Keeping Deepwater Pipelines Flowing

Published December 20th, 2000 - 02:00 GMT

The buildup of paraffin in some deepwater oil pipelines can pose a "million-dollar-a-mile" remediation problem for offshore oil producers.  

 

Wax deposits can restrict the flow of crude oil and natural gas liquids, curtailing operations from offshore platforms that can represent billions of dollars of investment. 

 

Now, a new project between the U.S. Department of Energy, the University of Tulsa and 14 private companies will tackle the problem of wax accumulation in deepwater pipelines using one of the world's most highly instrumented "flow loop" test facilities.  

 

The Energy Department will provide $1.2 million in research funds from its Fossil Energy petroleum technology program.  

 

Tulsa University and its industry partners will add another $1.3 million for the 3-year project.  

 

Virtually all crude oils contain long-chained molecules of wax in proportions that can vary up to as much as 60 percent of the crude oil's weight.  

 

In refineries, the paraffin wax can be separated and sold as a commercial product.  

 

But in a pipeline or a well-bore, especially where temperatures are cold such as in the offshore waters of the Gulf of Mexico, the paraffin can deposit along the inside walls of the pipe, restricting its flow, increasing the strain on pumping equipment, or in the worst cases, shutting off production or causing a rupture in the pipe and accidental release into the environment.  

 

Re-mediating pipeline blockages in water depths of around 400 meters can cost a million dollars or more per mile.  

 

The new University of Tulsa project will begin by enhancing computer models developed in prior Energy Department projects.  

 

Previous experiments using the University's flow loop testing facilities confirmed that a much broader collection of experimental data, including other oil samples, is necessary to develop more accurate methods for predicting the complex processes of paraffin deposition.  

 

Researchers will flow a variety of crude oils and oil/gas mixtures through the test loop to improve understanding of the physical properties of paraffin and the mechanisms that control its accumulation.  

 

Using data from these experiments, computer programs developed in prior projects for predicting paraffin buildup will be enhanced and tested against actual field data from operating pipelines.  

 

Tulsa University's highly instrumented flow loop could also be used to test and qualify subsea measurement sensors that are being developed to detect deposit thickness in flow lines and pipelines.  

 

Better models and paraffin sensors could reduce or eliminate the need for costly duplicate pipelines that are required for round-trip "pigging" operations – the sending of a cylindrical "scraper" through the pipeline to remove paraffin from the pipeline walls.  

 

Better computer models could also tell operators where to place safety valves to minimize the chances of failures because of paraffin fouling.  

 

These and other improved methods of preventing and re-mediating paraffin accumulation could save billions of dollars per year in maintenance and repair costs, improving project economics of many marginal offshore Gulf of Mexico fields to where they could be produced.  

 

Taxes and royalties from the additional production could significantly increase the $6 billion in annual federal revenue derived from these operations.  

Source: United States Energy Information Administration. 

© 2000 Mena Report (www.menareport.com)

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