Summary
Flow assurance has been one of the major considerations in deepwater
completion design, in which undesired heat loss from production tubing
contributes to the formation of gas hydrates and causes the deposition of
paraffin and asphaltene materials. Traditionally, controlling annular heat loss
has been achieved with the injection of steam, the application of silicate
foam, the pressurization of the annulus with inert gas, the use of gelled oil
as an insulating packer fluid, and the use of vacuum insulated tubing (VIT).
Each of these applications, however, has drawbacks because of either its
working mechanism or the higher cost associated with the technology.
To secure the insulation of the wellbore and to reduce heat transfer from
the production tubing to the surrounding areas, various aqueous insulating
fluid systems with superior thermal properties have been developed in recent
years. Field applications of these fluids have demonstrated significant
reduction in heat loss by reducing conduction and minimizing convection. These
thermal insulating fluids have been implemented with great success in more than
75 deepwater riser and packer applications in the Gulf of Mexico (GOM) over the
last several years. Case histories have demonstrated that installation of these
water-based insulating fluids is an effective alternative to conventional
insulation options and is becoming the preferred insulation method in many
deepwater projects.
This paper will highlight the evolution of different insulating fluid
systems and the field experience with each system. Proper testing methods
relevant to oilfield flow assurance will be discussed and testing results for
these fluids will be detailed. Field cases in the GOM will be summarized, and
the effectiveness of these fluid systems will be demonstrated.
Introduction
Deepwater-oil and -gas exploration and development in the GOM has been a
great success since the oil industry took the first step in the middle of
1990s. By the end of 2004, production from the deepwater fields in the GOM grew
to an estimated 3.9 billion cubic feet of natural gas per day and 953,000
barrels of oil per day, which accounted for approximately 65% of the GOM oil
production in 2004. The trend of exploration and development within the
deepwater GOM shows no sign of diminishment, as evidenced by the 118 deepwater
projects on production as of 2006 (U.S. Department of the Interior 2006). It
has been forecast that the deepwater fields in the GOM would be producing
nearly 2.0 million B/D in 2008.
As more multiphase hydrocarbons are produced from deepwater fields and
transported for long distances, flow assurance becomes a more critical factor
in the design stages of any oil- and gas-production system.
Flow assurance covers all issues related to the maintenance of the flow of
oil and gas from reservoir to reception facilities. Being a multidiscipline
activity, it involves the assessment of multiphase production systems and
management of possible flow stoppages caused by the formation and deposition of
solids. Prediction or modeling, prevention, and redemption of the formation of
gas hydrate, paraffin, asphaltene, and scale buildup within the production
tubing and flowlines are essential requirements.
The temperature in deepwater is usually near 40°F, or 4.4°C, which can cause
flow problems in riser and export pipeline through undesired heat loss from
production tubing by forming and depositing gas hydrate, paraffin, and
asphaltene materials. Therefore, effective control of annular heat loss is
critical to keep pipelines free of solid accumulations.
© 2009. Society of Petroleum Engineers
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History
- Original manuscript received:
30 August 2006
- Meeting paper published:
5 December 2006
- Revised manuscript received:
23 April 2008
- Manuscript approved:
5 May 2008
- Published online:
2 March 2009
- Version of record:
26 February 2009
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