Pumping solutions for extreme conditions

Paul Boughton
The oil and gas industry needs pumping solutions that can handle hazardous and extreme conditions, without causing process upsets or requiring extensive maintenance.

Flowserve Corporation has won a three-year contract from Bangchak Petroleum Public Company Limited (Thailand) to implement its online assurance programme. The Bangchak programme will incorporate the IPS APEX data acquisition system, with embedded 'equipment edge' intelligent diagnostics, and will initially focus on monitoring the critical enhanced hot separator pump system that is part of the refinery's HyCycle Unicracking process unit. This online asset management programme incorporates Web-based data aggregation tools and is designed to enable specialised technical experts from Flowserve to monitor process conditions and anticipate failure modes for critical plant assets.

A vital part of the online assurance programme is the Flowserve Technology Advantage Portal, a Web-based data/information aggregation system. Through this portal, Bangchak plant operators and Flowserve technical experts can collaboratively view a centralised repository of plant asset information aggregated from numerous sources. In addition, critical information can be exchanged about equipment and process conditions to ensure maximum equipment and unit availability.

"The asset management and optimisation programmes offered by Flowserve are designed to provide tangible value to our customers by increasing plant uptime and reducing the life cycle cost of their equipment," said Colin Chua, vice president, Asia Pacific, Flowserve Flow Solutions Group. "This programme with Bangchak is another example of how our proprietary technologies enable Flowserve to synthesise essential data for our customers' most critical pieces of equipment and proactively manage the conditions that can impact plant performance."[Page Break]

In a separate development, Flowserve has entered into a definitive agreement to acquire Lawrence Pumps, a privately-owned US manufacturer of highly engineered critical service centrifugal pumps used primarily in the petrochemical and oil and gas industries.

The acquisition of Lawrence will provide Flowserve with severe service API and chemical slurry pump technology that is critical to the refining, oil sands, polyolefin and polyethylene industries- all of which are core markets for Flowserve.

"Lawrence has consistently been an industry leader in critical slurry services solving complex pumping problems involving solids and high temperatures in our core markets," said Tom Ferguson, president, Flowserve Flow Solutions Group. "The Lawrence brand has an outstanding reputation, and many Lawrence products have proprietary niche applications that strategically complement our industry-leading portfolio. We look forward to leveraging our expansive network of service centres and global sales force to expand the reach of Lawrence products and capture unrealised aftermarket potential as we continue to serve the needs of our customers."[Page Break]

Progressive cavity pumping

The Anschutz Ranch in Evanston, Wyoming, is an old gas field that has been operating for almost 20 years. The natural gas is trapped in the porous rock like water in a sponge. As the gas is removed it also draws out a large amount of ground water. When the field was first developed it had a natural pressure of over 700psi. The natural gas, water and other hydrocarbons were moved through the field pipelines by the natural pressure of the field. Slowly the natural pressure in the field dropped.

Eventually, it became necessary to use compressed air to push the natural gas and hydrocarbons out of the rock formation. The air would then push the natural gas, hydrocarbons and water through the porous rock to an extraction point. At first, the added production more than paid for the additional cost of large compressors and to separate the air, water and natural gas. But the economics of the field changed. As the natural gas in the field became further depleted a significantly greater amount of compressed air was needed and the process was no longer feasible.

So BP had a challenge to improve production and keep the field profitable. At this point it became evident that the compressed air was travelling through the more porous areas of the rock formation where the natural gas had already been removed. Also, where the formation was less porous and contained large amounts of very high quality gas, the compressed air was not effective. If the injection into the formation was to be discontinued, then the higher quality gas would come out naturally, however, the volume would be lower. It was determined that the benefits of this high quality natural gas would offset the cost of operating the compressors. Dropping the field pressure would mean that the gas, hydrocarbons and water mixture would need to be pumped across the field. This would require a novel pump solution.

After investigating many different types of pumps, the one that best met the requirements was a Seepex progressive cavity pump with a net positive suction head (NPSH) of less than seven feet. The Seepex pump is efficient to operate and economical to install.

The pumps operated in high fluid vapour pressure and low atmospheric pressure. The altitude at the site is approximately 7000feet above sea level. Other pumps would have required that they be placed at much lower levels than Seepex pumps due to NPSH considerations. In the Rocky Mountain region of Wyoming the added cost of blasting and excavating several feet of almost solid rock is phenomenal.

After the pumps had been put into operation, the customer commented that the Seepex pumps were one of the best investments they had made.[Page Break]

Safety first

To remove the residual moisture in natural gas, ethylene glycol must be injected in the gas drying system at high pressure. This process demands a pump with above-average reliability, long service life, and low residual pulsation. ABEL's international customers who are known to maintain a high level of safety use ABEL triplex high pressure pumps from the HP and HPT series. In addition to quiet operation, this pump has an especially low residual pulsation, which is further reduced by optimally placed pulsation dampeners.

When there is not enough natural pressure from the gas left in the reservoir to pump the oil to the surface, the boreholes are filled with water. This conveys the remaining oil to the surface. ABEL Series HP and HPT pumps are also ideal for this purpose, because they can be used for pressures up to 25.0MPa (3625psi). Conveying oily bilge water is a similar application. ABEL pumps are used to perform this task on a large drilling platform in the Caspian Sea.

Finally, Grundfos has opened a global competence centre in Copenhagen (Fig.1). The new centre will aim to gather know-how and develop new technologies that will bring the company to the forefront when it comes to offering sustainable and innovative pumping solutions.

"In Grundfos we have already got technologies that can solve some of the challenges.

"With this new centre, we are preparing ourselves to become even better, said Soren O Sorensen, group executive vice president. Sorensen estimates the global potential within the area is up to EUR10billion/y.

The centre is located close to Copenhagen, in Brondby. This location is no coincidence, added Sorensen: "We shall be closer to some of our big customers and some of the educational institutions with which we already have excellent cooperation."

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