Offshore Power Generation Using Natural Gas From Remote Deepwater Developments
Authors: Hill Peter J. , Inozu Bahadir , Wang Ting , Bergeron John J. 
Published: October 2008

This paper will explore an alternative technology for the disposition of natural gas from remote deepwater developments. The application of floating production storage and offloading (FPSO) units in the Gulf of Mexico has as a significant hurdle the Minerals Management Service's policy with regard to conservation. In other parts of the world where FPSOs have been operating, gas is reinjected or flared. For an FPSO deployed on the U.S. OCS, these conservation policies require that produced gas be delivered to market.

Remote deepwater locations present significant technical challenges to use of pipelines for export of gas. Gas compression or liquefication technologies present other technical challenges and introduce new risks.

A floating power generation plant will be examined from a standpoint of concept and feasibility. The paper will present a consolidated view developed with input from offshore oil and gas producers, academics, and the electrical power generation and distribution industries. Specifically the paper addresses four primary areas of this technology:Generation plant size and configurationElectric power transfer systemsDelivery of gas from production unit to the generation plantSubmarine Cable Technology

Examination of this topic should encourage discussion and investment in new solutions that will add flexibility to deepwater development options with respect to the disposition of gas, and introduce a potential new source of electrical power generation.

Introduction

The next major step for oil and gas development in the Gulf of Mexico will involve facilities that are well beyond existing pipeline infrastructure. The FPSOs is the probable choice for the next wave of deepwater development. The offshore industry, through the Deepstar consortium, sponsored the completion of an environmental impact statement to identify any issues that might impact FPSOs operating in the Gulf of Mexico.

The conservation requirements1 established by MMS have the objective of assuring all economically recoverable resources are produced to market. This position precludes two practices commonly employed by FPSOs in other regions of the world, specifically the flaring or venting of produced gas to the atmosphere and the reinjection of produced gas back into the well formation.

FPSOs, by definition, store their produced oil on board for a period of time and export it by means of shuttle tankers. Technologies for the disposition of the produced natural gas include construction of an export pipeline from the FPSO to shore or existing pipeline infrastructure, or compression or liquefication of the gas into a transportable form and the subsequent transport of the gas by some form of shuttle tanker. The conversion of natural gas to a transportable medium requires specialized equipment on the FPSO and specialized vessels for transport. While this technology exists, it is complex, expensive, and poses many new risks not normally encountered or mitigated on offshore facilities.

Natural gas pipeline technology also approaches limits in deeper water applications. The sea-floor topography of deeper waters is more severe and varied, resulting in potential stresses and elevation changes that can promote hydrate formation.