Aerated lagoons are commonly used for domestic and industrial wastewater treatment due to their low cost and minimal need of operational requirements. However, little information is known regarding microbial communities that inhabit these ecosystems. In this study, a 16S-DGGE approach was used to estimate bacterial diversity and to monitor community changes in two aerated lagoons from a wastewater treatment plant receiving urban and industrial effluents. Pronounced shifts between bacterial communities collected in winter-spring and summer-autumn months were detected. Temperature, dissolved oxygen (DO) and pH were the variables that most influenced the bacterial communities. Phylogenetic affiliation of predominant members was assessed by the determination of the 16S rDNA sequence of correspondent bands. Affiliations to Cytophaga-Flexibacter-Bacteroides (CFB) group, Firmicutes, and beta- and epsilon-proteobacteria were found.

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Internal corrosion is one of the major problems affecting the integrity of pipelines and process equipment. For this reason, the internal corrosion monitoring becomes essential to anticipate eventual problems and to select the most appropriate strategy to mitigate the corrosive process. Due to the problems related to the cost, logistics and safety inherent to coupon and electric resistance probe retrieving, it is very important to seek alternatives to the current methods, to optimize the monitoring tasks. The use of non-intrusive equipment to monitor internal corrosion is an alternative that aims at optimizing this step. Additionally, the non-intrusive equipment has easy installation and maintenance, higher data reliability and faster results. These systems consist of estimating the trend of the corrosion rate through devices installed on the external side of pipelines without the need of access fittings, unlike conventional techniques. The great advantage of using this technique is the absence of interventions for components retrieving, minimizing operational risks. To evaluate such equipment, tests were carried out under dynamic conditions, varying the fluid characteristics to verify the speed of response of some commercial devices, always comparing them to conventional methods (coupon and electric resistance probe). Experimental results showed that the trend of measured corrosion rate obtained by the non-intrusive equipment converged with corrosion coupons and electric resistance probe data.

This paper illustrates the importance of internal corrosion management and integrity strategy in the development of new offshore production areas at shallow and ultra deep waters in Brazil, where there is no other production facility nearby. Starting production activities in these areas without any facility, especially pipelines, is a challenge as the investment necessary is high, particularly when the first area to be produced is a gas block. The financial feasibility of a small or medium size gas field with very low condensate production is extremely delicate as such kind of project usually demands high initial investments, particularly with topside facilities, platform structures and pipelines. The scenario worsens as the first investment should consider not only the area to be put in production but also other potential nearby areas with exploration still underway. To foresee fluid composition and all flow parameter scenarios is a complex but necessary exercise to reduce risk and keep the OPEX as low as possible. One of the aims of this paper is to show Petrobras experience in the design of offshore gas fields in the shallow waters of EspÍrito Santo - Brazil, where pipeline corrosion management and integrity strongly affected the CAPEX and OPEX factors as its flow rate capacity was over designed to transport future production from adjacent fields. This Paper discusses issues related to the CO2 corrosion risk assessment and the integrity strategies as some of them are new in Petrobras. Regarding the ultra deep water fields, the paper also briefly discusses some current key issues related to areas of uncertainties due to internal corrosion, like pipelines operating under super critical flow and steel catenary risers under corrosion-fatigue environment. Introduction This paper highlights the importance of pipeline corrosion management and integrity strategy in the development of new offshore production areas in Brazil. In the last years, Petrobras found gas and light/heavy crude fields in new offshore areas in shallow and deepwater depths without any other production facility nearby. Starting production activities in areas without any facility, especially pipelines is a challenge as the investment necessary is high, particularly when the first area to be produced is a gas block. The life cycle cost of marginal gas fields with very low condensate production is extremely delicate as such kind of project usually demands high initial investments, particularly with top side facilities, platform structures and pipelines which should be compensated by the gas market potential consumption needs and its tariffs which are usually low. The scenario becomes more complex as pioneer projects should contemplate the opportunity to produce not only the block with known and proven reserves but also potential vicinity blocks with exploration still underway as we can see today in new offshore areas in Brazil and West Africa. It is very important because pioneering projects can have a significantly positive effect upon operators future spending plans. The project should consider in some cases to build oversized pipeline and separation facilities considering the opportunity of production of part of the reserves from these vicinities areas. One alternative usually done by operators is to cut investment cost reducing platform structure and topside facilities sending all production to shore under corrosive multiphase flow where treatment facilities are installed.

Summary. An experimental method is proposed for quantification of oil in effluent samples from displacement tests with liquids. On a mass basis. this new procedure is offered as an alternative to the classic volumetric approach. A known amount of a suitable organic solvent with good selective solubility and density contrast relative to the oil phase is thoroughly mixed with the effluent sample. After centrifugation, the oil/solvent mixture is analyzed for density. Subsequently, the oil mass fraction in the pseudobinary mixture (oil/solvent) is obtained through a previously determined correlation of this parameter vs. density. With these data-amount of solvent and oil mass fraction-plus the definition of the latter in a binary mixture, one arrives at the actual mass of oil in the effluent sample. The method is applied to a crude oil from Miranga field in the Reconcave basin (northeastern Brazil). Accuracy is thoroughly analyzed and compared with that of the volumetric approach. The method is also tested under such severe conditions as emulsified oil production. Finally, recommendations are made to implement the method in continuous oil-recovery monitoring, which would be a major step in the full automation of laboratory displacement tests. Introduction Displacement tests with liquids are conducted in the laboratory either for recovery studies or simply in relative permeability determinations. In both applications, the effluent from the displacement is most often made up of oil and water phases. Frequently, at least one of these phases is a fairly stable emulsion. Normally, material-balance calculations are carried out on a volumetric basis through the visual observation of the effluent sample previously submitted to centrifugation. Typical sampling flasks consist of 15-cm centrifuge tubes graduated in 0.1-cm increments (+/-0.05 cm uncertainty). Displacement tests representative of EOR experiments, for example, use plugs or series of plugs 3.8 cm [1.5 in.] in diameter and 30 to 50 cm [12 to 20 in.] in length with porosities in the range of 20 to 30%. Under these circumstances, total PV, s are on the order of 100 cm . On the other hand, cumulative fluid injection in these kinds of tests reaches up to 4 to 5 PV's. If sample size is limited to 5% PV, a complete run may yield 100 or more samples to be analyzed for oil and water. Regardless of the evaluation method applied, the numbers above call immediate attention to error accumulation and its effect on final oil recovery. An additional source of error specific of the volu-metric approach is the eventual emulsification of the effluent. Standard centrifugation is hardly effective in surfactant-type stabilized emulsions. In spite of its well-known limitations, the assessment of oil recovery on a volumetric basis is widely applied because of its simplic ty and straightforward execution. To the best of our knowledge, however, its accuracy has never been thoroughly investigated. The following have been proposed as alternative methods:oil/water on-line separators with selective wettability membranes 1;oil/water on-line acoustically monitored separators: andoil-saturation scanning devices that use microwave, ultra-high frequency (UHF), gamma ray, and X-ray attenuation and, more recently, computed tomography. While the first approach is still highly specific with respect to the oil/water system, the second has been tested with success on in-house-developed units and a commercial apparatus recently has been offered to the public- The third, although regarded by tome as the ultimate material-balance and saturation profile tool, requires fairly sophisticated equipment along with highly trained personnel. Our proposition is to present an inexpensive alternative to the classic volumetric approach to oil-recovery calculations in laboratory displacement tests. The new procedure, based on the solvent-extraction (SE) principle, is shown to be simple and yet more ac curate than the conventional volumetric approach. In parallel, the study includes the treatment of a specific problem very common to EOR experiments, that of emulsified oil production. Both the volumetric and the SE methods are tested with simulated effluents from water, alkaline, and surfactant flooding processes. The final analysis to demonstrate the effect of error prop-agation was conducted on a complete set of samples from an actua water/alkali displacement test. Experimental Procedure Modern electronic density meters rely on the change of the natural frequency of a hollow oscillator when filled with different liquids or gases. There is a linear relationship between the differences in the square of the change in natural frequencies and the densities of any two fluids separately filling the oscillator cell. One such apparatus, which can measure density with an accuracy of up to five significant figures, was used throughout this work. Other features of the instrument are the precise temperature control, short measuring intervals, and small sample sizes (- 1 cm). Furthermore, by means of a built-in processor, the instrument may be adjusted to read solute mass fraction in a binary mixture directly. The only requirement is a linear density/frequency behavior in the range of interest. These instrument features encouraged us to experiment with an SE technique and the corresponding correlation of density vs. oil-in-solvent mass fraction to quantify the mass of oil in effluent samples from displacement tests. The first requirement in attempting this task was to identify a proper solvent with enough contrast in density relative to crude oils in general to take advantage of the instrument's accuracy. Our choice was chloroform, with a listed density of 1.489 g/cm and water solubility of only 0.82 wt% (at 20 deg. C [68 deg. F]). The next step was to determine the correlation of density vs. reservoir oil mass fraction in the mixture with chloroform. Throughout this study, dead crude oil from Miranga field in the Reconcave basin (northeastern Brazil) was used. Its density was 0.8191 g/cm at reservoir temperature (60 deg. C [140 deg. F]). SPERE P. 1057^