Advanced cavity pump process monitoring

Louise Davis

Jörg Eitler reveals how the real-time transfer of pump data increases the production of existing oil fields

Progressing cavity pumps (PCP), are suitable for particularly demanding media, such as paraffin and sand mixtures. In an effort to reduce the number of cost intensive pumping installations and expansions of the pump systems and at the same time increase the productivity of existing oil fields, an oil field operator, located near Bremen in northwest Germany, has begun to look for an efficient and durable system, which can be installed relatively easily and whose operation is automatically adjusted to the condition of the borehole so that it can be optimally exploited. The company chose a system with an underground driven progressing cavity pump from Netzsch: the ESPCP pump system.

To make the application as effective as possible, Netzsch offered a combination of a progressing cavity pump with a submersible motor, which was finally installed. It is a so-called ESPCP pump (Electric Submersible Progressing Cavity Pumps), a progressing cavity pump, which is driven underground by a permanent magnet motor and delivers with the help of a downhole sensor the pump data in real time via the power cable to the surface unit. The electrical surface unit consists of a switch cabinet and a transformer. The associated electrical drive technology in the switch cabinet controls and regulates the motor, which adapts the speed of the pump to the current pressure conditions in the borehole via direct gear ratio.

The design of the ESPCP system that installed in this oil field is adapted to local conditions. It can thus convey the highly viscous medium, which contains bitumen and paraffin sediments, sand content of up to 40%, or salt deposits, with a pressure of up to 300 bar. A gas proportion of up to 40% at the pump intake does not pose a problem during extraction, because the technology of the progressing cavity pump allows conveying different phases of a fluid. It also conveys low volumes of 3 to 20m³/day as efficiently as medium volumes of 10 to 100m³/day.

Easy cavity pump monitoring

With the integrated automatic pump control, the operating data of the pump can be conveniently monitored and controlled from the control centre. Optionally, this is also possible via mobile devices with remote control. This data includes information about the production as well as the machine condition. The data forms the basis for a factually well-founded interpretation of borehole problems and helps to optimise production from the depth. The measured data include, among other things, the vibration, the liquid temperature, the pressure above the sensor and the motor temperature. The downhole sensor sends the collected data to the surface unit via supply cable. A dry running of the pump, for example, is successfully prevented in advance or even after a power failure, the restart of the pump is automatically controlled. However, a decisive factor is that the data collected from the borehole can be used to increase crude oil production from an existing oil field. By closely observing the pressure, information is obtained about the inflow or the current level of the borehole. With this information, the pump automatically adjusts the speed of the rotor so that as much of crude oil as possible is conveyed to the surface without lowering the oil level too much. In this way, there is no dry running and the production volume from the existing borehole can be increased significantly.

Jörg Eitler is with Netzsch

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