Cascade Control Experiments of Riser Slug Flow Using Topside Measurements

Abstract

Anti-slug control applied to two-phase flow provides a very challenging and important application for feedback control. It is important because it allows for operation that would otherwise be impossible, and challenging because of the presence of both RHP-poles and RHP-zeros.To conduct experiments on pipeline-riser anti-slug control, a small-scale slug-loop has been build. The loop has been modelled and analyzed using the simplified riser-slug model by Storkaas. The aim has been to find ways to control the flow using only topside measurements, as subsea measurements can be unavailable offshore. The results from this analysis and experimental results using a cascade controller are presented in this paper.

Multi-Phase Flow Metering in Offshore Oil and Gas Transportation Pipelines: Trends and Perspectives

“…The effectiveness of a cascade controller, which is i.a. based on flow measurements, is presented in [47]. This is supporting the importance of reliable and accurate flow measurements provided by e.g., MPFMs.…”

Multi-Phase Flow Metering in Offshore Oil and Gas Pipelines

“…Hence, the need for measurement of all three phases prior separation is necessary. Another way to prevent a thick emulsion layer between the oil and water is electrostatic coalescence, which has been described in [50][51][52]. The stream of the multi-phase flow inside a pipeline can also be directly connected to corrosion [53].…”

Learning control for riser-slug elimination and production-rate optimization for an offshore oil and gas production process

“…Often the lowpoint pressure of the riser pipeline is not measured on offshore platforms, however a topside pressure transmitter is often available. This transmitter can be used to estimate the the lowpoint pressure (Helgesen (2010), Sivertsen and Skogestad (2005)).…”