Multiphase flow meter

A multiphase flow meter is a device used in the oil and gas industry to measure the individual phase flow rates of petroleum, water and gas mixtures produced during oil production processes.

Background

Knowledge of the individual fluid flow rates of a producing oil well is required to facilitate reservoir management, field development, operational control, flow assurance^[1], and production allocation ^[2].

Conventional Solutions

Conventional solutions concerning two- and three-phase metering systems require expensive and cumbersome test separators, high maintenance, and field personnel intervention. These conventional solutions do not lend themselves to continuous monitoring or metering. Moreover, with diminishing oil resources, oil companies are now frequently confronted with the need to recover hydrocarbons from marginally economic reservoirs ^[3]. In order to ensure economic viability of these accumulations, the wells may have to be completed subsea, or crude oil from several wells sent to a common production facility with excess processing capacity. The economic constraints on such developments do not lend themselves to the continued deployment of three-phase separators as the primary measurement devices. Consequently, viable alternatives to three-phase separators are essential. Industry’s response is the multiphase flow meter (MPFM).

Historical Development

The oil and gas industry began to be interested in developing MPFMs in the early 1980s. Prior to the 1980s, single-phase measurements alone were sufficient to meet the industry’s needs. However, depleting oil reserves, along with smaller, deeper wells with higher water contents, saw the advent of increasingly frequent occurrences of multiphase flow where the single-phase meters were unable to cope. After a lengthy gestation period, MPFMs capable of performing the required measurements became commercially available. Since 1994, MPFM installation numbers have steadily increased as technology in the field has advanced, with substantial growth witnessed from 1999 onwards ^[4]. A recent study estimated that there were approximately 2,700 MPFM applications including field allocation, production optimisation and mobile well testing in 2006 ^[5].

A number of factors have instigated the recent rapid uptake of multiphase measurement technology: improved meter performances, decreases in meter costs, more compact meters enabling deployment of mobile systems, increases in oil prices and a wider assortment of operators. As the initial interest in multiphase flow metering came from the offshore industry, most of the multiphase metering activity was concentrated in the North Sea. However, the present distribution of multiphase flow meters is much more diverse.

Market

Industry experts have forecast that MPFMs will become feasible on an installation per well basis when their capital cost falls to around US$40,000 – US$60,000. The cost of MPFMs today remains in the range of US$100,000 – US$500,000 (varying with onshore/offshore, topside/subsea, the physical dimensions of the meter and the number of units ordered). Installation of these MPFMs can cost up to 25% of the hardware cost and associated operating costs are estimated at between US$20,000 and $40,000 per year ^[6].

A number of novel multiphase metering techniques, employing a variety of technologies, have been developed which eliminate the need for three-phase separator deployment. These MPFMs offer substantial economic and operating advantages over their phase separating predecessor. Nevertheless, it is still widely recognised that no single MPFM on the market can meet all multiphase metering requirements ^[7].

References

1. ^ http://gashydrate.fileave.com/Investigation%20of%20interactions%20between%20gas%20hydrates%20and%20several%20other%20flow%20assurance%20elements.pdf
2. ^ Department of Trade and Industry (UK), ‘Guidance Notes for Petroleum Measurement’, Issue 7, December, 2003, pp. 8 – 9.
3. ^ Scheers, A.M., Noordhuis, B.R., ‘Multi-phase and Wet Gas Flow Measurement’, 5th Annual Multi-Phase Metering Conference, Aberdeen, Scotland, 1999.
4. ^ Mehdizadeh, P., ‘Multiphase Measuring Advances Continue’, Oil & Gas Journal, 9th July, 2001.
5. ^ Mehdizadeh, P., ‘2006 Worldwide Multiphase and Wet Gas Metering Installations’, Production Technology Report 03232007, 2007.
6. ^ Scheers, L., Busaidi, K., Parper, M., Halovorsen, M. and Wideroe, T., ‘Multiphase Flow Metering Per Well – Can it be Justified?’, 20th North Sea Flow Measurement Workshop, St. Andrews, Scotland, 2002.
7. ^ Babelli, I.M.M., ‘In Search of an Ideal Multiphase Flow Meter for the Oil Industry’, Arabian Journal of Science and Engineering, Volume 27, Number 2B, October 2002, pp. 113 – 126.