At the Anschutz Ranch in Evanston, US was a gas field that had been operating for nearly twenty years. On the site was natural gas trapped underneath porous rock, as gas need to be removed it also draws out large volumes of ground water. When the gas field was first industrialized it had a natural pressure of more than 700 psi. The natural gas, water and other hydrocarbons were transported through the field pipelines by the natural pressure of the field. Gradually the natural pressure in the gas field dropped and it became essential to use compressed air to drive the natural gas and hydrocarbons out of the rock foundation. The air would then move the natural gas, hydrocarbons and water through the porous rock to an extraction point. Initially, the extra production more than paid for the added cost of large compressors and to separate the water, air and natural gas.
Unfortunately the economics of the field changed as the natural gas in the field became depleted with greater amount of compressed air was required and the process was no longer possible. BP had a task to improve production and keep the gas field profitable. It became obvious that the compressed air was conveyed through the more porous areas of the rock formation where the gas had previously been removed. Where the formation was less absorbent and confined large amounts of very high gas making the compressed air not effective.
If the instillation into the rock formation was to be stopped, then the higher quality gas would come out naturally, though the volume would be lower. It was confirmed that the benefits of this high quality natural gas would counterbalance the cost of operation for the compressors.
Reducing the field pressure would mean that the mixture would need to be pumped across the gas field requiring a special pump. After examining many different types of pumps, the one best suited for the task that met all the requirements was the Seepex progressive cavity pump, the most efficient to operate and economical to install.
The pumps operated in high fluid vapour pressure and low pressure. The height of the site is nearly 7000 feet above sea level, other pumps would have need to be placed at much lower levels than Seepex pumps due to NPSHR recommendations. In the Rocky Mountain region of Wyoming the added cost of excavating and blasting numerous feet of practically solid rock is remarkable.
After the progressive cavity pumps had been installed and operating, the customer remarked that the Seepex pumps were the best investment they had ever made. To enquire about our SEEPEX product range. Contact Dynapumps on 1300 788 579 or email sales@dynapumps.com.au.