Abstract

In this paper we will present new techniques for measuring three phase flow using the following approaches:

  1. Homogenisation

  2. In line separation, metering and recombination

  3. Inline metering; leave as it is

Within the concept of "In line metering; leave as it is" the use of the Multi Capacitance technique or the Combination of dissimilar flow sensors and energy absorption probes, are with some limitations in a fast track to be considered proven technologies.

Latest field test results of the Multi Capacitance technique wilI be presented.

1. INTRODUCTION

The measurement of multiphase flow with good rangeability and acceptable accuracy will be a very cost effective solution for the development of new satellite fields as well as for the optimisation of existing fields.

The combination of multiphase (oil/water/gas) metering and multiphase pressure boosting also under development will contribute for a tremendous reduction on surface facilities.

Before we enter in the several measurement concepts it is important to know the different types of flow regimes under which multiphase flow occurs. These flow regimes for horizontal flow lines are shown in the Mandhane flow pattern map in Figure 1.

Most of the encountered flow regimes are Slug, Plug, Annular, Stratified and Bubble.

As far as required Oil, Gas and Water Cut accuracies for Reservoir Management we are in the opinion that 10% for all the fluids is an acceptable figure.

The three type of concepts for multiphase flow metering are:

a - Homogenisation

In this system the three phases are mixed together being therefore distributed homogeneously across the pipe. The mixture is thereafter measured as an homogeneous total and the fractions of Gas, Oil and Water measured in some other way.

b - In line separation, metering and recombination.

This technique as far as measurement is concerned is similar to the old test separators where gas is separated from oil/water mixture and fluids measured separately. The main difference is that the "in line separator" is not bulky and heavy.

c - In line metering, leave as it is.

In this concept the flow is not disturbed or changed, measured directly.

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