Client: PERENCO Tunisia

Site: South-West of Tunisia

Years: 2007-2008

PERENCO-Tunisia, since 2006, is holding a development project for El-Franig and Baguel concessions in the South-West of Tunisia southern of Chott El-Djerid.

The project consists in developing EL-Franig field (250 BCF) reserves at its optimum capacity, by drilling two additional wells EFR#5 and EFR#6.

Production from El-Franig, Baguel and Tarfa facilities are collected to Oum Chiah CPF by means of a 10” Pipeline of 115 Km. At CPF, gas used to be dried and sent to STEG for treatment. Being limited by the rating of its treatment facilities, STEG is no more able to process all the gas coming on El-Borma –Gabes Pipeline. It has been agreed to deliver On Spec Gas directly from Oum-Chiah CPF to the national gas network through a 10” Loop Pipeline that gave its name to the Project.

The Loop Project included:

• Installation of a new pipeline between the Perenco’s CPF and the STEG Plant in Gabes.
• Installation of a Condensate recovery unit @ CPF Oum Chiah to reduce the gas HHV to the commercial value.
• Installation of a new compression Unit.
• Upgrade of the existing process equipment and piping.
• Drilling of the 2 additional wells.
• Installation of a Vapour recovery compression Unit to avoid flaring and to recover a gas phase and a pseudo GPL liquid phase exported to STEG as a raw stream.

AEI Contribution

ALPHA Engineering has been asked, in the frame of this project, to make a Review of the overall design performed during the FEED Phase of the project. It includes the following activities:

• Basic Engineering Design of CPF Oum Chiah relief system including the following:

- Depressurizing System Design (Simulation Model Building using Visual Flow, Flare Knockout Drum Sizing, BDVs Sizing)

- Overpressure Protection Design for different cases (Fire Exposure, Full Flow or Partial Flow).

ü Flare Stack Re-design (Radiation Calculations, Flare Tip Definition and Flare Positioning).

• Flow Assurance Study For EL-FRANIG – CPF Oum Chiah including the following:

- Model BUILDING on PIPESIM environment (Existing Situation and Planned Situation)

- Pressure Drop Calculation;

- Flow Regime analysis (Existing Situation and Planned Situation);

- PT map determination (Existing Situation and Planned Situation);

- Hydrate formation analysis for various ambient temperatures.

• Shutdown Philosophy Definition for CPF Oum Chiah including:

- Existing Shutdown System Study

- Shut-Down Logic Definition For Each Node

- Fire & Gas And ESD Philosophy

- Detectors Positioning

- Cause & Effect Diagrams Elaboration

• Conducting a HAZOP Study

• Process Design Review for CPF Oum Chiah (Process Control Review, H&M Balance Review, Overall Operability Analysis, Criticality Analysis, Complexity Analysis…)

During the Development of the FEED, ALPHA ENGINEERING Int. has proposed to make few modifications on the Design by re-rooting LTS condensates back to LPG Unit instead of Slug Catcher. This configuration improves sales gas HHV value and keeps it fairly away of the spec limit and decreases Compressors’ duties. Economically, it increases by 119% Pseudo-LPG production (in standard conditions) improving profitability of the project.

• Detail Engineering for the Tie-ins of EFR#5 and EFR#6 Wells to the existing process facilities at El-Franig Site (Piping Arrangement Drawings update, Dismantling P&IDs, Dismantling Isometric Drawings, update P&IDs and Isometric Drawings, Location map & Layout update, piping supports details, Wellhead Control Panel Specs, Flowline PSVs Design…)