This paper addresses the basic configuration of simple subsea completions.
In an attempt to present an overview of the options open to an operator, examples are taken from various systems which have been designed and/or installed. Features from more advanced designs have become available to upgrade the state of the art in this field.
It should be emphasized that like land and platform wellheads and trees, a vast array of options and customized designs are available to meet particular requirements in this environment, and it is difficult to propose particular requirements in this environment, and it is difficult to propose a standard completion.
To enable a concise view of a subsea completion all major areas have been touched, from the drilling equipment required, the interface equipment and finally the tree and control systems typically available.
Wellheads for offshore wells fall into three main categories.
Marine Wellheads for Floating drilling units.
Mudline Suspension/Surface Wellhead for 'fixed bottom' Jackup units.
A Hybrid System of 1 and 2 generally a special purpose design for specific applications.
MARINE WELLHEADS (See Figure 1)
This type of wellhead is located on the ocean floor level. Its primary functions are:
To provide a termination of the casing strings with a means to connect the primary well pressure control equipment.
Provide a means of guidance for the Blowout Preventor stack, and guidance of any additional equipment such as a subsea tree (if required).
Provide a means of suspending the various casing strings and sealing the annuli.
The footing rig used to drill the well is equipped with a subsea Blowout Preventor stack (BOP). Preventor stack (BOP). p. 10–1 p. 10–1