Page 9 - Handbook Of Multiphase Flow Assurance

Savings from using flow assurance 3

vibration at pipe bends. Hydrodynamic slugging occurs as liquids holdup is displaced by an
increasing flow of gas from a flowline in form of a liquid surge. If the surge volume is sig-
nificant, the hydrodynamic slugs can be as detrimental as severe slugs. Hydrodynamic slugs
occur once per a change in production rate and don't repeat.
In all three cases of liquid loading, severe slugging and terrain slugging gravity plays the
key role in overcoming the energy emerging from the expanding gas or a single phase or su-
percritical fluid (also known as the dense phase) or an aquifer which is less than sufficient to
lift the liquids to the separator or a slugcatcher.
Analysis of multiphase fluid flow is in part based on information from reservoir modeling
prediction of flow rates and on thermodynamic PVT characterization of produced fluids.
Software which tracks and balances masses and velocities of produced fluids is available to
help predict and analyze the flow velocities and the quantities of accumulation (also known as
holdups) of liquid and other phases in the production system. An accurate prediction allows
the design engineer to select proper sizes for the well production tubing and for gathering
flow lines, and also to identify which technologies would be necessary and most economi-
cally suited to produce gas and oil from a reservoir.

Savings from using flow assurance

Flow, which may be single phase (natural gas, oil, water, CO 2 ) or multiphase (two or more
single phases) is the key metric of the main product of petroleum companies. Those companies
which have more barrels of flowing product per employee generally do well, and vice versa.
Flow assurance is becoming a critical path discipline when other disciplines such as pipe-
line engineering, subsea layout, artificial lift equipment, and, in some projects, reservoir
engineering, wait for flow assurance to compare and validate the viability of an overall archi-
tecture for a concept of field development before proceeding with the design. The accuracy
in flow assurance makes a project more, less or not at all profitable. This handbook helps
organize and streamline the work in flow assurance, in order to make it more accurate.
The use of flow assurance technology saved billions of dollars for oil companies. There
are several examples of how multiphase flow tools have resulted in savings for Statoil, Shell,
BP, ENI:
• Multiphase technology & OLGA—Norske Shell—Troll—30 Billion NOK
The flow assurance savings for the Norske Shell—Troll field from multiphase technology and
the use of an early version of the OLGA software were 30B NOK which is billions of dollars.
“Direct electric heating has saved us billions of kroner on the Norwegian shelf,” said Atle
Harald Børnes, who is a specialist at Statoil's Technology and New Energy Business Area.
This system has been installed during the laying of pipelines linked to the Åsgard, Huldra,
Kristin, Urd, Tyrihans, Alve and Morvin fields. A version of this heating system has also been
prepared as a contingency measure for installation on the pipeline leading from the Ormen
Lange field to Aukra.
The heating system was also installed at the BP-operated Skarv field, which has been put
on stream after 2011.
The Italian company ENI has also opted to utilize the same system for its Goliat field devel-
opment offshore Finnmark (Nilsson et al., 2010).
• Hydrates and electrical heating—Statoil, BP—N.Sea—Billions of NOK