Taking measure of flow meters in phase-contaminated oil flow.

Author:van Puten, Dennis

Accurate allocation measurement results are a key financial and commercial driver for E&P companies. Yet despite limited evidence of the performance of Coriolis and ultrasonic flow meter technology, they are being increasingly deployed for oil flows contaminated with water or natural gas.

This article updates efforts to increase knowledge and understanding of Coriolis and ultrasonic meters at a time when oil and gas operators are facing significant measurement challenges in optimizing production and generating more from reservoirs.

Short-Term Agility, Long-Term Resilience, DNV GL's seventh annual benchmark study on the outlook for the oil and gas industry, surveyed over 700 senior sector players and revealed that nearly half of respondents (47%) believed their organization would look to increase the efficiency of the assets already in operation. A further 39% expected their business to focus on extending the lifespan of assets over the next 12 months, while 11% of global respondents planned investment in new technologies to target enhanced oil recovery (EOR). There is little doubt that production optimization is of high importance for the oil and gas sector.

One main challenge, however, is how to deal with the measurement of multiphase flows. The application of multiphase flow meters (MPFMs) has increased significantly over the last several decades to overcome this challenge. In principle, these MPFMs have the capability to cover the entire multiphase flow regime, but might not be the best choice when considering costs and accuracy.

Many oil fields are producing small levels of phase contamination (i.e. small volume fractions of water and gas). This may be caused by using enhanced oil recovery (EOR) techniques or due to the production toward the end-of-life of a field. These phase contaminations are typically small compared to the main flow, and, therefore, single-phase measurements with appropriate compensation methods might be used.

In many situations, an MPFM may not be fit-for-purpose and the single-phase flow meter might outperform the MPFM in terms of accuracy and costs. For these applications, an uncertainty of 5-10% is typically allowed, which aids in the successful application of single-phase flow meters.

Single-phase flow meters are often installed in situations where normally a pure oil stream is expected, for example, downstream of a separator, at custody transfer locations, or at bunkering stations. The transported fluids are often...

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