Next Generation FPSO: Combining Production and Gas Utilization
Authors: Alvarado Skip , Cone R.S. , Wagner Jan V. 
Published: October 2008

Current Floating Production Storage Offloading (FPSO) concepts, with few exceptions, focus primarily on oil production. Associated gas utilization and/or conversion are not prime concerns at present. The current method of associated gas disposal is re-injection, flaring is normally only permitted in an emergency situation and for a short duration. It is expected that for many future oil production projects more emphasis may be placed on the regulatory process which may force operators through legislation or tax regime to look for alternatives to gas re-injection.

This paper evaluates the following gas utilization options on a combined oil/gas production FPSO:Liquefied Natural Gas (LNG)Compressed Natural Gas (CNG)Gas to Liquids (GTL)Gas to Wire (GTW) In addition to technical aspects, this paper also looks at project execution issues for this new generation FPSO. Increased complexity and size of the project as well as new required skills will impact and tax the current project management, engineering, procurement and fabrication methods and project execution approach. The increased topsides weight and complexity will stretch the module construction and installation capabilities of most present day offshore fabrication yards as well. The size and scope of these larger FPSOs may result in the need to fabricate topside modules in more than one location to optimize availability of construction equipment and/or skilled labor.

The paper is based on Fluor's past and current project execution experience on similar projects. Typical project execution strategies which could be applicable to the challenge of managing these ever-larger and technically complex projects are discussed.

1.0 Introduction and Background

Current Floating Production Storage Offloading (FPSO) concepts, with few exceptions, focus primarily on oil production. The associated gas issues are mostly dealt with in order to, more or less, satisfy regulatory requirements. Associated gas utilization and/or conversion are not prime concerns at present. The current methods of associated gas disposal are either re-injection into production reservoir to maintain reservoir pressure or injection into a storage zone as an energy conservation measure. Flaring is normally only permitted in an emergency situation and for a short duration.

From a reservoir-management point of view, long-term gas injection is not always possible or practical. In many instances prolonged gas injection may result in gas break through. As a result, oil production rates or recovery levels may be negatively impacted.

Gas injection as an energy conservation measure has its own limits as well. A suitable reservoir may not be available, some gas will be lost to the storage reservoir and in addition the gas has to be reprocessed during the recovery cycle. All this makes it more difficult to justify the gas recovery step economically as a subsequent project as opposed to an incremental project to initial oil production.

It is also expected that for many future oil production projects more emphasis may be placed on the regulatory process which may force operators through legislation or tax regime (e.g. carbon tax in Norway) to look for alternatives to gas re-injection.