Decommissioning Insight 2016 - Oil & Gas UK

DECOMMISSIONING INSIGHT REPORT 2016

Floating, production, storage and offloading vessel – a floating vessel used by the offshore oil and gas industry for the processing of hydrocarbons, storage of oil and the offloading of the oil either to a tanker or into a pipeline.

FPSO

Remedial work carried out in a well using a mast powered by hydraulic fluid.

Hydraulic workover unit

Fixed rig installed at the well location, usually self-contained, with steel or concrete legs anchored to the seafloor. Well servicing operations conducted within a completed wellbore to restore or improve production or injection. Self-contained combination drilling rig and barge with legs that can be raised and lowered independently onto the seafloor. A short segment of flexible pipe with a connector half at either end. A jumper is commonly used to connect flowlines and/or subsea facilities together. These structures weigh less than 10,000 tonnes and are yard fabricated before being transported horizontally or vertically on a barge to the field. Once at the field, the jacket is lifted from the barge into position using a suitable crane vessel. ‘Making safe’ of facilities includes cleaning, freeing equipment of hydrocarbons, disconnection and physical isolation, and waste management. ‘Making safe’ of pipelines involves depressurising them and removing any hydrocarbons. Then the pipelines are cleaned and purged, with the cleaning programme based on the specific needs of the system. This may involve the use of pigs, which are maintenance tools used to clean or inspect the insides of pipelines. A manifold in the context of oil and gas production is a pipe to which wells are connected in order to collect, co-mingle and direct fluid flow from more than one well. Such an installation can be on a platform or on the seabed for accumulating several subsea wells. Manifolds can be used for the distribution of fluids for injection into a series of wells. Mattresses are often used to provide protection, for stabilisation, and as crossover support for pipelines. These comprise flexible blocks linked with rope or wire, or concrete forms or grout bags filled with cement. A mill or similar downhole tool is used to remove casing in the well where a barrier needs to be installed in case of pressure or potential movement of hydrocarbons behind the casing. The objective is to prevent fluids flowing into another formation or to the surface. Rig designed in modules that can be lifted onto a platform by crane to be erected on site. Maximising Economic Recovery from the UKCS

Integral rig

Intervention

Jack-up rig

Jumper

Lift-installed jackets

Making safe

Manifold

Mattresses

MER UK

Milling

Modular rig

Northern North Sea

NNS NUI OGA

Normally Unmanned Installation

Oil and Gas Authority

Over-trawl surveys make sure the seabed is safe for normal fishing activities to resume.

Over-trawl surveys

A device used to clean pipelines.

Pig

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