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Collaborating Authors
Results
Surface BOP System for Subsea Development Offshore Brazil in 1900 m of Water
Tarr, Brian Anstey (Shell Intl. E&P Inc.) | Schroeder, James Robert (Penn Virginia Oil & Gas Corp.) | Taklo, Tor (Shell Intl. E&P Co.) | Olijnik, Luiz Augusto (Cooper Cameron Corporation) | Shu, Hongbo (Shell Intl. E&P Inc.) | Hudson, Andy (Shell Philippines Explor. B.V.) | Greff, Richard (GlobalSantaFe Corp)
Abstract A surface BOP system with a seabed isolation device (SID) was successfully used to extend the water depth capability of the D.P. semi-submersible rig Stena Tay for exploration drilling activities in ultra-deep water to 2,887 m offshore Brazil and to 2,447 m offshore Egypt in 2003. This provided the necessary experience to take the next step towards reducing the cost of deepwater developments utilizing a surface BOP system deployed from an earlier generation, lower specification, deepwater rig. This paper presents the configuration and specifications developed for the surface BOP drilling and subsea completion system to be deployed offshore Brazil in the first phase of the Parque das Conchas development (block BC-10) that encompasses several reservoirs in up to 2,100 m of water. The rig selected for the project had to meet certain minimum requirements to safely deploy the planned surface BOP system, and these requirements led to the selection of the Arctic I, a moored rig capable of operating in 945 m of water using a conventional 18–3/4" subsea BOP stack and marine riser system. The new elements incorporated in the surface BOP system include:Site specific pre-laid polyester taut-leg mooring system Slim-bore wellhead system (to land production casing hanger) Purpose built 16" OD high pressure riser system (to replace casing riser) Added pressure test hose line, strapped to riser (to pressure test tubing hanger & packer) Replaced lower shear ram in SID with fixed 7–5/8" pipe ram (to seal on ported slick joint) Added power and hydraulic lines in SID umbilical (to reduced ROV support needed) Vertical subsea tree, Tubing Head Spool and slim bore tubing hanger with hydraulic running tool Development drilling operations with this surface BOP system are now expected to commence in the first quarter of 2008. Introduction Surface BOP (SBOP) technology extends the use of smaller, cheaper 2nd/3rd generation rigs into water depths they are unable to achieve conventionally. Following successful exploration drilling campaigns in South East Asia the technology was extended to more demanding metocean conditions offshore Brazil and Egypt with the implementation of a Seabed Isolation Device (SID). The technology has therefore advanced to the level of proven technology for exploration drilling operations in deep water. When the application of SBOP technology was investigated in the Well Concept Selection phase for the Parque das Conchas Field Development Plan, in block BC-10 offshore Brazil, it was considered technically immature with regard to interfacing with subsea completion hardware and subsea completion operations. However, the application of further risk assessment and opportunity analysis indicated the application of SBOP technology was not only feasible for drilling operations but also for completion installation and completion workover activities. Also, the use of a moored rig, using pre-laid moorings, was found to be attractive based on the multi-well drill centers planned that would facilitate the application of batch operations.
- Africa > Middle East > Egypt (0.44)
- North America > United States > Texas (0.28)
- South America > Brazil > Espírito Santo > South Atlantic Ocean (0.24)
- South America > Brazil > Espírito Santo > South Atlantic Ocean > Campos Basin > Block BC-10 > Parque das Conchas Field (0.99)
- South America > Brazil > Campos Basin (0.99)
- Asia > Middle East > Qatar > Arabian Gulf > Rub' al Khali Basin > North Field > Laffan Formation (0.99)
Abstract This paper describes the risk management process that was undertaken for the first surface BOP operation to be executed from a Dynamically Positioned drilling vessel in ultra deepwater (9474 ft WD). The paper briefly describes the case for change that presented itself to the operations drilling group and outlines the steps that were taken in order to ensure that the overall safety of the operation was equal to, or superior to, that of conventional subsea operations. A number of the key conclusions established from the risk management process are also presented. Introduction For several years now we have been exploring the deepwater margins in several continents around the world, most notably in the GOM and West Africa. And as we have gone into deeper and deeper water our industry has addressed the technical challenge of these well prospects by building larger and more complex vessels. However, it is also worthy of note that the drilling solutions we use today on our ultra deepwater vessels are similar to the solutions we developed when offshore drilling operations first started several decades ago. Driving change in an industry that is especially comfortable with the solutions it has lived with for decades can be a thankless task. Therefore when a new solution presents itself to challenge those paradigms it is essential that a comprehensive and flawless risk management process can be presented, and worked, in order to ensure that the solutions proposed for that new concept will work successfully first time. This paper describes the factors that persuaded a major international oil and gas company to invest in an alternative concept for drilling ultra deepwater wells and outlines the significant steps the implementation team took in order to engage all stakeholders to ensure that this concept met the criteria for success of this project; that the overall safety of the operation would be equal to, or superior to, that of existing subsea operations. Case for Change The most important deepwater oil and gas reservoirs are located in areas with narrow margins between pore pressure gradients and fracture gradients. Many of these reservoirs are also found at relatively shallow depths below mud line. Tradional methods for well control are far from ideal for these conditions. Excessive pressure drop in long choke lines, short time available before the kick is above the BOP's, and gas expansion in the riser are some of the critical issues related to conventional subsea BOP operations. In addition, hydrate plug formation below rams or in choke and kill lines can severely complicate well control situations when the BOP's are located on the sea bed. Furthermore, the industry has seen a number of dramatic and severe incidents relating to marine drilling risers and subsea BOP's. These incidents have been associated with parting of risers, drawworks failures, tensioner failures, etc resulting in spills of oil based drilling fluids, BOP's and risers being dropped on the sea bed, and weeks and sometimes months of resultant downtime for the rig owners and operators. As equipment is being pushed ever closer to design limits in deeper and deeper water, it's becoming clear that conventional riser solutions in ultradeep water might represent a probability of failure that is getting close to being intolerable.
- North America > United States (0.28)
- Africa > West Africa (0.24)
- North America > Cuba > Gulf of Mexico (0.89)
- Africa > West Africa (0.89)