Novel & Marginal Field Offshore Structures - Elective 2 Introduction

Technical Basis for Developing Novel Offshore Structures

• Drilling barges are used for shallow-water inland drilling in areas such as canals, lakes, rivers, and marshes, but are not suitable for open sea conditions due to water movement.

Offshore Structures

• Semisubmersible platforms are offshore oil rigs with floating drill units that incorporate pontoons and columns, and can sink to a predetermined depth if flooded.
• They are the most common type of offshore drilling rig and come in three types: ship-shaped, column-stabilized, and bottle-type semisubmersibles.
• Dynamic Positioned Drillships are ships used for drilling operations, featuring a drilling platform and derrick, and a "moonpool" for the drill string to extend into the water.
• FPSO (Floating Production Storage and Offloading) is a production system that separates and treats crude oil and gas, and stores the treated oil for export.

Offshore Engineering

• Offshore structures differ from onshore structures in terms of pre-service and in-service characteristics, with fabrication, assembly, and installation taking place onshore and offshore.
• Construction methods, material specifications, and acceptable construction tolerances differ between offshore and onshore structures.

Oil and Gas Field Developments

• A preliminary decision to develop an oil or gas field is made after studies defining the reservoir, evaluating site and environmental characteristics, and identifying technically feasible development concepts.
• Field development parameters include reservoir characteristics, drilling, production, and export requirements, site and environmental characteristics, and design rules and regulations.

Field Development Parameters

• Reservoir characteristics include the type of oil or gas, and its properties.
• Drilling, production, and export requirements include the number of production and injection wells, system capacities, and production specifics.
• Site and environmental characteristics include water depth, foundation material, seismicity, ice, wind, wave, and current.
• Design rules and regulations, and management philosophy also influence field development.

Structure Types

• Bottom-Supported Structures include jacket- and tower-type fixed platforms, jackups, gravity base structures, and subsea production systems.
• Compliant structures include guyed towers and delta towers that rotate about their base and generate inertia forces to reduce net applied loads.
• Floating Structures include semisubmersibles, FPSO, and dynamic positioned drillships.

Bottom-Supported Structures

• Jacket platforms are a type of bottom-supported structure.
• Jack-up platforms are a type of bottom-supported structure.
• Subsea systems can be installed in both shallow and deep waters, and are used for extraction and transfer, not drilling.