Multiphase pumps for oil-water-sand-gas mixtures reduce installation costs in oil fields
The global hunger for oil and gas continues unabated, so extraction companies must tap into hard-to-reach oil reserves, optimize existing fields and deal with rising cost pressures. These include in particular sources in which heavy oils with extremely high viscosities and high solids content are produced. The development of oil fields with heavy oils or bitumen as well as oil fields, which are located in hard to reach areas, place ever higher demands on the conveying equipment and the pump technology.
In order to be able to build up efficient production under such conditions, it is above all the conveying systems that have to be matched to the media and the ambient conditions. For this reason, NETZSCH Pumps & Systems has developed a whole range of specialized positive displacement pumps, especially multi-phase pumps, for various applications.
Task
However, especially in times of low crude oil prices, the costs of oil production must be reduced. However, the development costs of new fields are very high when separation technology for gas, water and oil separation at the well is needed. To counteract this, drastic cost reduction can be achieved by installing a multi-phase pumping system because the multiphase mixture can be pumped from different wells directly to a central treatment station. This eliminates the costly separation in the oil field. Furthermore, the oil yield is increased. Normally, downhole pressure must overcome the pressure drop to the nearest separator station, which reduces the flow rate of the oil well. If a multi-phase pump is installed, it will take over the transfer to the next separation, reducing the borehole pressure and thus increasing the oil yield. The multi-phase pumping system must be able to cope with highly fluctuating delivery conditions. Thus, the ratio between gas and oil changes continuously, inlet pressures up to 100bar and 100% gas-rich phases are possible. Even with sand shares of 3%, long lifetimes are achieved.
Solution
NETZSCH has developed a multiphase pump precisely for this application. It manages mixtures of oil, water and gas with sand fractions and achieves delivery rates of up to 800 m³/h. Multiphase mixtures are pumped directly to a central treatment station and the complete separation technology at the borehole can be omitted. Thanks to the low shear forces and the low pulsation, there are hardly any emulsion effects during transport. At central separators, the media phases can be easily separated, significantly reducing infrastructure costs for the entire field. Now the use of the gas share becomes economic, avoids the flaming of gas in the fields and contributes to the ever-increasing environmental requirements. This method is used in the Palogue oil field in southern Sudan. The gas volume fraction (GVF) is on average over 80% with sand fractions of up to 3%. In order to be able to efficiently convey the multiphase mixture, 20 multi-phase pumps were installed, each directing the yield of up to 24 boreholes to a central separator station – some of them over 15 km away. To protect the pumps against solar radiation, which can heat the surface up to 70 ° C and from flooding after heavy rainfall, the pumps were equipped with roofs and mounted on elevated foundations. In order to achieve the highest possible operational reliability of the remote monitored & controlled pump systems, an extensive control system with connection to the supervisory process control system was installed. For the pump system itself a particularly robust (“heavy duty”) version was used.
