Natural gas conditioning

Natural gas conditioning

Slug Catcher

FEL (Front-End Loading)

Oil & Gas projects frequently need very large investments. The development of these projects therefore requires a stringent control of plant fixed costs (CAPEX) and operating costs (OPEX) in order to reduce investment risks. The methodology that is usually adopted is FEL (Front-End Loading) that is a “stage-gate process” which typical phases are shown here below.

FEL-1 Feasibility

In this stage the possible plant alternatives are screened in order to assess the economic viability. This conceptual study is also aimed to select the best available technologies.
The study would evaluate the different options considering the specific project requirements. Typically, it encompasses these subjects:

  • Project Design Basis
  • Technology evaluation and selection
  • Conceptual design
  • Project economics
  • Risk analysis

Gate-1 Option Selection.

The project owner takes the decision about the plant alternative to be considered for the next further development, based on technical and economical conclusions of FEL-1.

FEL-2 Basic Engineering

In this stage the selected technical alternative developed up to a level of detail that is enough to produce a preliminary cost estimate, a preliminary project schedule, and to make any critical decisions that will influence the final design of the plant.
In this stage a BEP (Basic Engineering Package) is issued. Typically, it encompasses these subjects:

  • Preliminary H&MB
  • Preliminary main equipment design
  • Preliminary layout
  • Preliminary cost estimate (+50% /-30%)
  • Preliminary schedule (Level 3)

Gate-2 Option Selection.

Based on BEP documentation, the project owner decides whether or not to proceed with the plant.

FEL-3 FEED (Front End Engineering Design)

In this stage basic engineering is developed and a FEED package issued.
FEED package should reflect all the owner’s project-specific requirements and should reach a good level of detail in order to avoid any major change during the execution phase and reduce the risks of claims by contractors.
FEED package generally includes:

  • Basis of Design
  • PFD, P&IDs, Safeguarding Diagrams
  • Main equipment data sheets and specifications
  • Valve, Line and Tie in Schedules
  • Instrument and Valve data sheets
  • General Arrangements Drawings for main equipment and main pipework.
  • Identification and specification of long lead items
  • HAZOP/HAZID/SIL/LOPA
  • HSE Plan
  • Project Execution Plan
  • Level 4 project schedule
  • Cost estimate (+/- 15%)

Gate-3 Approval for Detailed Engineering.

After FFED package review and approval, it is used as technical addendum to the invitation to bid for the Execution Phase Contracts (usually EPC or EPCI).
FEED package becomes the basis for the detailed engineering that is developed by the EPC contractor.