Jawaharlal Nehru Technological University Hyderabad B.Tech IV OFFSHORE ENGINEERING Previous Question Paper (February/March - 2022 - R15)

The development of a new offshore field is a complex process influenced by several critical parameters that dictate technical feasibility and economic viability:

• Reservoir Characteristics: The depth, pressure, temperature, and fluid properties (oil vs. gas, viscosity) determine the production strategy and the type of drilling and completion equipment required.
• Water Depth and Metocean Conditions: The depth of the seabed dictates the type of support structure (fixed vs. floating). Environmental factors such as wave heights, wind speeds, currents, and seismic activity define the design loads for the structure.
• Geotechnical Conditions: The nature of the seabed soil (clay, sand, or rock) influences the design of foundations, such as piles, gravity bases, or suction caissons, to ensure structural stability.
• Economic and Regulatory Factors: Capital expenditure (CAPEX) and operational expenditure (OPEX) estimates, oil price volatility, and local government regulations regarding safety, environmental protection, and local content requirements significantly impact the project's net present value.
• Logistics and Infrastructure: Proximity to existing pipelines, processing facilities, and support bases influences the choice of export method and the overall field layout.

Offshore structures are categorized based on their method of support and operational requirements. The following structures are key to field development:

• Fixed Platforms: These are permanently attached to the seabed. Jacket structures are steel truss frames used in shallow to medium depths, while Gravity Base Structures (GBS) rely on their own weight to remain stable on the seafloor, often used in harsh environments.
• Compliant Towers: These are flexible structures designed to sway with wind and wave forces. They are used in deeper waters where rigid fixed platforms become economically unfeasible due to the massive steel requirements.
• Floating Production, Storage, and Offloading (FPSO) units: These are ship-shaped vessels used for processing and storing oil. They are ideal for remote fields as they eliminate the need for long-distance pipelines to shore.
• Tension Leg Platforms (TLP): These consist of a buoyant hull moored to the seabed by vertical tendons under tension. This design suppresses vertical motion, making them highly stable for deep-water drilling and production.
• Spar Platforms: These feature a deep-draft cylindrical hull that provides high stability and low motion, suitable for extremely deep water applications.