Installation of Platform Cerveza
Authors: Menard Stafford J. , Gilmore Robert E. 
Published: October 2008

A review of the installation phase of Platform Cerveza, East Breaks Block l60-A is presented. It is a chronological presentation based on recorded project logs and on item observations. A comparison between predicted installation times based on historical data and the actual installation times is shown in Figure 1.

The review covers some of the planning for special requirements such as weather exposure limits, current considerations, on-bottom stability, and other areas of specific consideration, not normally analyzed for shallower water depth structures.

Introduction

Beginning in 1976 with the successful installation of the first modern day deep-water platform, the oil industry has focused more and more attention on deep water tracts and methods of producing them. The single piece jacket, by no means a new concept, had never before been used in waters of this depth. The advantages of installing a platform in 935 feet of water in one piece were clear from the start;reduced weather exposure and risk,reduced installation time,eliminated risk in re-connecting jacket sections offshore, andreduced cost since the platform could be installed in a more conventional manner without the need of sophisticated equipment.

Once the single piece concept had been decided upon, the task of identifying and solving problems of an unprecedented nature was undertaken.

Basic guidelines used in developing the platform's many systems were:keep it simple,limit the risk, andpreserve the economics.

Preplanning

Approximately eighteen months prior to the launch of project "Cerveza", an installation team composed of engineers and operational personnel was assembled for the pre-planning of the project. This team was responsible for the development, monitoring, and coordinating of the installation planning to insure the compatibility and feasibility of concepts with existing offshore equipment and techniques.

Included in the pre-planning was a detailed analysis of the inland waterway which was to be traveled by the tow. This analysis consisted of clearance checks for embankment limits, cross-section channel depths, and turning radii in channel curves. To insure passage, several test tows were conducted with the launch barge ballasted down to the anticipate draft. The data obtained from these tows was used in selecting the precise tow route followed.

A major function of the project team was the compiling of a step by step water phase operations manual detailing the procedures to be used for the installation beginning with the load out of the jacket and concluding with the installation of the platform deck.

Derrick Barge

The derrick barge utilized for the installation was a ship shape hull with an 1100 ton over the stern - 800 ton fully revolving crane and a convention a-point anchoring system.

Anchoring studies performed indicated that the existing anchoring system would require modifications to enable the barge to safely operate in 1000' water depths. These anchor modifications were carried out prior to the towing of the jacket. Concurrently with these modifications, special pile handling equipment and pile followers were transported and taken aboard the derrick barge.

Jacket Towing

A 650' × 170' launch barge was employed in the transportation of the "Cerveza" jacket.