Installation of a Deep-Water, Subsea Completion System
Authors: Stone W.H. 
Published: December 2007

This paper describes a deep-water subsea completion from the selection of a 1-atm-air, dry-habitat system to actual production after installation. The system was installed in 200 ft of water in the Gulf of Mexico. All phases of the system, from dry-land testing simulating underwater conditions, drilling, completion, and installing the wellhead cellar and underwater assembly to start-up of actual production, are discussed.

Introduction

The dry subsea completion described in this paper is the first nonexperimental "off-the-shelf" installation of a deep-water, 1-atm-air. "shirt-sleeve" environment, dry-habitat, subsea completion. This paper presents a chronological account of this installation from selecting the dry system to beginning actual oil production from the well. Selecting the total production system, testing it at a dry-land test site. simulating underwater conditions of the complete system (including the platform facilities and the TFL pumpdown system), drilling and completing the actual well, installing the wellhead cellar, flowline connection, and the underwater assembly, and starting up the actual production are included.This paper is intended to give operational engineering personnel a fundamental understanding of how this personnel a fundamental understanding of how this project was successfully accomplished. This paper is not a project was successfully accomplished. This paper is not a detailed technical treatise of the dry system for the scientific reader, as that information is available elsewhere. However, if the reader wishes to study details of specific aspects of the system's various components, the many vendors who contributed to this project are named so that the reader can obtain this information.

Objectives of the Project

As exploratory drilling advanced into deeper waters, sophisticated production systems were needed to produce reserves in deep water. However, the industry has little experience k deep-water production. "Deep water" is defined as water below the depth where divers can function effectively. Therefore, in 1974 Union Oil Co. of California's management created the Deep Water Subsea Completion Project with the following goals.1. To complete and to produce a well on the sea floor that would enable the company to gain experience and skills in deep-water production.2. To simulate, in an existing shallow-water field, conditions below depths where divers can function effectively.3. To use functional hardware and methods whenever possible, using off-the-shelf, rather than experimental, possible, using off-the-shelf, rather than experimental, hardware or methods. "Functional "is defined as having been used successfully in the field.The project's primary purpose was to gain deep-water subsea production experience, not to begin a research and development program. The entire project was planned and implemented by the company's Gulf Coast regional operations personnel, not by a research or staff study group. The project was divided into the following phases:a study of the state of the art of available systems,selection and procurement of equipment,dry land testing,offshore installation, andwell production.

Selection of System

When the state-of-the-art study was completed in 1974, it was obvious the flowline connection to the Christmas tree was the greatest obstacle to installing a conventional subsea completion without using divers.

JPT

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