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Daily RC Article 31

Crude oil pumping technology

Paragraph 1

Oil companies needs offshore platforms primarily because the oil or natural gas the companies extract from the ocean floor has to be processed before pumps can be used to move the substances ashore. But because processing crude (unprocessed oil or gas) on a platform rather than at facilities onshore exposes workers to the risks of explosion and to an unpredictable environment, researchers are attempting to diminish the need for human labor on platforms and even to eliminate platforms altogether by redesigning two kinds of pumps to handle crude.

These pumps could then be used to boost the natural pressure driving the flow of crude, which, by itself, is sufficient only to bring the crude to the platform, located just above the wellhead. Currently, pumps that could boost this natural pressure sufficiently to drive the crude through a pipeline to the shore do not work consistently because of the crude’s content.

Crude may consist of oil or natural gas in multiphase states—combinations of liquids, gases, and solids under pressure—that do not reach the wellhead in constant proportions. The flow of crude oil, for example, can change quickly from 60 percent liquid to 70 percent gas. This surge in gas content causes loss of “head”, or pressure inside a pump, with the result that a pump can no longer impart enough energy to transport the crude mixture through the pipeline and to the shore.

Paragraph 2

Of two pumps being redesigned, the positive-displacement pump is promising because it is immune to sudden shifts in the proportion of liquid to gas in the crude mixture. But the pump’s design, which consists of a single or twin screw pushing the fluid from one end of the pump to the other, brings crude into close contact with most parts of the pump, and thus requires that it be made of expensive, corrosion-resistant material.

The alternative is the centrifugal pump, which has a rotating impeller that sucks fluid in at one end and forces fluid out at the other. Although this pump has a proven design and has worked for years with little maintenance in waste-disposal plants, researchers have discovered that because the swirl of its impeller separates gas out from the oil that normally accompanies it, significant reductions in head can occur as it operates.

Paragraph 3

Research in the development of these pumps is focused mainly on trying to reduce the cost of the positive-displacement pump and attempting to make the centrifugal pump more tolerant of gas. Other researchers are looking at ways of adapting either kind of pump for use underwater, so that crude could be moved directly from the sea bottom to processing facilities onshore, eliminating platforms.

Topic and Scope:

Crude oil pumping technology; specifically, new technologies that may make offshore processing platforms obsolete.

Purpose and Main Idea:

Author wants to explain the difficulties inherent in the current system of processing oil offshore, and to sketch two possible technical solutions for those difficulties. This passage doesn’t have a traditional “main idea”—that is, a personal thesis that the author has developed and is trying to prove

Paragraph Structure:

Paragraph 1 outlines the problem and the solution, both of which hinge on what oil pumps can and cannot do. It’s easy to get lost in all of the technical minutiae about crude oil; the most important thing is lines 16-19, the clearest statement of the

current dilemma.

Paragraph 2 deals with definitions, pros, and cons of the two pumps under current

redesign (here we’ll call them the “p-d pump” and the “c-pump”).

Paragraph 3 briefly sketches out the kind of further work that’s being done.

The Big Picture:

  • A lot of students would save this passage till later in the Reading Comp. section, doubtless because of the unfamiliarity of the subject matter. That the questions turned out to be relatively easy doesn’t make the decision to postpone an unwise one. Go with your instincts! Better that, than hitting the passages in order just because that’s how they’re printed there.
  • Many passages begin as this one does, announcing a Big Problem and exploring one or more possible solutions. When that happens, keep the scope of the problem in mind (wrong choices are likely to go off into other, related areas) and make sure you notice which solution(s), if any, the author favours.
  • When passages are technically based, as this one is, make a mental picture of the situation. Even if your mental picture of the offshore platform, the crude coming up, and the pumps and pipelines is wildly at odds with real life, who cares? It’s going to make the unfamiliar technical matters a lot more comprehensible.

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