Lectures

A R&D project has been designed to investigate first time the Multiphase Pump Technology (MPT) connected to an existing sour gas field. The final dual porosity and permeability model representing the fractured dolomite formation contains 332,280 total and 201,619 active cells respectively.

Surplus energy in high pressure oil and gas wells today is controlled by chokes on the wellhead. By using chokes the hydraulic energy (pressure) is wasted. Multiphase twin-screw pump are used since years to add energy to the well-stream. The same technology can be used to generate electrical power from the surplus energy in the wellstream. The presentation will highlight the theoretical background, the results of the mathematic simulation and compare the theoretical results with test results.

Long distance transmission of electrical power through cables to operate a subsea asynchronous – squirrel – cage motor does have several limitations in regard to cable length and efficiency. The model, built up during this study, considers several parameters such as motor, cable, and frequency converter output. This model shows, that the natural limitation in cable length will be about 50km for stable operation of the motor. During this study a method has been developed to provide stable operation of the motor also for much longer cables. This method will be shown during this presentation.

During the ISUP (Integrated System for Underwater Production of Hydrocarbons) research project an innovative, modular and "open" control and automation system for the complete production plant including all subsea components has been developed and tested. Some of the key features are safe and secure data transfer, near real time control, OPC compatibility, integration of video streams and worldwide accessibility via Internet.

Since the Multiphase Pump technology has been introduced to the oil and gas industry as a new solution, it has shown a lot of advantages. It has proven to be a more efficient alternative, as no field separation is required, only a single flowline can be used, and for this early gas transport no extra compressor is required.

In the Tasbolat Oil Field in Kazakhstan two Multiphase Pumps have been installed, where one is operating and the other provides for full redundancy. While several production issues could be resolved, moreover the operation of those pumps has led to a considerable production increase

The main task of using twin screw multiphase pumps is to compress the casing gas in order to eliminate flaring. Further the casing annulus is unloaded from backpressure, thus increasing the hydrodynamic level and in the efficiency of the downhole pumps. No flares are necessary and the environment is prevented from extra CO2 loads.
The stream entering the pump varies considerably in regard to its composition. In any case it has to be considered as wet gas.

The transport of multiphase fluids, especially in the presence of sour gases and erosive particles, can lead to an enormous strain on metallic materials. The lecture will discuss how the material selection for multiphase boosting systems is accomplished in a laboratory setting, by conducting different test series and by using specially developed numeric models for lifetime assessments.

Components used in oil and gas production often are exposed to a combination of dynamic loads, corrosion and wear. In order to ensure a safe operation, it is necessary to perform an analytic strength assessment. This paper presents a new way of analytic strength assessments under such operation conditions. In contrast to conventional methods, it incorporates the ef-fects of corrosion and wear.

Subsea Multiphase Pumps today typically do include a liquid cooled electrical motor. This is done by water coolers in direct contact with sea water. The subsea location requires highest availability. As a consequence the number of active components should be limited. The cooling requirements are depending on pump speed and pump load while the temperature of the liquid filling should remain in the optimal range. A self controlled cooler without any control components (valves, etc.) has been developed and will be presented.

Solubilties of gases in oil affect the performance of twin-screw multiphase pumps, as dissolution and degassing occur in the conveying chambers and gap streams. Modelling the solubilty and phase fractions shows good agreement with experimental results of the two-phase flow at the inlet and outlet of a twin-screw multiphase pump obtained from an electrical capacitance tomography system.

Multiphase flow in pipelines has been investigated since decades already. However, still available models and computer simulation programs bear certain risks for day-to-day operations, and there is a great chance to do things wrong. This is not only true for upstream, but also downstream scenarios of multiphase pumps.

While pipeline separation effects are responsible for gas slugs of uncertain duration at pump inlet, downstream issues may even result in a no flow scenario!

An introductory presentation about the issues and challenges envisaged will be given by Ivar Brandt, SPT Group in Norway, who serve the industry with the well-known OLGA simulation program.

New Subsea Installations are often remotely located and thus have to be tied back over long distances to supply control signals and power. Especially the operation of variable speed electric motors poses different challenges. Since there are no submersible DC-Motors available and reliable subsea converters are still in development, AC has to be transmitted over long distances although the losses in the cable are much higher than with DC. In addition the quality of the sinus signal is affected too, and the power system reacts slower to sudden changes of the motor load. These challenges require new solutions that shall be discussed in this workshop.

Requirements on subsea multiphase pumps to provide very high differential pressures due to very long tie back distances is increasing. The background for this requirement and alternatives will be evaluated. The influence on the multiphase boosting process and consequences on rotors and efficiency will be discussed, latest research results on materials and rotor design will be presented.

Serial installation of multiphase pumps as well as the possibility of developing hybrid-pumps are options to fullfill the high differential pressure requirement.

Why Petroamazonas decided to use multiphase technology in der Panacocha project - An Application example.

Multiphase boosters can provide a useful alternative to more conventional field development technology and, in some cases, can be the ‘enabling’ factor for an economic development. The presentation outlines technical and commercial aspects of a number of multiphase pump applications and touches on some of the problems hindering their more widespread application.