1. “DIMENSIONING OF AN OFFSHORE SYSTEM FOR TRANSSHIPMENT OPERATIONS”
Diogo Pereira Costa
Process Engineer – Petrobras
Marcus Felipe Valle
Pipeline Engineer – Transpetro

2. Introduction to TRANSPETRO
Present in the majority of states in Brazil
More than 14 thousand km of oil ducts and gas ducts
48 terminals
28 marine terminals
20 on-shore terminals
60 oil tankers
Stores oil, oil byproducts and gas and transports them to different points in Brazil

3. Dimensioning of an offshore system for transshipment operations
Presentation with focus in the process engineering
Conceptual project
Using the installations of an existing marine terminal

4. Marine terminal with potential for simultaneous operations of transshipment and transfer from oil tanker to the terminal
The oil transfer system consists of 2 identical calm buoys linked together via two parallel subsea pipelines.
Piggable pipeline
The buoys are connected with 2 parallel flexible hoses to the subsea pipeline via a PipeLine End Manifold (PLEM).
Distance between buoys MB2 and MB3: 2000 meters
Water depth monobuoy MB2: 24 meters
Water depth monobuoy MB3: 27 meters
Floating hoses → 20” main hose / 16” tail hose
Submarine hoses → 20” hoses

5. Proposed system

6. PLEM
Each one with block valves of 34 inch and 20 inch

7. Operational requisites for the transshipment operation:
→ Minimum flow rate: 6500 m³/h
→ Oil tanker operating pressures: 7 kgf/cm² (minimum)
10 kgf/cm² (maximum)
→ Minimum fluid temperature: 20 °C
→ Maximum fluid temperature: 55 °C

8. Hydraulic simulation
Product quality: density 885 kg/m³ and viscosity 12,3 55 °C
Softwares:
Stoner Pipeline Simulator 9.7
Pipeline Studio®

9. SIMULATION RESULTS
STEADY STATE

10. STEADY STATE TRANSFER RATE

11. Closure of tanker manifold valves
RESULTS
SURGE ANALYSIS
Closure of tanker manifold valves
Product at 40 ºC

12. Through the results of the surge analysis we can determine
→ All pressure rating classes (ASME)
→ The Maximum Allowable Operating Pressure (MAOP) of the pipeline
→ The rated working pressure of the marine hoses

13. Scenario 1 - Crossover valves closed

14. Scenario 1 – Crossover valves closed
Flow rate
3711 m³/h
per pipeline

15. Scenario 1 - Crossover valves closed
The Maximum Allowable Operating Pressure (MAOP) of the pipeline has to be bigger than 20 kgf/cm²
Pressure Rating Class: ASME 300
Marine hoses: rated working pressure → 21 bar
The marine hoses have to support overpressures of up to 50% its rated working pressure (according to OCIMF 2009*)
*Guide to Manufacturing and Purchasing Hoses for Offshore Moorings

16. Scenario 2 - Crossover valves opened

17. Scenario 2 - Crossover valves opened
Flow rate
3711 m³/h

18. Scenario 2 - Crossover valves opened
The transient waves have more area of propagation, for this reason the surge pressures are smaller
Pressure rating class: ASME 150
The rated working pressure of the marine hoses can be of 15 bar and should be suitable for occasional pressure variations of up to 50% its rated working pressure (approximately 22,5 bar).

19. CONCLUSIONS
The considered system fulfills the operational minimum requirements for the viability of the project
In case that an operational procedure is created that leaves the crossover valves opened, the project it will have a lesser cost.

20. Thank you! Diogo Pereira Costa Marcus Felipe Valle
Marcus Felipe Valle