Inherently safer sustained casing pressure testing for well integrity evaluation

This paper presents the use of a model to predict sustained casing pressure (SCP), from early pressure buildup data, as a basis for inherently safer well integrity testing. Inherently safer principles aim to eliminate or reduce the hazards by design rather than by using protective features. SCP, a well integrity issue exhibited in many wells, is any measurable pressure that rebuilds after being bled down and attributable to causes other than artificially applied pressure or temperature fluctuations in the well. Intrusion of gas, resulting in SCP, can occur because of poor cement bond in the casing or cement deterioration. Gas entering the annulus migrates to the wellhead and represents a hazard due to increased wellhead pressure and the gas inventory. Compromised well integrity can have catastrophic consequences on both environmental and safety aspects.Most regulations require the monitoring, testing and, eventually, the elimination of SCP. However, test data analysis is predominantly qualitative and limited to arbitrary criteria. Due to the high percentage of wells that present SCP, accurate, safe and preferably fast testing methods are needed. This paper implements an analytical model, rooted in the transport processes and thermodynamics of the system, to predict pressure profiles and gas accumulation during SCP testing from early-time pressure buildup data. The amount of gas accumulated during different testing criteria, being 1) current practices and 2) early diagnostic by the analytical model, is calculated and compared. Results show that using the analytical model as a predictive tool, testing time is reduced significantly, thereby limiting the amount of gas accumulated and reducing the risk. This makes the testing procedure inherently safer as well as less time consuming.     

Preparation of Co–MgO mixed oxide nanocatalysts for low temperature CO oxidation: Optimization of preparation conditions

In this study, a series of Co–MgO mixed oxides (30 wt.% Co) were prepared by co-precipitation method and employed as catalyst in low temperature CO oxidation reaction. The preparation conditions were optimized by the Taguchi method of experimental design to synthesize a sample with high catalytic performance toward CO oxidation reaction. The effects of four variables, pH of solution, aging temperature, aging time and molarity of precursor solution at three levels were investigated. The optimized sample was characterized by X-ray diffraction (XRD), temperature programmed reduction (TPR), temperature programmed desorption of oxygen (O₂-TPD), N₂ adsorption/desorption, thermal gravimetric and differential thermal analysis (TGA/DTA), and transmission electron microscopy (TEM) techniques. The results revealed that the optimized sample showed a mesoporous structure with a narrow pore size distribution centered in the range of 7–17 nm and particle size about 5.5 nm. It was found that the molarity of solution and aging time had the most influence on the CO conversion, respectively. The catalytic results showed that the highest CO conversion obtained from samples synthesized by Taguchi orthogonal array was about 90% at 200 °C, while the CO conversion for optimized sample was 95%. In addition, the effect of operational conditions was studied over optimized sample.     

移动式甲烷检测及远程处置系统设计

设计了一个甲烷气体巡检及远程处置系统。采用可调谐半导体激光吸收光谱技术（TDLAS）对甲烷气体浓度进行移动探测,通过全球定位模块获取地理坐标等信息,通过无线网络传输数据。对数据进行远程计算、处理、分发,视不同情况发送报警信号。应用于城镇区域甲烷泄漏、积聚状况的巡检、预警及应急指挥。便于及时发现事故隐患,科学应急处置。     

确保地表建筑物安全矸石充填开采原料配比及充填量的确定

为确定某矿的矸石充填开采过程中最优充填材料配比和最佳的矸石充填量。设计了一种新型的矸石压缩模具,应用该模具和YE-200A液压试验机对十种不同粒径配比的矸石进行压缩试验,得出均匀配比的矸石为最优充填配比。采用最小二乘法拟合的数学模型,确定了均匀配比矸石充填材料与压力的变化规律。最后推出了均匀配比的矸石充填高度与采厚、顶板允许下沉量及顶板压力的函数关系。     

“十二五”太湖富营养化控制与治理研究思路及重点

在总结“十一五”太湖富营养化治理成效、存在问题的基础上,提出“十二五”期间水体污染控制与治理科技重大专项太湖富营养化控制与治理项目的总体设计思路. 项目以综合示范区水质改善为目标,重点研发园区化乡镇企业工业废水中难降解含氮、磷有机物的深度削减技术,农田种植业和农村分散式生活污水的控源减排技术,“湖荡湿地-入湖河流-湖滨缓冲带”为一体的生态拦截与修复技术;以湖泊水生态安全保障为目标,研发湖泛与水华灾害应急处置技术及建立水资源优化调度决策平台. 选择太湖流域重污染型竺山湾小流域、面源污染主控型苕溪小流域和城市化型太湖新城三大典型综合示范区,通过控源减排和生态修复关键技术的研发、集成和综合实施,实现综合示范区污染负荷得到有效控制、示范区水环境质量得到改善和规模化蓝藻水华发生得到有效控制的目标.      

国内地下式污水处理厂的设计要点

对目前国内在建和已建的地下式污水处理厂的设计要点进行了研究和总结。研究表明：地下式污水厂的工艺选择一般有MBBR和MBR工艺,结构形式主要为伸缩缝设计和无缝设计两种,建筑防火分区一般为2 000 m^2或以上;消防可以采用自动灭火系统和消火栓系统,局部变电站采用气体灭火系统。地下式污水处理厂投资较高,约为地上污水厂的两倍,但占地面积远远小于地上污水处理厂,可以节省大量的土地成本,同时地上绿化增加了城市的环境效益和社会效益。     

Characterization of CANON reactor performance and microbial community shifts with elevated COD/N ratios under a continuous aeration mode

COD/N at low ratios (0–0.82) improved N removals of CANON. CANON performance decreased after COD/N up to 0.82. The relative abundance of AOB decreased continuously with increasing COD/N. AOB outcompeted at a high COD load led to CANON failure. The relative abundance of AnAOB decreased and increased with increasing COD/N. The effects of increasing COD/N on nitrogen removal performance and microbial structure were investigated in a SBR adopting a completely autotrophic nitrogen removal over nitrite process with a continuous aeration mode (DO at approximately 0.15–0.2 mg/L). As the COD/N increased from 0.1 to≤0.59, the nitrogen removal efficiency (NRE) increased from 88.7% to 95.5%; while at COD/N ratios of 0.59–0.82, the NRE remained at 90.7%–95.5%. As the COD/N increased from 0.82 to 1.07, the NRE decreased continuously until reaching 60.1%. Nitrosomonas sp. (AOB) and Candidatus Jettenia (anammox bacteria) were the main functional genera in the SBR. As the COD/N increased from 0.10 to 1.07, the relative abundance of Nitrosomonas decreased from 13.4% to 2.0%, while that of Candidatus Jettenia decreased from 35% to 9.9% with COD/N<0.82 then increased to 45.4% at a COD/N of 1.07. Aerobic heterotrophic bacteria outcompeted AOB at high COD loadings (650 mg/L) because of oxygen competition, which ultimately led to deteriorated nitrogen removal performance.     

Statistical modeling of radiolytic (60Co g) degradation of Ofloxacin,antibiotic: Synergetic effect,kinetic studies & assessment of its degraded metabolites

Linear, interactive and quadratic effects of process parameters were studied. Degradation of Ofloxacin (Ofx) was related with G value of irradiation process. The synergistic effect of H₂O₂ on lower dose of g-irradiation was established. The process follows pseudo first order with dose constant (d = 0.232 kGy^–1). The impact of human activities in the past few decades has paved the way for the release of pollutants due to the improper effluent treatment. Recent studies revealed that, Ofloxacin, an antibiotic as one of the major pollutant affecting surface water and ground water. In this study, the radiolytic potential of Ofloxacin was investigated. The effects of pH, dose and concentration of Ofloxacin were analyzed using One Factor At a Time (OFAT) and the interactive effects between the parameters were studied using Face Centered Central Composite Design. The statistically optimised developed model shows 30% degradation at initial antibiotic concentration of 1mM at pH 3.0 and at 2 kGy dose of gamma ray. The process efficiency was evaluated in terms of G value and its correlation with the concentration of antibiotic was also established. The process of degradation was augmented by the addition of H₂O₂ (1.5 mM). The reaction kinetics for the process was evaluated, the dose rate constant and the rate of degradation for the augmented process was found to be 0.232 kGy^-1 and 0.232 mM/kGy, respectively. The degraded metabolites of the radiolytic degradation of Ofloxacin were analyzed through change in pH, reduction in TOC and GC-MS spectrum.     

Metallic wastewater treatment by sulfate reduction using anaerobic rotating biological contactor reactor under high metal loading conditions

An-RBC reactor is highly suited to treat metallic wastewater. Metal removal is due to sulfide precipitation via sulfate reduction by SRB. Cu(II) removal was the best among the different heavy metals. Maximum metal removal is achieved at low metal loading condition. Metal removal matched well with the solubility product values of respective metal sulfide salts. This study was aimed at investigating the performance of anaerobic rotating biological contactor reactor treating synthetic wastewater containing a mixture of heavy metals under sulfate reducing condition. Statistically valid factorial design of experiments was carried out to understand the dynamics of metal removal using this bioreactor system. Copper removal was maximum (>98%), followed by other heavy metals at their respective low inlet concentrations. Metal loading rates less than 3.7 mg/L?h in case of Cu(II); less than 1.69 mg/L?h for Ni(II), Pb(II), Zn(II), Fe(III) and Cd(II) are favorable to the performance of the An-RBC reactor. Removal efficiency of the heavy metals from mixture depended on the metal species and their inlet loading concentrations. Analysis of metal precipitates formed in the sulfidogenic bioreactor by field emission scanning electron microscopy along with energy dispersive X-ray spectroscopy (FESEM-EDX) confirmed metal sulfide precipitation by SRB. All these results clearly revealed that the attached growth biofilm bioreactor is well suited for heavy metal removal from complex mixture.     

两株自养型氨氧化细菌的分离、鉴定及系统发育分析

以水产养殖废水处理工程的生物膜为菌源,采用传统的富集、分离纯化等微生物学手段,筛选出2株自养型氨氧化细菌A.P-7和A.P-8,并将其转接至液体分离培养基中培养17 d,定量检测结果表明,菌株A.P-7和A.P-8的氨氮去除率均可达到90%以上. 对2株菌的形态特征与生理生化性质分析结果表明,2株菌与假单胞菌属成员相似. 进一步测定2株菌的16S rDNA基因序列,测序结果提交至GenBank进行同源性检索分析,并通过MEGA 4.0软件进行比对和系统发育分析,结果显示2株菌均属于假单胞菌属,与门多萨假单胞菌的同源性最高,达99%以上.