Measuring and testing – Volume or rate of flow – Of selected fluid mixture component
Reexamination Certificate
1999-11-10
2002-05-07
Fuller, Benjamin R. (Department: 2855)
Measuring and testing
Volume or rate of flow
Of selected fluid mixture component
Reexamination Certificate
active
06382032
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to the measurement of the mass rate of flow for multiphase flow streams. The present invention relates more specifically to a method and apparatus for measuring the mass rate of flow for multiphase flow streams, and in particular, gas streams having entrained liquids with low (less than 15%) liquid mass fractions.
2. Description of the Related Art
Various methods have been developed and utilized for measuring the flow rate of multiphase flow streams where widely varying amounts of gas and liquid are encountered and where high degrees of measurement accuracy may or may not be important. Orifice meters are often used to meter gas flow streams by creating a pressure differential across an orifice plate from which can be calculated a mass flow rate. Various standard metering equations and commercial metering systems have been developed to meter dry gas (flow streams that are 100% gas) to accuracy levels appropriate for situations involving the sale or transfer of ownership for the material product in the flow stream. Such “fiscal level” metering of dry gas provides an accuracy suitable for contract sale of gaseous products such that no significant monetary cost error occurs in the contract sale. There are clearly situations where even greater accuracy might be desired, such as in technical research and development environments, but for the purposes of the present invention, such fiscal level metering for wet gas flow streams is a suitable objective.
In many situations where flow stream metering is desired and performed, the flow stream is composed of both gases and liquids. The presence of liquids in the flow stream will result in errors in the mass flow rate measurement due to the use of equipment and measurement interpretation techniques intended primarily for dry gas flow measurements.
Production streams from gas wells and the like, flow streams in the gas leg of two or three phase separators, and flow streams in some gas transportation lines, all have entrained liquids in small to moderate amounts. These entrained liquids result from a number of factors ranging from dew point effects to moderate levels of inherent liquid fractions. From an economic standpoint, it is desirable to meter these flow streams without the necessity of conditioning the flow stream with a separator or a dehydration system. This is even more desirable in off-shore oil and gas production where the elimination of the need for a conditioning facility can significantly reduce the necessary platform space, load, and auxiliary requirements, and therefore, reduce the overall cost of the off-shore platform.
In general, by eliminating the need to condition a multiphase flow stream, several costs are avoided. These include the capital costs of the conditioning facility, the installation and maintenance cost of the conditioning facility, and the operating expenses associated with such a facility.
There have been attempts in the past to measure the mass flow rate of multiphase flow streams by a variety of more or less complex systems. Many of these systems are directed to the measurement of steam flow where condensate has an effect on the accuracy of the flow rate measurements. Many are directed to multiphase flow in the oil and gas industry. The following are representative of the state of the art in the measurement of mass flow rate for multiphase flow.
U.S. Pat. No. 1,540,533, issued to Bullock on Jun. 2, 1925, entitled “Flow Meter Installation”, describes an early system for utilizing pressure differential to measure flow rate with a combination orifice/venturi nozzle metering run.
U.S. Pat. No. 1,559,155, issued to Bullock on Oct. 27, 1925, entitled “Multirange Flow Nozzle”, describes the use of an array of flow nozzles for the creation and measurement of differential pressures.
U.S. Pat. No. 2,136,900, issued to Woolley on Nov. 15, 1938, entitled “Measuring Apparatus”, describes an early flow rate system that incorporates auxiliary factors for the correction of standard parameters in measuring the flow.
U.S. Pat. No. 3,100,840, issued to Morganstern on Aug. 13, 1963, entitled “Methods and Apparatus for Measuring and Testing”, describes an early use of radiation in the measurement of flow rate.
U.S. Pat. No. 3,378,022, issued to Sorenson on Apr. 6, 1968, entitled “Fluid Flow Sensing System”, describes a more complicated system of orifice metering and differential pressure measurement analysis.
U.S. Pat. No. 4,337,668, issued to Zupanick on Jul. 6, 1982, entitled “Orifice Wear Compensation”, describes a system for modifying a metering equation constant according to the deterioration of an orifice over a period of time.
U.S. Pat. No. 4,453,417, issued to Moyers et al. on Jun. 12, 1984, entitled “Unitized Measurement Instrument Connector Apparatus”, describes an orifice metering system specifically including an array of valves and roddable inserts to improve the operation and maintenance of the system.
U.S. Pat. No. 4,562,744, issued to Hall et al. on Jan. 7, 1986, entitled “Method and Apparatus for Measuring the Flow Rate of Compressible Fluids”, describes an orifice plate metering system that integrates temperature differentials into the standard metering equations.
U.S. Pat. No. 4,683,759, issued to Skarsvaag et al. on Aug. 4, 1987, entitled “Characterization of Two-Phase Flow in Pipes”, describes the use of gamma radiation transmission measurements to determine the distribution of voids within a gas/liquid mixture flowing in a pipe.
U.S. Pat. No. 4,836,032, issued to Redus et al. on Jun. 6, 1989, entitled “Method of Determining the Quality of Steam for Stimulating Hydrocarbon Production” describes the use of an orifice plate in combination with a choke to measure both steam quality and mass flow rate.
U.S. Pat. No. 5,025,160, issued to Watt on Jun. 18, 1991, entitled “Measurement of Flow Velocity and Mass Flow Rate”, describes the use of gamma radiation using dual energy transmission techniques to facilitate a more accurate measurement of flow rate.
U.S. Pat. No. 5,031,465, issued to Redus on Jul. 16, 1991, entitled “Steam Quality and Mass Flow Rate Measurement Using Critical Flow Choke Upstream of an Orifice Plate”, also describes a pressure differential metering system that incorporates both a choke and an orifice plate.
U.S. Pat. No. 5,031,466, issued to Redus on Jul. 16, 1991, entitled “Methods and Apparatus for Determining Steam Quantity and Mass Flow Rate”, also describes a differential pressure measurement system utilized in conjunction with an orifice plate metering system.
U.S. Pat. No. 5,315,117, issued to Hatton et al. on May 24, 1994, entitled “Volume Meter System”, describes a system for determining the liquid or gas fraction of a two-phase flow stream.
U.S. Pat. No. 5,343,041, issued to Ruscev et al. on Aug. 30, 1994, entitled “Method and Apparatus for Determining the Physical Characteristics of a Water Flow”, describes a more complex use of gamma ray radiation for measuring the flow of water along a well.
U.S. Pat. No. 5,400,657, issued to Kolpak et al. on Mar. 28, 1995, entitled “Multiphase Fluid Flow Measurement”, describes a multiphase metering system that incorporates densitometers in conjunction with a flow meter.
U.S. Pat. No. 5,404,745, issued Chien on Apr. 11, 1995, entitled “Method and Apparatus for Determining Steam Quality From Steam Velocity Measurement”, describes a system and method for measuring the critical velocity of steam flowing through a nozzle.
U.S. Pat. No. 5,421,209, issued to Redus et al. on Jun. 6, 1995, entitled “Measurement of Steam Quality and Mass Flow Rate”, describes yet another system of pressure measurement involving both an orifice plate and a critical flow venturi.
U.S. Pat. No. 5,479,020, issued to Mohn on Dec. 26, 1995, entitled “Metering Device For a Fluid”, describes a meter for use in multiphase flow that incorporates radiation densitometers and is directed to the more accurate use of such radiation techniques.
U.S. Pat. No. 5,501,099, issued Whorff on Mar. 26,
Hatton Gregory J.
Svedeman Steven J.
Cox & Smith Incorporated
Dickens Charlene
Fuller Benjamin R.
Southwest Research Institute
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