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Collaborating Authors
Offshore vessels are industrial vessels primarily utilized in the offshore petroleum industry for exploration or exploitation of subsea resources. The most common types of offshore vessels in use today are the column-stabilized semisubmersible unit, the self-elevating or jack-up unit, and surface-type units such as the drillship and barge. In the truest sense, whether they are operational afloat, as are the semisubmersible, drillship and barge, or operational while bottom supported, as is the jack-up, due to their mobility they are marine vessels with systems nominally the same as conventional ships. Due to their mission requirements, however, their systems have features that are unique when analyzed by the traditional marine engineer, and although these vessels contain mechanical and electrical components similar to those used in conventional ships, they serve different systems and have unique applications. This paper discusses the major marine engineering aspects of mobile offshore vessels that are unique and which have made them a distinct category of marine vessel.
- North America > Canada (0.67)
- North America > United States > Texas (0.28)
After two decades of oil exploration on the world's continental shelf, various design types of mobile drilling rigs have evolved, namely the submersible, the jack-up, and the floater. The authors consider that the current stage of development of these rigs has sufficiently established design patterns which are worthy of investigation and review. The authors have selected the floater type for discussion and presentation as being of germane interest to the naval architect and marine engineer. Section 1 of the paper reviews the design aspects of floating drilling vessels by considering them in two groups: "surface hull" type and "column stabilized" type. Functional design requirements are discussed, including some fundamentals on rotary oil drilling to familiarize the naval architect with its basic techniques. Requirements and recommendations for deck areas and volumes are given, together with representative weights for drilling equipment and vessel weight summaries. Hydrostatic, stability, and motion characteristics are compared between the two types. Structural design, safety features, and logistic support systems are reviewed. Section 2 describes the offshore drilling vessel Reforma as typical of one of the large surface-hull-type rigs incorporating the latest drilling techniques and marine systems. The rig, one of a fleet of three, is owned and operated by Perforadora Mexico, S. A., a private drilling contractor under contract to Petroleos Mexicanos, off the east coast of Mexico.
- North America > United States (1.00)
- North America > Mexico (1.00)
- Asia > Middle East > Saudi Arabia (1.00)
- (5 more...)
- North America > United States > New Mexico > Permian Basin > Golden Lane Field > Strawn Formation (0.98)
- Europe > United Kingdom > North Sea (0.95)
- Europe > Norway > North Sea (0.95)
- (2 more...)
Abstract This paper deals with the design parameters, fabrication and sea trials of the first ship equipped for dynamic stationing having the specific requirements for drilling exploratory wells in open ocean environment. Design criteria are reviewed with regard to sea state, environment, propulsion requirements and drilling performance, including automatic control and sensing systems. Model studies and dynamic simulation analyses are presented and compared with the results of early sea trials. Operating systems are summarized, and performance expectations are related to prospective utilization of the vessel in specific ocean areas. Preliminary conclusions are given with respect to vessel response to control and propulsion parameters. Introduction The trend in offshore exploration clearly indicates that the Oil Industry must extend its search for oil and gas into water depths beyond the continental shelf. The need for additional oil and gas reserves; and the belief that sizable reserves could indeed exist in greater water depths have encouraged interest in deepwater exploration. This deepwater exploration has resulted in the need for new techniques and tools for water depths of 2,000 feet and greater. Royal Dutch/Shell Group, with their established world-wide interest in offshore exploration and production and their technological achievements in the offshore environment, has taken a natural step to undertake early development of drilling techniques and tools to explore in the deeper waters. Extensive study of exploration objectives and research into the means of achieving these culminated in Royal Dutch/Shell engineers drawing up comprehensive engineering specifications for a highly mobile drill ship. Early in 1970, the drilling contractor, SEDCO, Inc., was engaged to design, construct and operate the drilling unit, now known as the "SEDCO 445." At the same time, Royal Dutch/Shell and SEDCO engineers undertook detailed final development of advanced forms of dynamic stationing and underwater drilling equipment. The major limiting factors to existing offshore exploration drilling are the anchoring capability and the underwater drilling equipment system. A specially designed ship equipped with dynamic stationing has the capability of anchoring in unlimited water depths. The use of new techniques such as Electro-Hydraulic BOP controls; acoustical re-entry; and riser buoyancy increase the capability of the underwater drilling equipment system to something greater than 3,000 feet.
A Conceptual Development of a Slim Drill Ship
Mortensen, Asbjorn (Keppel Offshore & Marine Technology Centre Pte Ltd) | Kah Keong, Alex Tan (Keppel Offshore & Marine Technology Centre Pte Ltd) | Geok Soon, Ricky NG (Keppel Offshore & Marine Technology Centre Pte Ltd) | Dimble, Abhijit Dnyaneshwar (Keppel Offshore & Marine Technology Centre Pte Ltd) | Vincent, Sudhan (Keppel Offshore & Marine Technology Centre Pte Ltd) | Ostvold, Tom Waitz (Keppel Offshore & Marine Technology Centre Pte Ltd)
Abstract This paper outlines a proposal for a slim drillship optimised for re-entry into existing subsea wells. The ship is designed to perform intervention operations using wireline and coil tubing equipment, through a high pressure riser string between the ship and the subsea wellhead, for access to the pressurised well. The slim drillship is also equipped with machinery and tools enabling it to drill new hole sections inside existing wells, for example long horizontal extensions, using slim jointed pipe that enters the well inside its production tubing. A key feature of a slim drillship is its high pressure (HP) riser, giving intervention tools access to the well containing hydrocarbons, eliminating the need to kill the well first with drilling mud. This feature does also enable the ship to use Manage Pressure Drilling (MPD) methods. The drillship is initially designed for 7500 ft of water depth as well as well depth below the drill floor of 22500 ft. This is believed to be a practical depth limit for some known subsea fields in the North Sea area, Mexican Gulf, Brazilian shelf and areas offshore West Africa, and future areas in South Asia. It is possible to configure the ship for deeper wells. This paper focus on the drill floor layout and open deck areas for storage of tubulars and equipment. An open mast for hoisting is proposed in order to enable a large drill floor for third party equipment. The mast is telescopic so the ship can lower the crown block and pass through the Straits of Bosporus and the Panama Canal, enabling the ship to move fast between arctic locations and tropical waters without passing south of South America. A novel vertical pipehandling method is used, with cylindrical rotating setbacks at a lower elevation than the drillfloor, and offline stand building on this lower deck. The use of an open mast layout as opposed to an enclosed derrick gives access to the well centre for intervention equipment, and enables rapid turnover between various tools going into the well.
- North America > Panama (0.55)
- North America > Mexico > Gulf of Mexico (0.24)
- Europe > United Kingdom > North Sea (0.24)
- (3 more...)
ABSTRACT: Odeco has upgraded a Victory class semisubmersible and a Bethlehem slot jack-up rig to accommodate the heavy loads associated with drilling wells below 20,000 feet in the Gulf of Mexico. Several world records have been set with these rigs since their upgrades. This paper will discuss the numerous operational and economic challenges a drilling contractor is faced with in order to strengthen and upgrade a rig for drilling ultra deep wells below 20,000 feet. These include analyzing rig capacities such as drilling equipment, setback, combined substructure, well control, liquid and bulk systems, solids control, deck storage, variable deck and leg loading and power plant. A precise inspection plan must be formulated before and during the well for all the contractors equipment. Additionally the entire analysis and upgrade must be done economically and generally in less than 60 days in order to compete in today's marketplace. While many rigs are capable of drilling deep wells, few rigs can safely accommodate all the demanding aspects of ultra deep drilling. It is important that the "whole" rig, it's equipment, and its; operational capability meet all requirements, not just a vast majority of those requirements. INTRODUCTION: The downturn in the contract drilling industry during the past several years has forced survivors within the contract drilling business to upgrade their existing drilling rigs rather than build new rigs in order to accommodate heavy loading associated with ultra deep drilling. Construction of a new rig designed for ultra deep drilling can easily exceed 80 million dollars for a semi-submersible, 675 million dollars for a jack-up, and take in excess of 2 years to complete. In comparison, an existing semi-submersible or jack-up with an already adequate variable deck load capacity may be upgraded for less than 5 million dollars depending on the accessory equipment added to the rig during the upgrade process. The drilling contractor is faced with many operational and economic challenges in order to strengthen and upgrade an entire rig and remain competitive in today's marketplace. Those challenges which will be discussed in this paper include:Evaluating a rig's existing capacities and equipment with the requirements of an operator's proposed well program. Coordinating and planning the upgrade process among the drilling contractor equipment manufacturers, operator and repair facilities within the operator's critical time table of less than 60 days. Logistics of performing equipment inspections for critical load carrying components. Performing the entire upgrade economically in order to compete in today's marketplace. P. 361