. Enteritidis by 35.5% and the mixed culture biofilm by 58.5%. The rhamnolipids at 0.25% concentration removed 58.5% the biofilm of S. aureus, 26.5% of L. monocytogenes, 23.0% of S. Enteritidis and 24.0% the mixed culture after 2 h contact. In general, the increase in concentration of biosurfactants and in the time of contact decreased biofilm removal percentage. These results suggest that surfactin and rhamnolipids can be explored to control the attachment and to disrupt biofilms of individual and mixed cultures of the food-borne pathogens.     

Rhamnolipid and surfactin: Anti-adhesion/antibiofilm and antimicrobial effects

Biofilm growth in food industrial processing environment increases the probability of product's microbial contamination by spoilage and pathogenic microorganisms. Biosurfactants represent a great strategy to reduce biofilms due to their environmental-friendly nature when compared to synthetic surfactants. In order to evaluate biosurfactants potential on controlling biofilms, surfactin and rhamnolipid were tested against Listeria monocytogenes and Pseudomonas fluorescens. Adhesion/biofilm formation on polystyrene and stainless steel 304 surfaces, and physicochemical parameters were used to analyze and discuss findings. Adhesion was reduced up to 79% and 54% on polystyrene, while biofilm formation was reduced up to 83% and 73% on stainless steel surfaces (rhamnolipids and surfactin, respectively). Surfactants altered surfaces physicochemical characteristics. When added to the culture medium, microbial adhesion was inhibited up to 100%, depending on the product. Biosurfactants showed antimicrobial activity. Results demonstrate good potential of tested biomolecules to decrease adhesion and biofilm formation on food-contact surfaces.     

水平气液混输管路清管操作的数值模拟

混输管路清管技术的研究对混输管线的运行管理具有非常重要的意义,在分析清管物理模型的基础上,建立了清管器前段塞流动的特征参数计算模型、动态数学模型以及相应的数值计算方法,并进行了数值模拟.利用拉格朗日法跟踪清管球和段塞运行情况,计算得到了测压点的压力随时间的变化,并与实验数据进行了比较,得到了清管过程中压力变化规律.利用数学模拟方法可以计算清管过程中管线的压力分布,利用压力分布可以跟踪清管球在管线内的运行状况,这为混输管路的运行管理提供了理论依据.     

Effectiveness of a phage cocktail as a biocontrol agent against L. monocytogenes biofilms

Listeria monocytogenes can persist and form biofilms in a food environment which are difficult to eradicate because biofilms are inherently resistant to a variety of antimicrobial treatments. Therefore, alternative approaches such as bacteriophages have been suggested as a promising biocontrol agent against biofilms. The aim of this study was to evaluate the efficacy of a cocktail bacteriophage product (ListShield™) against L. monocytogenes biofilms. These biofilms were established on lettuce, stainless steel, rubber, and a MBEC biofilm device and exposed to the ListShield™ phage preparation (1 × 10⁸ PFU/mL) for 2 h. ListShield™ had sufficient potency to significantly reduce the biofilm (P < 0.05) in all cases. Biofilm reduction achieved after ListShield™ treatment on the stainless steel coupon was 1.9–2.4 log CFU/cm² and on the rubber surface approximately 1.0 log CFU/cm². Phage application on lettuce inactivated biofilm bacteria up to 0.7 log CFU/cm². These results suggest that bacteriophage preparation ListShield™ is an effective tool for the inactivation of L. monocytogenes biofilms in the food industry.     

A comparison of saturated steam and superheated steam for inactivation of Escherichia coli O157:H7, Salmonella Typhimurium,and Listeria monocytogenes biofilms on polyvinyl chloride and stainless steel

This study was performed to compare the effectiveness of saturated steam (SS) and superheated steam (SHS) in the inactivation of Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes biofilms on polyvinyl chloride (PVC) and stainless steel. Biofilms were formed on PVC and stainless steel coupons by using a mixture of three strains each of three foodborne pathogens at 25 °C. After biofilm development, PVC and stainless steel coupons were treated with SS at 100 °C and SHS at 125, 150, 175, and 200 °C for 5, 10, 20, and 30 s on both sides. The viable cell numbers of biofilms were significantly (p < 0.05) reduced as SHS temperature and exposure time increased. For all biofilm cells, SHS treatment resulted in an additional log reduction compared to SS treatments. After exposure to 200 °C steam for 30 s or 10 s on PVC or stainless steel, respectively, the numbers of biofilm cells were reduced to below the detection limit (1.48 log). This study demonstrated that SHS treatment effectively reduced populations of biofilm cells and reduced disinfection time compared to SS treatments and further evaluated its potential as an excellent intervention for controlling microbial biofilms and enhancing safety in the food processing industry.     

Parametric analysis of the effect of operation parameters on asphaltene deposition: An experimental study

Changing pressure, temperature, and composition cause instability in crude oil and create a problematic issue which is called asphaltene deposition. Asphaltene deposition causes problems in wettability alteration and flow assurance in different parts of petroleum industry so asphaltene deposition becomes a challenging issue in petroleum engineering. Hence, it is necessary to predict asphaltene deposition and investigate parameters which effect on asphaltene deposition. In this contribution, because of similarity between pore throat of reservoir rock and capillary tube, to investigate parameters such as asphaltene content, precipitant ratio, flow rate, and temperature effect on asphaltene deposition, a capillary setup was constructed and a model was developed to relate pressure drop along capillary tube to permeability reduction.     

对加快建立中国石油管道建设行业统一企业标准体系的探讨

根据近几年中国石油管道工程建设的实践,借鉴国外有关标准规范的先进经验,站在中国石油管道建设行业的整体高度,从设计、施工、验收以及项目评估、项目管理、项目监理等方面,分析了管道建设标准体系存在的问题和不足,探讨了加快建立中国石油管道建设行业统一企业标准体系的方法。     

Bacillus cereus hazard and control in industrial dairy processing environment

Bacillus cereus is one of the most important spoilage microorganisms in dairy environment and its growth may result in various dairy defects. Moreover, it is a great safety concern for dairy industry as it is associated with incidences of food poisoning by producing enterotoxin. Because of its outstanding ability to adhere to stainless steel surfaces of dairy plant and form biofilm, B. cereus can lead to serious hygiene problems and economic loss due to spoilage of dairy products and equipment impairment. Biofilms are more resistant to antimicrobials and cleaning regimes compared to planktonic cells, and this makes their elimination from dairy industry a big challenge. B. cereus biofilms may develop particularly in storage and piping systems that are partly filled during operation or where residual liquid has remained after a production cycle. These biofilms in pasteurizer and storage tanks can be a source of post-pasteurization recurrent contamination. Cleaning-in-place (CIP) regimes, commonly used in dairy industry, showed a varied effectiveness in eliminating B. cereus biofilms. Optimization of alkali-based CIP significantly increases B. cereus biofilm cell removal, as compared to the reference CIP usually used in dairy industry. Thus, optimization of the existing cleaning processes and development of novel and effective strategies as well are of utmost importance to the dairy industry, as these may lead to quality improvement of products and processes. This review discusses the characteristics, and spoilage and toxigenic potential of B. cereus in dairy industry, with an emphasis on biofilm development and emerging control strategies.     

Nucleolytic enzymes from the marine bacterium Cobetia amphilecti KMM 296 with antibiofilm activity and biopreservative effect on meat products

Cultivation of Pseudomonas aeruginosa (P. aeruginosa), Bacillus subtilis (B.subtilis), Salmonella enterica (S. enterica), and Staphylococcus aureus (S. aureus) isolated from meat products together with the marine bacterium Cobetia amphilecti KMM 296 (Cobetia marina) resulted in inhibition of their cell growth and complete degradation of biofilms of P. aeruginosa and B. subtilis. The degradation patterns of their mature biofilms treated with Cobetia amphilecti (C. amphilecti) extracellular nucleolytic enzymes revealed that the highly active alkaline phosphatase CmAP could be a significant antibiofilm factor. Moreover, CmAP possessed strong dose-dependent inhibition effect on de novo biofilm formation by bacterial cells regardless of the species. The concentration of CmAP for exhibition of maximal effect on microbial growth and biofilms was 1.1 μg/ml with activity of 2.5 units/ml that diminished total aerobic mesophilic and lactic acid counts in sausage shells by 3.5 log units for 5 days and 2.5 log units for 6 days, respectively. The stabilized antifungal effect continued the same period of storage. The nuclease-like enzymes CmEEP and CmNUC were species-independent and largely degraded biofilms at lowered pH. The biopreservative effect on meat products at low concentration and psychrophilicity of CmAP can be used for enzymatic cleaning of surfaces in food industry.     

用标准规范解析非金属管在石油行业应用中出现的问题

管材技术标准和管道设计规范是工程材料选择的直接依据,系统理解标准规范的含义才能确保管材的合理选择。近年来,石油行业非金属管道在投入运行后发生破损泄漏的现象时有发生,不仅有施工质量和材料质量的问题,也有标准规范执行不彻底的原因。文章依据管材技术标准和管道设计规范,结合具体案例,从管材的性能及适用范围、管道的结构设计两个方面对泄漏原因进行解析,以期为非金属管在石油行业中得到更好的应用提供参考。     

我国原油天然气输送用管发展展望

从油气能源是制约国民经济发展的主要因素之一和石油工业的发展战略，论述了２１世纪初将是我国管道工业达到世界先进水平的发展时期。作者从几条跨国管道和国内管道建设的预测和设想介绍了我国管道工业未来发展的四个特点：（１）长运距，成网络，天然气管网发展更为突出；（２）大输量，大口径，高压力；（３）高品质，高强度，高韧性；（４）彩和直缝埋弧焊钢管，最后提出了对我国油气输送用钢管的研制，开发，生产的七点建议，其     

集输管道内腐蚀原因分析及对策研究

在石油石化行业,腐蚀是危害管道安全、引起管道失效的重要因素。统计数据表明:腐蚀相关的事故占总体事故比例在25%以上。通过对某区块采出液成分进行分析,发现腐蚀形态以局部点蚀为主,腐蚀机理主要是垢下浓差腐蚀和细菌腐蚀,腐蚀的主要介质是H2S、CO2、SRB,水中的Cl-作为催化剂对腐蚀起到自加速的作用,随后通过添加缓蚀剂、旋转气流法管道内涂层和非开挖内衬修复技术对腐蚀管道进行防护与修复,其中旋转气流法适用于新建或未发生过腐蚀穿孔的管段,PCE内衬修复技术适用于腐蚀较为严重的管段,目前3种防护措施都取得了良好的应用效果,可实现隔离腐蚀介质、延长管道寿命的目的,研究结果可供其他油气田和管道行业借鉴。     

A Reliable Model for Estimating the Wax Deposition Rate During Crude Oil Production and Processing

Deposition of wax in surface and subsurface pipes and even perforations can lead to serious problems including pore spaces blockage, plugging of pipelines, and minimum profitability. Therefore, understanding wax deposition and wax related-properties improves the oil recovery and processing operations in petroleum industry. In this research work, the rate of wax deposition is correlated to a number of main parameters such as the dynamic viscosity of crude oil, shear stress, gradient of wax molecular concentration and temperature difference in pipeline system through implementation of a newly developed model, known as least squares support vector machine (LSSVM) along with the coupled simulated annealing (CSA) optimization strategy. The possible outliers are detected through employing the Leverage technique which involves residual errors plots, Williams' plot, and Hat matrix. The results imply that whole collected real data are in applicability domain of the proposed model. Using a comprehensive statistical investigation, a very good agreement between the predicted LSSVM-CSA outputs and real wax deposition rate is found such that the average relative error percentage and determination coefficient (R2) are 0.048% and 0.999, respectively. Such a study can assist to provide better designs (technically and economically) for underground and surface facilities while dealing with wax deposition cases.     

The specific anti-biofilm effect of gallic acid on Staphylococcus aureus by regulating the expression of the ica operon

Staphylococcus aureus (S. aureus) biofilms are of considerable interest in food safety because biofilms can increase the risk of food contamination and enhance the pathogenicity of bacteria. The ica-encoded polysaccharide intercellular adhesin (PIA) plays an important role in biofilm formation. In this study, the MIC of gallic acid against S. aureus in suspension and in biofilms was 2 mg/mL and 4 mg/mL, respectively. Quantitative crystal violet staining of biofilms showed that 2 mg/mL gallic acid can effectively inhibit biofilm formation and the ESEM images clearly showed the three-dimensional biofilm morphology of the S. aureus and the resulting anti-biofilm effect. The determination of viable bacteria in the biofilm revealed that gallic acid penetrated the biofilm to kill S. aureus, the bactericidal effect on the biofilm bacteria was comparable to that of planktonic bacteria. We further explored the influence of gallic acid on ica family gene expression and polysaccharide slime formation in S. aureus biofilm formation. The results showed that icaR was significantly activated that; icaA and icaD were downregulated in a dose-dependent manner with increasing concentrations of gallic acid; however, the expression of icaB and icaC was not significantly affected. The polysaccharide slime formation was reduced as well. Based on these results, gallic acid, as a natural substance, may play an important role in the food industry.     

The specific antibacterial effect of the Salvia oil nanoliposomes against Staphylococcus aureus biofilms on milk container

The Staphylococcus aureus (S. aureus) biofilm on container is the main source of microbial contamination in milk. In this study, the nanoliposomes encapsulating Salvia oil (SO) has been prepared. Based on the damage effect of pore-forming toxin on cell membrane, α-toxin secreted from S. aureus has been used to trigger the release of SO from nanoliposomes to achieve antibacterial effect on S. aureus biofilm on milk container. Firstly, the minimum biofilm eradication concentration (MBEC) and biofilms time-dependent killing of SO were tested. The results showed that the MBEC of SO against S. aureus biofilms was 0.2% and SO effectively eradicated the biofilms after treating for 4 h. Subsequently, SO was encapsulated into nanoliposomes in order to increase its stability. The particle size, poly dispersity index (PDI), zeta potential, pH, turbidity, and entrapment efficiency of SO nanoliposomes were analyzed systematically. Gas chromatography–mass spectrometry (GC–MS) has been utilized to observe the controlled release of SO form nanoliposomes incubated with S. aureus. The scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) images have also visually showed that SO nanoliposomes have high anti-biofilm activity against S. aureus biofilms on milk container.     

稠油油藏蒸汽吞吐井注采参数系统优化

蒸汽吞吐热力采油的效果取决于由注采参数决定的注入蒸汽的热能利用程度。将蒸汽在地面管线、井筒及地层中的流动作为一个整体系统，在地面、井筒管流及油藏数值模拟研究的基础上，基于节点分析技术，建立蒸汽吞吐注入系统组合模型，提出蒸汽吞吐井注采参数整体系统优化的设计方法。考虑蒸汽吞吐井的注入、采出费用建立经济评价模型，用模拟退火算法优化注采参数。应用结果表明，采用此方法优选出的参数进行生产，可提高蒸汽吞吐井的热能利用率和开采效果。图2表2参8     

四维管理是管道完整性管理发展的必然趋势

全面分析了油气管道HSE管理、管道完整性管理和资产完整性管理的发展历程，指出了目前存在的管理问题，首次提出了管道四维管理理论。针对管道四维理论，对四维理论的管理要素、管理领域、管理空间、管理时间进行了结构层次的分析，提出了管理原则和管理的流程；其管理的主要内容为：通过空间地理位置与时间相结合，对管道系统实现全过程、全方位、时时的系统控制管理，其中包含了对管道完整性、管道运行、管道应急的全过程、时时管理，通过信息系统的整合来实现思想、方法、技术、组织、管理者交互性的智能控制管理过程。管道四维管理理念的提出，为完整性管理的进一步发展提供了理论和实践方向，对中国石油管道行业的技术进步和管理创新给出了新的思路。