Statoil soon became one of the major users of multiphase meters and have since then gained extensive operating experience.

During the development of the Mikkel field in 2002-2003, it became clear that current multiphase metering technology was not proper for the Mikkel field flow profiles, and a suitable metering system was not commercially available. Hence, a new generation of multiphase meters had to be developed in cooperation with the suppliers. The feature of the next generation multiphase meters focused on improved regularity, repeatability and measurement accuracy.

In addition, formation water detection and product allocation became important issues.
A development project with one vendor was formed to develop and qualify wet gas meters. For the development of the Snøhvit and Ormen Lange fields, the wet gas meter technology developed for Mikkel, was further developed. The goal for Snøhvit and Ormen Lange was to increase the reliability of the wet gas meter and to have formation water detection.

The wet gas meters developed for Mikkel, Snøhvit and Ormen Lange were extensively tested at the special multiphase flow lab at the Statoil gas plant at Kårstø (K-Lab) to document and verify the performance of the technology. The test at K-lab revealed that more R&D effort was needed to further increase the sensitivity of formation water.

In 2004 a JIP was initiated by a vendor, together with Statoil, Hydro and four other operating companies, in order to develop and qualify a new high performance multiphase meter. The operating experience over many years, as well as numerous field applications, has contributed to ensure product compliance to field requirements. It was also a goal that the same meter should be able to handle both multiphase flow and wet gas flow. Wet gas is gas, oil and water flow characterised by gas volume fraction (GVF) larger than 90%. Multiphase flow is characterised by a GVF lower than 90%.

The new technology developed in this JIP represents an important progress in multiphase metering. It is based on tomography in order to establish three dimensional measurements of the flow inside the pipe and reduce measurement uncertainties in all multiphase and wet gas flowing regimes.

As with all new equipment introduced to the oil industry, a comprehensive qualification program was required before the product could be taken into use. Statoil first tested the meter at K-Lab in October 2006.

The meter was then installed as a pilot at the Gullfaks A platform in series with the test separator for further tests at different conditions. The tests proved the performance of the meter for oil, gas and water rate measurements, and the meter was also able to measure accurately the salinity of the produced water from the wells. Significant time saving can be achieved by actively using the meter for well testing.

The meter has now been operational at Gullfaks A since November 2006 without any malfunction of hardware or software. The performance of the meter has demonstrated accurate measurements with good repeatability compared to the test separator measurements for several wells for a wide range of flow rates at gas volume fractions (GVF) from 5 to 95% and water-liquid-ration (WLR) from 0 to 95%.

By testing the same wells at several times, the required repeatability of the meter has been demonstrated. The qualification program for this top side meter was completed in November 2007.

Statoil explores new applications where multiphase and wet gas metering will be important, in addition to consider using the meters for new field developments. For instance, two 3” meters have been purchased for measurement on, and control of, new subsea compact equipment for deep water. A 10” meter is applied for measurement and control functions in a subsea wet gas compressor system.

Today Statoil has more than 150 multiphase and wet gas meters in operation and more than 10 years of experience from use of this technology. This is a result of close cooperation with different suppliers and other end users. The vast operational experience and the experience gained from developing new technology, is essential when the multiphase meter technology is taken into new field developments, such as heavy oil and high pressure applications. For such applications, the multiphase metering becomes far more demanding since the process conditions are more challenging.
Multiphase meters have been tested for heavy oil applications in Brasil, in a joint project between Statoil and Petrobras. The results indicate that more effort and testing is needed to meet required measurement specifications for heavy oil applications.

To meet process conditions and water depth in current and future field developments in deep water areas like Gulf of Mexico, more demanding specifications are required. New qualification programs are initiated for these applications. Typical high pressure/high temperature (HPHT) qualification requirements include process conditions up to 1000 Bar and 250C and water depth of 3500 m.

To promote successful commercialization of promising new technologies, Statoil has a program for supporting potential vendors, through a product and vendor development program (LOOP agreement).