Subsea Technology In The North Sea Environment
Authors: Bendiks Carlos 
Published: December 2007

American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc.

This paper was prepared for the SPE-European Spring Meeting 1975 of the Society of Petroleum Engineers of AIME, held in London, England, April 14–15, 1975. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriate journal provided agreement to give proper credit is made. provided agreement to give proper credit is made. Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines.

This paper reviews the current subsea production techniques as applicable to the production techniques as applicable to the North Sea and discusses the possibilities of utilizing the newly developed subsea completion systems of the SEAL or Lockheed type with temporary production facilities or permanent platforms. platforms. A representative case study is discussed to indicate the magnitude of the cost savings involved.

Introduction

The object of this paper is to review the current subsea production techniques and advanced applications in the immediate future as applied to the North Sea environment.

For the petroleum industry, offshore is where "the action" is; and the North Sea is at the top of "the action" list. The pace of activities in this offshore area has been impressive as measured by reserves discovered, number and size of drilling rigs, water depths, well productivities, platform sizes and last but not least, capital development costs. As offshore exploration moves into deeper waters north of the 61 degrees parallel of latitude, new technologies will be required for economical and efficient exploitation of reservoirs. Drilling of subsea wells in deep waters has been proven and can be accomplished with present and proven and can be accomplished with present and future rigs. For example, the semi-submersible drilling rig Penrod 71 capable of drilling in 1,000 feet of water will soon drill in the North Sea. The new semi-submersible Penrod 74 is scheduled to drill off New Zealand in 1,600 feet of water. A recent announcement was made for the construction of a dynamically positioned drillship of the Discoverer 534 class positioned drillship of the Discoverer 534 class designed to operate in 6,000 feet of water. However, petroleum production has as yet to be established from such water depths. Drilling and production platforms have been used up to now; however, current platform designs cannot be extended indefinitely into deeper waters without incurring tremendous costs.

The newly developed subsea production systems offer a solution to the problem of deep water production. These systems, used in conjunction with or substituting for, conventional platforms, offer exploitation of deep water platforms, offer exploitation of deep water reservoirs without practical limitation on water depth, by eliminating or reducing the huge costs of pipelines and fixed platforms and may reduce the time lag between discovery and production of a deep water reservoir.