Design, Fabrication, Installation and Operation of a Single Anchor Log Mooring (SALM) Tanker Term ina lin 300 Feet of Water
Authors: Kiely William L. , Pedersen K.I. , Gruy R.H. 
Published: October 2008

This paper will cover the design, fabrication, installation and operation of a Single Anchor Leg Mooring (SALM) system which is presently functioning as a tanker loading terminal and is an integral component of an offshore oil production field located in nearly three hundred feet of water. The paper will deal with the design and installation techniques which were used to adapt this system to the deep water application and with the operational performance of the system. The SALM is used to permanently moor a tanker which is receiving product directly from the production platform. Included will be a discussion of the unique problems encountered during the design and installation of this very deep water mooring system and with the unique but increasing application of an SPM as part of an offshore production field.

INTRODUCTION

Within the past several years, the Oil Industry has experienced the necessity to search for and develop oil fields in geographic locations which are increasingly remote. These locations are not necessarily suitable for economic development by conventional methods and therefore require the utilization of new techniques in order to achieve production at acceptable costs.

One of these techniques is the implementation of a tanker loading terminal as an integral part of the 'field production equipment. This can allow for direct load-out of the oil into transport tankers and negate the necessity for lengthy and expensive submarine pipelines and related shoreside equipment.

Typically, the loading terminal may be a Single Point Mooring (SPM), located one and one-half to two miles from the production platform and connected to the platform by a length of submarine pipeline. A shuttle tanker moored to the SPM will receive product through the pipeline and will, when loaded, carry the product to the specified point of discharge for further processing, while another shuttle tanker is being loaded at the SPM.

Alternatively, a Slave Tanker, or floating storage vessel, may be permanently moored to the SPM continuously receiving the crude oil production and discharging the product into separate shuttle tankers for transport to discharge ports. Utilization of such a Slave Tanker eliminates the necessity for "shutting-in" the, production periodically, as in the case when shuttle vessels are repeatedly moving on and off the mooring.

Historically, SPMs have been used as transfer terminals for oil products being moved to or from shore stations. As such, the systems have normally been located in sheltered waters and in relatively shallow depths. Integration of these systems into an offshore production complex subjects the facilities to much more extreme environmental conditions and often require their installation in significantly deeper water than heretofore experienced.

In order to function properly in such an environment, the Single Point Mooring Facility must be properly designed and fabricated. Additionally, system design and installation sequence must be coordinated to insure a properly executed installation utilizing techniques which are applicable to exposed location, deep water construction operations.