Fabio Braga de Azevedo

Pipeline Shore Approach Installation by Horizontal Directional Drilling

Whenever an export pipeline coming from offshore fields to onshore facilities is designed, a shore approach solution needs to be provided, once it can become a very complex project in terms of offshore pipeline installation. At this phase the pipeline on-bottom stability is analyzed for surf zone, the possibility of using concrete coating is verified as well as the necessary burial depth. In addition, the pipeline installation stress analysis is performed, the potential for local scour is verified, among other things. In this context, horizontal directional drilling (HDD) emerges as an alternative method in which, in addition to overcome the technical aspects mentioned above, the environmental issues can also be minimized.Many factors determine the success of an HDD project. Failure to complete the borehole is often the main concern, as the project would not be attempted if the pipeline could not be installed. However, the successful design and construction of an HDD is measured in more than a successful pullback. The achievements, as in any project, include the completion of the project for a reasonable cost with minimal environmental impact and according to the schedule. And of course, the pipeline integrity shall be ensured. That is the focus here in this work.This paper presents discussions regarding to the proper design of the export pipeline section installed by HDD in the shore approach area. To ensure a proper design and pipeline integrity are important parts in the success of a shore approach HDD crossing. It must be noted that there are no methods for in situ repair of damaged pipelines installed by HDD. The point is a proper design, construction and installation, which includes, for instance, do not overstress the pipeline during installation, mainly pullback operation, as well as the proper selection of the drill path in order to place the pipeline within stable ground and isolated from obstacle’s active conditions, to properly consider the corrosion protection, etc., for the design life of the product pipe.Copyright

Thermo-Mechanical Design of Canapu PIP System

This paper discusses the thermo-mechanical design of the pipe-in-pipe (PIP) flowline installed in the Canapu field, located in Espirito Santo State, offshore Brazil. The pipeline is approximately 20km in length and connects the gas producing well 4-ESS-138 positioned in a depth of 1608m to Cidade de Vitoria FPSO, located in Golfinho field. The Canapu PIP will operate under high pressure and temperature (HP/HT) conditions and is laid on the seabed. Due to the operational conditions, the thermo-mechanical design evaluated the susceptibility of the pipeline to the phenomenon of lateral buckling and pipeline walking in addition to free spanning and on-bottom stability. The lateral buckling behavior of the PIP is the major challenge for the design. It can be a safe and effective way to accommodate the thermal expansion of a hot pipeline, however high stress and strains can be developed in the buckles and a conventional stress based approach is not suited to design a pipeline that buckles laterally. The conventional stress limits are therefore relaxed and replaced by a strain limit. For this the methodology and recommendations of the SAFEBUCK JIP were adopted. The thermo-mechanical analysis selected a buckle initiation strategy based on distributed buoyancy. The strategy combines three distributed buoyancy triggers along the route together with the beneficial effect of the bathymetric out-of-straightness. The analysis shows that this initiation strategy is robust and highly reliable. From the start, this project represented a great challenge for Petrobras; it is the first PIP in Petrobras; has a low value specified for OHTC; and the pipeline is susceptible to lateral buckling. Besides all that, since the Canapu project was included among the priorities of Petrobras Plangas, it was executed as a fast track project.Copyright

Pipe-in-Pipe for Gas Production in Deep Water Offshore Brazil

Based on flow assurance studies a Pipe-in-Pipe solution was selected to assure the flow for a gas pipeline connecting the well 4-ESS-138 to FPSO Cidade de Vitoria located in Canapu field. The flow assurance studies also define the value of 0.8W/m2 K for the overall heat transfer coefficient (OHTC) in order to prevent hydrate formation. The temperature of 87°C on the wellhead should be preserved to permit the proper gas flow in 20km PIP length between wellhead and FPSO. Canapu field is located in the offshore area of Brazil (Espirito Santo state) in water depths of 1608m. This paper presents the main aspects related to the detailed design, thermo-mechanical requirements, materials specifications, functional qualification tests performed on materials and on pipe-in-pipe systems to satisfy installation constraints defined by the reel-lay method and operational issues.© 2009 ASME

Enhanced Collapse Resistance for Different D/t Ratios of UOE Pipes for Ultra Deepwater Application

Energy consumption outlook shows that the demand for Oil and Gas is increasing worldwide and since most of the undemanding reserves are already being explored, new reserves means longer distances from the shore and increasing water depths, of up to 3,000 meters. Collapse resistance has become a key factor in the design of pipelines for ultra-deepwater applications. UOE process is commonly used for manufacturing pipelines of large diameter and the cold work involved in this forming process modifies the mechanical properties of the pipes. This paper presents the effect of thermal treatment on final material properties, proving the validity of enhancing collapse for different D/t, as allowed by DNV-OS-F101 αFab, and extending what has been shown as valid on previous studies. In this work, the inputs for the processing strategies are presented, along with coupon compression testing and full scale testing, in order to qualify the selected route as compliant with producing pipes with αFab equal to 1, for usual D/t combinations. An analysis of the predicted collapse pressure compared to the real collapse pressure of the pipes is also presented. The extension of the qualification process achieved successful results and allows the use of a fabrication factor equal to 1 in ultra-deepwater offshore pipeline projects. This enables the reduction of wall thickness, generating reductions in material and offshore installation costs and also potentially enhancing the feasibility of many challenging offshore projects.Copyright

Collapse Resistance Enhancement in UOE SAWL Line Pipes During Coating Heat Treatment for Ultra Deepwater Applications

Large diameter UOE pipes are being increasingly used for the construction of offshore pipelines and in the last few year, since oil discoveries are moving towards ultra-deepwater areas, such as Pre-Salt in Brazil, collapse resistance is a key factor in the design of the pipelines the demand for pipes with high thickness near the limits for fabrication and installation capacity. It is known that the cold forming, and the final expansion in the UOE line pipe manufacturing process, reduces the elastic limit of the steel in subsequent compression. Due to this, the DNV collapse formula includes a fabrication factor that de-rates by a 15% the yield strength of UOE Pipes. However, DNV also recognizes the effect of thermal treatments and the code allows for improvement of the fabrication factor when heat treatment or external cold sizing (compression) is applied, if documented. In previous work [1] it was presented the qualification of UOE pipes with enhanced collapse capacity focusing the use of a fabrication factor (alpha-fab) equal to 1. A technology qualification process according to international standard has been performed. The main aspects of the qualification process were presented and included significant material, full scale testing and final analysis. In this paper, we compare those results with the ones of the new qualification tests analyzing the more important variables affecting the collapse resistance such as ovality, compressive material strength, thermal treatment control, etc. This new qualification obtained even better results than the previous one, which will allow the use of a fabrication factor equal to 1 directly in deepwater and ultra-deepwater offshore pipeline projects with a possible reduction in material and offshore installation costs and also potentially enhancing the feasibility of many challenging offshore projects.Copyright

Design Challenges of Gas Export Pipelines for Pre-Salt Area Offshore Brazil

Recently the pre-salt development is a great challenge for Petrobras regarding the offshore exploration and production activities. The pre-salt area comprises several ultra-deepwater fields located far off the Brazilian coast.In order to flow the produced gas of these pre-salt fields, Petrobras has planned to install large diameter gas export pipelines as trunklines. The design of large diameter gas pipelines in ultra-deepwater of about 2200m has hydrostatic collapse and installation loadings being the major issues to be faced by the technical team. Reduction of pipeline wall thicknesses may improve the technical and economic feasibility of its installation in ultra-deepwater and sometimes can also increase the number of laying barges / vessels able to perform the installation. However, reduction in wall thickness is only feasible if the pipeline integrity under external pressure as well as under combined loadings is ensured in accordance with the applicable design code and the engineering best practices.This paper presents the assessment of some design parameters able to reduce the wall thicknesses along the pipeline length, while keeping the commitment to the engineering good practices and complying with all requirements of the DNV-OS-F101 design code. In order to illustrate the assessment, this paper presents results of two gas pipelines designed in accordance with DNV standards, one of them being optimized. The benefits of this optimization are emphasized in this work.© 2013 ASME

Qualification of UOE SAWL Linepipes With Enhanced Collapse Resistance for Ultra Deepwater Applications

Large diameter UOE pipes are being increasingly used for the construction of offshore pipelines. Since oil discoveries are moving towards ultra-deepwater areas, such as Pre-Salt in Brazil, collapse resistance is a key factor in the design of the pipelines.It is known that the cold forming, and the final expansion in the UOE linepipe manufacturing process, reduces the elastic limit of the steel in subsequent compression. Due to this, the DNV collapse formula includes a fabrication factor that derates by a 15% the yield strength of UOE Pipes. However, DNV also recognizes the effect of thermal treatments and the code allows for improvement of the fabrication factor when heat treatment or external cold sizing (compression) is applied, if documented.This paper presents the qualification of UOE pipes with enhanced collapse capacity focusing the use of a fabrication factor (αfab) equal to 1. TenarisConfab has performed a technology qualification process according to DNV-RP-A203 standard “Qualification Procedures for New Technology”. The main aspects of the qualification process are presented in this paper which included significant material and full scale testing, including combine load testing, and final analysis.The qualification process achieved successful results and this will allow use of a fabrication factor equal to 1 directly in deepwater and ultra-deepwater offshore pipeline projects with a possible reduction in material and offshore installation costs and also potentially enhancing the feasibility of many challenging offshore projects.Copyright

Final Design and Installation Constraints of a Shallow Water Oil Pipeline at the Capixaba North Terminal Offshore Brazil

The Petrobras Capixaba North Terminal - TNC is located in the state of Espirito Santo, in Brazil and is being built to receive the heavy and high viscosity oil produced onshore in the Fazenda Alegre field. This oil shall be heated prior to be pumped into the pipelines and it will be exported through a monobuoy and a tanker system. The two export pipelines are being laid to connect the onshore Terminal to a subsea PLEM to be installed under the monobuoy. The pipelines and PLEM were designed to operate with oil containing H2 S in cyclic high temperature. This paper addresses the special concerns defined by the design activity to cope with the TNC operation conditions. It also focuses the modifications imposed to the installation process to fulfill the design and operation requirements.Copyright

Design and Installation of Buried Heated Pipelines at the Capixaba North Terminal Offshore Brazil

The export pipelines of the Capixaba North Terminal (TNC) offshore Brazil will be operating with a great thermal stability potential due to the high temperatures that are necessary to assure an adequate flow. This paper focuses on the challenges for the design and installation group, due to the very strict maximum allowable imperfection (prop), in order to find a feasible solution for the installation process by a conventional lay barge. Also, the paper employs a finite element model and carries out a parametric study based on the soil coverage requirements and the maximum allowable imperfection originated from laying operations and pipeline burial process. The upheaval buckling will be studied in full detail in order to evaluate predefined curvatures, with the objective of finding the minimum cover height to limit the pipeline displacement and thus assuring its integrity. This work also aims to establish a numeric tool that will serve as basis for the upheaval buckling analysis in new pipeline design.© 2004 ASME