L52288 Investigative Ultrasonic Meters in Heavy Oil Service
Author(s): Harvey
Abstract/Introduction:
Investigation into the status of Ultrasonic Flow Measurement in heavy oil service, specifically in fiscal measurements. The objective of the study was to determine the status of current technology, its limitations and gaps, affecting Ultrasonic Flow Measurement performance and to provide direction for future research and initiatives. Result: The first task completed was an industry standard survey of Ultrasonic Flow Measurement vendors. This survey required the research of existing publications, interviewing operators of existing installations and interviewing qualified ultrasonic meter vendors. A questionnaire was developed and distributed to the vendors for completion, operators identified and supplied with the identical questionnaire and the results inputted within a comparison matrix which was used for rating the various vendors and status indicators of ultrasonic flow measurement technology in heavy oil service. The second task completed was a compilation of the survey results including the detailed responses and summary of all findings. Benefit: The report identified several barriers preventing the expanded use of ultrasonic flow meters in heavy oil service. The report also includes recommendations on who best to overcome these barriers for expanded use and identified future research required to broaden the adoption of ultrasonic flow measurement for heavy oil service (crudes).
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L52299 Revised Analysis of Orifice Meter Expansion Factor Data
Author(s): George
Abstract/Introduction:
Orifice meter expansion factor data collected at Southwest Research Institute (SwRI) between 2003 and 2005 have been reviewed to assess the effect of an assumption made during data reduction. In accordance with the North American orifice meter standard, AGA Report No. 3, Part 1, the data were originally analyzed using a constant value of the isentropic exponent, k 1.3. By comparison, the expansion factor equation adopted by ISO employs the real isentropic exponent, K, which is a function of pressure, temperature, and gas composition. The SwRI orifice meter expansion factor data have been re-reduced, using values of the real isentropic exponent from archived test data in place of the ideal gas value of k 1.3. The original expansion factor data were obtained in such a way that the expansion factor values themselves were unaffected by the value of the isentropic exponent. However, the use of k 1.3 influenced the values of the acoustic ratio, the independent variable used with the AGA and ISO equations to compute values of the expansion factor in measurement applications. The use of the ideal isentropic exponent in the original SwRI data, instead of real values of the isentropic exponent, was found to have caused an average shift in the acoustic ratio.
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NMCQ4YK Development of a Low Cost Inferential Natural Gas Energy Flow Rate Prototype Retrofit Module
Author(s): Kelner, et al
Abstract/Introduction:
In 1998, a multi-year project to develop a working prototype instrument module for natural gas energy measurement was initiated. The module will be used to retrofit a natural gas custody transfer flow meter for energy measurement, at a cost an order of magnitude lower than a gas chromatograph. Development and evaluation of the prototype energy meter in 2002-2003 included: (1) refinement of the algorithm used to infer properties of the natural gas stream, such as heating value (2) evaluation of potential sensing technologies for nitrogen content, improvements in carbon dioxide measurements, and improvements in ultrasonic measurement technology and signal processing for improved speed of sound measurements (3) design, fabrication and testing of a new prototype energy meter module incorporating these algorithm and sensor refinements and (4) laboratory and field performance tests of the original and modified energy meter modules.Field tests of the original energy meter module have provided results in close agreement with an onsite gas chromatograph. The original algorithm has also been tested at a field site as a stand-alone application using measurements from in situ instruments, and has demonstrated its usefulness as a diagnostic tool. The algorithm has been revised to use measurement technologies existing in the module to measure the gas stream at multiple states and infer nitrogen content. The instrumentation module has also been modified to incorporate recent improvements in CO2 and sound speed sensing technology. Laboratory testing of the upgraded module has identified additional testing needed to attain the target accuracy in sound speed measurements and heating value.
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PR-015-05600-R01 Assessment of Sampling Systems for Monitoring Water Vapor in Natural Gas Streams
Author(s): Barajas, George
Abstract/Introduction:
Research has been conducted to assess the usefulness of various sampling and delivery methods in transporting a representative sample of a natural gas stream for analysis of moisture content. Three sampling configurations commonly used by the natural gas industry were evaluated, including a sample system with a regulated probe heated above ambient conditions, the same system held at a constant temperature simulating ambient conditions, and a heated sample system incorporating a membrane filter. Each configuration was used to transport samples of distribution-quality natural gas with levels of water vapor within common tariff limits, as well as samples of a water-saturated stream of methane simulating a common dehydration system upset. The time response of samples in each configuration to step changes in water vapor content between these two conditions was also evaluated. Measurements were performed using both manual chilled mirror dew point testers and automated analyzers.
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PR-015-05600-R02 Development of Accurate Methods for Predicting Hydrocarbon Dew Points
Author(s): George
Abstract/Introduction:
Many different calculational methods are available for computing hydrocarbon dew points of natural gas streams from gas chromatograph analyses. These various methods often produce results that are inconsistent from one method to another, and for some gas streams, have been found to significantly underpredict hydrocarbon dew point temperatures. Several approaches have been evaluated for predicting hydrocarbon dew points of natural gas streams using compositional data available from field gas chromatographs, particularly GC data reported as a lumped C6+ fraction. The primary objectives were to evaluate the accuracy of several C6+ characterization methods used with generic equations of state to predict dew points for a wide range of production, transmission, and distribution gases, and to identify the characterization methods that produce the most accurate predictions for this range of gas compositions. Characterizations were tested using the GERG-2004 equation of state, and the Peng-Robinson and Soave-Redlich-Kwong (SRK) cubic equations of state.
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PR-015-05602-R01 Evaluation of Clamp-on Ultrasonic Meters as Diagnostic Tools
Author(s): George
Abstract/Introduction:
This study has evaluated the ability of commercially available clamp-on ultrasonic meters (USMs) to diagnose natural gas flow conditions that can produce measurement errors in traditional natural gas meters, and quantify the errors in measurements made with traditional metering technologies under these conditions. Commercially available clamp-on meters were tested in a fully developed, steady flow downstream of a high-performance flow conditioner to evaluate their measurement repeatability and reproducibility. The clamp-on meters were then installed on a conventional orifice meter run and an in-line ultrasonic meter run. Data were collected from all meters under ideal conditions and different adverse conditions, including an improperly installed orifice plate, orifice runs altered to simulate scale or dirt on the orifice plate and tube walls, and a partially plugged flow conditioner generating an asymmetric flow profile in the ultrasonic meter run.
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PR-015-06603-R01 Tests of Instruments for Measuring Hydrocarbon Dew Points in Natural Gas Streams Phase 1
Author(s): George
Abstract/Introduction:
Two commercially-available hydrocarbon dew point analyzers, an Ametek Model 241 CE II and a Michell Condumax II, were provided by JIP participants for testing. An experimental HCDP research apparatus, first designed at Southwest Research Institute to gather reference hydrocarbon dew point data, was modified to test the automated analyzers. Both automated analyzers, along with a Bureau of Mines chilled mirror device serving as a reference, were installed in the apparatus. Gravimetrically-prepared gas blends containing hydrocarbons through decane were used as test gases, and a small warm box was built to keep the test gases above their hydrocarbon dew points at various simulated line pressures.
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PR-015-06603-R02 Tests of Instruments for Measuring Hydrocarbon Dew Points in Natural Gas Streams Phase 2
Author(s): George, Hart
Abstract/Introduction:
Research has assessed the accuracy of two commercially-available hydrocarbon dew point (HCDP) analyzers, an Ametek Model 241 CE II and a Michell Condumax II. During a previous phase of this project, both automated analyzers, along with a Bureau of Mines chilled mirror device serving as a reference, were tested on gravimetrically-prepared gas blends chosen to simulate a transmission-quality gas and a production gas. The measurement repeatability of both units was found to be better than the manual chilled mirror. Trends in the analyzer and manual chilled mirror measurements suggested that differences in performance between the automated units were related to their measurement techniques and default set points. During the second phase of the project, the Ametek and Michell automated analyzers were tested again on the transmission-quality test gas used in Phase 1, but with specific levels of contamination added to gain knowledge of their performance under adverse conditions. In one round of tests, water vapor was added to simulate a transmission gas with water vapor levels above common tariff specifications. In the second round of tests, the test gas contained both methanol and water vapor, simulating a stream to which methanol has been added to prevent hydrates. Contaminants were added to the test gas stream in amounts such that, depending upon the pressure of the test stream, the contaminant dew point would be reached first, the HCDP would be reached first, or the two phases would condense simultaneously. Multiple HCDP measurements were made with the analyzers to determine their ability to accurately measure HCDPs under these adverse conditions. Analyzer results were again compared to HCDP measurements taken with the Bureau of Mines chilled mirror device and a digital video camera. Results were adjusted for small changes in the heavy hydrocarbon content of the test gases over time, using predictions from an equation of state and gas chromatographic analyses of the test gases.
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PR-015-07604-R01 Clamp-On Ultrasonic Flow Meters as Diagnostic Tools
Author(s): Grimley, Hart, Viana
Abstract/Introduction:
Over the past several years, improvements in clamp-on ultrasonic meter technology have caused increased interest in applying this technology within the natural gas industry. Clamp-on ultrasonic meters (CUSMs), which are mounted on the outside of a pipe, send and receive ultrasonic waveforms through the pipe wall. This configuration offers several potential advantages over in-line meters, including portability and the ability to be installed without shutdown and disassembly of the pipeline. CUSMs, like their in-line counterparts, use sophisticated electronics to control the meter operation and to monitor parameters such as transducer signal strength, path velocities, and speed of sound. Because of these features, CUSMs are being considered for their potential as in-situ verification and as diagnostic tools. Having such portable tools to quickly verify meter performance would save considerable time in troubleshooting causes of lost and unaccounted-for (LAUF) gas, thus, minimizing overall LAUF totals. The ability to validate meter performance in-situ would also significantly reduce operating and maintenance costs of metering stations, particularly costs of unnecessary recalibrations. This project specifically addressed the ability of a CUSM to measure distorted profiles with sufficient resolution to determine if the flow is properly conditioned for flow measurement by other meter types. It also addressed the accuracy with which CUSM measurements, performed with sufficient spatial fidelity, can be used to provide a reference flow rate for in-situ meter proving. The test approach was to traverse a single ultrasonic transducer pair around the perimeter of the pipe in sufficiently small increments to measure the flow field at a given pipe cross section independent of the amount of flow distortion present. Velocity profile measurements performed at the same locations were used as an independent check of the CUSMs profile sensitivity.
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