Abstract

Today there is renewed interest in deepwater drilling and production.1 Anticipating this trend, a concept for a specialized diving system to support deepwater drilling rigs is discussed and presented in this paper.

The ARMS Delivery Vehicle (ADV) system concept described herein is a deepwater, remotely operated vehicle (ROV) with capabilities equivalent to that of present day manned one-atmosphere rig support diving systems designed for intermediate water depths. This system can be fabricated using existing technology. Its configuration will be developed using historical operational experience to enable it to perform all the tasks required in rig diving support.

The rig support tasks are defined and critical vehicle components are then selected to fulfill the requirements for each task. After selection of components, three vehicle conceptswi11bi discussed. Comparison of these concepts will show that the ADV will be more effective than either a manned or adapted production ROV system in deep water. Finally, an economic comparison will show the ADV concept to be more cost-effective in water depths greater than 3000 feet when compared with manned systems and 5000 feet when compared with adapted production ROV?s.

Introduction

The Ocean Margi n Drilling Program and recent awards of deepwater leases have renewed interest in deepwater drilling. This in turn has generated new engineering studies and resurrected some of the deepwater concepts studied in the past. These studies have shown that drilling to depths of 8000 feet is feasible with modifications to certain existing offshore drilling vessels and equipment.

In the field of deepwater drilling, one question these studies have attempted to answer is, "What sub sea support will be required?". This has been answered in several ways but it is generally agreed that there is a lack of equipment capable of performing all rig support tasks required in deep water today. The only currently operational commercial system capable of performing work in depths exceeding 3000 feet is the Pisces VI manned free-swimming submersible, which is now installed on the Discoverer Seven Seas drillship.

For the purpose this paper, water depths are classified in the following depth ranges

  • Shallow- surface to 600 ft.

  • Intermediate- greater than 600 ft to 3000 ft.

  • Deep- greater than 3000 ft. to 8000 ft.

  • Ultra deep- greater than 8000 ft.

This paper will discuss the concept of an effective deepwater drilling support diving system based on existing technology, combining features of both manned and unmanned vehicles. The equipment discussed is capable of using projected fiber optics umbilical technology advances to further increase its operating capabilities.

The concept discussed is called the ARMS Delivery Vehicle (ADV) by the author.

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