Abstract

Having a park of four liquefaction chains, Algeria is considered as one of the principal natural gas and LNG suppliers of Mediterranean Europe and America. The LNG market, characterized until now by long term contracts of the "take or pay" type, will tend to change. This will result mainly in the quest by the customers of a larger flexibility in the contracts and the multiplication of spot removings. Consequently LNG chains, must anticipate those evolutions and include new organization forms of their exploitation.

LNG chain is a complex system, 20 to 30% of the amount that is transited is used for energy consumption. This high value justifies the necessity to elaborate optimization algorithms in order to reduce energy costs. To carry out this objective efficiently, a global optimization of the chain including gas pipelines, liquefaction plants, storage capacity, port and LNG tankers fleet are necessary. For this, a stochastic dynamic programming model has been designed .The input data of the model are given by:

  • ARMA model for the modeling of the LNG expeditions;

  • Simulation model of the port functioning and storage state;

  • Reliability model of the liquefaction plants and gas pipeline compressor stations;

  • Optimization model of the gas pipeline and the LNG plant using a dynamic programming procedure and MINLP (mixed integer nonlinear programming).

An application to Algerian chain Hassi R'mel - Skikda will be given.

Introduction

With the increased demand of natural gas, liquefied natural gas (LNG) is emerging as an important source of natural gas and getting a second look as a fuel option in the world.

The Algeria historically played a pioneering role in the development of LNG industry and the global LNG trade. The perspectives of excess liquefaction capacities bound to the coming on line of new trains on a given number of plants through the world will ineluctably influence on the future evolution of the LNG market.

The LNG market, characterized until now by long term contracts of the "take or pay" type, will tend to change. This will result mainly in the quest by the customers of a larger flexibility in the contracts and the multiplication of spot removings. This spot, or short-term trade has grown from 1.3% of total world exports in 1992 to nearly 4% in 1999. The emergence of the spot market is due to several factors, including excess capacity in new projects, which is available until purchasers take full volumes; an increasing number of buyers and sellers: and the availability of capacity at terminal.

Consequently LNG chains, characterized by a given rigidity because of the strong depend

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