On-Line Subsea Multiphase Flow Measurement
Authors: High G. , Frantzen K-H. , Marshall M. 
Published: October 2008

This paper describes the final detailed design, engineering, and installation phase of a Joint Industry Programme to qualify a robust subsea multiphase flowmeter module for long-terminstallation on a North Sea manifold tie-in.

Multiphase subsea production has become a common method of hydrocardon recovery in all areas of offshore E and P. In the North Sea, many developments are subsea satellites with multiphase well-fluids being commingled prior to processing. The system described meets this challenge by offering a cost effective solution to real-time well monitoring asan alternative to the conventional test separator, removing the need for test lines and shutting in wells for testing. The multiphase instrument allows on-line ell fluid analysis, and is also an important tool forreservoir management and field analysis, and provides a means of implementing field allocationmetering thereby simplifying small/marginal field developments.

This project is one of the first subsea multiphase flowmeter installations engineered for long-term subsea service, and designed as an integratedcomponent of the subsea production control system.

Introduction

The long term objective of this development is to demonstrate the effectiveness of subsea multiphase measurement. Amerada Hess United (AHL) is committed to the develoment of new technology to support and enhance its business activities of locating, developing and producing offshore hydrocarbon resources. To this end AHL have launched a Business Driven New Technology Initiative which seeks to identify key technology requirements, to initiate R&D projects, to fulfill them, and to ensure that the results are commercially exploited.

Amongst the spearhead areas are health and safety, the environment, drilling costs, mini-field developments, reservoir characterization and performance, and geological basin modeling.

This project is to run concurrently with the South Scott Development, which includes a production control system for installation in May 1995. The subsea multiphase flowmeter will be installed on the South Scott manifold, and will provide on-line well fluid analysis for up to four producing wells.

The financing for this project has been led by Amerada Hess Norge, with Amerada Hess (UK) Ltd contributing project co-ordination and monitoring. Further project funding has been made by Kvaerner FSSL Ltd. This joint industry approach has been made to establish a commercially viable solution to real-time multiphase metering based on a leading instrument technology, the Ruenta MPFM1900. The project has been conducted in three phases.

Phase 1 was completed in 1992. ref 1. This involved the purchase and testing of a basic fraction meter version of the device. The meter was installed and tested in the new independent 3-phase laboratory at the National Engineering Laboratory (NEL) in East Kilbride, near Glasgow. The aims of Phase 1 were to prove the integrity of the technology, and determine by experimentation the application limitations of the instrument. This was successfully completed. A great deal of time and effort was invested at this stage into modeling real flow conditions on the test skid. The NEL team and the industrial collaborators are extremely satisfied with the results so obtained.