Slug Flow Calculation Algoritm Matlab Install Sensing Devices

It has been found that the method of the invention provides very satisfactory results without the need for sensors located at the riser base to be provided.

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Further signals dependent on fluid flow properties are received from the plurality of sensors in the topside area of the riser pipe.

The method, controller and system may be arranged to prevent the excessive growth of slug flow by choking the flow by varying the aperture of the valve.

In the case of wells located on a seabed there may be a considerable rise of the fluid from the base of the riser to the processing apparatus on the sea surface.

Low pressures are typically present where a well is nearing the end of its useful life, a so called brown oil field, and under such conditions it is common for the flow of fluid in a riser pipeline to give rise to slug flow.

Because of the problems of slug flow, wells are often considered to have reached the end of their useful life sometime before they are exhausted simply because of the low pressures which give rise to troublesome slug flows.

Known solutions focus on active control of the flow by opening and closing a control valve, or choke valve, located at the topside of the riser pipeline.

This has been shown to be effective in preventing the formation of severe slugs but it inevitably reduces the overall flow rate through the pipeline when measured over an extended period of time.

Since the profitability of the system depends on getting out as much oil and gas as quickly as possible this loss of flow is disadvantageous.

Furthermore, many current systems of flow control using choking rely upon the measurement of pressure from the base of the riser being available.

Slug Flow Calculation Algoritm Matlab Install Sensing Devices

This is unsatisfactory as it is expensive to install sensing devices at the riser base, especially in deep seas, and there are obvious difficulties with maintaining the sensors in such a location.

For hydrodynamic slugs, due to the small size of slugs, the riser base pressure can only provide an average measurement over many slugs in the riser, hence the instability in the system cannot properly be observed.

Once the third stage is completed the method may return to the second stage, whereafter it may loop continuously between the second and the third stages as long as the controller is online.

The control gain may be tuned using any existing tuning techniques to stabilise the flow fluctuation.

The measured signals may be optimally weighted through multivariate analysis techniques such as principal component analysis (PCA).

This time may correspond to at least 2 or more periodic cycles of slug flow in a manually set system (e.g.

In effect the method comprises finding a good variable for control using measurements from sensors, the variable being sensitive to slug flow.

From multivariate statistics theory, it is known that variation directions in signals can be represented by several linear combinations (typically principle components) of the signals through PCA.

Of course, one or more of the other principal components could be used or a combination of more than one principal component could be used.