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Lewis Norman, Ph.D.

Heavy OilHeavy Oil

Flow Assurance ChallengesFlow Assurance Challenges

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Heavy Crude Oil

Heavy Crude Oil orExtra Heavy Oil is any type of crude oil which does

not flow easily. It is a relative term, compared to light crude oil, but relates

to specific technical issues of its own on production, transportation, and

refining. Physical properties that distinguish heavy crudes from lighter ones

include higher viscosity and specific gravity, as well as heavier molecular

composition. Extra heavy oil from the area north of the Orinoco river in

Venezuela, which has by far the largest volume of the 30 or more countries

with known reserves, has a viscosity of over 10,000 centipoise and 10 APIspecific gravity. Generally a diluent is added at regular distances in a

pipeline carrying heavy crude to facilitate its flow.

Some petroleum geologists categorize bitumen from tar sands as extraheavy oil although bitumen does not flow at ambient conditions.

Fr om W i k i p e d i a , t h e f r e e e n c y c lo p e d i a

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Heavy Oil: Big Picture

INCLUDES

Production

Transportation

Refining

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Global Reserves

Large resource, but contribution to supply so far has been modest

0-10 API

11-15 API

16-20 API

21-26 API

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Albertas Oil Sands

Pictures: Suncor, Petro-Canada Map: CAPPSource: The oil sands at a glance, Petroleum

Economist

In short , i t is an enterpr ise of epic propo rt ions , akin to the bui ld ing of the

pyram ids or Ch inas Great Wal l . Only bigg er. Prime Minister Harper to the

Canada-UK Chamber of Commerce, Ju ly 2006

Peace River

Athabasca

Cold

LakeEdmonton

Calgary

Ft. McMurray

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Heavy Oil Flow Assurance

Pipeline flow from subsea well head to processing facility.

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The Viscosity Problem

Given Conditions:

Pipe ID = 8

Density of fluid 1.0 g/cc

Flow rate ~ 6.5 ft/sec

Maximum pressure 800 psig

Steel pipe, smooth wall

vDRe

=

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Heavy Oil Contains

1. Base Fluid

2. Insoluble Materials3. High Molecular

Weight- polymer likematerials

Relationship between viscosity and number of hydrocarbon

@25C*

* CRC-Handbook for Chemistry 82nd, 2001-2002

Base Oil Viscosity

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Heavy Oil Characteristics

Viscosity as a function of molecular weight2Viscosity and API gravity1

1 Reprinted from Oilfield Review, Autumn 2002, pp 31

2 Duplicated from P.J. Closmann & R.D. Seba JCPT, July-August, 1990vol.29, No 4 pp115

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0

2

4

6

8

10

12

14

16

Methane Gasoline Diesel 35 gravity oil 25 gravity oil 5 gravity oil Asphaltene Coal

Carbon to Hydrogen Ratios

Carbon to Hydrogen Ratios

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Insoluble Materials

Relationship between viscosity and internal phase @ 25C*

*R. Pal, Ind. Eng. Chem. Res, 2001, p40

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High Molecular Weight

Relationship between viscosity and polymerconcentration*

Relationship between viscosity and polymerMolecular weight for PAM in 0.2M Na

2SO

4at 25C**

*E.R. Morris, A.N. Cutler, Carbohydr. Polymers, 1981,1, p5

**R.S. Harland, R.K. Prudhomme, Polyelectrolyte Gels ACS Symposium Series 480, 1990, p59

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How to Reduce Heavy Oil Viscosity

Approaches:

Thermal Thinning (16 refs*)

Inhibitors (281 refs*)

Solvent Dilution (161 refs*)

Emulsions (14 refs*)

Cracking (33 refs*)

* Sc iF i n d e r S ea r c h En g i n e f o r p u b l i c l i t e r a t u r e d om a i n

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Emulsion for Heavy Oil Transport

Creating

Oil/Water

Emulsion

Separating

Oil/Water

Heavy

Oil

Pipeline

Transport

Heavy Oil

To Refining

Process

Water

Emulsifiers

I. Emulsification II. Transport III. Separation

Graphic of W/O Emulsions*

*Courtesy of Halliburton, Corp

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Emulsion

Cost in some cases

Significant friction pressure remains as [$oil]

Chemical/Equipment and H2O recycle can beproblematic

Fricti

onP

ressure

of O/W Emulsion

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Thermal & Piping Methods

Minimize heat loss duringheating process of a heavy oil to

reduce

Electronic heating Pipe-in-pipe system

Advantages: Uniform heat transfer

Drawbacks:

Cost!!!

Insulation issues especially on the

sea bed pipelineGraphic of Pipeline Insulation (Pipe-in-pipe systems)

*Courtesy of StatOil Corp.

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Some Technical Opportunities

Cracking / Catalyst

Inhibitors / Thinners

Mechanical Systems

New Ideas

WHAT?