F c = 2 ṁ ω v r... (1)

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1 UPM Coriolis Measurement Employing Asset Health and Performance Monitoring for Conventional or Unconventional Production Measurement Jerry E. Stevens, Endress+Hauser, Inc. Abstract Coriolis flowmeters have continued to be applied in numerous allocation and production applications throughout the upstream Oil & Gas sector. These applications are increasingly demanding in nature, due to application locations and the availability of skilled manpower. This has given rise to the need for both Asset Health and Asset Performance Monitoring data that users can reliably act on. Typical Coriolis flowmeters produce obscure event notifications which can delay the resolution of these events. As such, events should be simply categorized for easier recognition of how users resolve the events either proactively or reactively. Asset Health Monitoring provides a structured approach for users with remedy based information to reduce maintenance resolution time and define the appropriate actions. Throughout the flowmeter life cycle, process impacts can prejudice the device measurement quality or even lead to a device failure. This gives rise to the need for more intelligent flowmeters that can maximize production uptime and provide insightful information into their own performance. This paper will explore Asset Performance Monitoring that gives reliable data on process impact factors related to corrosion, coating or build up, and entrained gas and present metrology based techniques to verify measurement quality by a traceable and attested means. Coriolis Usage Grows in Production Measurement Coriolis flow measurement is relatively new as an applied technology for the Oil & Gas industry in use since the 1980 s which is even employed to replace many traditional mechanical and electronic instruments. Hundreds of thousands of Coriolis applications exist in the areas of fracking, well stimulation and completion, enhanced oil recovery, production, reservoir management, well testing, allocation and lease applied custody transfer (or LACT) in both permanent and portable forms. Successful adoption of Coriolis technology has highlighted areas where industry knowledge in the application and integration of this technology can be improved. Coriolis flowmeters produce two independent measurements. The first independent measurement is mass flow rate accomplished using the gyrostatic principle and the influence of Coriolis acceleration. F c = 2 ṁ ω v r.... (1) When the fluid is flowing (Fig. 1), the mass particles move through the measuring tube and are subjected to superimposed lateral acceleration by the Coriolis forces (F c ). As they enter the tube, the mass particles (m) drift away from the center of rotation (Z 1 ) and return toward the center (Z 2 ) as they approach the outlet end. Consequently, the Corioilis forces act in opoosed directions at inlet and outlet and the measuring tube starts to twist. This change in the measuring tube s oscillation induced geometry is registered as a phase difference by sensors (A, B) at each end of the tube. This phase difference (Δϕ) is directly proportional to the mass of the fluid and to the flow velocity (v), and therefore also to mass flow.¹ The second independent Coriolis measurement is the fluid density. Once placed into its oscillatory movement, (Fig. 2) the Coriolis system will achieve a resonance frequency (f r ) as an empty tube (ρ 1 ). This resonance frequency is dependent on the sensing tube material, its size and mass, and temperature (f 1 ). When a media is introduced into the sensor, the mass of the sensing system will change the frequency of oscillation (f 2 ). The resulting frequency will be the direct determinant of the fluid density (ρ 2 ). Asset Health Monitoring. Coriolis meters are advanced micro-processor systems capable of producing multivariable outputs related to mass or volume flow, corrected volume, density, reference density, temperature and even viscosity. Most Coriolis meters produce a form of selfdiagnostics to give the user some level of information about the health of the device or process. Asset Health Monitoring (AHM) is the first area of focus for users to leverage both process and device information provided by Coriolis technology.

2 Coriolis meters are like most field instruments. When properly applied, they can operate in diverse and changing process conditions with high repeatability and accuracy. Too often they are used in a run to fail mode without regard to intermediate diagnostic or process event notifications that may have been available. Globally, process related industries lose five percent of annual production due to unscheduled downtime and poor measurement quality². The ARC Advisory Group estimates that nearly 80 percent of these losses are preventable². Coriolis technology owners can use several methods to surveil assets today: directly at the device display, by a discrete output or fail-safe state (ex. contact closure), wirelessly, through a digital bus system (ex. Modbus or Ethernet), through Process Automation Solutions (PAS), or customized analytics solutions. Surveillance activities can leave Oil & Gas users trying to decipher obscure event messages and struggle with their resolution. Apart from revamping training regimes for company personnel, diagnostic messages historically provide little clarity as to their severity level and the necessary action steps required to resolve the condition successfully. As an industry, categorizing Coriolis events both safely and efficiently has been addressed for manufacturers. Safety recommendations driven by the Chemical Industry through NAMUR are now appearing in newer instrument generations. NAMUR NE 107 is one such recommendation. This guide is not limited to just Coriolis meters; manufacturers of all electronic instrumentation technologies have guidance set by NAMUR NE 107. NE 107 guidance addresses the most important application specific faults and safety related fault conditions for field devices. Coriolis events are categorized in four areas and judged by the frequency of occurrence of the faults or fault conditions: Failure, Out of Specification, Maintenance Required and Check Function (Fig 3). What do the Coriolis event categories contain? Failure (sensor failure, main or secondary electronics failure, tube(s) not oscillating, temperature sensor defects, memory or data storage failures, software incompatibilities, input or output failures) Out of Specification (sensor frequency limits exceeded, gas bubbles in liquid, fluid homogeneity, sensor signal asymmetry, programming limits for outputs, operating temperatures too high or low, range exceeded for external inputs) Maintenance Required (software errors in memory, failure in software updates, validity of software flash files, device configuration conflicts) Check Function (verification active, output or input simulation active, flow override function active, processing parameter download active - from software updates) Which event classes should be handled reactively or proactively? Failure, Out of Specification and Maintenance Required events must be handled reactively due to their impact on measurement accuracy, repeatability or reproducibility. Check Function events are generated by maintenance operations initiated by the user. In these circumstances, users are expected to complete verifications, software updates and output or input simulations proactively to return to normal measurement conditions. The Coriolis events listed above are just part of over 100 possible events in next generation devices. Coriolis devices following AHM messaging may provide logbook or device memory to retain these historical events. Additionally, Coriolis manufacturers can voluntarily include a fifth category for Information messages. Information messages may include device logins, changes in access codes and passwords, or changes to device IP addresses for web server based models entering the market. AHM can simplify operational work flow within the Oil & Gas industry. AHM occurs automatically without manual intervention. Users are able to manage a process by exception. Automated Coriolis asset health routines produce real-time insight intermediate to proving or scheduled maintenance. With the classification of diagnostic events and their associated remedies, the potential exists for even higher maintenance efficiency gains and production operating time when implemented. What are the first two considerations to achieve remote AHM from Coriolis meters? First, a control system or telemetry modem must provide a physical layer capable of acquiring the device data. Second, the information layer must support the Coriolis profile. A Coriolis profile is manufacturer specific to registers, drivers, add-on instructions, pre-designed Supervisory Control and Data Acquisition (SCADA) faceplates or object libraries needed for integration. Only then can the asset health event classification system be fully utilized to an operator s advantage. Asset Performance Monitoring. Oil & Gas Coriolis applications are the most diverse and demanding for the technology. Coriolis meters can be exposed to variable 2

3 (transient) and adverse (permanent) process conditions. Variable process conditions can appear as cavitation, gas carry under or breakout in liquids, or liquid carryover in gas. Adverse conditions can impose coating, corrosion, erosion, or depositing solids effects. All of these conditions can negatively impact Coriolis meter repeatability and reproducibility for those applications requiring proving. Asset Performance Monitoring (APM) provides user access into these secondary process or system parameters to provide a window into the process (Fig 4). Oil & Gas users are the most likely to predict the adverse conditions that could occur in their processes. Adverse process trending has focused on flow rate, density, internal temperature, process pressure, viscosity, sensor zero point or Reynolds number alone. These same users have not yet recognized that a wealth of added information is generated by the Coriolis system related to the process itself (Fig 5). An APM strategy to drive fiscal and maintenance efficiencies requires a three step approach. Coriolis system suppliers must advise users on which parameters are available for variable and adverse trending. The user can then make an informed decision to acquire, accumulate and then assess the best information to manage their most problematic variable and adverse processes. APM trending requires a protocol, bandwidth and acquisition interval target to successfully acquire secondary Coriolis information. Digital output protocols allow multiple process and secondary Coriolis system variables to be accessed. Trending multiple parameters can slow overall digital system transmission speeds if not considered. Because of this, the data acquisition interval is important to define. If transient gas breakout recognition is the goal, an acquisition timing interval of once per second may be required to catch these random events. Slow changing, adverse trends like sensor coating or corrosion can occur over time; the sampling period for these events could be set in minutes. Evaluation techniques under APM will continue to evolve. This evolution has come via on demand, internal methods of Coriolis meter verification. Verification by definition is: the act or process of confirming the accuracy of, or validity of something. ³ Verification of a Coriolis measurement system is a qualitative assessment of the factors which impact the Coriolis measurand. This process does test the sensor, signal conversion, electronics and output for a complete system assessment. (Fig 5) Coriolis verifications should define a total test coverage which lead to device out of specification at a stated uncertainty. Consequently, verification is not meant to replace calibration or proving. The true value of verification is created by intermediate, documented health evaluations between calibration, proving and maintenance intervals. APM with verification allows a more frequent analysis of the Coriolis measurement system following known metrology standards (e.g. ISO-9001:2008 Section 7.6 a, Control of monitoring and measuring equipment ⁴). Verification has the potential to be applied in allocation or regulatory applications requiring traceable documentation. Therefore, Oil & Gas users are encouraged to have Coriolis suppliers substantiate the reliability and validity of their APM verification techniques. Verification validity can be assured through manufacturer attestation. Attestation by definition is: to show, prove or state that something is true or real. ³ Attestation is achieved by third party audit and report. A verification attestation will define the test specification(s), a test of function on demand, and declare a specified measuring tolerance at a stated total test coverage. Once qualified, verification can be used to produce electronic quality, audit safe report assurance. In Summary. Coriolis meters will continue to be employed in the upstream sector and the Oil & Gas industry as a whole. Their value beyond measurement accuracy, repeatability and reproducibility has yet to be completely realized. The potential for gains in fiscal, process, facility and maintenance efficiencies is only limited by that user s vision. Asset Health and Performance Monitoring should become the topics to bring that vision clearly into focus.. Conclusions 1. Coriolis flowmeter usage is expected to continue to grow into more regulated, fiscal and challenging applications for the upstream Oil & Gas Industry. 2. Coriolis meters with Asset Health Monitoring can drive higher production efficiency gains and operating time benefits 3. Asset Performance Monitoring techniques allow user insights into transient and permanent meter effects that jeopardize quality, repeatability and reproducibility. 4. Implementation of Asset Health and Performance Monitoring require an end user commitment to acquire, accumulate and assess the information provided by the Coriolis meter. 3

4 5. Coriolis meter verification in an attested form ensures a qualified, audit safe assessment of device measuring quality. Verifications of this type may be used intermediate to proving and maintenance activities to assess Coriolis measurement performance. Acknowledgements The author wishes to thank TrueAnalytics for graphical representation of the condensate process used in this presentation. Nomenclature AHM = APM = ISO = NAMUR = Asset Health Monitoring Asset Performance Monitoring International Standards Organization "Interessengemeinschaft Automatisierungstechnik der Prozessindustrie" (Automation Systems Interest Group of the Process Industry). References 1. Flow Handbook, A Practical Guide: Measurement Technologies Applications Solutions page 137, 3 rd Edition, Endress+Hauser Flowtec-AG, 2006 (No ) 2. Achieving High Availability in Process Applications, Art Pietrzyk, Rockwell Automation, PROCES-WP004A-EN-P, January Merriam-Webster Definition of Verification, Definition of Attestation 4. ISO 9001:2008 Section 7.6 a, International Standards Organization 4

5 APPENDIX A: TECHNICAL REFERENCE Fig. 3 NAMUR NE 107 diagnostic event categories relate to fault severity levels and required user response Fig. 1 Coriolis force (Fc) in an oscillating system and resulting phase offset (Δφ) proportional to mass flow rate Fig. 4 Diagnostic status, secondary process and system parameters enable Asset Health and Performance Monitoring Fig. 5 Condensate process impacted from high water and gas carry under events in successive weeks of operation Fig. 2 Resonance frequency (fr) of Coriolis sensing tube vibration is a direct determinant of the fluid density (ρfl) 5

6 Fig. 6 Verification by a qualitative assessment of sensor system, electronics, signal processing and output IO 6