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Q&A: Key considerations before ordering your next subsea drilling riser

Lifecycle stage
Drilling Decommissioning

UNDERSTANDING THE INTERFACES

The majority of considerations to do with interfaces centre on the jack-up rig. Blow out preventers (BOP’s) can have a finite operating position which has to be accommodated, whilst their riser connection can vary from rig to rig.

Operators should seek information on the rig’s tension system for restrictions on vertical loads and whether lateral (side) loads are possible. If a new tension system is required alongside a new riser, operators need to check the limitations of their Texas deck too.

The subsea interfaces centre on the wellhead itself plus any surrounding subsea architecture.

DEPLOYMENT RESTRICTIONS

There are a lot of deployment restrictions that operators should be aware of, starting with the jack-up rig itself. The drilling riser package is physically large therefore the main deck space should be of a large enough area to accommodate the equipment spread – not to mention the space in preparation for deployment.

Operators also need to think about the handling of the subsea connector and associated equipment, as these have to be manoeuvred underneath the drill floor for deployment – not all jack-up rigs are built with subsea equipment in mind.

TIME TO PLAN THE WORK

Operators should understand that a typical subsea riser takes around 12-18 months to manufacture – a timeframe that should be factored into any new build project. This makes the call for both riser analysis and rig survey even more important to start as early as possible.

CLAXTON – DEFYING THE TREND

In the midst of field development projects being deferred or cancelled, Claxton has been privileged to work on projects that are defying the trend of the industry. For example, Claxton recently supplied a subsea high-pressure drilling system to Premier Oil for the Catcher area field development in the Central North Sea Block. The multi-well project, which is set for first oil in 2017 and to conclude drilling in 2019, first involved Claxton with an initial riser deployment in August 2015.

Defying the trend has also involved a great deal of support work behind the scenes here at Claxton. Current market conditions have provided the ideal opportunity to drive innovation into the sector in order to improve efficiency and reduce operating costs. Developing insight and educational aids such as the interactive animation has enabled us to speak to and influence operators as early as possible in a project.

The aim of this animation is to educate operators and engineers on the essential products and ancillary equipment required to run a new drilling riser. The interactive animation takes users right from the blow out preventer to the subsea wellhead.

To take a tour of the interactive animation, click here.

Interactive Drilling Riser Animation

This animation illustrates how a riser is installed, the ancillary equipment used, and how it connects to the well and interfaces with the jack up drilling rig.