Tomography for multi-phase flow measurement in the oil industry

Electrical capacitance tomography (ECT) is regarded as a successful method for visualising cross-sectional distribution and measuring multi-phase flows (MPFs). Because of the "soft-field" nature of ECT and the non-linear relationship between electrical measurements and the permittivity of the measured material, image reconstruction for ECT is complicated. However, ECT offers some advantages over other tomography modalities, such as no radiation, rapid response, low cost, being non-intrusive and non-invasive, and the ability to withstand high temperature and high pressure. In principle, ECT can deal with the complexity of MPF measurement by explicitly deriving the component distributions at two adjacent planes along a pipeline. Images of the component distributions can be cross-correlated to obtain the velocity profile of the flow. Multiplying the component concentration and velocity profiles yields a measure of volumetric flow rate for each phase accurately. This paper covers the development of ECT for MPF metering and oil separator in the oil industry. The principal strategies and technologies that may be used to measure three-phase flows will be discussed, and the status of currently available tomography solutions will be reviewed. (c) 2005 Elsevier Ltd. All rights reserved.