Electrical network representation of a distributed system

#This invention relates generally to a method for determining the composition and characteristics of the individual materials in a multi-material object, and, specifically, to a representation and analysis of the multi-material object as an electrical network.

#Electrical impedance tomography (EIT) is a minimally invasive measurement technique that can be used to quantitatively map material distributions within multi-material objects. In EIT, a map of the electrical conductivity and permittivity is used to infer the distributions of different materials within that object. Different current patterns or voltage patterns are applied to the object through electrodes surrounding the object, and the corresponding voltages or currents are measured. Based on the current-voltage relations, the internal impedance or internal admittance distribution is determined.

#One example of a multi-material object is multiphase flow in which at least two materials or phases are flowing together inside a pipe or a conduit. Multiphase flow processes are important to a variety of industries including, for example, petroleum, pharmaceutical, food, and chemical industries. There is a need for direct knowledge of the internal characteristics in these types of multiphase flow processes to enable improved design and increased operational efficiency of existing and new processing equipment. Characteristics used to predict performance of multiphase processes may include, for example, spatial distribution of the phases (spatial volumetric phase fractions), flow regime, interfacial area, and absolute and relative velocities between the phases or materials. Knowing the spatial distribution of the materials is particularly useful because non-uniform distribution of the materials tends to reduce the interfacial area between materials available for chemical reaction or conversion and may result in recirculating flows creating spatially non-uniform reaction zones or concentrations. Further, the volumetric phase fraction and velocity are important parameters that enable proper and timely control of multiphase flows.

#These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:

#FIG. 1 is a block diagram of a oil production facility according to an example embodiment;

#FIG. 2 is a schematic of an electrical impedance tomography (EIT) based multiphase flow meter to be used in accordance with an embodiment of the present invention;

#As discussed in detail below, embodiments of the present invention function to provide a system and a method for measuring characteristics of a multi-material object. In an example of a multiphase flow, the characteristics of the object may include volumetric fractions and flow rates of oil, water, and gas (in this context referencing gaseous hydrocarbons) flowing through conduits. Although the invention is described with reference to a use in oil/gas/water measurements, it is by no means limited to such applications; rather, aspects of the invention find application in a wide variety of industrial, healthcare and chemical processes such as, for example, cancer diagnosis and water treatment processes. The characteristics of such multi-material objects may be quite different from the examples given for multiphase flow.

#FIG. 1 shows an oil production facility 10 according to an example embodiment. The oil production facility typically includes multiple oil wells 12 that are each interconnected to a piping system 14. The piping system 14 includes a production manifold 16 coupled to multiphase flow meters (MPFMs) 18. A multiphase flow meter enables measurement of unprocessed well streams very close to the well and thus can provide continuous monitoring of well performance, which may be used for better reservoir management. Fluids pumped from oil wells 12 are sent to a production separator 20 through the production manifold 16. It should be noted that a test separator (not shown) may additionally be used along with MPFMs in the facility 10 or may alternatively be used. One advantage of a MPFM over a test separator is the reduction in time needed to perform a measurement. While the test separator must be allowed to fill and stabilize when changing wells, the MPFM responds more quickly to changes in well fluids and needs less time to stabilize.

#The production separator 20 separates oil, gas, and water pumped from the wells. The production separator 20 may include one or more measurement devices. The measurement devices may include, for example, a water meter to measure an amount or rate of water extracted from a well and an emulsion meter to measure an amount of oil extracted from the well. Further measurement devices may include other devices typically utilized to monitor well performance such as a wellhead pressure sensor, thermometer, salinity meter and a pH meter.