Summary
Recent technological advances are making the exploitation of heavy crude oil
reserves increasingly profitable. This paper compares nozzle-type disc-stack
centrifuges to conventional separation technology for dehydration of heavy oil
and bitumen.
The nature and composition of heavy oil leads to a number of undesirable
properties, such as its tendency to form stable emulsions in the presence of
asphaltenes, particles, and other emulsifiers occurring naturally in the oil.
This, combined with a high viscosity and a relatively high solids content,
makes dehydration a challenging task that introduces new concerns when compared
to dehydrating light crude oil.
As the density of the heavy oil increases and approaches that of water,
conventional static and gravity-based separation systems become unacceptably
large and require excessive heating and chemical addition to produce
pipeline-specification oil. Hence, the disc-stack centrifuge is proposed as a
compact and efficient solution, enabling breakdown of stable emulsions and
removal of dispersed water droplets and solid contaminants from heavy and
viscous crudes in both onshore and offshore installations.
Introduction
The world is increasingly dependent on oil as a source of energy. Market
activity around the globe is driven by an ever-increasing demand for oil
production. As a result, there is an intensified push to find and exploit new
reserves in emerging regions, such as South America, Eastern Europe, former
Soviet territories, and the Far East. At the same time, emphasis is being
placed on extracting greater yields from large, established offshore fields by
venturing into deeper water and using the latest advancements in exploration
technology.
There is also a drive to develop onshore and offshore reserves that have
formerly been considered to be marginal, either because of the small size of
the field or the poor quality of the crude oil. Such is the case with heavy
crude oil. It is estimated that 15% of the world’s recoverable oil reserves
consist of heavy crude oil. However, until recently, these deposits have not
been exploited for a variety of reasons, such as poor recovery potential,
transportation problems, and limited marketability (Weissman and Kessler
1996).
Despite recent discoveries of light and medium crude oil deposits, the
heavier and more sour oil fields account for a growing percentage of the
world’s overall oil production. Turning these fields into profitable assets
means an increased focus on technologies that make the exploitation of heavy
crude oil economically viable. In essence, that means finding a profitable way
to upgrade the heavy crude oil by removing sulfur, water, salts, and other
impurities, decreasing the density, and/or reducing the viscosity.
These trends are expected to continue, if not accelerate. For instance, in
August 2004, ConocoPhillips and BP announced plans for the largest-ever heavy
oil development program in Alaska, increasing the West Sak oil field production
to approximately 45,000 BOPD by 2007 (ConocoPhillips 2004).
© 2007. Society of Petroleum Engineers
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History
- Original manuscript received:
1 September 2005
- Revised manuscript received:
18 August 2006
- Manuscript approved:
19 August 2006
- Version of record:
20 May 2007
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