Hydrate blockage in subsea systems is responsible for a portion of lost profits in several deepwater oil fields. This problem tends to worsen in the fields recently discovered in Brazilian Pre-Salt layer due to greater water depth, higher pressure, lower temperature, and oil more prone to agglomerate. Additionally, in this scenario, the logistic for hydrate remediation, if a rig is required, is even more complex due to the greater distance from shore. The overall conditions found in Brazil offshore fields prior to Pre-Salt development allowed applying a less conservative hydrate prevention design when compared to other areas throughout the world. Now, while the global trend is to reduce the safety margin to manage hydrate risk rather than simply avoid them, it may be interesting to increase flow assurance design robustness for some critical fields. This paper presents some suggestions in order to meet this goal.

Significant part of the Brazilian oil reserves is located in ultradeepwater fields (WD > 1500 m). In this scenario, flow assurance plays a crucial role due to the existing high pressures and low temperatures.This paper focuses on the strategies concerning flow assurance issues for the near future. These strategies are strongly based on our specific field experiences as well as on the foreseeable technological scenario. The future, as treated in this work, refers to the short and mid-term future and not to the prospective long term one. Thus, it will mainly discuss current R&D in flow assurance activities to tackle existing problems and the ones foreseen for the discoveries already in development.In order to facilitate the understanding of our vision, a brief summary about todays flow assurance issues is presented. Currently, the main flow assurance concerns are related to hydrate formation and wax deposition. Accordingly, design criteria and operational procedures to avoid these problems are briefly described.There is also an increasing concern about heavy and extraheavy oil production, since a relevant part of recent offshore discoveries involves this type of oil.Among the initiatives that are being taken aiming at optimizing flow assurance design in the near future, one can mention:-rheology of heavy oil and water in oil emulsion; -heavy oil multiphase flow (gas-liquid) simulation; -hydrate slurry transportability; -improvements on wax deposition modeling; and -improvements on heat management.

The development of a mechanistic procedure to estimate the convection heat transfer in horizontal gas-liquid intermittent-or slug-flow is presented. In broad terms, the mean convective heat transfer coefficient is calculated following an averaging procedure based on the unit cell model of the slug flow pattern. The flow parameters (i.e., unit cell frequency, liquid slug and elongated bubble length and velocity, and liquid hold-up) were obtained from empirical data for air/water flows in a 15 m-long, 25.4 mm ID copper pipe and for natural gas (mostly methane and ethane) and oil or water flows in an actual size, 200 m-long, 150 mm ID steel pipe. A time-averaging procedure based on the unit cell parameters was then used to calculate the mean convective heat transfer coefficient. The slug flow parameters taken on the small scale air/water loop and the actual size pipeline were used for comparisons. Heat transfer data from the small scale air/water loop were used to validate the results calculated using the averaging procedure. Finally, the approach herein proposed also showed good agreement with previously published data and well-known correlations.

Copyrlghl 199S OFFSHORE TECHNOLOGY CONFERENCE Thos papar was FePared for presen fat ton al the Offshore Technology C0nferenc9 held In Hw5tcfI T.xas 69 May 19S6 Thts paper was sd!ecfec for prnsentatm" by I he OTC Program C.anmdttw folkn9 renew of Warm'dt!cm cc$ha$cud m an ?&tract subm!ffed by the author(s) CWten!s of the Pqe$ a. preserded, have not ben rewewd by Ihe OfWwro TechIw42Qy and are subjecf to c.xmclon by the abthor(s) The material, as presented, CLWS cat nncasssnfy reffecl any PO$IIIX! of me Off$hcfe Technokgy Cotiererce or fis affKRIs Perrmsswn 10 COPYm remr!cfed m an abstract of nof mcfe than 302 words 111.stratbcmsmay not be copma The abstrad shdd ccdam umspkxous adwwwledgmenl 01 where and by whom the paw was pwsen!ed AbstractThis paper describes the impact that the use of a subsea boosting sys[em will have on the development of a deepwater field . The analysis covers the technology demands and constraints encountered on screening studies executed for the fields of Marlim, Albacora and Barracuda, as well as an overview of the economic benefits encountered. The paper will focus on the technological demands and constrains identified as well as some considerations about possible alternatives . The demands and constrains identified in the study will provide the industry with some more input to guide the development of the subsea boosting technology, as well as a better understanding of how to apply this new tool on the development of deepwater prospects. The results of the screening study are showing that the subsea boosting systems are a valuable tool to reduce the costs of deepwater developments, provide that the industry could meet the technology demands that are indicated on the study. The cost cutting possibilities through an integration between the "conventional" subsea hardware and the subsea boosting systems and the combination of boosting systems are promising alternatives The subsea boosting systems are a new tool that have -although still under development -recently been added to the tool box of the subsea engineers. [derr[ifying the way to get the most out of it, that is, how to use to the full extent this new technology could help the industry to make the deep water developments profitable. The encouraging economic results found, as well as the demands and constraints raised on the paper will be of use for those trying to apply these technologies in various areas of the world.

This paper was seleded for presentation by the OTC Program Committee following review of information contained in an abstract submitted by the auhor(s). Contents of the paper, as presented, have not been reviewed by the Offshore Technology Conference and are subjd to mrrection by the authw(s). The material, as presented, does not necessarily r e f l d any po8i(m of the Offshore Technology Conference or its otlicers. Electronic reprodudion, distribution, or storage of any part of his paper for commercial purposes wilhout the written consent of h e Offshore Technology Conference is prohibited. Permission to reproduce in print is restrided to an abstract of not more than 300 words; illustrations may not be copied. The abstract must contain conspicuous advlowledgment of where and by whom the paper was presented. AbstractMost of Brazilian oil and gas reserves are located in offshore deep waters. In this scenario, high well productivity is essential. Artificial lift will certainly play an important role in the exploitation of those deep water fields.This paper describes the most important artificial lift methods, their main characteristics and application niches. It also shows what Petrobras is currently doing in order to make them available for subsea use.The following methods are analysed:gas lift; electrical submersible pump; hydraulic jet pump; progressing cavity pump;multiphase pump; subsea separation system.