TULSA, OK -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 wellbore, 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.
Remediating 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 remediating 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.